寄主植物对草地螟种群增长的影响

根据草地螟对寄主植物的选择性和转主取食的特性,研究了寄主植物对草地螟种群增长的影响.结果表明,不同寄主植物不仅影响草地螟的生长发育,而且也影响其产卵量和交配率.如幼虫取食灰菜和大豆苗时发育历期较短(约17天),存活率高,蛹重较大;雌蛾产卵量分别达到238、222 粒/头,交配率分别为75%、67%,其种群增长指数较高.而取食玉米和马铃薯苗时发育历期则延长到24天,存活率不足40%,蛹重较轻;其雌蛾产卵量分别为93、50粒/头,交配率均为40%,种群增长指数较低.转主取食有利于草地螟的生长和繁殖,而且提高其种群增长指数.如低龄幼虫取食灰菜至3龄再转食玉米或马铃薯苗,其发育历期、蛹重、产卵量和交配率均比仅取食玉米或马铃薯苗的有明显改善.寄主植物对成虫干重及甘油酯含量的影响亦表现出类似的结果.

Effects of host plants on population increase of meadow moth,Loxostege sticticalis L

Host plants significantly affected development and growth of meadow moth,Loxo-stege sticticalis L.(Lepidoptera:Pyralidae).Developmental periods of larvae and pupae werearound 17 days when larvae fed with lambsquarter or soybean but those fed on maize or potatoplants needed 24 days to complete their development.Pupal weight from larvae fed with soy-bean and lambsquarter were heavier than those fed with maize and potato plants.In addition,larvae fed with the former two plant species had higher survival rates than those fed with potatoand maize.Adults from larvae fed with lambsquarter had higher mating percentage,shorter pre-oviposition period,and greater lifetime fecundity than those from other tested plants.Dryweight and glyceride content of adult grown from lambsquarter were the highest,followed bysoybean,corn and potato in a decreasing order.Results also demonstrated that the develop-ment,pupal weight and survival rate were greatly improved in larvae that shifted from lambs-quarter to maize or potato plants since 3rd instar.Under such a condition,the lifetime fecundi-ty,mating rate,dry weight and glyceride content of the adult were also greatly improved,sug-gesting that food for the first-3 instar larvae is crucial to the development and reproduction and,hence population increase of meadow moth.The implications of these results in population dy-namics and integrated pest management of L.sticticalis were discussed under the light of pub-lished findings.