Developmental and biochemical effects of hexaflumuron and spirodiclofen on the ladybird beetle, Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae)

The ladybird beetle, Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae) is one of the most important natural enemies of the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae). The effects of hexaflumuron and spirodiclofen were investigated on development and carbohydrates and total lipid contents of 4th instar larvae of H. variegata. The insecticides had significant effects on the mortality of eggs, but no significant effects on mortality of larvae or pupae. Hexaflumuron significantly increased the length of development of eggs (2.89 days) and first instar larvae (3.28 days), but had no significant effects on other instars or pupae. Spirodiclofen had no significant effects on developmental stages of H. variegata. Glycogen content was significantly reduced by spirodiclofen (17.42 mg/g fresh body weight) and hexaflumuron (16.07 mg/g fresh body weight). Trehalose content in hexaflumuron (1.89 mg/g fresh body weight) and spirodiclofen-treated larvae (2.02 mg/g fresh body weight) was significantly lower than control (8.01 mg/g fresh body weight). Glucose content in spirodiclofen-treated larvae (0.96 mg/g fresh body weight) was significantly higher than in hexaflumuron-treated larvae (0.24 mg/g fresh body weight) and control (0.15 mg/g fresh body weight). Significant reduction in the amount of lipid was observed in spirodiclofen-treated larvae (5.29 mg/g fresh body weight), but not in hexaflumuron-treated larvae (7.11 mg/g fresh body weight). These results suggest that substantial physiological events in the life of larvae are affected in response to the action of the tested insecticides.