Study On Potential Of A Novel Natural Enemy Insect Picromerus Lewisi Scott In Biological Control

Picromerus lewisi Scott belongs to Asopinae,Pentatomidae,Hemiptera.It is a natural enemy insect for biological control.Both nymph and adult can prey on variety of Lepidoptera pest larvae.At present,the research on P.lewisi is still focused on morphological classification and a few biological characteristics.What' s more,its application value in biological control needs to be evaluated.This paper mainly evaluated the potential of P.lewisi in biological control from three aspects.The first is growing development and population of P.lewisi;the second is the predation potential;and the last is the effect of pesticides on P.lewisi.The main research conclusions of this paper were as follows:1.Under different temperature conditions,the duration P.lewisi and the demographic parameters of P.lewisi was different.In the temperature range of 18-32?,P.lewisi could develop successfully,while the egg hatching rate of P.lewisi was 0 at 36?.The development rate of P.lewisi is linearly positively correlated with the temperature between 18 and 32?.The relationship model between the development rate of P.lewisi from egg to adult and the temperature was: Y = 0.002533* x-0.03648,the degree-day requirements was 394.7dd,and the lower regression equations of P.lewisi was 14.40?.The temperature hardly effect body weight of P.lewisi.The body weight of the female was larger than that of the male.The population life table showed that the net reproductive rate of P.lewisi population was highest at 28?(179.50),and the generation time in days was shortest(57.50).The net reproductive rate and the generation time in days was 125.64 and 64.59 respectively at 25?.And the Intrinsic rate of increase was highest(0.0903)at 32?.2.The functional response of P.lewisi to Lepidoptera larvae showed a great predatory strategy.The function responses of P.lewisi to the larvae of Plutella xylostella and Spodoptera frugiperda were all type II equations.The function responses of P.lewisi to the larvae of Spodoptera exigua and Spodoptera litura were almost type II equations,and a few were type III equations.The predation amount of 5th instar nymphs and adults was little different,and more than predation amount of 3rd and4 th nymphs.The interference response model showed that when prey was fixed,the interference effect was gradually enhanced with the increase of the number of P.lewisi.3.Study on the adaptability of P.lewisi to pesticides.Treatment with two pesticides,abamectin and bifenthrin,had no effect on the hatching rate of P.lewisi eggs,while the hatching time of P.lewisi eggs in treatment with bifenthrin(9.091 days)was significantly longer than that of treatment with abamectin(7.071 days)and CK(6.445 days).The survival rate of 3-5 instar nymphs and adults of abamectin and bifenthrin was significantly lower than that of the control group.The female adults of P.lewisi treated with abamectin prolonged longevity(47.33 days)and increased their oviposition(283.8eggs),while longevity of female adults with bifenthrin significantly shortened(19.6 days)and oviposition significantly decreased(89.00 eggs).However,the activity of related enzymes(acetylcholinesterase,insect cytochrome P450,glutathione-S-transferase,and insect carboxylesterase)was increased in the female adults of P.lewisi treated with both agents.