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''Larinus minutus'' is a species of true weevil known as the lesser knapweed flower weevil. It is used as an agent of biological pest control against noxious knapweeds, especially diffuse knapweed (''Centaurea diffusa'') and spotted knapweed. The adult weevil is dark mottled brown with a long snout. It is long in total. It is active throughout the summer with a 14-week maximum adult lifespan. During this time the female lays up to 130 eggs, depositing them in the knapweed flower head. The larva emerges and burrows into the flower head where it feeds on the developing seeds. The larva damages the plant by reducing seed production (all of the seeds of diffuse knapweed and 25-100% of spotted knapweed)〔 and the adult does damage by defoliating the plant as it feeds on the leaves prior to flowering.〔Wilson, L.M., Randall, C.B., 2003. Biology and Biological Control of Knapweed. Forest Health Technology Enterprise Team, Technology Transfer.〕〔Piper, G.L., 2004. Biotic suppression of invasive weeds in Washington state: a half-century of progress. In: Cullen, J.M., Briese, D.T., Kriticos, D.J., Lonsdale, W.M., Morin, L., Scott, J.K. (Eds.), Proceedings of the XI International Symposium on Biological Control of Weeds. CSIRO, Canberra, pp. 584–588.〕〔Norton, A.P., Blair, A.C., Hardin, J.G., Nissen, S.J., Brunk, G.R., 2008. Herbivory and novel weapons: no evidence for enhanced competitive ability or allelopathy induction of ''Centaurea diffusa'' by biological controls. Biological Invasions 10, 79–88.〕 After flowering, adult weevils switch to feeding on flowers. In spotted and diffuse knapweed, ''L. minutus'' directly consumes another biological control agent released to control the species, the gall-forming flies ''Urophora affinis'' Frfld and ''Urophora quadrifasciata'' Meigen (Diptera: Tephrididae) 〔 This weevil is native to southern Europe and the Mediterranean. It was first released as a knapweed biocontrol in the United States in 1991 from Greece.〔Lang, R.F., Story, J.M., Piper, G.L., 1996. Establishment of ''Larinus minutus'' Gyllenhal (Coleoptera: Curculionidae) for biological control of diffuse and spotted knapweed in the western United States. Pan Pacific Entomology 72, 209–212.〕 It is now established in knapweed populations throughout the western United States, especially in warm, dry areas. It feeds on knapweeds, preferring diffuse knapweed over others, and it has not been shown to attack native flora. This weevil has been shown to reduce diffuse knapweed density at several sites.〔Seastedt, T.R., Gregory, N., Buckner, D., 2003. Effect of biocontrol insects on diffuse knapweed (''Centaurea diffusa'') in a Colorado grassland. Weed Science 51, 237–245.〕〔 It has been less successful in controlling spotted knapweed.〔Smith, L., 2004. Impact of biological control agents on Centaurea diffusa (diffuse knapweed) in central Montana. In: Cullen, J.M., Briese, D.T., Kriticos, D.J., Lonsdale, W.M., Morin, L., Scott, J.K. (Eds.), Proceedings of the XI International Symposium on Biological Control of Weeds. CSIRO, Canberra, pp. 589–593.〕〔Story, J.M., Callan, N.W., Corn, J.G., White, L.J., 2006. Decline of spotted knapweed density at two sites in western Montana with large populations of the introduced root weevil, ''Cyphocleonus achates'' (Fahraeus). Biological Control 38, 227–232.〕 ==External links== *(Cornell Biocontrol Profile ) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Larinus minutus」の詳細全文を読む スポンサード リンク
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