Defensive and Offensive Behavioral Interactions between Shelter-Building Caterpillars and Hunting Wasps.

Abstract

Many animals build shelters to avoid predation, but some predators cope with these shelters to prey on them. To explore the behavioral interactions between shelter-building prey and their predators, we investigated the shelter defenses of two caterpillar species (Lepidoptera: Crambidae) and the hunting behavior of each predator species (Hymenoptera: Vespidae: Eumeninae) under laboratory conditions. Female wasps of Anterhynchium flavomarginatum and A. gibbifrons were observed attacking the larvae of Haritalodes derogata and Demobotys pervulgalis (Lepidoptera: Crambidae), which construct open and closed leaf shelters, respectively. The attack behaviors differed between the two wasp species. Anterhynchium flavomarginatum employed two attack strategies: (I) boring holes in shelters and driving caterpillars out, and (II) invading shelters and searching for prey inside. In contrast, A. gibbifrons utilized a single strategy: cutting the silk threads binding the leaves with their mandibles to open the shelters and search for prey inside. Approximately half of the prey caterpillars could avoid predation; the shelter morphology and behavior of each caterpillar species likely contributed to evading the wasps. Each caterpillar species may have adapted a specific anti-wasp defense, while each wasp species may have acquired offensive traits to overcome the defense of each prey.