Pupation Behaviors,emergence Successes And Reproduction Of Ectropis Grisescens(Lepidoptera:Geometridae) In Response To Different Substrate Types And Moisture Contents

Ectropis grisescens Warren(Lepidoptera: Geometridae)is an important defoliator pest of tea plants(Camellia sinensis L.).This pest widely distributes in the tea-producing provinces of China,and causes great damages in tea production.In the recent years,the use of chemical pesticides has caused many problems,and therefore,the IPM of tea pests has received increasing attention.Previous studies showed that E.grisescens commonly pupates in soil.This behavior may provide an effective target for the control of E.grisescens.However,little is known about this behavior.In the present,choice and no-choice tests were conducted to investigate the pupation behaviors and emergence successes of E.grisescens when responding to different substrate types(sand,sandy loam 1,sandy loam 2 and silt loam)and moisture contents(5%-,20%-,35%-,50%-,65%-and 80%-moisture).Moisture-choice bioassays showed that E.grisescens preferred to pupate in soil(sandy loam 1,sandy loam 2 and silt loam)that was at the intermediate moisture levels.However,the percentage of E.grisescens in 5%-and 35%-moisture sand was significantly higher than that in 80%-moisture sand.Substrate-choice bioassays showed that when the soil(sandy loam 1,sandy loam 2 and silt loam)was dry(20%-moisture)or wet(80%-moisture),E.grisescens preferred to pupate in sand over other substrates,but there was no difference among the four substrates under 50%-moisture conditions.No-choice tests showed that the burrowing rate of E.grisescens was significantly lower when soil(sandy loam 1,sandy loam 2 and silt loam)was dry(20%-moisture)or wet(80%-moisture).In addition,20%-moisture soil(sandy loam 2 and silt loam)significantly decreased the body water content of pupae and emergence success of adults as compared to 50%-moisture soil.However,when compared among different moisture levels of sand,there was no difference in pupation depth,burrowing rate,body water content,and emergence success.Burying bioassays showed that the emergence success of buried(80%-moisture soil)E.grisescens was significantly lower compered to unburied ones.In addition,this study showed that presence of a pupation substrate and moisture levels(20%-,50%-or 80%-moisture)during the pupal stage significantly affected the physiological and fitness traits of adult E.grisescens.The body water content of female moths emerged from 20%-moisture soil was significantly lower compared to 80%-moisture soil,but there was no significant effect on male moths.When paired,moths emerged from 20%-moisture soil laid significantly fewer eggs than those that emerged from 50%-moisture soil.In addition,the number of offerings(hatched larvae)were significantly lower when moths emerged from no-soil containers compared to 50%-moisture soil.In addition,the longevity of both male and female moths that emerged from 20%-moisture soil was shortest.This study showed that E.grisescens can distinguish different substrate types and moisture contents and avoid pupate in wet or dry substrate conditions.In addiotion,the no-substrate and low-moisture conditions during the pupal stage had adverse affects on E.grisescens adults.This study increased the understanding of the ecological ecology of E.grisescens,and may provide some methods for the control of E.grisescens.