Abstract

The purpose of this study is to determine the effects of pyriproxyfen (an insect growth regulator compound) on cellular energy allocation of a heterometabolous insect, Brachynema germari Kol. The fifth instar of this insect was treated with 0, 20, 60, 100, 200 and 500 mg l^-1 formulation of pyriproxyfen (Admiral 10EC) and the amount of energy available (E_a), energy consumption (E_c) and cellular energy allocation (CEA) were compared. The resulting calculated energy reserves (carbohydrate, glycogen, lipid and protein) showed that total lipid amount varied significantly among doses and between each dose and control. Lipid amounts fell as doses grew to 200 mg l^-1 and then increased. A significant difference was observed in total carbohydrate between each dose and control (P < 0.05); however there were no significant differences among doses. The amount of glycogen and total protein and also the amount of energy consumption did not differ significantly from control. Study results showed that pyriproxyfen at low concentrations, raised cellular energy allocation but decreased it at high concentrations.

Key words: Pyriproxyfen, Brachynema germari, cellular energy allocation, lipid, glycogen, protein.

Abbreviation

Ea, Energy available; Ec, energy consumption; CEA, cellular energy allocation; ETS, electron transport system; IGRs, insect growth regulators.