Abstract

The kolanut weevil, Balanogastris kolae is usually referred to as a field-to-store pest as their infestation starts in the field and continues in storage. The distribution preferences of the weevil were investigated with a view of determining their vertical and horizontal distribution in storage baskets. The kola pods used for this experiment were obtained from kola groves at the Cocoa Research Institute of Nigeria (CRIN), Ibadan. After harvesting the pods, the nuts were extracted, skinned, cured and stored in baskets lined with banana leaves for 2 weeks (according to the traditional methods) before transferring them to experimental baskets. The weevils recorded in basket A were 74% which was significantly different (p < 0.05) from the 16.5% in basket B and 9.5% in C. The horizontal distribution at the peripheral section (D) of the basket was 70.1%. This was significantly (p < 0.05) higher than the distribution at the core section (E), which was 29.9%. Therefore in the storage baskets, 74.0% of adult weevils exhibited positive geotaxis while 70.1% had affinity for lateral distribution. Farmers should therefore concentrate more at the bottom section of the basket during regular sorting and removal of weevils and infested nuts from kolanuts in storage baskets.

Key words: Kolanuts, weevil, exposure, distribution, baskets.