Integration of multiple intraguild predator cues for oviposition decisions by a predatory mite

Abstract

In mutual intraguild predation (IGP), the role of individual guild members is strongly context dependent and, during ontogeny, can shift from an intraguild (IG) prey to a food competitor or to an IG predator. Consequently, recognition of an offspring's predator is more complex for IG than classic prey females. Thus, IG prey females should be able to modulate their oviposition decisions by integrating multiple IG predator cues and by experience. Using a guild of plant-inhabiting predatory mites sharing the spider mite Tetranychus urticae as prey and passing through ontogenetic role shifts in mutual IGP, we assessed the effects of single and combined direct cues of the IG predator Amblyseius andersoni (eggs and traces left by a female on the substrate) on prey patch selection and oviposition behaviour of naïve and IG predator-experienced IG prey females of Phytoseiulus persimilis. The IG prey females preferentially resided in patches without predator cues when the alternative patch contained traces of predator females or the cue combination. Preferential egg placement in patches without predator cues was only apparent in the choice situation with the cue combination. Experience increased the responsiveness of females exposed to the IG predator cue combination, indicated by immediate selection of the prey patch without predator cues and almost perfect oviposition avoidance in patches with the cue combination. We argue that the evolution of the ability of IG prey females to evaluate offspring's IGP risk accurately is driven by the irreversibility of oviposition and the functionally complex relationships between predator guild members.

Figure 1

Prey patch selection after first choice, and 1, 2, 3, 4, 5, 6 and 24 h by (a, c, e, g) IG predator-naïve and (b, d, f, h) predator-experienced P. persimilis females given a choice between a prey patch with only live spider mites (white bars) and a prey patch with live and dead spider mites with and without direct cues of the IG predator A. andersoni (black bars). (a, b) IG predator eggs (N = 32 and 27, respectively, for naïve and experienced); (c, d) traces of IG predator females (N = 30 and 23, respectively); (e, f) IG predator eggs and traces of IG predator females (N = 25 and 26, respectively); (g, h) without direct predator cues (N = 21 and 24, respectively).

Figure 2

Proportion of eggs (mean + SD) deposited by P. persimilis females in the patch with live and dead spider mites and with or without direct IG predator cues of A. andersoni when given a choice between a prey patch with only live spider mites and a prey patch with live and dead spider mites with and without direct predator cues of A. andersoni.

Figure 3

Total egg production (both patches combined; mean + SD) by IG predator-naïve and predator-experienced P. persimilis females given a choice between a prey patch with only live spider mites and a prey patch with live and dead spider mites with and without direct cues of the IG predator A. andersoni.