Olive fruit fly
Encyclopedia
The olive fruit fly is a species of fruit fly
which belongs to the Dacinae
subfamily (Diptera
Brachycera
Schizophora
Acalyptratae
Tephritidae
) MUNRO, 1984. It is a kind of phytophagous species, whose larva
e feed on the fruit of olive trees, hence the common name. It is considered the most serious pest in the cultivation of olives.
Until 1998, the fly had not been detected in the United States, and its range coincided with the range of the olive tree in the Eastern Hemisphere: northern, eastern and southern Africa, Southern Europe, Canary Islands, India, western Asia. In the Western Hemisphere, it is currently restricted to California.The olive fruit fly was first detected in North America infesting olive fruits on landscape trees in Los Angeles County in November 1998. It can now be found throughout the state. Its likely source of importation was from France.
The olive fruit fly received a bit of notoriety when an earmark for research designed to prevent infestation sponsored by Representative Mike Thompson
received public attention as alleged federal pork barrel
spending by persons who failed to understand its agricultural purpose.
and particularly, oil genus. It is found throughout the Mediterranean basin and in South Africa
. Since the late 1990s it has also been present in California
and has possibly spread throughout the area of olive cultivation in the Nearctic
region. It is considered the most serious pest towards olives in regions where it presides, significantly affecting both the amount and quality of production in most olive growing areas.
The impact of its attacks tend to worsen in the more humid and cooler growing areas, with significant variations depending on the variety grown, where it affects olive
cultivar
s and areas which have hot summers and less drought.
The larva
is Caecilian
and has a conical-cylindrical, narrow front. It develops through three stages (larva, 1st, 2nd and 3rd stage). The mature larva
is 6–7 mm long, white-yellowish colour, elongated, and sub-conical. The front sensors are bipolar and the second conic feature, the rear sensor, has 8 sensilla. The cephalo-pharyngeal skeleton has very short dorsal and ventral apodemes, the hypostomal scleritis
is triangular. It lacks a sub-hypostomal and the jaws are hooked. The oral lobes have 10-12 indents, preceded on each side by a sensory plate similar to the larva of the Ceratitis capitata. The frontal stigmas have 9-10 lobes. The three larval stages can be distinguished in different ways by its cephalo-pharyngeal structure. The different shapes of the frontal stigmas allow us to distinguish the larvae of 2nd and 3rd stages, while the larva at its first stage is metapneustic, equipped with one pair of posterior stigmas.
The pupa
stage takes place inside the pupate, an elliptical shell formed by the last exuvial transformation of the larva
. The pupate is 3.5 to 4.5 mm long, varying in colour from creamy white to yellow-brown, when it is dry. The change in colour of the pupate can determine the age of the pupae.
Adults are 4–5 mm long. In Italy
they are easily recognized in conjunction with other Tefritidae for the small dark spot at the apex of the wing and the length of the narrow, elongated anal cell.
The adult male has a hardened wing at the top of the anal cell, which is longer than the female's. The third urite shows the pectorals.
The adult female has a yellowish head with two strong circular spots under the antennas close to the compound eye, whilst the eyes are bluish-green. The chest can show various specks instead of the typical bands and lines. The mesonotum is bluish-gray with three blackish longitudinal lines. The humeral callus and areas mesopleurali metapleurali and mesoscutello are ivory. The wings are hyaline, with part of the pterostigma
with brown specks at the apex. The abdomen is light brown with variable colourings: typically there are pairs of blackish spots on the first to fourth urotergit, which often come together in bands. The ovipositor
is clearly visible, partly invaginated in the seventh urite which is always black. The length is 4–5 mm.
In the Asian variety (SILVESTRI), the whole body of the mesonotum is yellowish with strong, visible dark lines.
The egg hatching occurs over a variable period depending on weather conditions: from 2–3 days in summer, to about ten days in autumn. The newborn larva initially digs a tunnel on the surface, but later, moves deeper into the flesh to the core, which is not affected in any way. During larval development two changes occur which in turn increases the size of the larva.
Around the third change, larvae at their third stage move toward the surface and prepare the exit hole for the adult, gnawing at the flesh to leave a thin surface layer. During this phase, the olive clearly shows signs of the attack because its appears darker in conjunction with the tunneling. On the surface it is clear that there is a circular hole due to the remaining residual skin. The pupa remains dormant in the hollow below, protected within the pupates of the exuviae produced by the mature larva.
At maturity, the adult breaks the exuviae of the pupa and emerges from the pupate. It breaks the skin surface left by the larva by force and leaves the exit hole. In late autumn and winter its behaviour changes: the mature larva emerges from the olive and drops onto the ground where pupation takes place.
Adults are glycogenic and feed primarily on honeydew
. Since their basic diet
is low in protein
, they are particularly attracted to materials that emit volatile nitrogenous substances, such as bird droppings, for purposes of supplementing their protein requirements. This behavior is important because it can be used in programs for the fly's control and monitoring by using attractants such as hydrolysate proteins and ammonium salts.
and the state of the olives. Knowing these parameters, together with the monitoring of the population, is needed to implement effective pest management programs.
The climate influences the cycle especially with the temperature and less humidity. The duration of each stage is summarized below:
The duration of young larva therefore varies from a minimum of 20 days to a maximum of 5 months in the overwintering generation.
The temperature has an important role on the viability and rhythms of reproduction. Temperatures above 30 °C causes resorption of ovarian follicles by reducing the fecundity of females: a female lays 2-4 eggs on average per day in summer and 10-20 eggs in autumn. Persistent temperatures above 32 °C for several hours a day also cause mortality of over 80% of the eggs and larvae of that age.
Low temperatures therefore have a very limited effect because its activity is undermined by temperatures below 0 °C. Given ordinary climatic conditions it is clear that low temperatures and harsh winters interfere with population dynamics only in the northernmost areas of olive vegetation.
