Behavioral effects induced by organic insecticides can be exploited for a sustainable control of the Orange Spiny Whitefly Aleurocanthus spiniferus

Selma Mokrane,Elena Romero,Khaled Djelouah,Daniele Cornara,Giuseppe Cavallo,Alberto Fereres,Francesco Tortorici,Vincenzo Verrastro

doi:10.1038/s41598-020-72972-x

Abstract

The Orange Spiny Whitefly (OSW) Aleurocanthus spiniferus (Hemiptera: Aleyrodidae) represents a new serious threat to Citrus spp., grapevine and ornamental plants in the whole Mediterranean area. Such threat urgently calls for the development of a sustainable control strategy, including insecticides compatible with biological control, and applicable also in organic citrus farming that represent an essential part of Mediterranean agricultural economy. Therefore, we evaluated the toxicity and the effects on host searching, oviposition, and probing and feeding behavior exerted on OSW by organic insecticides supposed to have limited side effects on environment and ecosystem services, i.e. sweet orange essential oil (EO), extract of Clitoria ternatea (CT), mineral oil, pyrethrin and azadirachtin. Despite none of the compounds caused a significant mortality of any of the OSW instars, we observed interesting effects on whitefly behavior: (i) EO and pyrethrin showed a relevant repellent effect, with impairment of both adults landing and oviposition on treated plants; (ii) CT and pyrethrin strongly affected probing behavior. Here, in the light of our findings, we discuss possible OSW sustainable control strategies and further research perspectives.

Highlights

Among invasive insect pests, many whiteflies (Hemiptera: Aleyrodidae) species have become widely distributed due to anthropogenic activities, especially national and international trade, with dramatic consequences for agriculture, due to their ability to cause direct damages to the crop and to transmit plant v iruses[18,19]
Behavioral effects caused by an insecticide that is apparently non-toxic for the insect in conventional tests, could permit to contain the insect populations and associated yield losses
Organic-certified pesticides could be even integrated with synthetic insecticides in alternate treatment regimes, preventing or at least delaying the development of resistance, and reducing the environmental impact of pest control p ractices[37,42]

Summary

Introduction

Many whiteflies (Hemiptera: Aleyrodidae) species have become widely distributed due to anthropogenic activities, especially national and international trade, with dramatic consequences for agriculture, due to their ability to cause direct damages to the crop and to transmit plant v iruses[18,19]. The whitefly seems rapidly adapting to the European environment; A. spiniferus is creating new trophic associations with previously unreported host plants, such as grapevine, Parthenocissus sp., Ailanthus altissima, and other cultivated and ornamental p lants[21,24,26]. Such plants can be just transient hosts serving as shelter during periods when the main hosts, i.e. Citrus spp. plants, become unsuitable/less s uitable[24,26]. We tested the effects of different organic-certified pesticides on OSW, both in terms of lethal toxicity and of sublethal effects on insect’s behavior, i.e. on host searching, landing, oviposition, and probing and feeding behaviors

Methods

Results

Conclusion