The Effects Of Foods And Insecticides On The Growth,Development And Reproduction Of Cyrtorhinus Lividipennis

Cyrtorhinus lividipennis(Reuter)(Hemiptera:Miridae)is an important predatory in the rice paddy.It mainly feed on the eggs and young nymphs of brown planthopper(Nilaparvata lugens stal),white-backed planthopper(Sogatella furcifera Horvath),and green leafhopper(Nephotettix virescens Distant).In order to use the function of C.Lividipennis to control rice pests effectively.Our study examined the feasibility of C.Lividipennis raised by the alternative feed-Corcyra cephalonica's eggs.In addition,we evaluated the effects of five insecticides with sublethal concentration(LC20)(imidacloprid,triazophos,deltamethrin,pymetrozine and chlorantraniliprole)on the fecundity of C.Lividipennis.The results were as follows:(1)In our work,we studied the effects of C.Lividipennis raised by C.cephalonica's eggs on development period,nymphal survival rate,sex ratio,pre-ovipositing period,fecundity,egg hatchability and life parameters,respectively.The egg's development period of C.Lividipennis raised by C.cephalonica's eggs(treated group)was showed to be similar with the C.Lividipennis raised by N.lugens's eggs(control group).But first and second instar development period of treated group decreased 8.6%and 14.7%,respectively.To the third,fourth and fifth instar development period of treated group increased 15.0%,34.1%and 16.8%than the control group,respectively.Taken together,the nymphal development period was 11.5± 0.1 d,and increased 5.2%to the control group.The nymphal survival rates and sex ratio,pre-ovipositing period,fecundity,egg hatchability,intrinsic rate of increase(rm),net reproductive rate(Rn),finite rate of increase(?),mean generation time(T),population doubling time(t)of treated group had no significant difference with the control group.But the female's longevity was 12.55 ±0.5d and decreased 18.5%.Therefore,we infer that C.cephalonica's eggs were a adaptive food for raising C.Lividipennis.(2)In this paper,Adults of C.lividipennis were exposed to sublethal concentrations(LC20)of five insecticides(imidacloprid,triazophos,deltamethrin,pymetrozine,chlorantraniliprole)by pesticide-membrane method.The sublethal effect of five insecticides on the reproduction were investigated.The number of eggs laid by the control group was 65.0±4.2.However,the numbers of the different mating pairs(? cK ×? t??t×?t??t×?CK)that treated with the LC20 concentration of imidacloprid were 92.8±7.2,95.8±7.6 and 102.8±7.4,which increased by 42.9%,58.1%and 47.3%,respectively.This trend was also observed at the LC20 for triazophos,deltamethrin,pymetrozine,chlorantraniliprole.So,we infer that the sublethal concentrations of these insecticides could stimulate the reproduction of C.Lividipennis.The effect of three insecticides(imidacloprid,triazophos,deltamethrin)on the Vitellogenin(Vg)expression were investigated.The expression level of Vg was up-regulated in Imidacloprid,Triazophos and Deltamethrin compared with control group,increasing by 55.1%,48.0%and 63.4%,respectively.We speculate that sub-lethal concentrations of insecticides to stimulated the reproduction of C.Lividipennis is related to the stimulating effects on the synthesis of Vg.