Jumping plant louse

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Psyllidae
Psylla alni
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Hemiptera Suborder: Sternorrhyncha Superfamily: Psylloidea
Families
Calophyidae Carsidaridae Homotomidae Phacopteronidae Psyllidae Triozidae

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 aphids, coccids and whiteflies they form the group called Sternorrhyncha, which is considered to be a "primitive" group within the "true bugs" (Hemiptera). Psyllids have the fewest pest species of these four insect groups, and they are therefore the least well studied. They have traditionally been considered a single family, Psyllidae, but recent classifications divide the group into six families.

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.

[edit] 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. Plant pathogens, such as citrus greening, caused by a bacterium Candidatus Liberibacter asiaticum is an example of a plant pathogen that has coevolved with its insect vector, the Asian Citrus Psyllid, AsCP, Diaphorina citri, such that the pathogen causes little to no harm on the insect, but causes a major disease which can reduce citrus quality, flavor, and production as well as causing citrus trees to die. The AsCP was found in Florida in 1998, and has since spread across the southern U.S. into Texas. The disease, citrus greening, also known as Huanglongbing, was found in Florida citrus groves in 2005. Managment methods to reduce the spread of this disease and psyllid populations depend on an Integrated Pest Managment approach using insecticides, parasitoids, predators, and pathogens specific to the AsCP.

[edit] See also

• Carsonella rudii