ارزیابی اثرات سوء چند حشره‌کش‌ روی سنOrius laevigatus در شرایط آزمایشگاه

Along with the process of the flumetoquine registration as a new pesticide for Thrips tabaci control in onion, its side-effect was evaluated on Orius laevigatus, a general predator of the pest. First, 30-50 pairs of the predator were confined into a Plexiglas box (30×30×30 cm) and provided with fresh-frozen eggs of the Mediterranean flour moth (MFM) as food at 25±1℃, 60±10% RH, and 16:8 h (L:D). Garden geranium leaves, bean pods and bean and soybean seedlings were used as egg-laying substrates. Field-recommended doses (FRD) of the flumetoquine (0.750 and one L/ha), abamectin + thiamethoxam (0.750 and one L/ha), and thiacloprid + deltamethrin (one L/ha) were prepared and applied to the newly emerged adults and 4th instar nymphs of the predator in contact and oral methods. Distilled water was used in the control treatment. Each treatment was replicated 4 times and one replication included 6 insects. Observations were made on the direct mortality, and development duration, fecundity and longevity of the survived predators. Mortality was corrected by Abbott’s formula and by comparing the fecundity changes in the treatments with that of control, the Total Effect (%E) of each pesticide was calculated and used in their ranking based on the IOBC method. Results revealed the contact effect of all pesticides caused 100% mortality in adults and nymphs of O. laevigatus. Likewise, all adult predators died one day after feeding on the MFM eggs treated with 0.750 and one L/ha doses of abamectin + thiamethoxam. Similarly, nymphs had 100 and 95% mortality with one and 0.750 L/ha doses of abamectin + thiamethoxam in the oral method after 3 and 7 days, respectively. Similarly, thiacloprid + deltamethrin (one L/ha) caused 76% mortality to adults and nymphs 3 and 7 days after ingestion, respectively. Predators ingested doses of 0.750 and one L/ha of flumetoquine and one L/ha of thiacloprid + deltamethrin realized 90, 23.52, and 50.58% of their fecundity, respectively, compared to that of control. Finally, concerning the calculated Total Effect (%E), flumetoquine with 59.10% and 97.86% by doses of 0.750 and one L/ha had the minimum and maximum Total Effect in oral application to O. laevigatus, respectively. Nonetheless, thiacloprid + deltamethrin had an 86.20% Total Effect by the dose of one L/ha. Therefore, flumetoquine with the dose of 0.750 L/ha was classified as slightly harmful (rank 2) and flumetoquine and thiacloprid + deltamethrin with the dose of one L/ha both were classified as moderately harmful (rank 3) for the predator.