Potential control of two-spotted spider mite,Tetranychus urticae koch (acari: Tetranychidae) by crude extracts of Duabanga grandiflora (Lythraceae) and Diospyros cauliflora (Ebenaceae)

Laboratory bioassays were carried out to determine the toxicity and repellency of duabanga grandiflora and diospyros cauliflora crude extracts against tetranychus urticae female. toxicity and repellency tests were performed using leaf disc no choice and leaf disc choice tests. crude methanol extract of d. grandiflora was found to have less toxicity with maximum mortality of 35.6% when compared to control while chloroform crude extract of d. cauliflora showed 45.6% repellency which is equalled to those of d. grandiflora crude methanol extract,26.7% mortality of t. urticae at 8% (w/v) concentration on leaf disc no choice test 3 days after exposure. both crude extracts were also able to reduce the number of eggs with a maximum of 92.2 and 94.6% at the hightest concentration. results also indicated that 8% (w/v) concentration of d. grandiflora crude methanol extract exhibited the strongest repellency and oviposition deterrent activities to t. urticae throughout the experiment with only 0.0-9.5% alive mites and 0.0-3.4% of eggs laid on the treated sides under leaf disc choice test. besides,2.2-18.7% and 0.5-6.6% were recorded for alive mites and eggs laid,respectively on the treated sides by highest concentration of d. cauliflora crude chloroform extract. the oviposition-deterrent indices decreased as time progressed at all concentrations of the crude extracts,except the highest concentration (8% w/v) of crude methanol extract of d. grandiflora and crude chloroform extract of d. cauliflora where the odi is ranging from 92.8-100.0 and 88.3-99.0,respectively during the experiment. copyright 2015 zoological society of pakistan.