The Effect of the Time of Day and Different Day Length Conditions on Foraging Behavior of an Aphid Parasitoid, Lysiphlebus fabarum on Aphis fabae Scopoli

Animals that can estimate their desirable habitat quality are better able to accordingly adapt their life behaviors. The life cycles of parasitoids are so closely adapted as to match their hosts life behavior. Among the various host-parasitoid interactions, a peculiarity is the seasonal synchrony between host and parasitoid activity. The foraging and oviposition behaviors of Lysiphlebus fabarum as influenced by (1) a female’s previous experience of encountering different day length conditions in larval and in adult stages and (2) the time of day are investingated in this study. In order to test, L. fabarum females were individually released onto bean leaf disks infested with A. fabae and while continuous observations being made, the females’ proportional time allocations were assessed. Furthermore, numbers of aphid defensive behaviors including kicking, raising and swiveling of the body, releasing the plant and escape from attack and well as attempts to smear the attacker with cornicle secretions were recorded. Wasps that experienced only short day conditions spent more time in arenas than wasps that experienced other conditions, obtaining higher scores for the incidence and duration of all behaviors associated with parasitism. Furthermore, the females of this treatment parasitized more aphids than the two treatments the larvae of which were developed under long day conditions. Because of the high effect of treatment on patch residence time, the incidence or duration of various behaviors was expressed as a fraction of patch residence time and then re-analyzed. Data showed that the incidence and duration of all the behaviors were higher for females the larvae of which developed only under longlasting days. In the second experiment, foraging females behaved no differently in patch residence times, incidence or duration of various behaviors, and the number of aphids parasitized within the patch, either in the morning or in the afternoon