Males cannibalise and females disperse in the predatory mite Phytoseiulus persimilis

Abstract

Cannibalism is a widespread phenomenon in nature, often occurring when food is scarce, for example among predators that have overexploited a local prey population. Instead of cannibalising, predators can disperse, thereby avoiding being cannibalised or cannibalising related conspecifics, which results in inclusive fitness loss. Theory on prey exploitation in ephemeral predator-prey systems predicts that predators may be selected to display prudent predation by dispersing early, thus saving food for their remaining offspring. This is especially advantageous when average relatedness in the local population is high. Less prudent predators refrain from dispersing until all prey are exterminated. These prey exploitation strategies may also have repercussions for cannibalism, especially when it is driven by food shortage. We therefore investigated to what extent adult females and males cannibalise or disperse after prey have been exterminated locally. We used two lines of the haplodiploid predatory mite Phytoseiulus persimilis that were selected for early and late dispersal, respectively. In wind tunnels, we observed the cannibalistic and dispersal behaviour of individual adult predators of these lines on a rose leaf with only conspecific larvae as food. Both selection lines behaved similarly, indicating that selection on dispersal behaviour did not result in correlated effects on cannibalism behaviour. Male predators stayed significantly longer on the leaf and engaged more often in cannibalism than females. The results suggest that there might be gender-specific differences in cannibalistic tendency in relation to dispersal. Future theoretical studies on the evolution of cannibalism and dispersal should take differences between the genders into account.

Artificial selection for timing of dispersal in predatory mites yields lines that differ in prey exploitation strategies

“…For example, females have higher energy requirements than males, because reproduction is costly (Harshman & Zera, 2007) and we can therefore expect that females and males might have different exploitation strategies. Indeed, a previous study has shown that females of P. persimilis disperse earlier than males when food is limited (Revynthi et al, 2020). Similar behavior was observed in the current and previous population dynamics experiments (Revynthi et al, 2018).…”

“…Indeed, a previous study has shown that females of P . persimilis disperse earlier than males when food is limited (Revynthi et al, 2020 ). Similar behavior was observed in the current and previous population dynamics experiments (Revynthi et al, 2018 ).…”