Intraguild interactions between the predatory hoverfly Episyrphus balteatus (Diptera: Syrphidae) and the Asian ladybird, Harmonia axyridis (Coleoptera: Coccinellidae): Effect of larval tracks

Raki Almohamad,Eric Haubruge,François J Verheggen,Frédéric Francis

doi:10.14411/eje.2010.004

Abstract

The effects of the larval tracks of Episyrphus balteatus DeGeer (Diptera: Syrphidae) and Harmonia axyridis Pallas (Coleoptera: Coccinellidae) on the egg laying behavior of females of the predatory hoverfly E. balteatus were investigated in two-choice experiments. The oviposition response of H. axyridis to larval tracks of E. balteatus was also tested in one-choice experiments. Gravid E. balteatus females laid significantly fewer eggs on leaf discs with aphids and contaminated with tracks of conspecific or heterospecific larvae than on control leaf discs. H. axyridis females laid similar numbers of eggs in Petri dishes with aphids and contaminated with the tracks of E. balteatus larvae as in control Petri dishes. This indicates that E. balteatus females lay fewer eggs at sites where there are conspecific and heterospecific larval tracks, whereas the tracks of the syrphid larvae did not deter H. axyridis females from laying eggs.

Highlights

Aphidophagous hoverflies and ladybirds are known to exploit temporary aphid colonies as food resources and significantly suppress aphid abundance (Chambers & Adams, 1986; Dixon, 1985; Dixon et al, 1997; Lee & Kang, 2004)
It has been demonstrated that the survival of the larvae of these aphid predators and their efficiency in reducing aphid populations mainly depends on the quality and the quantity of the patches of aphid prey (Kan, 1988; Hemptinne et al, 1993; Kindlmann & Dixon, 1993; Almohamad et al, 2007, 2008)
Compared to the control, gravid H. axyridis females were not deterred from ovipositing by the tracks of E. balteatus larvae (Fig. 2)

Summary

Introduction

Aphidophagous hoverflies and ladybirds are known to exploit temporary aphid colonies as food resources and significantly suppress aphid abundance (Chambers & Adams, 1986; Dixon, 1985; Dixon et al, 1997; Lee & Kang, 2004). Several authors have shown that ovipositing insect predators respond to chemical cues (i.e. ovipositiondeterrents) indicating that a prey patch is already being exploited by conspecific larvae (RĤžiþka, 1994, 1996, 1997; Doumbia et al, 1998; RĤžiþka & Havelka, 1998; Yasuda et al, 2000; Oliver et al, 2006; Michaud & Jyoti, 2007) Most of these studies have focused on coccinellids and chrysopids, while studies on syrphids are very recent and scarce (e.g. Scholz & Poehling, 2000; Pineda et al, 2007; Almohamad et al, 2008; Putra et al, 2009). The hoverfly E. balteatus is usually the most abundant syrphid aphid predator in Europe, where it naturally occurs in high numbers in numerous crops (Tenhumberg & Poehling, 1991; Gilbert, 1993; Colignon et al, 2001; Miñarro et al, 2005) These two aphid predators are known to be important biocontrol agents of aphid populations (Chambers & Adams, 1986; Chambers, 1988; Koch, 2003; Roy et al, 2006; Pineda & Marcos-García, 2008)

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