蠋蝽成虫对黏虫生长发育和繁殖的非取食效应

Non-consumptive Effects of the Predatory Stinkbug Arma custos Adults on Growth,Development and Reproduction of the Oriental Armyworm Mythimna separata

捕食性天敌对害虫控制作用的室内评估往往观测所捕食的害虫数量或其衍生度量,但捕食者的存在本身可能对猎物的行为和生物学造成负面影响,即“非取食效应”,该效应可能通过影响猎物的生殖而抑制其种群增长。本研究旨在探明捕食性天敌蠋蝽对黏虫是否有非取食效应。将1头剪掉喙端部的蠋蝽成虫和1头黏虫幼虫放入同一培养皿中共处一段时间,对黏虫造成捕食威胁;设3个威胁期处理:黏虫幼虫孵化后4~8 d(长至3龄左右,称为“早期威胁”),孵化后9~13 d(长至6龄左右,“晚期威胁”),幼虫整个发育期(“全期威胁”);以单独完成生长发育的黏虫幼虫为对照。对8日和13日龄幼虫称体鲜重,观测幼虫发育历期、蛹历期、蛹体鲜重,并测定雌成虫终身产卵量。对8日龄黏虫幼虫体重的测定结果表明,与对照幼虫的体重(57.67 mg)和发育历期(14.5 d)相比,早期威胁处理使黏虫幼虫体重增大11.5%、发育历期缩短2.2%,全期威胁处理使黏虫幼虫体重增大12.0%。对13日龄黏虫幼虫体重的测定未发现非取食威胁的影响。对3日龄蛹体鲜重测定结果发现,与对照蛹体重(446.76 mg)相比,早期威胁处理的黏虫蛹重降低5.2%,全期威胁处理的黏虫蛹重降低6.5%。非取食威胁处理不影响黏虫的蛹历期、产卵前期、产卵期和产卵量。本研究结果说明,蠋蝽成虫对黏虫幼虫早期的非取食威胁可较小程度地影响黏虫生长发育,但对生殖力没有影响。

The impact of predator natural enemies on pests is generally assessed in laboratory by measuring the number of prey individuals preyed by a predator or other metrics based on it.But this approach does not consider the potential negative impact on the behavior,development,or reproduction of the prey exerted by the presence of predators,i.e.,the so-called non-consumptive effects.This report presents our laboratory study aiming at investigating non-consumptive effects of the predatory stinkbug Arma custos on the life history traits of the oriental armyworm Mythimna separata.Larvae of M.separata were individually exposed to a stinkbug adult in a petri-dish containing artificial diets for a certain period of time with three treatments of the exposure:5 days in the early stage from 4th to 8th day after hatching,referred to as“Early risk”;5 days in the late stage from 9th to 13th day after hatching,as“Late risk”;and the whole larval stage,as“Throughout risk”.The control larva was left alone.Body masses of both the 8-and 13-day old larvae were individually measured;developmental durations of larvae and pupae and pupal body mass were measured;number of eggs laid during lifetime was counted.Body mass of the 8-day old caterpillars increased by 11.5%for the early-risk and 12.0%for the throughout-risk,as compared with the control(57.67 mg).Body mass of the 13-day old caterpillars were not affected by the treatment.Caterpillar development time was shortened by 2.2%for the Early-risk compared to the control(14.5 d).Caterpillar pupal body mass was reduced to 423.49 mg for the Early-risk and to 417.65 mg for the Throughout-risk,as compared to the control(446.76 mg).Pupal duration,adult pre-oviposition period,oviposition period and lifetime fecundity of M.separata were not influenced by the non-consumptive risk treatment.The results suggest that A.custos may have a slight non-consumptive effect on M.separata when the risk occurs at the early larval stage but may not when the risk occurs at the late larval stage,and there may not be non-consumptive effects on fecundity of M.separata.