Effects of pyriproxyfen on bioenergetic resources of Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

Colorado potato beetles (CPB) overwinters as adults in the soil, thus, their survival is related with their energy reserves. The present study examined the biochemical changes in adults treated with sub-lethal concentrations (≤LC 30 ) of pyriproxyfen. First, both the plants and overwintered adults were sprayed with different levels of pyriproxyfen (0, 250, 500 and 750 µl/l) under field conditions and were tested at 3, 6 and 12 days after treatment. Next, the adults from the first experiments were re-sprayed 1 week later with pyriproxyfen at the same concentrations and were re-sampled at 3, 6 and 12 days after the second treatment. The lipid, sugar, glycogen and protein levels of 4 males and 4 females were determined (mg/g; w/w). Results revealed a significant decline in lipid (87.7%), glycogen (50%) and caloric contents (75%) levels with respect to controls. Sugar and protein levels increased 7.89 and 5.79 times with respect to the controls. The best results were obtained at 250 µl/l of pyriproxyfen. The second round of testing demonstrated the additive effects of pyriproxyfen on bioenergetic reserves. Only the protein level showed a significant difference by sex.