Jumping plant louse
Encyclopedia
Psyllids or jumping plant lice are small plant-feeding insects that tend to be very host specific, i.e. they only feed on one plant species (monophagous) or feed on a few related plants (oligophagous). Together with aphid
s, phylloxerans
, scale insect
s and whiteflies
they form the group called Sternorrhyncha
, which is considered to be the most "primitive" group within the true bugs (Hemiptera
). They have traditionally been considered a single family, Psyllidae, but recent classifications divide the group into a total of seven families
; the present restricted definition still includes more than 70 genera in the Psyllidae.
Psyllid fossils have been found from the early Permian
before the flowering plants evolved. The explosive diversification of the flowering plants in the Cretaceous
was paralleled by a massive diversification of associated insects, and many of the morphological and metabolic characters that the flowering plants exhibit may have evolved as defenses against herbivorous insects
.
Several genera of psyllids, especially among the Australia
n fauna, secrete coverings called "lerps
" over their bodies, presumably to conceal them from predators and parasites
.
", ACP, Diaphorina citri, such that the pathogen causes little or no harm to the insect, but causes a major disease which can reduce citrus quality, flavor, and production as well as causing citrus trees to die. The ACP was found in Florida in 1998, and has since spread across the southern U.S. into Texas. This disease, also known as Huanglongbing
, was found in Florida citrus groves in 2005. Management methods to reduce the spread of this disease and psyllid populations depend on an Integrated Pest Management approach using insecticides, parasitoids, predators, and pathogens specific to the AsCP. Due to the spread of Citrus Greening world wide and the growing importance of psyllid spread diseases an "International Psyllid Genome Consortium" was established. Insect genomics provides important information on the genetic basis of the pests biology which may be altered to suppress psyllid populations in an environmentally friendly manner. The emerging psyllid genome continues to elucidate psyllid biology, expanding what is known about gene families, genetic variation, and gene expression in insects. Thus far two new psyllid viruses have been discovered, and are being examined as potential biological control agents to reduce psyllid populations. Psyllid cell cultures have also been established by several researchers working with virus propagation, and as a system to propagate the Can. Liberibacter bacterium for molecular studies on infection and replication. Studies on the microbiota have also identified four new species of bacteria. Thus far ten microbial organisms have been identified within these psyllids, among them the primary endosymbiont, whose genome has been sequenced and posted at the NCBI database, as well as a Wolbachia
species.
Some of the agriculturally-important pest species are now classified in the family Triozidae
.
/ Institute of Food and Agricultural Sciences
Featured Creatures website
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
s, phylloxerans
Phylloxeroidea
The Phylloxeroidea is a small superfamily of the Hemiptera closely related to the aphids, and often traditionally included in the Aphidoidea, which is the sister taxon...
, scale insect
Scale insect
The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...
s and whiteflies
Whitefly
The whiteflies, comprising only the family Aleyrodidae, are small hemipterans. More than 1550 species have been described. Whiteflies typically feed on the underside of plant leaves.-Agricultural threat:...
they form the group called Sternorrhyncha
Sternorrhyncha
Sternorrhyncha is a suborder of the Hemiptera which contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the order Homoptera. "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the head...
, which is considered to be the most "primitive" group within the true bugs (Hemiptera
Hemiptera
Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
). They have traditionally been considered a single family, Psyllidae, but recent classifications divide the group into a total of seven families
Psylloidea
Psylloidea is a superfamily of true bugs, including the jumping plant lice and others which have recently been classified as distinct families....
; the present restricted definition still includes more than 70 genera in the Psyllidae.
Psyllid fossils have been found from the early Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
before the flowering plants evolved. The explosive diversification of the flowering plants in the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
was paralleled by a massive diversification of associated insects, and many of the morphological and metabolic characters that the flowering plants exhibit may have evolved as defenses against herbivorous insects
Plant defense against herbivory
Plant defense against herbivory or host-plant resistance describes a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Plants use several strategies to defend against damage caused by herbivores...
.
Several genera of psyllids, especially among the 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...
n fauna, secrete coverings called "lerps
Lerp (biology)
In biology, a lerp is a structure of crystallized honeydew produced by larvae of psyllid insects as a protective cover.-Host plants:Some of the host plants on which lerp is often found include:* Eucalyptus dumosa...
" over their bodies, presumably to conceal them from predators and parasites
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
.
Coevolution
Insect-plant interactions have been important in defining models of coevolution and cospeciation, referring to whether plant speciation drives insect speciation and vice versa, though most herbivorous insects probably evolved long after the plants they feed on.Status as pests
Citrus greening, known as "Huanglongbing" is associated with the presence of a bacterium Liberibacter asiaticum is an example of a plant pathogen that has coevolved with its insect vector, the "Asian Citrus PsyllidDiaphorina citri
The Asian citrus psyllid, Diaphorina citri, is a sap-sucking, hemipteran bug in the family, Psyllidae. It is an important pest of citrus being one of only two known vectors of the serious citrus disease, Huanglongbing or greening disease. It is widely distributed in southern Asia and has spread to...
", ACP, Diaphorina citri, such that the pathogen causes little or no harm to the insect, but causes a major disease which can reduce citrus quality, flavor, and production as well as causing citrus trees to die. The ACP was found in Florida in 1998, and has since spread across the southern U.S. into Texas. This disease, also known as Huanglongbing
Citrus vein phloem degeneration
Huanglongbing , also known as HLB, citrus vein phloem degeneration , citrus greening disease, yellow shoot disease, leaf mottle yellows in the Philippines, libukin in Taiwan and citrus dieback in India, is probably the worst disease of citrus caused by a vectored pathogen...
, was found in Florida citrus groves in 2005. Management methods to reduce the spread of this disease and psyllid populations depend on an Integrated Pest Management approach using insecticides, parasitoids, predators, and pathogens specific to the AsCP. Due to the spread of Citrus Greening world wide and the growing importance of psyllid spread diseases an "International Psyllid Genome Consortium" was established. Insect genomics provides important information on the genetic basis of the pests biology which may be altered to suppress psyllid populations in an environmentally friendly manner. The emerging psyllid genome continues to elucidate psyllid biology, expanding what is known about gene families, genetic variation, and gene expression in insects. Thus far two new psyllid viruses have been discovered, and are being examined as potential biological control agents to reduce psyllid populations. Psyllid cell cultures have also been established by several researchers working with virus propagation, and as a system to propagate the Can. Liberibacter bacterium for molecular studies on infection and replication. Studies on the microbiota have also identified four new species of bacteria. Thus far ten microbial organisms have been identified within these psyllids, among them the primary endosymbiont, whose genome has been sequenced and posted at the NCBI database, as well as a Wolbachia
Wolbachia
Wolbachia is a genus of bacteria which infects arthropod species, including a high proportion of insects , as well as some nematodes. It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere...
species.
Some of the agriculturally-important pest species are now classified in the family Triozidae
Triozidae
Triozidae is one of seven families collectively referred to as jumping plant lice. They have traditionally been considered part of a single family, Psyllidae, but recent classifications divide the group into a total of seven families; most of the genera remain in the Psyllidae, but Triozidae is...
.
External links
On the University of FloridaUniversity of Florida
The 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...
/ Institute of Food and Agricultural Sciences
Institute of Food and Agricultural Sciences
The 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 website