In general it is said that the optimum temperatures for oviposition and for larval development are between 20 °C and 30 °C, together with a need for humid weather.
The second controlling environmental factor is the obvious characteristics of the olives and the phenological stage of the plant. Females receive sensory stimuli that denote the degree of receptivity of the olive, a phenomenon that allows them to choose the olive: before oviposition, the female first “analyses” the size, colour and odour and, it seems, the presence of certain bacterial species. They are especially frequent in summer, caused by the females with a sterile puncture to test the receptivity of the olive. The ethology of the fly is something which has been paid particularly regarded in recent years when analysing study control methods based on the use of prior insect repellents (copper, kaolin, etc.).
Larval development is instead influenced by the consistency of the pulp and especially the size of drupe. In table olives, in fact, mortality of the larva is lower in summer because they can escape the lethal effects of high temperatures by migrating deeper. The consistency of the pulp is instead an intrinsic characteristic. Not even susceptibility of olive fruit fly attacks make much difference according to cultivar
.
The population size varies throughout the year, but there are two peaks: one in the middle of spring, at the development of the winter generation of adults. The second, more intense, occurs in early autumn when the olives are at the highest degree of receptivity, the temperatures drop slightly and the climate becomes wetter. In Sardinia
the larva population peaks typically occur during the months of April–May and September–October.
or agronomic factors should not be overlooked.
Ultimately the environmental conditions favorable to fly attacks are as follows:
Because of these factors, the incidence of olive fruit fly attacks increase, passing from the southern to northern areas, and coastal to inland regions. As for the season in general, the summer infestations are usually contained with the exception of cooler environment and more susceptible cultivars. On the other hand, there are infestation peaks from the months of September until cold weather arrives, especially with a rainy climate.
Another unique factor is the relationship between the alternation of production, a phenomenon in which the olive tree is particularly susceptible and the intensity of the attacks: The attacks are usually most intense in years of low production and high production. The cause of this behaviour is partly biological, partly agricultural.
In low seasons following a high one, there is usually a significant amount of olive residue on the plants from the previous year, so it has a higher population at its production peak in spring, and a higher reproductive potential occurring with more intense and earlier attacks. The attacked olives fall early in autumn and this causes a higher incidence of mortality during the winter.
In the subsequent good year for the population of first generation olives production is quite low, with modest reproductive potential. The attacks will therefore be later and help a mass-production.
From a quantitative point of view the damage is caused by larvae of second and especially third stages, by the removal of the significant proportion of the pulp which as a consequence results in reduction in the yielding of olives. Part of the production is also lost due to premature falling of the attacked fruit. In olive bites and holes dug by the larvae in the initial phase, they do not have a significant impact on the yield. In table olives, however, the damage extends to the sterile punctures which cause the variation in production.
A qualitative aspect to be considered is the significant deterioration in the quality of the oil extracted from olives with a high percentage of attacks by larvae of the third stage. The oil obtained from infected olives has a high acidity level (expressed as oleic acid
, from 2% to 10% depending on the percentage of the infestation) and a lower shelf life as it has a higher peroxide value
. Secondarily qualitative impairments of varying severity derive from the olive fruit fly attacks due to the arrival of mold
through the eclosions. This deterioration in quality is evident in significantly flawed oils obtained from olives harvested from the ground or stored for several days before pressing.
in Pisa
from 1872 to 1917, author of the famous monografo dell’olive. According to Caruso (chapter XV paragraph 14) he calls the insect Dacus olae (Fabr.), providing other scientific names proposed by different authors in dialect:
It follows a detailed description of all stages of the life cycle, focusing on the larvae and the damage caused by them.
The remedies suggested are empirical. Among the undoubted merits of Caruso is that he had suggested a designated control zone to farmers.
The treatments are carried out by spraying the olive trees with insecticides dimethoate
, deltamethrin
, and Phosmet
. The insecticide dimethoate is commonly used for its effectiveness and relatively low cost. It is also felt that this may be preferable because it would leave few residues in olive oil
since it is water soluble and would pass through the amurca
. In the near future, legislative authorization for the withdrawal of use of dimethoate is to be implemented. Among the products with low impact should be cited azadirachtin
, a natural repellent extracted from the fruits of the Neem tree. However, its effectiveness against the olive fruit fly has not yet been sufficiently tested. Among the organic insecticide literature rotenone
is also mentioned, however the use of this active ingredient, not readily available, must be authorized by established competent bodies after demonstrating the need for it.
The larvicidal treatment is carried out according to the criteria of the scheduled pest management, pest management and integrated pest management.
Scheduled pest management. It usually occurs with periodic preventive treatments from the period when the larvae appear during an average infestation (from mid-summer in areas with higher incidence or in September in areas with lower incidence). The treatment is repeated on average every 20 days (in the case of dimethoate) or at the interval of active use. The downside to the scheduled treatment is the risk of carrying out unnecessary treatments.
Pest management and integrated pest management. This is used if the problem exceeds the threshold. This can be estimated each week by noting the trend of the population of adults with the use of traps for monitoring or detecting the number of active infestation (bites and fertile mine of larvae I and II age). In order to be reliable the system first requires a suitable response in the trial, because the intervention thresholds vary depending on the type of trap and the environment. In northern Sardinia
, an intervention threshold - for cultivar
s of oil - was reliably evaluated, with a weekly catch of 10 adults per sticky trap in summer and 30 adults per trap in October. Further reliable information used is the sampling of olives to estimate the extent of infestation. In this case, the threshold for intervention of an active infestation is recommended between 10-15% on cultivar
s for oil production and 5% for table cultivars. Sampling is carried out weekly and taken randomly over a large area for an olive tree at head height. A sample is separated from samples of 100-200 olives, which are to detect the presence of live and uninfected eggs and larvae at first and second stages. The presence of eclosions, larvae and pupae third stage should not be counted because the damage has already occurred and the treatment would be worthless.
