The effect of predation risk on spermatophore deposition rate of the eriophyoid mite, Aculops allotrichus.

Katarzyna Michalska

doi:10.1007/s10493-015-9998-9

Abstract

Eriophyoids are minute herbivores in which males deposit spermatophores on a substrate while females, independent of the presence of males, pick up sperm (sex dissociation). Their most dangerous enemies are phytoseiid mites. Eriophyoids can successfully avoid the predation by, e.g., forming galls in which they live, by inhabiting narrow spaces on plants, or by climbing up leaf trichomes for the time of quiescence. All these behaviours, however, are fixed and independent of the actual risk of predation. The aim of this study was to examine whether eriophyoids can respond to the cues of predation risk and how this could affect their spermatophore deposition rate. Aculops allotrichus is a vagrant eriophyoid which inhabits leaves of the black locust tree, Robinia pseudoacacia. On leaf arenas with injured conspecifics (pierced with a fine needle which simulated the attack of phytoseiids), single males of Ac. allotrichus deposited a similar number of spermatophores as on control, ‘clean’ leaves. They did not respond to the cues left by the non-enemy, yeast-fed acarid mite Tyrophagus putrescentiae either. However, they deposited significantly fewer spermatophores on leaf arenas previously exposed to the presence of the eriophyoid-fed phytoseiid mite Amblyseius swirskii. This is a first report indicating that eriophyoids can respond to the cues left by predators and change their reproductive activity accordingly. The ultimate and proximate factors that may influence the behaviour of Ac. allotrichus males are discussed.

Highlights

When searching for mates, courting or copulating, males and females tend to become more conspicuous and vulnerable to predators (Gwynne 1989; Rowe 1994; Kemp 2012)
On the leaf arenas previously exposed to predators, males of Ac. allotrichus deposited significantly fewer spermatophores than they did on clean leaves (U = 21, P = 0.028; both N = 10) (Fig. 1a)
Males of Ac. allotrichus significantly decreased their spermatophore output on leaf arenas previously exposed to the phytoseiid mites

Summary

Introduction

When searching for mates, courting or copulating, males and females tend to become more conspicuous and vulnerable to predators (Gwynne 1989; Rowe 1994; Kemp 2012). In pairing taxa, the mating frequency, intensity and duration of courtship or female guarding often diminish under an elevated predation risk (Sih et al 1990; Acharya and McNeil 1998; Koga et al 1998; Maier et al 2000; Taylor et al 2005; Oku and Yano 2008) This applies to species reproducing via spermatophores deposited on a substrate, e.g., the salamander Desmognahtus ochrophaeus Copein males, which inhibited courtship behaviour and spermatophore deposition in the presence of a predator (Uzendoski et al 1993). Recent findings reveal that phytophagous mites, such as spider mites, can respond to predation risk by avoiding leaf patches with cues of phytoseiid mites or other predatory arthropods and/or injured conspecifics on them (Kriesch and Dicke 1997; Grostal and Dicke 1999, 2000; Magalhaes et al 2002; Oku et al 2003; Choh and Takabayashi 2007; Bowler et al 2013; Otsuki and Yano 2014). They reduce oviposition when under elevated predation risk (Grostal and Dicke 1999, 2000; Oku et al 2004; Skaloudovaet al. 2007; Fernandez-Ferrari and Schausberger 2013; Hackl and Schausberger 2014)

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