Maize weevil
Encyclopedia
The maize weevil known in the United States
as the greater rice weevil, is a species of beetle
in the family Curculionidae
. It can be found in numerous tropical areas around the world, and in the United States, and is a major pest of maize
. This species attacks both standing crops and stored cereal products, including wheat
, rice
, sorghum
, oats
, barley
, rye
, buckwheat
, peas
, and cottonseed. The maize weevil also infests other types of stored, processed cereal
products such as pasta, cassava
, and various coarse, milled grains. It has even been known to attack fruit while in storage, such as apples.
, the maize weevil has a length of 2.5 mm to 4 mm. This small, brown weevil has four reddish-brown spots on the wing covers (elytra). It has a long, thin snout, and elbowed antennae
. Sitophilus zeamais appears similar to the rice weevil
(Sitophilus oryzae), but has more clearly marked spots on the wing covers, and is somewhat larger. It is able to fly.
Although the maize weevil and rice weevil do look alike, and are easily confused with one another, there are several distinguishing features:
grown, including: Polynesia
, Argentina
, Brazil
, Burma, Cambodia
, Greece
, Japan
, Morocco
, Spain
,
Syria
, Turkey
, United States
, USSR, and Yugoslavia
. It is also widely distributed throughout agricultural areas of northern Australia
. This species has also been recorded Canada
, in the provinces of Ontario
and Quebec
, and has been intercepted at ports, but is not well established there. It has, however, been present for several years in Montreal
, where grain from the U.S. is stored.
is removed, with a waxy secretion that creates a plug. The plug quickly hardens, and leaves a small raised area on the seed surface. This provides the only visible evidence that the kernel is infested. Only one egg is laid on inside each grain. When the egg hatches into a white, legless grub, it will remain inside and begin feeding on the grain. The larvae
will pupa
te while inside, then chew a circular exit hole, and emerge as an adult beetle. A single female may lay 300 to 400 eggs during her lifetime. Adults can live for 5 to 8 to eight months. Breeding conditions require temperatures between 15 and 34° C and 40% relative humidity.
When the adults emerge, the females move to a high surface and release sex pheromones. Males are then attracted to this pheromone.
, oats
, barley
, sorghum
, rye
and buckwheat
. It can breed in crops with a moisture content of a much wider range than S. oryzae, and has been found in fruit, such as apples during storage. Although the maize weevil cannot readily breed in finely processed grains, it can easily breed in products such as macaroni and noodles, and milled cereals that have been exposed to excessive moisture.
is evident. Infested grains contain holes through which adults have emerged. A possible indication of infestation is grain, when placed in water, floating to the surface. Ragged holes in individual grains, similar to damage caused by the rice weevil and granary
weevil, may indicate infestation. In large stores of grain, an increase in temperature may be detected. The most obvious sign of infestation is the emergence of adults. One study recorded, 5 weeks after infestation, the emergence of 100 adults per kg per day.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
as the greater rice weevil, is a species of beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
in the family Curculionidae
Curculionidae
Curculionidae is the family of the "true" weevils . It was formerly recognized in 1998 as the largest of any animal family, with over 40,000 species described worldwide at that time...
. It can be found in numerous tropical areas around the world, and in the United States, and is a major pest of maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
. This species attacks both standing crops and stored cereal products, including wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
, rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
, sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...
, oats
OATS
OATS - Open Source Assistive Technology Software - is a source code repository or "forge" for assistive technology software. It was launched in 2006 with the goal to provide a one-stop “shop” for end users, clinicians and open-source developers to promote and develop open source assistive...
, barley
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...
, rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
, buckwheat
Buckwheat
Buckwheat refers to a variety of plants in the dicot family Polygonaceae: the Eurasian genus Fagopyrum, the North American genus Eriogonum, and the Northern Hemisphere genus Fallopia. Either of the latter two may be referred to as "wild buckwheat"...
, peas
PEAS
P.E.A.S. is an acronym in artificial intelligence that stands for Performance, Environment, Actuators, Sensors.-Performance:Performance is a function that measures the quality of the actions the agent did....
, and cottonseed. The maize weevil also infests other types of stored, processed cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
products such as pasta, cassava
Cassava
Cassava , also called yuca or manioc, a woody shrub of the Euphorbiaceae native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...
, and various coarse, milled grains. It has even been known to attack fruit while in storage, such as apples.
Description
A close relative of the rice weevilRice weevil
The rice weevil is a serious stored product pest which attacks several economically important crops, including wheat, rice, and maize.- Description :...
