EFFECTS OF TRIFLUMURON ON LARVAL INTUGEMENT OF SIXTH-INSTAR GALLERIA MELLONELLA (L.) (LEPIDOPTERA: PYRALIDAE)

The chitin synthesis inhibitory (CSI) effect of triflumuron on integuments of sixth-instar Galleria mellonella (L.) larvae was investigated. The LC 50 (lethal concentration, 50%) value of triflumuron for oral administration was determined to be 400 ppm with probit analysis. Concentrations of 400 ppm and its decreasing levels of 200, 100, 50, 25, and 12.5 ppm were used in the study. For three concentrations of triflumuron (100, 200, and 400 ppm), morphological deformities were observed, albeit not at the same rate, and larvae failed to molt. For three other concentrations (12.5, 25, and 50 ppm), in spite of continuing to develop and molting to next instar, abnormalities were observed on wings of adults kept in 12.5 and 25 concentrations; larvae kept in 50 ppm failed to develop and died. Histologically, at the 50, 100, 200, and 400 ppm concentrations of triflumuron, along with deformation of lamella structure in endocuticle, intracellular granular formations, condensation of cytoplasm and cytoplasmic losses were observed in epidermal cells. In addition to these formations, vacuolar formations were observed for the 200 and 400 ppm concentrations. In the experimental groups, cuticle secretion of epidermal cells was blocked at higher rates with increasing concentrations depending on the dose/time relationship. Compared with the control group, due to decrease in cuticle secretion of larvae fed with diets containing 50-100 ppm, cuticle thickness decreased by 20%, whereas it decreased by 37%-38% for the 200-400 ppm concentrations, respectively.