Behavioural responses of the maize weevil, Sitophilus zeamais, to host (stored-grain) and non-host plant volatiles.

BACKGROUND

Four-arm olfactometer bioassays were conducted to assess the behavioural responses of the adult maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), to harvested seeds of host plants, i.e. white maize, yellow maize (Zea mays L.) and winter wheat (Triticum aestivum L.) (Poaceae), and non-host plant materials, i.e. alligator pepper, Aframomum melegueta (Rosk) K. Schum (Zingiberaceae), rhizomes of ginger, Zingiber officinale (Roscoe) (Zingiberaceae), and West African black pepper, Piper guineense Thonn and Schum (Piperaceae). Additional bioassays with host plant volatiles were conducted in the presence of three doses of non-host plant materials.

RESULTS

Both sexes of the weevil showed strong attraction to maize and wheat seed volatiles, but were significantly repelled (P < 0.001) by odours from A. melegueta, Z. officinale and P. guineense. Furthermore, S. zeamais avoided maize and wheat seeds presented in combination with the non-host plant material at 10% (w/w) and 33% (w/w) levels.

CONCLUSIONS

A. melegueta, Z. officinale and P. guineense have the potential for use in the protection of stored grains by resource-poor farmers with local access to these plants.