Protection of maize against Sitophilus zeamais Motsch using seed extracts from some indigenous plants

Petroleum ether extracts of the seeds of eight indigenous plants were tested for their efficacy as grain protectant against the maize weevil, Sitophilus zeamais Motsch. at a temperature of 28 +/- 2 degreesC and relative humidity of 75 +/- 5 %. The plants, whose seeds were used, include Aframomum melegueta K. Schum., Piper guineense Schumach. and Thonn., Jatropha gossypifolia L., Arachis hypogaea L., Citrus sinensis Osbeck, Parkia clappertoniana L., Adansonia digitata L., and Elaeis guineensis Jacq, at concentrations of 1 %, 2 % and 3 %. Results showed that A. hypogaea had the greatest insecticidal activity producing 100 % mortality of the weevils within 24 h of treatment, was most persistent of all the oil extracts tested and was still toxic after 28 days post treatment. P. guineense and E. guineensis also had high insecticidal activity at higher concentrations producing 90.0 % and 73.3 % within 96 h after treatment at 3 % concentration. The least effective and least persistent were A. melegueta and C. sinensis, The plant extracts did not affect the water absorption capacity of the seeds since the results obtained from the treated seeds were similar to those of the control seeds. The oil extracts did not adversely hamper seed viability.