Protection of stored cowpea from Callosobruchus maculatus (F.) attack by some plant extract formulations in different storage sacks
The efficacy of different formulations of the Citrullus colocynthis active ingredients in powder or emulsifiable concentrate in cowpea stored in different storage sacks (damour, polyethylene, gunny plastic and jute) protection against Callosobruchus maculatus attack was evaluated. All the formulations used were effective bioinsecticides against C. maculatus. They secured considerable protection for the stored seeds for different periods, depending on the kind of storage sacks and the kind and the formulation rate used. Damour and polyethylene sacks proved to be highly suitable for storage of cowpea seeds treated with different formulations. They completely protected the seeds from infestation for seven months in the majority of formulations. No infestation appeared during seven months and hence no weight loss was detected in the stored seeds. Gunny plastic and jute sacks protected the seeds for shorter periods. They were considered to be less suitable for storing the treated cowpea seeds. The weight loss detected depended on the storage method and the rate of formulation used. All the tested formulations significantly reduced the number of eggs laid in comparison to control. Powdered formulation of alcohol and chloroform extracts of C. colocynthis, applied at the doses of 8 and 16 g/kg of seeds and 16 g/kg, respectively, were superior in comparison to other formulations used, as the oviposition deterrent index (ODI) was 100%. Moreover, no adult C. maculatus was recorded during seven months of storage when damour sacks for storing cowpea seeds treated with alcohol or chloroform extract powder formulations were used. Different formulations used had no adverse effect on seeds’ germination.