Effects Of Four Ryanodine Receptor Insecticides On Diadegma Semiclausum(Hymenoptera:Ichneumonidae),a Parasitoid Of Plutella Xylostella (Lepidoptera:Yponomeutidae)

Plutella xylostella is a worldwide vegetable pest that is difficult to control due to its resistance to insecticides,its environmental very strong adaptation and its special biological properties.As a dominant parasitoid in the larvae of P.xylostella,Diadegma semiclausum has a good control potential to P.xylostella.Ryanodine receptor insecticide is a new type of insecticide with a unique mechanism of action and no cross-resistance with other types of insecticides.It can be used for the resistance control of P.xylostella.To evaluate the safety of ryanodine receptor insecticide against D.semiclausum,this study determined the toxicity and safety of recommended concentrations of four ryanodine receptor insecticides to pupae and adults of D.semiclausum.Compared the selective toxicities of four insecticides to P.xylostella and D.semiclausum.Studied the sublethal effects of SYP-9080 on different developmental stages of D.semiclausum.The main results are as followed:(1)The toxicity and safety of four ryanodine receptor insecticides to pupae and adults of D.semiclausumAfter treated with the recommended concentration of four kinds of ryanodine receptor insecticides,there was no adverse effect on the pupae and emergence of D.semiclausum.The vial residual film method showed that: Cyantraniliprole has a significant adverse effect on adults,the mortality rate was 96.87%;SYP-9080 and chlorantraniliprole has adverse effects on adults of D.semiclausum,and the mortality rates were 45.09% and 43.30% respectively.Flubendiamide had no adverse effect on adult of D.semiclausum.The feeding showed that:cyantraniliprole,SYP-9080 and chlorantraniliprole had a very significant adverse effect on D.semiclausum,the mortality rate was close to 100%.Flubendiamide had no adverse effect on D.semiclausum.The results showed that Flubendiamide was the safest for D.semiclausum.(2)The selective toxicities of four ryanodine receptor insecticides to P.xylostella and D.semiclausumThe order of toxicities of 4 insecticides to the larvae of P.xylostella was SYP-9080 >cyantraniliprole > chlorantraniliprole > flubendiamide,with the LC50 values of 0.25,0.43,2.56 and 3.00 mg · L-1,respectively.And the order of toxicities of 4 insecticides to D.semiclausum was cyantraniliprole>SYP-9080> chlorantraniliprole > flubendiamide,with the LC50 values of 5.60?51.31?121.26??2000 mg·L-1,respectively.Flubendiamide and SYP-9080 showed highly positive selectivity to D.semiclausum and P.xylostella with toxicity selective ratio >667.3,and 206.9,respectivity.Chlorantraniliprole and cyantraniliprole showed moderately positive selectivity,their toxicity selective ratio were 47.3 and 12.9,respectively.(3)The effects of SYP-9080 on different developmental stages of D.semiclausumSYP-9080 first treatment then parasitic P.xylostella larvae,the pupation rate of the parental parasitoid decreased by 10.32%,and the sex ratio also lower than the control,which had no effect on the parasitism rate,emergence rate and developmental duration of the parasitoid.The first parasitic then treatment P.xylostella larvae,the pupation rate of the parental parasitoid decreased by 18.95%,the developmental duration of the egg to larval stage was extended by 2.37 d,had no effect on the parasitic rate and emergence rate.But the sex ratio increased than the control.The field recommended concentration of SYP-9080 contact with D.semiclausum pupae to significantly decreased the parasitism rate of female adults emerged from pupae treated and pupation rate of the offspring,which decreased by 6.19% and 5.75%,respectively.And the insecticide had no effects on the emergence rate and developmental duration of their offspring,but could increase the sex ratio.The sublethal concentration of SYP-9080 contact with D.semiclausum adult had no effects on the pupation rate and emergence rate.But significantly decreased parasitism rate,compared with the control,the parasitism rate decreased by 7.39%,the sex ratio was increased.In addition,immature developmental times of offspring were not affected by SYP-9080 treatment,and shortened adult period by 0.31 d.(4)Effects of sublethal concentration of SYP-9080 on detoxification enzymes of D.semiclausumSublethal concentration of SYP-9080 had a certain inhibitory effect on three detoxification enzymes of D.semiclausum.The sublethal concentration of SYP-9080 was used to D.semiclausum,and the activity of c EST was significantly lower than the control at different treatment time,showed significant inhibition.The activity of GST was significantly lower than the control at 1 h and 12 h,and significantly higher than the control at 24 h and 48 h,showed first inhibition and then activated.The activity of MFOS was significantly lower than the control at 1 h,12 h and 24 h,and there was no significant difference compared with the control at 48 h,showed first inhibition and then recovery.