The preventive treatments are carried out by spraying the olive grove with poisoned protein baits. The point of this is that adults, being glycogenic, are attracted by nitrogenous substances necessary to supplement their low protein
diet. The substances used as bait for the flies are protein hydrolysates and are poisoned with organo-phosphate insecticides (usually dimethoate). The treatment should be carried out by spraying only part of the canopy of the trees, preferably the highest point nearest the sun. The intervention threshold for adulticide treatments are quite low (2-3 adults per trap per week). Recently the introduction of ready-made protein baits of spinosad
, a mixture of metabolites with insecticides of bacterial origin, are also authorized in organic farming.
Preventive treatments with baits have the advantage of requiring lower costs and have less environmental impact, also of preventing adults egg-laying and blocking the infestations directly. Generally they are applied to only 50% of the canopy of plants, preferably facing south, with a diameter of 50–60 cm, with limited use of water. The main problem is that they are not always effective. In general, the treatments with protein baits are effective in summer seasons in areas with low incidence, whilst from September–October there is usually no need for larvicide treatments.
Among the recent preventative measures acquired, together with the idea of pest management and integrated pest management, the treatment with copper-based pesticides has also been cited. It was found that copper
, although a pesticide
, exerts a repellent against flies, the females turn their attention instead to oviposition with olives that are not treated. The basis for this action would be the advance biocidal effect of copper against larvae of the symbiotic bacteria
, interfering with the physiology of the digestive system of the larva. These bacteria, which appear on the surface of plants and other materials, consist of adult females and transmit it to their offspring through the egg. This bacterial population would have a preferential attraction against flies, which can explain the repellent action. Repellent action would take place by kaolin also altering the perception of the colour of ripening by females. Overall, these measures should not be interpreted as solution methods, including on the basis of the information on the cases, as it is still limited. Nevertheless they are interesting because they are compatible with biological control and integrated pest management, which, therefore may play an priceless role in a strategy for integrated pest management.
, but in this case the biological measures showed a limited effectiveness, mainly because of difficulty reaching deep inside the larva.
Integrated pest management
is a more effective option as it uses the measures of nature by weathering (high summer temperatures) and natural enemies. Where appropriate, integrated pest management can be assisted with the release of parasitoids in late summer. The main criteria to be taken for the integrated pest management are:
The mass trapping has so far given results comparable to that of the chemical pest management test implemented with the protein bait and only if implemented on a large scale. It therefore pays for pest management programs in the area, while not offering excellent results if done at enterprise level, especially on limited foundations. In the 1970s, not yet having discovered the fly pheromone, mass trapping tests were carried out using yellow traps, but this technique, requiring the placement of at least 5 traps per plant, was discarded as uneconomic and a strong negative impact on useful entomofauna.
Until the 1990s the traps that have offered the best results were hand-crafted, made of wood soaked in a potent and long-lasting insecticide concentrate. Among the various insecticides the best results are obtained with deltamethrin
. These traps have been carried out, mass-trapping for over a decade with about 130,000 plants in Sardinia with results that are comparable to those obtained with the adulticide treatments using the protein bait. Since the late 1990s traps are commercially available on an industrial scale (Ecotrap) for the mass trapping of the olive fruit fly. The Ecotrap is triggered by using a form of double attraction: the pheromone of the olive fruit fly and the ammonium bicarbonate
, with biocidal action carried out by deltamethrin. Despite the limited series of tests carried out in recent years performed in some areas of the Mediterranean regions, the results are judged to be positive.
There are three types of attractants used in traps:
Currently, sticky traps are the most reliable way of monitoring, as the thresholds calibrated with the traps have been extensively tested, whilst threshold assessments are still uncertain with chemiotropic traps. These are best suited, however, for mass trapping by combining 2 or 3 attractants, preferably one sexual and one food-based.
Tephritidae
Tephritidae is one of two fly families referred to as "fruit flies", the other family being Drosophilidae. Tephritidae does not include the biological model organisms of the genus Drosophila , which is often called the "common fruit fly". There are nearly 5,000 described species of tephritid...
which belongs to the Dacinae
Dacinae
The Dacinae are a subfamily of the fruit fly family Tephritidae. Its 41 genera are distributed among three tribes:* Tribe Ceratitidini:* Capparimyia* Carpophthoromyia* Ceratitella* Ceratitis* Eumictoxenus* Neoceratitis...
subfamily (Diptera
Diptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
Brachycera
Brachycera
Brachycera is a suborder of Diptera. It is a major suborder consisting of around 120 families. The most distinguishing characteristic of the suborder is reduced antenna segmentation...
Schizophora
Schizophora
Schizophora is a section of true flies containing 78 families, which are collectively referred to as muscoids, even though - technically - the term "muscoid" should be limited to flies in the superfamily Muscoidea; this is an example of informal, historical usage persisting in the vernacular...
Acalyptratae
Acalyptratae
Acalyptratae is a subsection of Schizophora, commonly referred to as the acalyptrate muscoids . It is a very large assemblage, exhibiting very diverse habits, with one notable and perhaps surprising exception; there are no known acalyptrates that are obligate blood-feeders , though this is a life...
Tephritidae
Tephritidae
Tephritidae is one of two fly families referred to as "fruit flies", the other family being Drosophilidae. Tephritidae does not include the biological model organisms of the genus Drosophila , which is often called the "common fruit fly". There are nearly 5,000 described species of tephritid...
) MUNRO, 1984. It is a kind of phytophagous species, whose larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e feed on the fruit of olive trees, hence the common name. It is considered the most serious pest in the cultivation of olives.
