''Longitarsus jacobaeae'' is a species of

flea beetle The flea beetle is a small, jumping beetle of the leaf beetle family (Chrysomelidae), that makes up the tribe Alticini which is part of the subfamily Galerucinae. Historically the flea beetles were classified as their own subfamily. Though m ...

known as the tansy ragwort flea beetle. It is used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

against the nectar-rich

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or liv ...

known as ragwort (''Senecio jacobaea'' reclassified as ''

Jacobaea vulgaris ''Jacobaea vulgaris'', syn. ''Senecio jacobaea'', is a very common wild flower in the family Asteraceae that is native to northern Eurasia, usually in dry, open places, and has also been widely distributed as a weed elsewhere. Common names inc ...

''). The adult beetle is light golden brown in color and between and long. The female is larger than the male, especially when

gravid In biology and human medicine, gravidity and parity are the number of times a woman is or has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These terms are usually coupled, sometimes with additional te ...

. The beetle has enlarged

femurs The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with t ...

for its main locomotion method of hopping. The female lays eggs on or near the ragwort, its host plant. The

larva A larva (; plural larvae ) 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 ...

emerges in about two weeks and burrows into the ground to feed on the roots. The larvae and adults are dually responsible for damage to the plant. The adult defoliates plants which are often already weakened by larval damage at the roots. This two-pronged attack is quite successful in preventing ragwort growth and development. The beetles have prevented entire populations of ragwort from reaching flowering stage at several monitored sites. The beetle is not choosy between species in the genera in which it feeds from, and recent studies with the beetle have shown "that selection pressure by specialist herbivores is not likely a driving force in evolutionary diversification" of the plants which contain the alkaloids that the beetle dines on. This beetle is native to Eurasia. It was first introduced to the United States as a ragwort biocontrol agent in 1969 and it is now established in much of the western United States. The beetle is most effective when used in conjunction with the

cinnabar moth The cinnabar moth (''Tyria jacobaeae'') is a brightly coloured arctiid moth found as a native species in Europe and western and central Asia then east across the Palearctic to Siberia to China. It has been introduced into New Zealand, Australia a ...

(''Tyria jacobaeae''), another ragwort biocontrol agent. The beetle is not known to attack other plants. A close relative, '' Longitarsus ganglbaueri'', which also feeds on ragwort, does attack other plant species; it is not used as a biocontrol agent for this reason.

Notes

References

* Coombs, E. M., et al., Eds. (2004). ''Biological Control of Invasive Plants in the United States''. Corvallis: Oregon State University Press, 338.

External links

Biocontrol Info Sheet

Photos of Tansy Ragwort Flea Beetle
{{Taxonbar, from=Q1634537 Longitarsus Biological pest control beetles Insects used for control of invasive plants Beetles described in 1858 Beetles of Asia Beetles of Europe