Relationship between Adult Feeding and Emigration from Beans of Azuki Bean Weevil, Callosobruchus chinensis LINNE (Coleoptera : Bruchidae)

The life history of the azuki bean weevil, Callosobruchus chinensis LINNE in the field, especially the process of weevil emigration from store to field has not been made clear. The mechanism of the emigration process was analyzed with specially designed apparatus in the laboratory. The presence of beans firmly suppressed emigratory activity in the first five days of adult life. The supplied diet (saccharose solution and yeast) moderately suppressed the emigratory activity, especially of older weevils. Males emigrated density-independently throughout their longevity, while females emigrated density-dependently until the fifth day and thereafter density-independently. Supply of the diet after different periods of starvation resulted in elongation of longevity and recovery of fecundity. When the diet was supplied on the first to third day after emergence, the total number of eggs and mean longevity were two and three times, respectively, as many as the control for whom no diet was supplied for adults. When diet was started on the fifth day, the fecundity in two days increased to the same level as when the diet was started just after emergence. The diet supplied adults nine days after emergence did not result in an increase of either fecundity or longevity.