Functional responses of two predatory bugs (Hemiptera: Anthocoridae) to changes in the abundance of Tetranychus urticae (Acari: Tetranychidae) and Bemisia tabaci (Hemiptera: Aleyrodidae)

Serkan Pehlivan,Ekrem Atakan,Tugcan Alinc,Tange Denis Achiri

doi:10.14411/eje.2020.005

Abstract

Orius spp. (Hemiptera: Anthocoridae) is well-known genus of generalist predators, which feed on numerous pest insects and mites infesting crops. In this study, the functional responses of the predatory bugs, Orius laevigatus (Fieber) and Orius vicinus (Ribaut), to different densities of the eggs of the whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and red spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), were determined under laboratory conditions. Different numbers of eggs (2, 4, 6, 8, 16, 32, 64 and 128) of both species of prey were offered to females of the above predators for 24-h in a controlled environment of 25 ± 1°C, 60 ± 10% RH and under a 16L : 8D photoperiod. The parameters of the functional responses were assessed using Holling's Disc Equation. Both predators showed a Type II response to both prey. The attack rates (a) and handling times (Th) of the predators were computed for spider mites eggs: O. laevigatus (a: 0.972, Th: 0.007) and O. vicinus (a: 1.113, Th: 0.005), and whitefly eggs: O. laevigatus (a: 1.022, Th: 0.002) and O. vicinus (a: 0.772 Th: 0.006). Furthermore, the average number of B. tabaci eggs consumed by O. laevigatus females was greater than by those of O. vicinus. In contrast, O. vicinus was a more efficient predator of T. urticae eggs than O. laevigatus. Consequently, these results indicate that together these predators might be effective biological control agents in regulating populations of B. tabaci and T. urticae in agricultural ecosystems.

Highlights

The cotton whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) are common phytophagous pests that damage many economically important agricultural crops around the world (Jeppson et al, 1975; Helle & Sabelis, 1985; Gerling et al, 2001; Aslan et al, 2004)
The results obtained from the logistic regression analysis of the functional response experiments had significantly negative P1 values indicating that the functional responses of both species of Orius to different densities of the eggs of T. urticae and B. tabaci were of type II (Table 1)
The proportion of eggs of T. urticae and B. tabaci consumed by each predator declined and plateaued above a density of 64 eggs (Fig. 1)

Summary

Introduction

The cotton whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) are common phytophagous pests that damage many economically important agricultural crops around the world (Jeppson et al, 1975; Helle & Sabelis, 1985; Gerling et al, 2001; Aslan et al, 2004). Tetranychus urticae feeds on leaves causing damage to chlorophyll and thereafter serious loss of yield (Nachman & Zemek, 2002). For the control of these pests, farmers mostly apply chemical treatments to keep their abundance below economic damage threshold levels (Knowles, 1997; Denholm et al, 1998; Van Leeuwen et al, 2010). Alternative pest control strategies including biological control have been adopted to control whiteflies and spider mites around the world in recent years (Lester et al, 2000; Bostanian et al, 2003; Roy et al, 2005; Calvo et al, 2009; Drobnjaković et al, 2016)

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