Studies of control method of Hypera postica (Coleoptera: Curculionidae) using decoy food
2006
Yamaguchi, D.(Kyushu Univ., Fukuoka (Japan)) | ; Kagiyama, I. | ; Yonamine, K. | ; Tadauchi, O. | ; Yukawa, J.
In order to consider a control method against the alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) in winter season, we surveyed the adult behavior of H, postica during the period from the beginning of aestivation to their arrival to fields of milk vetch, Astragalus sinicus Linnaeus (Fabaceae) . All adults survived during the aestivation period and started to leave aestivation places in early August. They dispersed to various places until late November, but their destinations could not be clarified. The length of aestivation period varied greatly with individuals. In contrast to the high survival rate during aestivation, the mortality rate after dispersal seemed to be very high because the number of adults collected from milk vetch fields during the period from late autumn to winter was extremely low. Therefore, we conclude that the period from late autumn to winter is the best season to control the adults that have just arrived in milk vetch fields. To control the adults more effectively, we should gather them to milk vetch fields as many as possible. For this purpose, we recommend to cultivate milk vetch as soon as possible after harvesting rice plant because milk vetch has been cultivated late in seasons to avoid the attack of H, postica. In this case, alfalfa, Medicago sativa Linnaeus (Fabaceae), could be a better alternative plant to attract H. postica, because the weevil was more abundantly attracted to alfalfa than to milk vetch in our field survey. To kill the weevil, we recommend application of an insecticide to alfalfa, because the weevil fed on the treated alfalfa without avoidance.
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