Effect of Different Doses of Gamma Irradiation on Biology and Life Table of Tetranychus urticae Koch (Acari: Tetranychidae) of Two Ornaments Plants

Abstract

Developmental times, reproduction rate and life table parameters of Tetranychus urticae Koch of two ornaments plants Marshmallow and Salvia treated with four doses of gamma radiation 15, 25, 35 and 45 Kilo rad was studied under laboratory conditions at 25 ± 2°C, 65% RH. The results indicate that applied of gamma radiation had a significant effect on the duration of male and female feeding on salvia and Marshmallow leaves irrigated. The life cycle and generation period of irradiated females increased with increasing doses of gamma radiation and were significantly higher than the control. The female oviposition and longevity periods of T. urticae significantly increased with an increased dose of gamma radiation. The mean fecundity and daily rate significantly decreased with increasing doses of gamma radiation on salvia and marshmallows. A significant positive correlation was found between all immature stages, generation, and oviposition periods and the dose of gamma radiation. The Intrinsic rate of increase (r m) and net reproductive rate (R0) of T. urticae was the lowest at 45 Kilo rad (0.148 female/female/day and 20.59 female/female) and the highest value was found at control (0.256 female/female/day and 44.70 female/female), respectively on salvia leaves. The radiation of salvia and Marshmallow seeds reduced the fecundity of T. urticae females and prolonged the generation time than in control.