Effects of α,β-unsaturated lactones on larval survival and gut trypsin as well as oviposition response of Aedes aegypti

Lactones are organic cyclic esters that have been described as larvicides against Aedes aegypti and as components of oviposition pheromone of Culex quinquefasciatus. This work describes the effect of six alpha,beta-unsaturated lactones (5a-5f) on survival of A. aegypti fourth instar larvae (L-4). It is also reported the effects of the lactones on L-4 gut trypsin activity and oviposition behavior of A. aegypti females. Five lactones were able to kill 1.4 being the lactones 5a (LC50 of 39.05 ppm), Se (LC50 of 36.30 ppm) and 5f (LC50 of 40.46 ppm) the most promising larvicides. Only the lactone 5a inhibited 1.4 gut trypsin activity, with an IC50 of 115.15 mu g/mL. Lactones 5a, 5c, 5d and 5e did not exert deterrent or stimulatory effects on oviposition, whereas lactone 5b exhibited a strong deterrent oviposition activity. In conclusion, this work introduces new alpha,beta-unsaturated lactones as promising alternatives to control A. aegypti dissemination. The larvicidal mechanism of the lactone 5a can involve the disruption of proteolysis at larval gut. (C) 2015 Elsevier Inc. All rights reserved.