Until 1998, the fly had not been detected in the United States, and its range coincided with the range of the olive tree in the Eastern Hemisphere: northern, eastern and southern Africa, Southern Europe, Canary Islands, India, western Asia. In the Western Hemisphere, it is currently restricted to California.The olive fruit fly was first detected in North America infesting olive fruits on landscape trees in Los Angeles County in November 1998. It can now be found throughout the state. Its likely source of importation was from France.
The olive fruit fly received a bit of notoriety when an earmark for research designed to prevent infestation sponsored by Representative Mike Thompson
Mike Thompson
Michael C. Thompson , is the U.S. Representative for , serving since 1999. He is a member of the Democratic Party. The district includes Napa, Lake, Mendocino, Humboldt and Del Norte Counties as well as parts of Yolo and Sonoma Counties....
received public attention as alleged federal pork barrel
Pork barrel
Pork barrel is a derogatory term referring to appropriation of government spending for localized projects secured solely or primarily to bring money to a representative's district...
spending by persons who failed to understand its agricultural purpose.
Distribution and importance
This species is associated with plants of the OleaOlea
Olea is a genus of about 40 species in the family Oleaceae, native to warm temperate and tropical regions of southern Europe, Africa, southern Asia and Australasia. They are evergreen trees and shrubs, with small, opposite, entire leaves...
and particularly, oil genus. It is found throughout the Mediterranean basin and in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. Since the late 1990s it has also been present in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and has possibly spread throughout the area of olive cultivation in the Nearctic
Nearctic
The Nearctic is one of the eight terrestrial ecozones dividing the Earth's land surface.The Nearctic ecozone covers most of North America, including Greenland and the highlands of Mexico...
region. It is considered the most serious pest towards olives in regions where it presides, significantly affecting both the amount and quality of production in most olive growing areas.
The impact of its attacks tend to worsen in the more humid and cooler growing areas, with significant variations depending on the variety grown, where it affects olive
Olive
The olive , Olea europaea), is a species of a small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean Basin as well as northern Iran at the south end of the Caspian Sea.Its fruit, also called the olive, is of major agricultural importance in the...
cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s and areas which have hot summers and less drought.
Morphology
The egg is around 0.7 to 1.2 mm long, elongated, and slightly flattened in its stomach with a small white microfleece nodule, which is important for the respiration of the embryo.The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
is Caecilian
Caecilian
The caecilians are an order of amphibians that superficially resemble earthworms or snakes. They mostly live hidden in the ground, making them the least familiar order of amphibians. All extant caecilians and their closest fossil relatives are grouped as the clade Apoda. They are mostly...
and has a conical-cylindrical, narrow front. It develops through three stages (larva, 1st, 2nd and 3rd stage). The mature larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
is 6–7 mm long, white-yellowish colour, elongated, and sub-conical. The front sensors are bipolar and the second conic feature, the rear sensor, has 8 sensilla. The cephalo-pharyngeal skeleton has very short dorsal and ventral apodemes, the hypostomal scleritis
Scleritis
Scleritis is a serious inflammatory disease that affects the white outer coating of the eye, known as the sclera. The disease is often contracted through association with other diseases of the body, such as Wegener's granulomatosis or rheumatoid arthritis; it can also be attained through disorders...
is triangular. It lacks a sub-hypostomal and the jaws are hooked. The oral lobes have 10-12 indents, preceded on each side by a sensory plate similar to the larva of the Ceratitis capitata. The frontal stigmas have 9-10 lobes. The three larval stages can be distinguished in different ways by its cephalo-pharyngeal structure. The different shapes of the frontal stigmas allow us to distinguish the larvae of 2nd and 3rd stages, while the larva at its first stage is metapneustic, equipped with one pair of posterior stigmas.
The pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
stage takes place inside the pupate, an elliptical shell formed by the last exuvial transformation of the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
. The pupate is 3.5 to 4.5 mm long, varying in colour from creamy white to yellow-brown, when it is dry. The change in colour of the pupate can determine the age of the pupae.
Adults are 4–5 mm long. In Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
they are easily recognized in conjunction with other Tefritidae for the small dark spot at the apex of the wing and the length of the narrow, elongated anal cell.
The adult male has a hardened wing at the top of the anal cell, which is longer than the female's. The third urite shows the pectorals.
The adult female has a yellowish head with two strong circular spots under the antennas close to the compound eye, whilst the eyes are bluish-green. The chest can show various specks instead of the typical bands and lines. The mesonotum is bluish-gray with three blackish longitudinal lines. The humeral callus and areas mesopleurali metapleurali and mesoscutello are ivory. The wings are hyaline, with part of the pterostigma
Pterostigma
The pterostigma is a cell in the outer wing of insects which is often thickened or coloured and so stands out from other cells. It is particularly noticeable in dragonflies, but present also in other insect groups, such as snakeflies, hymenopterans and megalopterans.The purpose of the pterostigma,...
with brown specks at the apex. The abdomen is light brown with variable colourings: typically there are pairs of blackish spots on the first to fourth urotergit, which often come together in bands. The ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
is clearly visible, partly invaginated in the seventh urite which is always black. The length is 4–5 mm.
In the Asian variety (SILVESTRI), the whole body of the mesonotum is yellowish with strong, visible dark lines.
Cycle
The females lay their eggs in the summer when the olive is at least 7-8mm in diameter. The egg laying is done by making a puncture with the ovipositor into the skin of the olive, leaving only one egg in the hollow below. The bite has a characteristic triangular shape due to an optical effect. A puncture has a dark green colour, whilst older bites have a yellowish-brown colour as a result of wound healing.The egg hatching occurs over a variable period depending on weather conditions: from 2–3 days in summer, to about ten days in autumn. The newborn larva initially digs a tunnel on the surface, but later, moves deeper into the flesh to the core, which is not affected in any way. During larval development two changes occur which in turn increases the size of the larva.
