Visually and olfactorily enhanced attractive devices for thrips management.

Robert W H M Van Tol,Melanie M Davidson,Willem Jan De Kogel,Ruth C Butler,David A J Teulon

doi:10.1111/eea.12969

Abstract

‘Lure‐and‐infect’ is an insect pest management strategy with high potential but so far there are few examples of its application. Using traps as surrogates for auto‐dissemination devices, we tested the attractiveness to naturally occurring thrips (Thysanoptera: Thripidae) of three trap types differing in colour and structure, with and without the thrips lure methyl isonicotinate (MI), and sticky plate traps as a control. The aim was to find more effective traps that could be further developed into devices for auto‐dissemination and lure‐and‐infect of thrips. The number of thrips captured varied substantially with trap type and the presence of the MI lure. We found a high visual response to a sticky ‘white ruffle’ trap (i.e., a 30‐cm‐long cylindrical outline of folded fabric), compared to a commonly used blue sticky plate trap (Bug‐scan) as the control. This effect was seen both in a greenhouse with roses (Rosa spp.), where we encountered western flower thrips, Frankliniella occidentalis (Pergande), and in a grass field, where we encountered onion thrips, Thrips tabaci Lindeman, and New Zealand flower thrips, Thrips obscuratus (Crawford). In the absence of MI, the white ruffle trap caught 7–22× more thrips than the control Bug‐scan trap. A similarly designed blue ruffle trap and a modified Lynfield trap caught lower thrips numbers than the white ruffle and the control Bug‐scan traps. Presence of MI substantially increased the captures of T. tabaci in all three trap types in the field (2.5–18×). In the greenhouse, without MI the white ruffle trap caught 3.5–14× more thrips than the Bug‐scan, blue ruffle, or modified Lynfield traps. Presence of MI increased the captures of F. occidentalis males and females in the Lynfield and blue ruffle traps (1.4–2.8×), but not in the white ruffle trap in the greenhouse (ca. 1.1×). The importance of visual and olfactory factors for the design of effective auto‐dissemination and lure‐and‐infect strategies for thrips management is discussed.

Highlights

‘Lure-and-infect’ is an insect pest management strategy with high potential but so far there are few examples of its application
Light reflection measurements indicated that 90% of the insect-visible ultraviolet A (UV-A) (315–400 nm) was transmitted in the greenhouse compared to 100% in the field, i.e., the greenhouse glass blocked 10% of the UV-A (Figure 3)
The concept of auto-dissemination relies on providing stimuli that elicit behavioural responses of pest insects that include attraction, landing on a device, and encouragement to walk around to pick up entomopathogenic fungus (EPF) spores, before leaving to disperse the spores to conspecifics, and eventually succumbing to infection from the EPF (Cork, 2016)

Summary

Introduction

‘Lure-and-infect’ is an insect pest management strategy with high potential but so far there are few examples of its application. In the present study we focus on insect attraction, and aim to increase attractiveness of the visual and olfactory cues of auto-dissemination devices to several species of thrips (Thysanoptera: Thripidae). Insect pathogens such as the fungi Metarhizium anisopliae (Metschn.) Sorokın and Beauveria bassiana (Bals.Criv.) Vuill. There is only one published description of an auto-dissemination device for a lure-and-infect strategy of thrips, a modified Lynfield trap, in which an EPF is used as the ‘infect’ component. A (visually) more attractive device may attract and arrest movement of more thrips, which may lead to more contact between thrips and EPF spores, which may in turn lead to more successful autodissemination or infection and transfer of spores to conspecifics (Quesada-Moraga et al, 2008; Yousef et al, 2018)

Methods

Results

Conclusion