Evaluation of the Insecticidal and Deterrence Properties of Pepper Fruit, Dennetia tripetala (G. Baker) and Ginger Zingiber officinale Roscoe against Maize Weevil Sitophilus zeamais (Motsch.)

Abstract

Laboratory studies were conducted to evaluate the insecticidal and deterrent properties of pepper fruits (Dennetia tripetala) and ginger (Zangiber officinale) against maize weevil Sitophilus zeamais. One hundred grams of maize were weighed into 500ml kilner jar and treated with 0%, 1%, 5% and 10% powders each of D. tripetala and Z. officinale in a 4x4 factorial combinations on weight by weight (w/w) basis. The experiments were laid out in a Complete Randomized Design (CRD) and replicated four times. Results showed significant (P<0.05) percentage mean adult mortality of 13.34, 15.34 and 16.33 post treatment with D. tripetala and 11.33, 14.33 and 18.7 post treatment with Z. officinale at 10% after 24, 48 and 72h respectively over other levels. At 5%, the percentage adult mortality was significantly higher than at 1% and the control after 72 hours post exposure. Significantly (P<0.05) higher percentage adult mortality was also observed in the 10% combinations of the tested plant products of 4, 5.33 and 5.67 after 24, 48 and 72 hours of storage for D. tripetala and Z. officinale respectively. Also, significantly (P<0.05) higher adult mortality 1065.66 and 1070.33 were observed on Z. officinale and D. tripetala treated seeds after 10 weeks storage period. The 10% treatment combination of the tested powders also showed significantly (P<0.05) higher adult mortality, which was however, not significantly different(P>0.05)  from the 10% D. tripetala and 5% Z. officinale and also10% Z. officinale and 5% D. tripetala. Significantly (P<0.05) higher percentage adult deterrence of 46.53% was obtained when 10% D. tripetala was applied compared to the other levels. Significant (P<0.05) reduction in the number of adults that emerged was observed when treatment concentrations increases. The studies showed that extracts of Z. officinale and D. tripetala can be used effectively singly or in combination as grain protectants in stored maize for the management of S. zeamais.

Keywords: Dennetia tripetala, Sitophilus zeamais, mortality, deterrence, protectants