EVALUATION OF SOME INDIGENOUS PLANT EXTRACTS AGAINST TWO-SPOTTED SPIDER MITE, Tetranychus urticae KOCH (Acari: Tetranychidae)

Abstract

An investigation was conducted to evaluate the efficacy of three different plant extracts namely neem, datura, and chilli in three different solvents viz., methanol, ethanol and acetone for their acaricidal, ovicidal activity and repellent properties against two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) under ambient temperature in the laboratory conditions during July 2016 to April 2017.These botanicals were applied at four doses @ 0.5, 1.0,1.5 and 2.0 % along with control and replicated four times. The result showed that all the doses of plant extracts had direct toxicity ,ovicidal activities and repellency effects on T. urticae. Among the doses, 2 % had the highest mortality and repellency. Among the extracts chilli fruit extract (67.71%) showed the most toxic against T.urticae. The results also showed that ethanol extract (71.11%) was more effective than other extracts. In case of datura leaf extract,adult toxicity showed in order (% mortality) as ethyl alcohol extract performed the best response and it possessed the highest mortality (96.05%) at 2 % level of dose after 24 hours after treatment (HAT) whereas acetone extract of datura showed the lowest mortality (57.80%). The mortality percentage followed in order ethanol (2%) > methanol (1.5%) > acetone (0.5%). On the other hand, neem leaf extract showed ovicidal activity in order (on the basis of considering all doses and the% mortality) as ethyl alcohol extract showed the best response and it possessed the highest mortality (92.10%). The mortality percentage followed in order ethanol (2%) > methanol (1.5%) > acetone (0.5%).On the basis of LD50 values it was found that at 24 HAT the ethanol extract (0.11%) showed the best response followed by methanol (0.38 %). It also indicated that all the three different solvent extracts of chilli was the most toxic to adults and eggs of T.urticae. In the repellent test the highest (91.63%) and the lowest (46.60%) mean repellency were found in datura and neem leaf extracts, respectively. Ethanol showed the highest mean repellency (repellency class V). On the other hand, the lowest mean repellency showed in acetone (repellency class III).