Flight activity in normal and active forms of Callosobruchus maculatus (F.) in a store in Nigeria

Abstract

A suction trap was run continuously in a Nigerian store containing cowpeas in order to capture flying adults of Callosobruchus maculatus. Of the 211 adults caught, 149 were females and 133 of these were of the active form. Adults were also removed from in all, 8 kg of cowpeas sampled on four occasions from the store and in these only one-third of the adults were active females. The numbers of adults caught by the traps were recorded hourly and from these records, using probability paper, two peaks of flight activity were detected, a small one with a mean at 07·20 hr ± 260 min and the main one at 17·50 hr ± 110 min. The beetles flew throughout the day and night with no inhibition by low light intensity. Temperature appears to be the most important factor and peak flight activity occurred at highest temperatures and low relative humidity. The first small peak activity in the morning was ascribed to the rise in temperature above the low ambient night temperatures which are probably lower than the threshold for the species.