A research on sublethal effects of some pesticides against Nesidiocoris tenuis reuter (Hemiptera: Miridae)

In this study, it was aimed to determine the subletal effects of 4 different pesticides (LC30) with active ingredients abamectin, spinetoram, pyriproxyfen and chlorantraniliprole on the predatory insect Nesidiocoris tenuis, which are used in biological control against Tuta absoluta in greenhouse tomato cultivation. The LC30 values, applied on the second instar nymphs of N. tenuis for abamectin, spinetoram, pyriproxyfen and chlorantraniliprole were determined as 1.795, 16.988, 1812.172 and 5042.087 mg (a.i.)/l, respectively. Then, the LC30 values determined for abamectin and spinetoram were applied to the second instar nymphs of N. tenuis. Recommended field dose, 50 and 35 mg (a.i.)/l for pyriproxyfen and chlorantraniliprole were used for these insecticides, since the determined LC30 values were higher than field doses. Daily viability, adult lifespan and the number of offspring were monitored in the treated individuals. In terms of total nymphal developmental duration, no statistical difference was found between the control (water) application and other insecticide applications except abamectin in both sexes. This period was determined as 9.54 days in the control treatment, while this period was determined as 10.67 days in males and 10.75 days in females in abamectin. Considering the total preoviposition period of N. tenuis female (from the egg period), except for abamectin, the other insecticides groups were in the same statistical group as the control group (15.85 days), while abamectin prolonged this period (17.18 days), significantly. The intrinsic rate of increase (r) was the lowest in abamectin treatment, with 0.180 day-1, and the highest in chlorantraniliprole with 0.219 day-1. A similar situation was determined for the finite rate of increase (λ), and these values were determined as 1.197 and 1.245 day-1, respectively, for both insecticides. No statistical difference was determined on the net reproductive rate (R0) and the gross reproduction rate (GRR) values between treatments. The mean generation time (T) was 22.39 and 23.15 days in spinetoram and abamectin, respectively, with a significant increase compared to control (21.27 days).