Oviposition behaviour of the cowpea seed beetle, Callosobruchus maculatus

The activity of female Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), the cowpea seed beetle, between making contact with a potential host seed and egg deposition is analysed in detail on cowpeas, mung beans and mung beans bearing conspecific eggs. The data differ from previous accounts in that descriptors do not ascribe function (inspection, patrolling, etc.) to the activities but are restricted to observable postures and movements. From the twenty-four discrete patterns of behaviour, kinetograms are constructed following analysis of a three-dimensional contingency table in which expected values have been calculated in eight models assuming various considerations of independence, from complete independence of each behavioural element to alternative two-way interactions among the three variables, viz preceding behaviour, following behaviour, and host. Core transitions were determined by calculation of standardized residuals, by their high conditional probabilities and transitional frequencies. There is a very clear sequence of oviposition behaviour, parts of which are the same on all three hosts. The simplest behavioural sequence was observed on mung beans which was shown to be the most acceptable of the three hosts. The presence of an egg resulted in a diversification of behaviour, The method provides a quantitative method of describing and comparing behavioural sequences and hence a means of determining one aspect of the acceptability of different hosts. Using this method the occurrence of a behavioural sequence has been determined with an objective statistical basis applicable to numerous multitrophic relationships.