Life Table Parameters, Thermal-Requirements and Development Rate of Stethorus gilvifrons (Mulsant) Reared on Two-Spotted Spider Mite Tetranychus urticae (Koch)

Abstract

Laboratory experiments were carried out in plant Protection Research Institute during 2016. The effect of temperatures under three different constant temperature (15, 25 and 35 oC) and rate of developmental time immature stages, growth index, developemantal rate, longevity, fecundity, and life table parameters of Stethorus gilvifrons (Mulsant), when reared on Tetranychus urticae (Koch) were studied. The relationship among developmental rate of each stage and tested temperatures was also investigated. There were significant ranges in total of developmental time immature stages of the predator (male and female) among the three tested temperatures when the predator was reared on T. urticae as preye. Mean while, developmental rate of S. gilvifrons male were higher at 35oC than 15 and 25oC when reared on this tetranychid mite. Adult male longevity was high significant shorter at 35 than 15 and 25oC. There were significant differences in pre-oviposition period at the three temperatures. In addition, there were significant ranges among pre-oviposition, oviposition, post ovi-position and total longevity when the predator was reared at the three constant temperatures. Fecundity rate was significantly higher at 35oC than at 15oC and 25oC when fed on the T.urticae prey. Mean generation time (T) and the doubling time (DT) were higher at 15oC than at 25oC and 35oC when fed on the T.urticae individuals. The value of the gross reproductive rate (GRR), net reproduction rate (Ro), intrinsic rate of increase (rm) and the finite rate of increase (λ) were higher at 35oC than at 15oC and 25oC.