Comparative efficacy of insecticidal plants on the management of groundnut bruchid (Caryedon serratus)

Laboratory study was conducted to determine the efficacy of four insecticidal plant extracts Azadirachta indica A. Juss., Lantana camara L. (Verbenaceae), Eupatorium odoratum L. (Asteraceae), Tephrosia vogelii Hook against the groundnut bruchid beetle ( Caryedon serratus ), and a synthetic insecticide (Cypermethrin) (10EC)) under ambient condition of temperature and relative humidity (30°C and 72%). Two hundred grammes of unshelled groundnut was weighed into jute bags and treated with powders of the insecticidal plants. Both treated and untreated bags of groundnut were then infested with newly emerged adult of C. serratus (20 per bag) and covered. The experiment was laid out in a Completely Randomized Design (CRD) with four replications. Parameters assessed included number of egg oviposited, number of eggs hatched (eclosion) and number of adults that emerged from each treatment, total developmental period (egg adult), sex ratio of the emerged adults and finally percentage germination of the treated seeds. Data collected were analyzed using analysis of variance and means were separated using Duncan multiple range tests at 5% level of significance. The lowest mean number of eggs was laid in A. indica, L. camara and T. vogelli treated seeds compared with the control which recorded the highest number. Similarly, results obtained showed that L. camara, T. vogelii, and A. indica powder significantly reduced damage by C. serratus and increased germination percentage compared with E. odoratum and control. In conclusion, L. camara, T. vogelii, and A. indica have the potentials as alternatives to synthetic insecticides in the management of C. serratus by farmers.