Evaluation of the Effect of Some Plant Extracts on Khapra Beetle Trogoderma granarium Everts

Abstract

Laboratory studies were carried out to determine the effects of some indigenous plant extracts on the larvae of Khapra beetle, Trogoderma granarium Everts.The lethal, antifeedant and repellency activity of powders and aqueous extracts of eight plants (e.g., Basil Ocimum basilicum, Henna Lawsonia inermis,, Senna Cassia senna, Lantana Lantana camara , Datura Datura alba, Usher Calotropis procera ,Chili Capsicum frutescens and Jatropha Jatropha curcas. ) were evaluated. Results revealed that at the three doses applied 10%,15% and 20%, all plants tested have played some potential insecticidal effect but C. procera , J. curcas and D. alba had the most high lethal and antifeedant effect on the 3rd larval instar of T.granarium. The highest percentages of dead larvae (5.87, 5.00 and 4.50) were scored at 30th day with concentration 20% of Usher, Jatropha and Datura respectively. Also, from the results, it is becoming evident that Datura and Jatropha displayed some potential as anti-feedants to the larvae. On the other side the repellency action of these plants was more effective against the pest .It was increased with increase in concentrations of the extract applied. However, Leaves water extract at 10% in C.procera showed the lowest repellency percentage (29.17%) class II, while the higher repellency effects were obvious at higher concentration 20% in J.curcus(77.15%) class IV. In the Weevil perforation index experiments (WPI), plant extracts of Datura, Usher and Jatropha were evaluated for their activity on T. granarium, in the ratios of 10%, 20%, and 30% (w/w).This test allows plant materials with strong, weak or negative grain protectant effects to be detected. The results showed that, Of the 3 plants screened, Datura alba showed the best grain protectant effects, with a WPI value of (24.63) at dose of 30% (w /w). In other experiments, treatments comprised application of mixed proportions of best two effective plants, leave powder extracts of Usher (U) and fruit powder extracts of Jatropha (J), at three doses 10%, 15% and 20%. The treatments were arranged in a completely randomized design (CRD) with three replications . Treatment concentrations were added to test containers with (10 g) dry Sorghum seeds, admixed with (10) 3rd instar larvae of T. granarium. Insecticidal effects of the plant mixture combinations at the 1st day and 10th day showed no significant difference (p>0.05) at all concentrations. However, there was significant difference (p<0.05) in the mortality of the insects as the time of exposure increased at 20th day and 30th day compared to control. The results also showed that, the more the concentration of Jatropha extract, the more will be its effect on larval mortality. Based on the results of this study, Powder extracts of C.procera, J. curcas and D. alba could be used in IPM program for control of T.granarium.