Aphid-induced Defences in Chilli Affect Preferences of the Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae).

Khalid A Saad,M N Mohamad Roff,Rebecca H Hallett,A B Idris

doi:10.1038/srep13697

Abstract

The sweetpotato whitefly (WF), Bemisia tabaci, is a major pest that damages a wide range of vegetable crops in Malaysia. WF infestation is influenced by a variety of factors, including previous infestation of the host plant by other insect pests. This study investigated the effects of previous infestation of host chilli plants by the green peach aphid (Myzus persicae) on the olfactory behavioural response of B. tabaci, using free-choice bioassay with a Y-tube olfactometer. We analysed volatile organic compounds (VOCs) emitted by non-infested and M. persicae-infested chilli plants using solid-phase microextraction and gas chromatography–mass spectrometry. Our results showed that female WFs preferred non-infested to pre-infested plants. Collection and analysis of volatile compounds emitted by infested plants confirmed that there were significant increases in the production of monoterpenes (cymene; 1,8-cineole), sesquiterpenes (β–cadinene, α-copaene), and methyl salicylate (MeSA) compared to non-infested plants. Our results suggest that host plant infestation by aphids may induce production of secondary metabolites that deter B. tabaci from settling on its host plants. These results provide important information for understanding WF host selection and dispersal among crops, and also for manipulating WF behaviour to improve IPM in chilli.

Highlights

The whitefly (WF) Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an economically important pest in agricultural ecosystems
When WF females were given a choice between volatile organic compounds (VOCs) from pre-infested chilli plants and clean air, they showed a significant preference for clean air (t = 4.43, P < 0.05) (Exp. 2)
These results show that VOCs released by pre-infested chilli plants play an important role in mediating the attraction of female B. tabaci

Summary

Introduction

The whitefly (WF) Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an economically important pest in agricultural ecosystems. The first record of B. tabaci in Malaysia was in 19352, where it was reported on chilli (Capsicum annuum L.), soybean (Glycine max (L.) Merr.), and okra (Abelmoschus esculentus (L.) Moench) in lowland areas It was initially an unimportant agricultural pest, WF has recently become destructive to many host plants, including brinjal (Solanum melongena L.), tomato (Solanum lycopersicum L.), and chilli[3]. Reciprocal effects of aphid infestation on WF preferences have not been extensively studied As such this work aimed to investigate the effects of chilli defence responses induced by pre-infestation with aphids on B. tabaci host selection, and to explore the fundamental mechanisms underlying the interspecific interactions between B. tabaci, aphids and the host plant. This knowledge will be useful for improving plant protection programs and to increase understanding of induced defenses in plants and their effects on other organisms

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