Discrimination against previously searched, host-free patches by a parasitoid foraging for concealed hosts

1. The foraging behaviour of the parasitoid wasp Halticoptera laevigata Thomson (Hymenoptera: Pteromalidae) was studied. This wasp attacks the first‐instar larvae of the fruit fly Myoleja lucida Fallén (Diptera: Tephritidae) within honeysuckle Lonicera xylosteum L. (Caprifoliaceae) fruits. It was hypothesised that, to forage efficiently, wasps should be able to maintain a systematic or at least non‐random search pattern on the level of the microhabitat, i.e. branches with fruits, and/or be able to recognise previously searched fruits. 2. Comparisons of observed patch visitation patterns on branches bearing uninfested fruits with expected values for systematic and random visitation patterns indicated that H. laevigata wasps visit patches randomly and do not avoid visiting host‐free patches that they have visited previously. 3. While wasps did not alter their search effort on uninfested fruits searched previously by conspecifics, they searched for much shorter times and probed less frequently for hosts on uninfested fruits that they had searched previously. 4. The results indicate that H. laevigata wasps engage in partially systematic search and increase their search efficiency through the recognition of self‐searched fruits. The reasons why partial rather than fully systematic search should be adaptive in this parasitoid are discussed.