Carbon dioxide narcosis modiWes the patch leaving decision of foraging parasitoids
Résumé
Gleaning information is a way for foragers to adjust their behavior in order to maximize their Wtness. Information decreases the uncertainty about the environment and could help foragers to accurately estimate environmental characteristics. In a patchy resource, information sampled during previous patch visits is eYcient only if it is retained in the memory and retrieved upon arrival in a new patch. In this study, we tested whether the braconid Asobara tabida, a parasitoid of Drosophila larvae, retains information gleaned on patch quality in the memory and adjusts its foraging behavior accordingly. Females were anesthetized with CO2 after leaving a Wrst patch containing a diVerent number of hosts and were allowed to visit a second patch containing only kairomones. CO2 is known to erase unconsolidated information from the memory. We show that in the absence of a short CO2 narcosis, females responded according to their previous experience, whereas anesthetized females did not. The anesthetized females stayed a given time in the second patch irrespective of what they encountered before. CO2 narcosis had no eVect on the residence time of the non-experienced females in a patch containing hosts or only kairomones in comparison with the non-anesthetized females that had a previous foraging experience. We conclude that CO2 narcosis erases the eVect of the previous patch quality, perhaps due to a memory disruption. Direct information processing is likely to be involved in parasitoid decision making through retention of the information on the previous patch quality into a CO2 sensitive memory.