Predatory mites avoid ovipositing near counterattacking prey.

Attacking prey is not without risk; predators may endure counterattack by the prey. Here, we study the oviposition behaviour of a predatory mite (Iphiseius degenerans) in relation to its prey, the western flower thrips (Frankliniella occidentalis). This thrips is capable of killing the eggs of the predator. Thrips and predatory mites - apart from feeding on each other - can also feed and reproduce on a diet of pollen. Because thrips may aggregate at pollen patches, such patches may be risky for oviposition by the predatory mites. We found that, in absence of thrips, predatory mites lay their eggs close to pollen, but further away when thrips are present. Predatory mite eggs near pollen were killed more frequently by thrips than when they were deposited further away. The oviposition behaviour of the predatory mite was also studied in absence of thrips, but in presence of the alarm pheromone of thrips. This pheromone is normally secreted upon contact with predators or competitors. When applied close to the pollen. predatory mites oviposited significantly further away from it. When the alarm pheromone was applied away from the food source, most eggs were found near the pollen. These results indicate that female predatory mites show flexible oviposition behaviour in response to the presence of their counterattacking prey.