Around the third change, larvae at their third stage move toward the surface and prepare the exit hole for the adult, gnawing at the flesh to leave a thin surface layer. During this phase, the olive clearly shows signs of the attack because its appears darker in conjunction with the tunneling. On the surface it is clear that there is a circular hole due to the remaining residual skin. The pupa remains dormant in the hollow below, protected within the pupates of the exuviae produced by the mature larva.
At maturity, the adult breaks the exuviae of the pupa and emerges from the pupate. It breaks the skin surface left by the larva by force and leaves the exit hole. In late autumn and winter its behaviour changes: the mature larva emerges from the olive and drops onto the ground where pupation takes place.
Adults are glycogenic and feed primarily on honeydew
Honeydew
Honeydew may refer to:* Honeydew , a cultivar group of melon* Honeydew , a sugar-rich sticky substance secreted by aphids and some scale insects* Honeydew, California, a town* Bunsen Honeydew, a fictional character from The Muppet Show...
. Since their basic diet
Diet (nutrition)
In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...
is low in protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, they are particularly attracted to materials that emit volatile nitrogenous substances, such as bird droppings, for purposes of supplementing their protein requirements. This behavior is important because it can be used in programs for the fly's control and monitoring by using attractants such as hydrolysate proteins and ammonium salts.
Environmental needs
The development cycle is closely linked to environmental conditions, in particular the climateClimate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
and the state of the olives. Knowing these parameters, together with the monitoring of the population, is needed to implement effective pest management programs.
The climate influences the cycle especially with the temperature and less humidity. The duration of each stage is summarized below:
| State | Summer | Autumn-Winter |
|---|---|---|
| Egg | 2–3 days | 10 days (autumn) |
| Larva | 10–13 days | 20 days or more |
| Pupa | 10 days | up to 4 months (hibernating pupas) |
| Adults | several months | |
The duration of young larva therefore varies from a minimum of 20 days to a maximum of 5 months in the overwintering generation.
The temperature has an important role on the viability and rhythms of reproduction. Temperatures above 30 °C causes resorption of ovarian follicles by reducing the fecundity of females: a female lays 2-4 eggs on average per day in summer and 10-20 eggs in autumn. Persistent temperatures above 32 °C for several hours a day also cause mortality of over 80% of the eggs and larvae of that age.
Low temperatures therefore have a very limited effect because its activity is undermined by temperatures below 0 °C. Given ordinary climatic conditions it is clear that low temperatures and harsh winters interfere with population dynamics only in the northernmost areas of olive vegetation.
In general it is said that the optimum temperatures for oviposition and for larval development are between 20 °C and 30 °C, together with a need for humid weather.
The second controlling environmental factor is the obvious characteristics of the olives and the phenological stage of the plant. Females receive sensory stimuli that denote the degree of receptivity of the olive, a phenomenon that allows them to choose the olive: before oviposition, the female first “analyses” the size, colour and odour and, it seems, the presence of certain bacterial species. They are especially frequent in summer, caused by the females with a sterile puncture to test the receptivity of the olive. The ethology of the fly is something which has been paid particularly regarded in recent years when analysing study control methods based on the use of prior insect repellents (copper, kaolin, etc.).
Larval development is instead influenced by the consistency of the pulp and especially the size of drupe. In table olives, in fact, mortality of the larva is lower in summer because they can escape the lethal effects of high temperatures by migrating deeper. The consistency of the pulp is instead an intrinsic characteristic. Not even susceptibility of olive fruit fly attacks make much difference according to cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
.
Population dynamics
Unlike other species, the succession of generations of the Bactrocera oleae is not markedly different for the scaling of ovipositioning and longevity of adults. Within a year, there are generally 3 to 5 generations, but in many years there can be a sixth generation, which grows in the spring on the olive tree but does not remain on the tree.The population size varies throughout the year, but there are two peaks: one in the middle of spring, at the development of the winter generation of adults. The second, more intense, occurs in early autumn when the olives are at the highest degree of receptivity, the temperatures drop slightly and the climate becomes wetter. In Sardinia
Sardinia
Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...
the larva population peaks typically occur during the months of April–May and September–October.
Predisposing factors
The predisposition to the fly's attacks is tied to several factors, both intrinsic and extrinsic. The main ones are climatic (temperature and rainfall), so there can be marked differences from year to year. However, other geneticGenetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
or agronomic factors should not be overlooked.
Ultimately the environmental conditions favorable to fly attacks are as follows:
- Conditions of moderate heat, with temperatures not exceeding 32-34 °C
- A humid climate.
- Premature cultivation.
- Mass or dual purpose cultivation.
- Cultivation under irrigation
Because of these factors, the incidence of olive fruit fly attacks increase, passing from the southern to northern areas, and coastal to inland regions. As for the season in general, the summer infestations are usually contained with the exception of cooler environment and more susceptible cultivars. On the other hand, there are infestation peaks from the months of September until cold weather arrives, especially with a rainy climate.
Another unique factor is the relationship between the alternation of production, a phenomenon in which the olive tree is particularly susceptible and the intensity of the attacks: The attacks are usually most intense in years of low production and high production. The cause of this behaviour is partly biological, partly agricultural.
In low seasons following a high one, there is usually a significant amount of olive residue on the plants from the previous year, so it has a higher population at its production peak in spring, and a higher reproductive potential occurring with more intense and earlier attacks. The attacked olives fall early in autumn and this causes a higher incidence of mortality during the winter.
In the subsequent good year for the population of first generation olives production is quite low, with modest reproductive potential. The attacks will therefore be later and help a mass-production.
Damages
The damages caused by the olive fruit fly are of two types: quantitative and qualitative.From a quantitative point of view the damage is caused by larvae of second and especially third stages, by the removal of the significant proportion of the pulp which as a consequence results in reduction in the yielding of olives. Part of the production is also lost due to premature falling of the attacked fruit. In olive bites and holes dug by the larvae in the initial phase, they do not have a significant impact on the yield. In table olives, however, the damage extends to the sterile punctures which cause the variation in production.
