The Impact of the Pesticides Abamectin and Spirotetramat on Biological Parameters of the Coccinellid Predator Cheilomenes Sexmaculata (Fabricius) Via Egg Exposure

Introduction: Due to the presence of pesticide residues in agricultural products, the security and safety of foods have taken on close attention. Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae) is a principal biological control agent in pistachio orchards, especially against Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae) that is the most damaging pest of pistachio. It is an effective predator to be used as a bio-control agent, which can reduce the use of pesticides in integrated pest management (IPM) program. Materials and Methods: In this project, the side effects of spirotetramat and abamectin were evaluated on C. sexmaculata by dipping the egg stage into the pesticide concentrations. Spirotetramat was tested at three concentrations of 100, 50, and 25 mg/L, representing 2/1, 1/1, and 1/2 of the maximum field recommended concentration (MFRC). Abamectin was also tested at a dilution series of 1/1, 1/2, 1/4, 1/8, and 1/16 of its MFRC, corresponding to 9, 4.5, 2.25, 1.12, and 0.56 mg/l, respectively. Results: Egg hatching was significantly reduced when eggs were exposed to all concentrations of insecticides except at 1/2 MFRC of spirotetramat. The results of the present project revealed that spirotetramat caused significant mortality only on first-instar larvae of C. sexmaculata. Pre-oviposition period, percentage of adult emergence, and developmental period of predator larvae were significantly affected by all tested concentrations of both insecticides. Egg hatching was significantly reduced when eggs were exposed to each tested insecticide at all concentrations of both insecticides except 1/2 spirotetramat. Conclusion: This research highlighted the importance of toxicity risk assessments, including lethal and sub-lethal effects, to obtain a more accurate estimation of the compatibility of insecticides in current IPM programs. Abamectin was not compatible with biocontrol agent C. sexmaculata and could not be used in IPM programs due to its strong lethal and sub-lethal effects. Spirotetramat was considered to be less harmful on C. sexmaculata than abamectin and could be compatible with augmentative releases of the coccinellid, C. sexmaculata.