Synergistic Larvicidal and Pupicidal Toxicity and the Morphological Impact of the Dengue Vector () Induced by Geranial and -Cinnamaldehyde.

Monoterpenes are effective and eco-friendly alternatives to conventional chemical larvicides. We tested single and binary mixtures of monoterpenes-geranial and -cinnamaldehyde-for their larvicidal and pupicidal activities against L. and for non-target toxicity on guppies ( Peters), using 1% (/) temephos as a reference. Geranial and -cinnamaldehyde at 250 ppm showed stronger larvicidal and pupicidal activities with a 100% mortality rate and an LT ranging from 0.3 to 0.6 h. All combinations were strongly synergistic against larvae and pupae compared to single formulations, with an increased mortality value (IMV) of 6% to 93%. The combination of geranial + -cinnamaldehyde (1:1) at 200 ppm showed the highest impact, with an IMV of 93%. The strongest larvicidal and pupicidal activities, a 100% mortality rate, and an LT of 0.2 h were achieved by geranial + -cinnamaldehyde (1:1) 500 ppm. They were thirty times more effective than a 1% temephos solution (LT ranging from 6.7 to 96 h) and caused obviously shriveled cuticles and a swollen respiratory system. All single and binary mixtures were not toxic to the guppies. Thus, the combination of geranial + -cinnamaldehyde has great potential as a safe insecticide for controlling mosquito larvae and pupae.