A qualitative aspect to be considered is the significant deterioration in the quality of the oil extracted from olives with a high percentage of attacks by larvae of the third stage. The oil obtained from infected olives has a high acidity level (expressed as oleic acid
Oleic acid
Oleic acid is a monounsaturated omega-9 fatty acid found in various animal and vegetable fats. It has the formula CH37CH=CH7COOH. It is an odorless, colourless oil, although commercial samples may be yellowish. The trans isomer of oleic acid is called elaidic acid...
, from 2% to 10% depending on the percentage of the infestation) and a lower shelf life as it has a higher peroxide value
Peroxide value
The peroxide value of an oil or fat is used as a measurement of the extent to which rancidity reactions have occurred during storage. Other methods are available but peroxide value is the most widely used....
. Secondarily qualitative impairments of varying severity derive from the olive fruit fly attacks due to the arrival of mold
Mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
through the eclosions. This deterioration in quality is evident in significantly flawed oils obtained from olives harvested from the ground or stored for several days before pressing.
Auxiliaries antagonised by the olive fruit fly
There are few natural enemies of the olive fruit fly, but they can play a significant role in containing populations in biological and integrated pest control. However, it was found that these biological factors by themselves cannot counterweigh the economic effects they cause, in particular due to the reproductive differences between flies and antagonists: in fact they can manage the attacks of the olive fruit fly when its population is contained, but less so in the case of heavy infestations. The enemies of the fly that play a significant role are mostly parasitoids.- HymenopteraHymenopteraHymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
Ichneumonoidea- Opius concolor (BraconidaeBraconidaeBraconidae is a family of parasitoid wasps and one of the richest families of insects. Between 50,000 and 150,000 species exist worldwide. The species are grouped into about 45 subfamilies and 1,000 genera, some important ones being: Ademon, Aphanta, Asobara, Bracon hebetor, Cenocoelius, Chaenusa,...
). It is a endoparasite of various Diptera Tefritidi including B. oleae. Naturally found in the African continent, after its discovery in 1910 it was introduced in many other regions, however, it is difficult to acclimate in the Italian regions, except, perhaps, Sicily. It is used as a replacement of the larvae Ceratitis capitataCeratitis capitataCeratitis capitata, the Mediterranean fruit fly, or medfly for short, is a species of fruit fly capable of causing extensive damage to a wide range of fruit crops...
(Mediterranean fruit fly).
- Opius concolor (Braconidae
- HymenopteraHymenopteraHymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
Chalcidoidea- Pnigalio mediterraneus (EulophidaeEulophidaeEulophidae is a large family of hymenopteran insects, with over 4,300 described species in some 300 genera . The family as presently defined also includes the genus Elasmus, which was previously treated as a separate family, "Elasmidae", and is now treated as a subfamily of Eulophidae...
). It is one of the most active of the ectoparasitic larvae of B. oleae. Although polyphagous, its summer generations are usually associated with the fly. - Eupelmus urozonus (EupelmidaeEupelmidaeEupelmidae is a family of parasitic wasps in the superfamily Chalcidoidea. The group is apparently polyphyletic, though the different subfamilies may each be monophyletic, and may be elevated to family status in the near future. As presently defined, there are over 905 described species in 45 genera...
). It is another polyphagous ectoparasite associated with olives and has 2-3 summer generations associated with the B. Oleae larva. Come autumn it moves to another Tefritide associated with the DittrichiaDittrichiaDittrichia is a genus of flowering plants in the daisy family. It was formed relatively recently by splitting genus Inula.-Species:This genus contains two species:*Dittrichia graveolens, stinkwort, sticky stinkweed...
. It can be used as a replacement of the fruit fly. It has a definite activity as a hyperparasiteHyperparasiteA hyperparasite is a parasite whose host is a parasite. This form of parasitism is especially common among entomophagous parasites....
against other parasitoids of the fly. - Eurytoma martellii (EurytomidaeEurytomidaeEurytomidae is a family within the superfamily Chalcidoidea. The group is apparently polyphyletic, though the different subfamilies may each be monophyletic, and may be elevated to family status in the near future...
). It is an ectoparasite of the B. Oleae larvae, of which not much information on the biology is known. In local contexts it can become the most common antagonist of the fly. - Cyrtoptyx latipes (PteromalidaePteromalidaePteromalidae is a very large family of parasitic wasps, with some 3,450 described species in some 640 genera...
). It is an ectoparasite of the B. Oleae larvae. It is an antagonist of minor importance as it is rare.
- Pnigalio mediterraneus (Eulophidae
- DipteraDipteraDiptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
- Lasioptera berlesiana (CecidomyiidaeCecidomyiidaeCecidomyiidae is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls.These are very fragile small insects usually only 2–3 mm in length and many are less than...
). Oofago is a predator of several insects, including B. oleae. This species contributes in no small way to containing the first summer infestations.
- Lasioptera berlesiana (Cecidomyiidae
Background on combating the fruit fly
One of the first authors who takes time to describe the damage caused by the “olive fruit fly” is Girolamo Caruso, dean of the facultyFaculty (university)
A faculty is a division within a university comprising one subject area, or a number of related subject areas...
in Pisa
Pisa
Pisa is a city in Tuscany, Central Italy, on the right bank of the mouth of the River Arno on the Tyrrhenian Sea. It is the capital city of the Province of Pisa...
from 1872 to 1917, author of the famous monografo dell’olive. According to Caruso (chapter XV paragraph 14) he calls the insect Dacus olae (Fabr.), providing other scientific names proposed by different authors in dialect:
- Musca oleae (Rossi, Lin., Gmelin, Fabr., Petagna, Olivier)
- Tephritis olea (Latr., Risso)
- Chiron, keirun, mouche de l'olive, the olive de ver, in Southern France
- Olive fly, olive fruit fly, worm, olives, olive bug, pidocchina in various Italian regions.
