Insecticidal potency of mixtures of plant powders and Actellic SuperTM (Pirimiphos-methyl + Permethrin) on Callosobruchus chinensis F. and Sitophilus zeamais Motch

Abstract

Insect pests still cause substantial quantitative and qualitative grain loss ranging from 20 to 100% in small holder farming systems in tropical countries. Synthetic pesticides are recommended as stop gap measures for the management of stored product insect pests. However, their application has not been fully exploited in small scale farming due to environmental, health, and economic concerns. As a result, new researches have shifted focus to exploiting pesticidal plants as alternatives to synthetic pesticides. Therefore, the current study evaluated mixtures of plant powders and reduced amount of Actellic super^TM (pirimiphos-methyl + permethrin) as alternative insecticide formulation against Callosobruchus chinensis and Sitophilus zeamais. Green grams and wheat grains were mixed with a mixture of plant powders in the ratios of 1:1, 1:3 and 1:9 to obtain four rates (0.0, 2.0, 6.0 and 10%w/w). Grains and plant powders were also mixed with reduced amount (10, 25, and 50 %) of recommended rate of Actellic Super^TM to obtain dosages as above. Twenty unsexed adults, 1-5 day old S. zeamais and C. chinensis were introduced into treated grains. The mixture of C. lusitanica: T. vogelii powders in the ratios of 1:1, 1:3 and 1:9 caused mortality in C. chinensis of 55, 95 and 85%, respectively. At the same ratio, E. saligna: L. camara mixture produced mortality in S. zeamais of 77, 82, and 85% respectively. In mixture of C. lusitanica and T. vogelii and reduced amount of Actellic Super^TM by 50% the mortality of C. chinensis was 85 and 80 % respectively. Similarly, E. saligna and L. camara and reduced amount of Actellic Super^TM by 50% caused a mortality of S. zeamais of 48 and 97% respectively. The application of plant powders and reduced amounts of synthetic insecticide has the potential to be applied in stored product pest control