Optimization Of Artificial Diets For Sesamia Inferens And Detection Of The Frequency Of Resistance Alleles To Bt Rice For Chilo Suppressalis

Chilo suppressalis (Walker) and Sesamia inferens (Walker) are the main target pests to Bt rice. Compared with the Chilo suppressalis, artificial diet of Sesamia inferens is not mature. An oligidic diet for larvae rearing of Sesamia inferens was optimized by using the uniform design-support vector machine (UD-SVR). This may laid a foundation of detection of resistance to Bt rice for Sesamia inferens. Detection of initial resistance allele frequeney of taget pests to Bt rice is the role basic of resistance risk manangement. We detect the initial resistance allele frequeney of Chilo suppressalis to Bt Huahui-1with the F2screening method. The main results are as follows:1. An oligidic diet for larvae rearing of the pink stem borer (PSB), Sesamia inferens (Walker), was optimized by using the uniform design and support vector regression (UD-SVR). The formulation of the optimized diet was as follows:agar powder3g, soybean powder8g, water bamboo powder11g, yeast powder16g, sucrose6g, rice powder3g, corn powder11g, wheat germ powder5g, casein7g, vitamin C0.8g, sorbic acid0.64g, aureomycin0.54g, cholesterol0.04g, Wesson’s salt1.5g, and distilled water200g. PSB had been reared on the diet for more than ten successive genenrations, which was much longer than the previously reports. The rate developed from the1st instar to pupal stage on the optimized diet was87.5%, which significantly higher than that of the benchmark diet. As for the ten succesive reared generations, the average of pupation rate, emergence rate, egg hatching rate and fecundity of PSB on the optimized diet was42.5-87.5%,79.7-95.8%,90.0-94.9%and95-252eggs per female, respectively. There was no significant difference between the10th genenation and the1st generation reared on the developed diet among measured parameters, except for the period of the male larval developmental stage. The period of the male larval developmental stage was significantly longer in the10th generation than that in the1st genenration. But it was not significantly different from that reared on the benchmark diet. Our results suggest that the optimized diet is suitable for the long-term artificial rearing and bioassay of PSB.2. The initial resistance allele frequeney of Chilo suppressalis of Fuyang population was estimated by using the F2method in2011-2012. There were total246isofemale lines established and screened. The estimated frequeney of resistance alleles to Bt Rice in field population was0.01109(95%CI=0.00567-0.01798). The conservative estimated resistance alleles was0.01923(95%=0.00916-0.03214) because there were only115isofemale lines screened over four families. All we do show that Chilo suppressalis from Fuyang, Hangzhou province is a field of insensitive population to Bt rice and their resistance risk is big enough to cause attention.