, the maize weevil has a length of 2.5 mm to 4 mm. This small, brown weevil has four reddish-brown spots on the wing covers (elytra). It has a long, thin snout, and elbowed antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
. Sitophilus zeamais appears similar to the rice weevil
Rice weevil
The rice weevil is a serious stored product pest which attacks several economically important crops, including wheat, rice, and maize.- Description :...
(Sitophilus oryzae), but has more clearly marked spots on the wing covers, and is somewhat larger. It is able to fly.
Although the maize weevil and rice weevil do look alike, and are easily confused with one another, there are several distinguishing features:
| Maize weevil (S. zeamais) | Rice weevil (S. oryzae) |
|---|---|
| Circular punctures on pronotal dorsum | Longitudinally elliptical punctures on pronotal dorsum |
| Pronotal punctures have no median puncture-free area and are nearly equally spaced apart | Pronotal punctures are separated by a flat, median, longitudinal puncture-free zone |
| More than 20 pronotal punctures along the approximate midline, running from neck to scutellum | Less than 20 pronotal punctures along the approximate midline, running from neck to scutellum |
| Scutellar elevations relatively farther apart compared to their longitudinal length | Scutellar elevations relatively closer together compare to their longitudinal length |
| Scutellar elevations extend longitudinally approximately halfway down the scutellum | Scutellar elevations extend longitudinally approximately more than halfway down the scutellum |
| Proepimera meets behind the fore coxae and has a barely discernable notch along the posterior edge at the site of the meeting point |
Proepimera meets behind the fore coxae and along the posterior edge, has a distinct curved notch |
| Aedeagus has two dorsal, longitudinal grooves | Aedeagus (in males) is smooth and shiny on the dorsal surface |
Distribution
S. zeamais occurs throughout warm, humid regions around the world, especially in locations where maize isgrown, including: Polynesia
Polynesia
Polynesia is a subregion of Oceania, made up of over 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are termed Polynesians and they share many similar traits including language, culture and beliefs...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Burma, Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
, Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
,
Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
, Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, USSR, and Yugoslavia
Yugoslavia
Yugoslavia refers to three political entities that existed successively on the western part of the Balkans during most of the 20th century....
. It is also widely distributed throughout agricultural areas of northern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. This species has also been recorded Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, in the provinces of Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
and Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
, and has been intercepted at ports, but is not well established there. It has, however, been present for several years in Montreal
Montreal
Montreal is a city in Canada. It is the largest city in the province of Quebec, the second-largest city in Canada and the seventh largest in North America...
, where grain from the U.S. is stored.
Life cycle
The complete development time for the life cycle of this species averages 36 days. The female chews through the surface of the grain, creating a hole. She then deposits a small oval white egg, and covers the hole as the ovipositorOvipositor
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 removed, with a waxy secretion that creates a plug. The plug quickly hardens, and leaves a small raised area on the seed surface. This provides the only visible evidence that the kernel is infested. Only one egg is laid on inside each grain. When the egg hatches into a white, legless grub, it will remain inside and begin feeding on the grain. The larvae
Larvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
will 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...
te while inside, then chew a circular exit hole, and emerge as an adult beetle. A single female may lay 300 to 400 eggs during her lifetime. Adults can live for 5 to 8 to eight months. Breeding conditions require temperatures between 15 and 34° C and 40% relative humidity.
When the adults emerge, the females move to a high surface and release sex pheromones. Males are then attracted to this pheromone.
Host range
The maize weevil commonly attacks standing crops, in particular, maize before harvest, and is also commonly associated with rice. It infests raw or processed cereals such as wheatWheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
, oats
OATS
OATS - Open Source Assistive Technology Software - is a source code repository or "forge" for assistive technology software. It was launched in 2006 with the goal to provide a one-stop “shop” for end users, clinicians and open-source developers to promote and develop open source assistive...
, barley
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...
, sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...
, rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
and buckwheat
Buckwheat
Buckwheat refers to a variety of plants in the dicot family Polygonaceae: the Eurasian genus Fagopyrum, the North American genus Eriogonum, and the Northern Hemisphere genus Fallopia. Either of the latter two may be referred to as "wild buckwheat"...
. It can breed in crops with a moisture content of a much wider range than S. oryzae, and has been found in fruit, such as apples during storage. Although the maize weevil cannot readily breed in finely processed grains, it can easily breed in products such as macaroni and noodles, and milled cereals that have been exposed to excessive moisture.
