Impact of kaolin-based particle film dusts on Callosobruchus maculatus (F.) and C. chinenesis (L.) after different storage periods of treated broad bean seeds
Adults of Callosobruchus maculatus (F.) and C. chinenesis (L.) were exposed to broad been seeds treated with kaolin-based particle film dusts (powder) at different concentrations 1.0, 0.8, 0.6, 0.4, 0.2, 0.1, 0.05, 0.025% w/w and untreated control. The effect of kaolin powder film was clearly effective in the first month of storage period of the treated seeds resulted a 100% protection of treated seeds at high concentrations from 1.0 to 0.2 w/w for both tested insects. After three months of storage of the treated seeds only the highest two concentrations 1.0 and 0.8 w/w gave a 100% protection for both tested insects. After six months of storage of the treated seeds, kaolin powder still could protect the broad bean seeds against C. maculatus and C. chinensis attacks although the efficacy of kaolin powder decreased with aging. Thus, residual effect of Kaolin powder film was reduced by prolongation of the storage period. A negative relationship was recorded between the kaolin concentration and the tested biological parameters (number of eggs laid, hatchability, developmental period, F1 adult emergence, and seeds weight loss%) for both tested insects C. maculatus and C. chinensis. The comparison of the kaolin application methods, kaolin powder was more effective than kaolin suspension which gave a better protection to the treated seeds. Broad bean seeds viability was slightly affected by kaolin powder application, the reduction of germination was most greatest at highest concentration. Keywords: Kaolin powder, Broad been seeds, Protection, Callosobruchus maculatus (F.), C. chinenesis (F.)
