Efficacy of selected insecticidal plant dusts on Sitophilus zeamais Motschulsky (maize weevils).

Abstract

The aim of the study was to evaluate the effect of using plant dusts as an alternative method controlling pests on stored maize. Maize grains infested with maize weevils was collected from maize market stores, the maize weevils were allowed to multiply. Plants samples were collected, air dried for four weeks, crushed into powders, weighed and stored within a dry atmosphere in polythene bags. 20-30 weevils were randomly selected and added to 250g of maize plus 50g of pesticidal dusts, these were then sealed in a storage bag containing pores to allow circulation of air. The sealed bags were kept for 1.5-2 month at room temperature, after which the bags were opened and the extent of infestation to the seeds assessed. Positive and negative controls were set in a similar manner. Brucea antidysenteria Miller (roots), Securidaca longipedunculata, and Solanum incanum L. had 0.99, 1.08, and 1.44 maize weevil infestation rates respectively. The three plant samples dusts showed that they could reduce fresh maize from being infested with maize weevils. It was concluded that plant dusts could provide effective but short term insecticidal protection against storage pests but combinations with certain stable plant dusts like Brucea antidysenteria Miller could increase efficacy and duration of protection. Key words: Efficacy, plant pesticidal dust, maize weavils