Combined effect of grain solarisation and oiling on the development of Sitophilus zeamais Motsch

Abstract

The maize weevil (Sitophilus zeamais Motsch. Coleoptera; Curculionidae) is one the most important storage pests of maize in East Africa. We investigated the combined efficacy of grain oiling with vegetable oil and 2- hour grain solarisation on S. zeamais damage to maize. Maize, Longe 1 variety was treated at dosages of 0, 1, 2, 4 ml per kg of grain, and artificially inoculated with 12- adult S. zeamais weevils. Combination of grain oiling and solarisation of grain at 1, 2 and 4 ml per kg significantly reduced weevil emergence (F=3.06, P< 0.001) compared to the singular treatments. Solarised grain had 5.5 ± 0.3% damage compared to less than 1% damage where grain was both solarised and oiled at 1, 2 and 4 ml per kg dosage levels. Oiled and unsolarised maize grain treatments significantly (F= 18.27, P< 0.001) had better percentage viability at 93.0 ± 0.7; 91.5 ± 0.9, 91.3 ± 0.9 at 1,2, 4 ml per kg respectively, compared to 76.5 ± 3.7 for the untreated maize grain. Combined oiling and solarisation provides residual grain protection to maize against S. zeamais on maize without compromising quality and provides an alternative management option for the pest.