Effects Of Sublethal Dosage Of SeMNPV On The Development And Reproduction Of Spodoptera Exigua

Spodoptera exigua (Lepidoptera: noctuidae) is an important polyphagous economic pestwith worldwide distribution tropical and subtropical regions. It can feed on more than290species of plants. Considering that S. exigua is one of the most damaging pests of field crops,it is urgent and imperative to develop effective biopesticides against the insect Spodopteraexigua multiple nucleopolyhedronvirus (SeMNPV) can effectively control the S. exiguapopulation. However, to achieve the high mortality with the viral insecticide alone in thefields, the dosage would have to be increased to the very high level. This would be muchmore expensive than using virus at a low dosage.. In this study, the effects of sublethal dosageof SeMNPV on the development and reproduction in S. exigua were investigated, which wasexpected to provide a method to control S.exigua using sublethal dosage of SeMNPV. Theresults were as follows:1) The10~2～10~3PIB/larva were the sublethal dosage of SeMNPV for the infection at4thS. exigua larvae.2) The food consumption and weight gain couldn’t be affected when S. exigua larvaewere infected at4th instar larvae with sublethal dosage of SeMNPV, but the pupation ratesignificantly reduced.3) The pupae emergence rate, adult fecundity and egg hatchability were effectively reduced when4th instar larvae of S. exigua were inculated with102PIB per larva and103PIBper larva. The pupae emergence rate were reduced from92.43%to83.89%and82.75%, theadult fecundity reduced by12.83%and24.02%, the egg hatchability reduced from81.52%to71.63%and62.74%, respectively.4) The ovarian development of S.exigua could be restrained when4th instar larvae ofS.exigua were inculated with102PIB per larva and10~3PIB per larva. The length of ovariantube was reduced by5.97%and12.91%, respectively and the weight of ovarian tube reducedby13.85%and19.48%.5) The viruses could be vertical transmission from parent to offspring and affect the foodconsumption, body weight gain and pupation of offspring when4th instar parental larvae ofS.exigua were inculated with102PIB per larva and10~3PIB per larva. The food consumptionof offspring larvae were decreased by21.10%and28.65%, respectively, the body weight gainof offspring larvae reduced by27.08%and40.19%, respectively, the pupation of offspringlarvae reduced from93.67%to76.72%and59.68%, respectively.