Abstract
Maize, Zea mays L. is an economic cereal in Egypt. Numerous pests infested maize, but only a few of them caused high crop losses, such as FAW, Spodoptera frugiperda. Therefore, this study is urgent to determine: the effect of chitin synthesis inhibitors on FAW larvae, and evaluate LC90 efficiency of CSIs on maize under the field. In this study, the mortality percentage increased with increasing exposure time to CSIs. Moreover, LC50 for hexaflumuron was low (0.487 mg/L), followed by flufenoxuron (0.5712 mg/L) on the 2nd larva. On the 4th larva, hexaflumuron and diflubenzuron were more lethal than other CSIs. LC90 of all CSIs ranged between 1.3815 5.0569; and 1.024514.6923 mg/L on the 2nd and 4th larvae, respectively. Results were elucidated that the toxicity index was low by novaluron and lufenuron treatments with high resistance ratios, respectively. However, it had a high value with diflubenzuron, followed by novaluron, with a few resistance ratios when compared with hexaflumuron, respectively. In field experiments, data showed that flufenoxuron, hexaflumuron and diflubenzuron could be used as recommended insecticides to FAW control, however, chlorfluazuron, lufenuron and novaluron were the lowest ones on maize. On the response of proteins, carbohydrates and lipids to CSIs, diflubenzuron, hexaflumuron and flufenoxuron caused the lowest significant reduction in protein. Wherever, the highest significant protein value was recorded with chlorfluazuron and lufenuron. The values of chitinase, phenoloxidase and carboxylesterase indicated a clear disturbance in physiological aspects for larvae. Now, CSIs are used for developing eco-friendly FAW management.
