Abstract
To identify the cue eliciting the switchover in the searching behavior of Coccinella septempunctata, the duration of area-concentrated search (GUT: giving-up time) was determined by the method described by NAKAMUTA (1982) after each of the following five feeding stimuli was provided: (a) contact with an aphid (Myzus persicae), (b) biting an aphid (an aphid was immediately removed after the beetle bit the prey), (c) consumption of an aphid, (d) contact with an agar block (ca. 2×2×2mm), (e) consumption of an agar block with a droplet of aphid body fluid on it. Switchover in searching behavior was observed in every case. It is suggested that the contact with a prey rather than its consumption is the cue that elicits the switchover. On the other hand, the GUT varied with the feeding stimulus (a≈d<b<e<c). The GUT was positively correlated with the feeding time of an aphid which represented the size of the prey consumed. To determine whether the GUT was controlled by the amount or by the size of the prey consumed, the GUT was measured after the labybeetle had fed successively on a large and a small aphid (Sequence A) and after it had fed on a small followed by a large aphid (Sequence B). Although the beetle consumed the same amount of aphids both in Sequence A and B, the beetle showed a longer GUT in Sequence B than in Sequence A. Therefore, it can be concluded that the GUT is determined by the size of the prey most recently consumed, which is not consistent with the predictions based on the classical patch use model developed by CHARNOV (1976).
