Joint effects of dimilin and Ambush on enzyme activities of Tribolium castaneum larvae

Abstract

Sublethal concentrations of 10 and 20 ppm (0.25 and 0.5 μ M) Ambush decreased amylase activity and increased acid phosphatase (AcP) and lactate dehydrogenase (LDH) activites in sixthinstar Tribolium castaneum. Dimilin at 250 and 500 ppm (8 and 16 μ M) raised activities of amylase, AcP, LDH, and alanine aminotransferase (ALAT) and depleted trehalase activity. The remaining enzymes, cholinesterase (ChE), alkaline phosphatase (AkP), asparate aminotransferase (ASAT), and isocitrate dehydrogenase (ICDH), were not affected by either insecticide. Mixtures of Dimilin and Ambush at 250 ± 10 and 500 ± 20 ppm resulted in a disturbance of almost all the enzymes tested in this study, suggesting a possible synergistic effect with reference to trehalase, ASAT, and AkP activities and an antagonistic effect with reference to amylase, AcP, LDH, ICDH, ChE, and ALAT activities. Feeding on untreated flour did not restore any of the affected enzyme activities to normal levels.