Population fluctuations of two bruchid species Callosobruchus maculatus (F.) and Bruchidius atrolineatus (Pic) (Coleoptera Bruchidae) and their parasitoids Dinarmus basalis (Rondani) and Eupelmus vuilleti (Crawford) (Hymenoptera, Pteromalidae, Eupelmidae) in a storage situation in Niger.
The biology of the bruchids Callosobruchus maculatus and Bruchidius atrolineatus and their parasitoids Dinarmus basalis and Eupelmus vuilleti was studied in a cowpea (Vigna unguiculata) store in Niger during November 1987-September 1988. Adults were collected in the store and caught in a trap outside. All 4 species appeared in the field when the crop was fruiting. Adults of B. atrolineatus were dominant at the beginning of storage and 2 generations occurred in the store. Adults of the 1st generation were sexually active, while those of the 2nd generation were in reproductive diapause. Of adults emerging from seeds, 80% left the store. The density of adults of C. maculatus was reduced at the beginning of storage. Several generations of apterous sexually active adults developed in the store. C. maculatus became predominant after 5-6 months. Alate adults, in reproductive quiescence, appeared during the rainy season and escaped from the store. D. basalis and E. vuilleti developed on both bruchid species and an increase in the numbers of bruchid larvae resulted in an increase in the parasitoid populations.