It follows a detailed description of all stages of the life cycle, focusing on the larvae and the damage caused by them.
The remedies suggested are empirical. Among the undoubted merits of Caruso is that he had suggested a designated control zone to farmers.
Chemical pest management
The chemical battle against the olive fruit fly can be implemented against larvae by using preventive treatments against adults.The treatments are carried out by spraying the olive trees with insecticides dimethoate
Dimethoate
Dimethoate is a widely used organophosphate insecticide used to kill insects on contact. It was patented and introduced in the 1950s by American Cyanamid. Like other organophosphates, dimethoate is an anticholinesterase which disables cholinesterase, an enzyme essential for central nervous system...
, deltamethrin
Deltamethrin
Deltamethrin is a pyrethroid ester insecticide.-Usage:Deltamethrin products are among the most popular and widely used insecticides in the world and have become very popular with pest control operators and individuals in the United States in the past five years. This material is a member of one of...
, and Phosmet
Phosmet
Phosmet is a phthalimide-derived, non-systemic, organophosphate insecticide used on plants and animals. It is mainly used on apple trees for control of coddling moth, though it is also used on a wide range of fruit crops, ornamentals, and vines for the control of aphids, suckers, mites, and fruit...
. The insecticide dimethoate is commonly used for its effectiveness and relatively low cost. It is also felt that this may be preferable because it would leave few residues in olive oil
Olive oil
Olive oil is an oil obtained from the olive , a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps...
since it is water soluble and would pass through the amurca
Amurca
Amurca is the bitter tasting, dark watery liquid which flows from pressed olives under light pressure, prior to the olive oil which only drains under greater pressure. Historically, amurca was used for numerous purposes, including as a building material, pesticide, herbicide, and even as an...
. In the near future, legislative authorization for the withdrawal of use of dimethoate is to be implemented. Among the products with low impact should be cited azadirachtin
Azadirachtin
Azadirachtin, a chemical compound belonging to the limonoid group, is a secondary metabolite present in neem seeds. It is a highly oxidized tetranortriterpenoid which boasts a plethora of oxygen functionality, comprising an enol ether, acetal, hemiacetal, and tetra-substituted oxirane as well as a...
, a natural repellent extracted from the fruits of the Neem tree. However, its effectiveness against the olive fruit fly has not yet been sufficiently tested. Among the organic insecticide literature rotenone
Rotenone
Rotenone is an odorless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant...
is also mentioned, however the use of this active ingredient, not readily available, must be authorized by established competent bodies after demonstrating the need for it.
The larvicidal treatment is carried out according to the criteria of the scheduled pest management, pest management and integrated pest management.
Scheduled pest management. It usually occurs with periodic preventive treatments from the period when the larvae appear during an average infestation (from mid-summer in areas with higher incidence or in September in areas with lower incidence). The treatment is repeated on average every 20 days (in the case of dimethoate) or at the interval of active use. The downside to the scheduled treatment is the risk of carrying out unnecessary treatments.
Pest management and integrated pest management. This is used if the problem exceeds the threshold. This can be estimated each week by noting the trend of the population of adults with the use of traps for monitoring or detecting the number of active infestation (bites and fertile mine of larvae I and II age). In order to be reliable the system first requires a suitable response in the trial, because the intervention thresholds vary depending on the type of trap and the environment. In northern Sardinia
Sardinia
Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...
, an intervention threshold - for cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s of oil - was reliably evaluated, with a weekly catch of 10 adults per sticky trap in summer and 30 adults per trap in October. Further reliable information used is the sampling of olives to estimate the extent of infestation. In this case, the threshold for intervention of an active infestation is recommended between 10-15% on cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s for oil production and 5% for table cultivars. Sampling is carried out weekly and taken randomly over a large area for an olive tree at head height. A sample is separated from samples of 100-200 olives, which are to detect the presence of live and uninfected eggs and larvae at first and second stages. The presence of eclosions, larvae and pupae third stage should not be counted because the damage has already occurred and the treatment would be worthless.
The preventive treatments are carried out by spraying the olive grove with poisoned protein baits. The point of this is that adults, being glycogenic, are attracted by nitrogenous substances necessary to supplement their low protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
diet. The substances used as bait for the flies are protein hydrolysates and are poisoned with organo-phosphate insecticides (usually dimethoate). The treatment should be carried out by spraying only part of the canopy of the trees, preferably the highest point nearest the sun. The intervention threshold for adulticide treatments are quite low (2-3 adults per trap per week). Recently the introduction of ready-made protein baits of spinosad
Spinosad
Spinosad is a new chemical class of insecticides that are registered by the United States Environmental Protection Agency to control a variety of insects...
, a mixture of metabolites with insecticides of bacterial origin, are also authorized in organic farming.
Preventive treatments with baits have the advantage of requiring lower costs and have less environmental impact, also of preventing adults egg-laying and blocking the infestations directly. Generally they are applied to only 50% of the canopy of plants, preferably facing south, with a diameter of 50–60 cm, with limited use of water. The main problem is that they are not always effective. In general, the treatments with protein baits are effective in summer seasons in areas with low incidence, whilst from September–October there is usually no need for larvicide treatments.
Among the recent preventative measures acquired, together with the idea of pest management and integrated pest management, the treatment with copper-based pesticides has also been cited. It was found that copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, although a pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
, exerts a repellent against flies, the females turn their attention instead to oviposition with olives that are not treated. The basis for this action would be the advance biocidal effect of copper against larvae of the symbiotic bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, interfering with the physiology of the digestive system of the larva. These bacteria, which appear on the surface of plants and other materials, consist of adult females and transmit it to their offspring through the egg. This bacterial population would have a preferential attraction against flies, which can explain the repellent action. Repellent action would take place by kaolin also altering the perception of the colour of ripening by females. Overall, these measures should not be interpreted as solution methods, including on the basis of the information on the cases, as it is still limited. Nevertheless they are interesting because they are compatible with biological control and integrated pest management, which, therefore may play an priceless role in a strategy for integrated pest management.