Damage and detection
Early detection of infestation is difficult. As S. zeamais larvae feed on the interior of individual grains, often leaving only the hulls, a flour-like grain dust, mixed with frassFrass
Frass is the fine powdery material phytophagous insects pass as waste after digesting plant parts. It causes plants to excrete chitinase due to high chitin levels, it is a natural bloom stimulant, and has high nutrient levels. Frass is known to have abundant amoeba, beneficial bacteria, and fungi...
is evident. Infested grains contain holes through which adults have emerged. A possible indication of infestation is grain, when placed in water, floating to the surface. Ragged holes in individual grains, similar to damage caused by the rice weevil and granary
Granary
A granary is a storehouse for threshed grain or animal feed. In ancient or primitive granaries, pottery is the most common use of storage in these buildings. Granaries are often built above the ground to keep the stored food away from mice and other animals.-Early origins:From ancient times grain...
weevil, may indicate infestation. In large stores of grain, an increase in temperature may be detected. The most obvious sign of infestation is the emergence of adults. One study recorded, 5 weeks after infestation, the emergence of 100 adults per kg per day.
Control
Instead of calling Pest Control for weevil problems in your kitchen, put the 'problem' food (such has pasta, flour, cereal) into the freezer for 24 hours. This will kill the weevils and hopefully eliminate any further weevil problems in your kitchen. The weevils originally come into the household in packaged food and gradually spread into other foods that are not stored properly. Pasta, flour, cereal (etc) needs to be packaged in an air-tight container to prevent weevil contamination.See also
- Granary weevil, also known as the wheat weevil (S. granarius)
- Rice weevilRice weevilThe rice weevil is a serious stored product pest which attacks several economically important crops, including wheat, rice, and maize.- Description :...
(S. oryzae) - Home stored product entomologyHome stored product entomologyHome stored product entomology is the study of insects which infest foodstuffs stored in the home. It deals with the prevention, detection and eradication of the pests...
- Invasive speciesInvasive species"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
- List of common household pests
- Pest controlPest controlPest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...
Further reading
- Proctor, D.L. 1971. An additional aedeagal character for distinguishing Sitophilus zeamais Motsch. from Sitophilus oryzae (L.) (Coleoptera: Cuculionidae). Journal of Stored Products Research, 6: 351-352.
- Peng, W.K., Lin, H.C., Wang, C.H. 2003. DNA identification of two laboratory colonies of the weevils, Sitophilus oryzae (L.) and S. zeamais Motschulsky (Coleoptera: Curculionidae) in Taiwan. Journal of Stored Products Research, 39(2): 225-235.
- Meikle, W.G., Holst, N., Markham, R.H. 1999. Population simulation model of Sitophilus zeamais (Coleoptera: Curculionidae) in grains stores in West Africa. Environmental Entomology, 28(5): 836-844.
- Nardon, C, Nardon, P. 2002. New characters to distinguish larvae and adults of the two sibling species: Sitophilus oryzae(L.) and S. zeamais Mots. (Coleoptera, Dryophthoridae). Annales de la Societe
- Meagher, R.L., Reed, C., Mills, R.B. 1982. Development of Sitophilus zeamais and Tribolium castaneum in whole, cracked, and ground pearl millet. Journal of the Kansas Entomological Society, 55(1): 91-94.
- Maceljski, M., Korunic, Z. 1973. Contribution to the morphology and ecology of Sitophilus zeamais Motsch. in Yugolsavia. Journal of Stored Products Research, 9: 225-234.
- Mason, L.J. (2003). Grain Insect Fact Sheet, E-237-W: Rice, Granary, and Maize Weevils Sitophilu soryzae (L.), S. granarius (L.), and S. zeamais (Motsch). Purdue UniversityPurdue UniversityPurdue University, located in West Lafayette, Indiana, U.S., is the flagship university of the six-campus Purdue University system. Purdue was founded on May 6, 1869, as a land-grant university when the Indiana General Assembly, taking advantage of the Morrill Act, accepted a donation of land and...
- Danho, M., Gaspar, C., Haubruge, E. 2002. The impact of grain quantity on the biology of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae): oviposition, distribution of eggs, adult emergence, body weight and sex ratio. Journal of Stored Products Research, 38(3): 259-266.
- Anonymous. 2009b. Maize weevil Sitophilus zeamais (Motsch.) Canadian Grain CommissionCanadian Grain CommissionThe Canadian Grain Commission, also known as the CGC, is a Canadian government department responsible for regulation of the grain handling industry.The Minister of Agriculture and Agri-food is responsible for the Canadian Grain Commission....
.