Effect of dietary benzoxadiazole on larval development, cuticle enzyme and antioxidant defense system in housefly (Musca domestica L.)

The toxicity and influence on chronic development regulation of dietary benzoxadiazole as well as the subsequent action on cuticle enzyme and antioxidant defense system in feed-thru housefly larvae are investigated. Dietary benzoxadiazole shows limited larvicidal activity and weak interference on larval pupation, but strong blockage against the succedent eclosion process. It does not change the content ratio of protein/chitin in the larval cuticle, but strongly regulates the constituents of cuticle proteins. Moreover, chitinase activities in the integument of third-instar larvae, in vivo, are enhanced and gradually decreased whereas phenoloxidase activities are inhibited and the inhibitory rates are gradually increased. Glutathione S-transferase activities are strongly improved whilst peroxidase activities decrease from about 42.25% to 17.36%, catalase activities decrease from about 80.31% to 27.98% and superoxide dismutase activities are almost unchanged during the different treatment procedures. Peroxidase SDS-PAGE analysis shows that band photodensities of 200.0 and 10.3 kDa proteins in feed-thru larvae are significantly weaker than the corresponding control band. Results suggest that dietary benzoxadiazole might exert strong regulation on larvae cuticle metabolism, interfere with cuticle enzymatic browning and protein sclerotization and weaken the self-protection of larvae against endogenetic oxidative damages.