ACARICIDAL AND OVICIDAL EFFICACIES OF LEUCAENA GLAUCA BENTH. SEED CRUDE EXTRACTS ON TETRANYCHUS URTICAE KOCH (ACARI: TETRANYCHIDAE)

Abstract

ABSTRACT The preliminary screening under laboratory conditions is a great value for evaluating the acaricidal and ovicidal activities of hexane, dichloromethane and methanol crude extracts of Leucaena glauca Benth.(Leguminosae) seeds against adults and eggs of Tetranychus urticae Koch (Acariformes). The leaf disc no choice and leaf disc choice tests were used to determine the acaricidal effects while direct spray method was used to investigate the ovicidal effects. Hexane and dichloromethane extracts of dried seeds demonstrated higher acaricidal effect than other extracts under leaf disc no choice test. The hexane and dichloromethane extracts of L. glauca dried seeds at 10000 ppm (v/v) induced the highest mortality rates of 80.6 and 98.9% of T. urticae female adults, respectively. These extracts also demonstrated oviposition deterring effects based on a 100% reduction of the total number of eggs on leaf disc treated with the extracts. This investigation indicated that hexane and dichloromethane extracts of dried seeds at all treated concentrations (100, 500, 1000, 5000 and 10000 ppm) also had a good potential for repelling this mite and decreasing the egg laying on the treated surfaces under leaf disc choice test since < 50% of alive mites and eggs were found on the treated sides. In the side of ovicidal activity, the hexane and dichloromethane extracts of L. glauca fresh and dried seeds caused higher percentage of egg mortality compared to the control. Egg mortalities of 59.8-98.8% and 82.3-97.6% were detected in hexane and dichloromethane extracts of L. glauca fresh seeds at concentrations ranging from 10000 to 50000 ppm, respectively. Egg mortalities of 95.8-99.6% and 64.9-97.5% were recorded when treated with hexane and dichloromethane extracts of dried seeds at the same concentrations of the fresh seeds, respectively. Hence, the hexane and dichloromethane extracts of L. glauca have the efficacy to be developed as botanical acaricides for T. urticae management.