Response of the Seed Beetle, Callosobruchus maculatus (F) to Differences in Seed Size in a Variety of Cowpea, Vigna unguiculata (L) Walp

T.I.OFUYA

ABSTRACT
This study investigated selective oviposition behaviour of the seed beetle, Callosobruchus maculatus (F.) originating from Bomo (Nigeria), Burkina Faso and Sierra Leone when provided with cowpea, Vigna unguiculata· (L.) Walp. (California
black-eyed variety) seeds of different sizes. Oviposition preference and effects of variation in seed size 011 food consumption, development, reproduction arid survival of the beetles were determined. Females of the three beetle populations always laid more eggs on the large seeds. More eggs were also laid on the medium seeds than on the
small seeds. For each beetle population, seed size did not influence development time. Larvae generally consumed more food from large seeds and yielded heavier females which were more fecund. Larvae of beetles from Burkina Faso were generally more voracious. Significantly. more adults emerged from the large seeds than from the small seeds, following an initial density of 10 or more hatched eggs per
seed. The results are discussed in relation to previously published reports.

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