Interspecific interactions between the larger grain borer Prostephanus truncatus and the maize weevil
Sitophilus zeamais were studied duringtwo storage seasons in maize stores, in Be´nin. Maize ears, randomly
sampled from farmers’ grain stores, were ‘reared out’, i.e., kept for 4 weeks under controlled conditions for F1
to emerge, and periodically sampled, in order to examine colonisation patterns of P. truncatus and S. zeamais.
For both storage seasons, P. truncatus and S. zeamais populations were sparsely aggregated and not associated
with each other. The degree and strength of association increased with each monthly sampling occasion with
the Ochiai, Jaccard and Dice indices of association. By the fourth samplingoccasion, P. truncatus was found
on most ears and on some ears in very high numbers (4300 insects). Almost all ears with P. truncatus
contained at least a few S. zeamais individuals, but many ears with S. zeamais contained no P. truncatus.
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