Environmental variables such as temperature are important factors that affect the efficiency of biological control agents. This study examined the effect of temperature on the sex ratio, longevity, oviposition periods, fecundity and life table parameters of the predatory thrips Scohthrips longicornis Priesner (Thysanoptera: Thripidae) fed on twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), at six constant temperatures: 15, 20, 26, 30, 35, and 37°C. Approximately 75% of the progeny were female, except at 37°C, at which temperature the proportion of males increased. Adult longevity as well as the preoviposition, oviposition, and postoviposition periods decreased significantly with temperature. Thus, adults lived for ≈5 wk at 15°C and <1 wk at 37°C with preoviposition, oviposition, and postoviposition periods ranging from 6.4 to 0.4, 24.4–3.1, and 7–0.8 d between the two temperature extremes, respectively. The maximum (56.48 eggs) and minimum (11.69 eggs) value of total fecundity was recorded at 26 and 37°C, respectively. The intrinsic rate of natural increase (rm) of S. longicornis increased linearly with increasing temperature from 0.056 d-1 at 15°C to 0.310 d-1 at 35°C. The lower temperature threshold for the population increase of S. longicornis was estimated to be around 5°C. The data suggest that the upper temperature threshold for the predatory thrips is ≈37°C. The results showed that populations of S. longicornis are able to develop at a broad range of temperatures and that this predator is well adapted to the high temperatures that occur in the Mediterranean region.
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Vol. 104 • No. 3