Kin recognition by the predatory mite Iphiseius degenerans: discrimination among own, conspecific and heterospecific eggs

1. Kin recognition is important in many social insects, but has also been found in several nonsocial insects such as parasitoids, where it plays an important role in oviposition behaviour. In nonparasitic arthropods, however, the fitness of ovipositing females also depends on the oviposition behaviour of related and unrelated females, especially when eggs are oviposited in clusters by several females.

2. In this paper, kin recognition in a predatory mite, Iphiseius degenerans, is studied. Mothers are capable of determining offspring sex ratio, and cannibalism on juvenile stages is a common phenomenon. Therefore, kin recognition is expected to occur in this predator.

3. Oviposition behaviour of this species is particularly interesting because it alternates foraging bouts in flowers with deposition of a single egg at a time on a leaf, where predation risk is lower. The eggs are not scattered but are deposited in clusters. After feeding in a flower, females therefore have to locate clusters of eggs.

4. Experiments on two-choice arenas showed that females prefer to oviposit close to conspecific eggs rather than close to heterospecific eggs. Females also showed a preference for ovipositing near closely related conspecific eggs rather than more distantly related eggs.

5. Females tended to displace eggs of heterospecifics more frequently than eggs of conspecifics.

6. These behavioural observations show that females can discriminate not only between conspecific and heterospecific eggs but also between eggs that vary in degree of relatedness. This enables females to oviposit in clusters containing related eggs and thus avoid cannibalism by non-kin and/or produce adaptive sex ratios despite the fact that the adults commute between flowers and leaves.