Efficacy of some cu.ltural management methods on Callosobruchus chinensis (L) infestation during storage of pigeonpea seed

Abstract

Studies were conducted at Kawanda Agricultural Research lnstiuite to determine the efficacies of three storage practices viz: traditional mud-straw-cowdung silo " tua" storage, pod storage and storage of split seeds, on the management of Callosobruchus chinensis infestations in dried pigeon pea seeds. Lowest pigeonpea seed infestation was observed in sealed "tua", followed by loosely covered "tua" (2,512 insects and 3.81% seed damage), and the highest in .sack stored pigeonpea. Higher temperatures were observed in the " tua" (scaled " tua" 36.2°C, loosely covered "tua" 31.8°C) than in sack storage (25.5°C). Seed viability was also higher in " tua" (sealed 72.7% , loosely covered 76.3%) than in sack stored seeds (35.0%). Pod stored pigeonpea was effective in controlling C. chinensis populations, with infestation and seed damage of only 3.9 insects (all dead) and 0.04% respectively, compared to 45,000 insects and 19.8% respectively, in seed stored trials. Pod stored pigeonpea also ma intained higher seed viability (85.8%) than sack stored pigeonpea (45.1 %). Pigieonpea splitting depressed infestation by C. chinensis, reducing pest numbers, from 320 insects on the first month of storage to 10 insects on the third month. Whereas in whole stored seeds, there wns a sharp rise in pest population from 900 in first month of storage to over 10,000 on third mouth.