Exploration of wheat leaves byCoccinella septempunctata L. (Coleoptera,Coccinellidae) larvae

A new method for the quantification of insect movements on leaves is presented and applied to larvae of a wheat aphid predator, C. septempunctata. The method results from behavioral definition of positions adopted by this predator during its advance along the wheat leaf. Through a factor analysis of multiple correspondences, the method allowed specification of some aspects of predator movements on plants, especially the frequency of position associations, to give a new definition of local search and to describe some behavioral interactions with aphids. The consequences for predator efficiency are discussed.     

Diel rhythmicity of prey-search activity and its predominance over starvation in the lady beetle, Coccinella septempunctata bruckii

ABSTRACT. The locomotor activity of the lady beetle, Coccinella septempunctata bruckii Mulsant (Coleoptera: Coccinellidae), was recorded during food deprivation in LD 16:8 h and continuous light. Activity was relatively low immediately after the lady beetle was fed to satiation but increased from 4 to 24 h later. It thereafter gradually decreased to a low level when the food was withheld for several days. Over a period of 10 days of starvation the beetles showed a high level of activity throughout the photophase and a low level during the scotophase in LD 16:8 h. In continuous light this rhythmic pattern persisted, with a free-running period of c. 22 h, significantly shorter than 24 h. The results suggest that the endogenous circadian timing predominates over 'hunger' as a determinant of search activity. The lady beetle accepted and consumed aphid prey presented at night, but the number of prey consumed was significantly lower than in the light. This suggests that, during the dark, activity related to prey-searching is suppressed, though lady beetles are able to accept and consume prey even at night.