Temperature dependent development, reproduction and population performance of Tetranychus hirsutus Zeity & Srinivasa (Acari: Tetranychidae), on medicinal herb, Gymnema sylvestre

Abstract

Rearing temperature conditions showed profound influence on the biology, reproduction and demography of the mite, Tetranychus hirsutus. The time required for the development of female mite from egg to adult was 10.12 to 22.51 days at the rearing temperature conditions of 20°C - 32°C. At 25°C, each mated female laid 76 eggs over 20 days and produced a female-biased progeny of 8:1 sex ratio. Also, higher Net Reproduction Rate of 67.83 female off-springs/female/generation, Mean Generation Time of 24.44 days, Doubling Time of 7.91 days and a weak population progression of 0.076 female offsprings/female/day were observed. The adaxial surface feeding by the mite caused characteristic yellowish to white specks on the leaves of the medicinal herb Gymnema sylvestre. As the population explodes, mites colonize the lower surface (abaxial) also, caused extensive feeding damage with profuse webbing.
Mite-infested leaves showed reduction in chlorophyll (15.89%), carbohydrate (90.90%), protein (69%) and flavonoid (17.60%) content, while alkaloid content was found increased (14.30%).