Biological and integrated pest management control
Biological pest management control, carried out so far with experiments on the Opius concolor, for now, offers only partial results and in any case is particularly costly. Biological pest management control have recently been carried out on Bacillus thuringiensisBacillus thuringiensis
Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. B...
, but in this case the biological measures showed a limited effectiveness, mainly because of difficulty reaching deep inside the larva.
Integrated pest management
Integrated Pest Management
Integrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...
is a more effective option as it uses the measures of nature by weathering (high summer temperatures) and natural enemies. Where appropriate, integrated pest management can be assisted with the release of parasitoids in late summer. The main criteria to be taken for the integrated pest management are:
- Choosing less susceptible cultivars.
- Advance of collections, particularly for susceptible cultivars.
- Use of insecticides with low environmental impact. In particular, wisely-used insecticides used for larvicide treatments should be excluded because they are harmful to useful insect fauna.
- Chemical treatment to be made only upon exceeding the intervention threshold.
- Preventive treatment with poisoned protein baits.
- Preventive treatments and repellents with copper-based products (Bordeaux mixture, copper hydroxide, copper oxychloride).
- Removal of entire production to prevent outbreaks of infestation in the spring.
- Monitoring of climatic conditions.
- Use of biotechnical pest management control methods.
Biotechnical pest management
Biotechnical pest management is currently mostly practiced on experimental or pilot farms or as an adjunct to the use of integrated pest traps, according to the function. It can be divided into two types:- Monitoring traps (trap-test) are used to detect the trends of the population of adults in order to estimate the thresholdThreshold-Film and television:* Threshold * Threshold , an adaptation of the 1958 science fiction film It! The Terror from Beyond Space* Threshold , an American science fiction drama series...
. Their density depends on the type of trap used and how it is used. The traps are strewn with a sticky entomological plastic substance. - Traps for mass trapping (trap mass) are used to capture adults in mass in order to remove the population to levels that keep infestations below the thresholdThreshold-Film and television:* Threshold * Threshold , an adaptation of the 1958 science fiction film It! The Terror from Beyond Space* Threshold , an American science fiction drama series...
. Their density must be high (one trap per plant with a sexual attraction and/or food).
The mass trapping has so far given results comparable to that of the chemical pest management test implemented with the protein bait and only if implemented on a large scale. It therefore pays for pest management programs in the area, while not offering excellent results if done at enterprise level, especially on limited foundations. In the 1970s, not yet having discovered the fly pheromone, mass trapping tests were carried out using yellow traps, but this technique, requiring the placement of at least 5 traps per plant, was discarded as uneconomic and a strong negative impact on useful entomofauna.
Until the 1990s the traps that have offered the best results were hand-crafted, made of wood soaked in a potent and long-lasting insecticide concentrate. Among the various insecticides the best results are obtained with deltamethrin
Deltamethrin
Deltamethrin is a pyrethroid ester insecticide.-Usage:Deltamethrin products are among the most popular and widely used insecticides in the world and have become very popular with pest control operators and individuals in the United States in the past five years. This material is a member of one of...
. These traps have been carried out, mass-trapping for over a decade with about 130,000 plants in Sardinia with results that are comparable to those obtained with the adulticide treatments using the protein bait. Since the late 1990s traps are commercially available on an industrial scale (Ecotrap) for the mass trapping of the olive fruit fly. The Ecotrap is triggered by using a form of double attraction: the pheromone of the olive fruit fly and the ammonium bicarbonate
Ammonium bicarbonate
Ammonium bicarbonate, a compound with formulaNH4, also called bicarbonate of ammonia, ammonium hydrogen carbonate, hartshorn, AmBic or powdered baking ammonia, is the bicarbonate salt of ammonia....
, with biocidal action carried out by deltamethrin. Despite the limited series of tests carried out in recent years performed in some areas of the Mediterranean regions, the results are judged to be positive.
There are three types of attractants used in traps:
- Colour. Attractiveness used in sticky traps. The adult olive fruit fly is attracted to the colour yellow. Since the yellow colour is not available, these traps can only be used for monitoring purposes.
- Pheromones. Synthetic pheromone (1,7-dioxaspire-5,5-undecane), is a reproduction of the main component of the natural sex pheromone emitted by the female to attract the male. Because of its selectivity, it is ideal for mass trapping, but the traps baited with the pheromone only show results that are not very effective: the pheromone of the olive fruit fly is in fact very volatile and 3–4 weeks after the maximum capacity is substantially less effective. Until the 1990s, the devices used for the provision in the gradual release of the pheromone proved unsuitable and it was necessary to replace them every 30–40 days.
- Food attractants. They are volatile nitrogenous substances that attract the flies to search for protein supplements to their diet. Protein hydrolysates and ammonium salts may be used as attractants. The disadvantage of these are that their function is affected by atmospheric conditions (temperature and relative humidity). The best results are achieved by combining a protein hydrolyzed with an ammonium salt in the same trap, or a combination of an attractive food with the pheromone.
Currently, sticky traps are the most reliable way of monitoring, as the thresholds calibrated with the traps have been extensively tested, whilst threshold assessments are still uncertain with chemiotropic traps. These are best suited, however, for mass trapping by combining 2 or 3 attractants, preferably one sexual and one food-based.
External links
- OliveOilSource U.S.A. Site.
- olive fruit fly on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
Featured Creatures Web site - http://afidol.org/tracoliv/records/accueilInternaute Online map net trapping updated in real time in France.