African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6858

Article in Press

Repellent effect of snake bean (Swartzia madagascariensis Desv.) pod powder on maize weevil (Sitophilus zeamais Motschulsky) on stored maize (Zea mays) grain

Handsen Tibugari

A research to examine the repellent effect of snake bean (Swartzia madagascariensis) pod powder on maize weevils (Sitophilus zeamais Motschulsky) on stored maize (Zea mays)grain was carried out in Women’s University in Africa farm laboratory in Marondera from March to May 2015 (3 months). A bioassay consisting of a rectangular flat-bottomed container was used to evaluate the repellence of S. madagascariensis. Two small bowls with treated and untreated maize grain were placed at the bottom of the container equidistance from the centre. The plant powder was evaluated at three concentrations (25g, 50g and 75g) and Actellic Super TM 2% dust (2g) included as a positive control. Alternate treated and untreated maize grains (100 g) were placed in the two plastic bowls. The treatments were arranged in a Completely Randomised Design with 3 replicates per concentration including a no-choice control with untreated maize in all portions. For each treatment, 20 adult weevils (9 days) were released at the centre of the basin. Weevil counts were taken on twelve hour basis for 48 hours to establish percent repellence. The magnitude of repellence of the weevils was significantly (P< 0.05) influenced by concentration of powder applied and exposure period. Maize grains treated with 75g of the pod powder of S. madagascariensis had the highest percent repellence value of 83.3 % at the 48 hour exposure time. The results from this study showed that S. madagascariensis exhibited contact-repellent properties against S. zeamais and that the test insects made oriented movements away from treated grains to get acceptable food as manifested in the alternate treated-untreated bioassay system. Although insects have a tendency to make movements and aggregate in a certain direction when exposed to unfavourable conditions like chemicals, it can be concluded from this study that the pods of S. madagascariens have the potential to repel weevils. The powder can be lined in granaries and on grain storage bins. Farmers may integrate the synthetic pesticides and S. madacascariensis pod powder to line their grain storage bins for effective control of weevils. It is recommended that further research be carried out on the effect of snake bean pod powder on mortality of weevils. Key words: Repellence, Swartzia madagascariensis, Sitophilus zeamais, storage, maize grain

Keywords: Snake bean, maize weevil, integrated pest management, storage.