An Ozonolysis Based Method and Applications for the Non-Lethal Modification of Insect Cuticular Hydrocarbons.

Cuticular hydrocarbons (CHCs) are important, multi-function components of the insect epicuticle. In Drosophila spp., CHCs provide protection from desiccation and serve as semiochemicals for both intra- and interspecific communication. We developed a non-lethal method for the modification of Drosophila CHCs profiles through the exposure of live insects to a high dose of ozone gas (~ 45,000 ppm). Drosophila suzukii that were treated with ozone showed a 1.63-3.10 fold reduction in unsaturated hydrocarbons with these CHCs shown to regenerate over 108 h. Changes in CHCs were correlated with significantly reduced desiccation resistance in both male and female D. suzukii at one h after ozone treatment. Interestingly, individuals treated with ozone showed increased desiccation resistance in comparison to controls at 108 h after ozone treatment. The methodology reported in this paper provides a novel approach to investigate the biosynthesis and functions of CHCs during the lifespan of an insect.

Exploring the Insecticidal Potential of Gaseous and Aqueous Ozone to Control Spotted-Wing Drosophila, Drosophila suzukii (Diptera: Drosophilidae).

Over the last decade, numerous companies have marketed aqueous ozone sprayers for insect and disease management, but little to no data has been published on their efficacy. Thus, we evaluated the potential of both gaseous and aqueous ozone as a potential preharvest insecticide against the adult life stage of the invasive fruit pest, spotted-wing drosophila, Drosophila suzukii (Matsumura). Gaseous ozone was applied at two dosages, 14,600 and 30,100 ppmv, for varying durations and the respective concentration-time (CT) exposure responses were modeled for sex-specific mortalities recorded at 0, 24, 48, and 72 h following treatment. We found that gaseous ozone primarily caused mortality immediately following exposure, with slight increases 72 h following ozone treatments. The female and male lethal concentration-time (LCT) 50 estimates were significantly different at 0, 24, 48, and 72 h after 30,100 ppmv treatments, where males observed an increased mortality response. However, the LCT 99 estimates confidence intervals (95%) of adult female and male D. suzukii were similar at 0, 24, 48, and 72 h after 14,600 or 30,100 ppmv ozone treatments. In contrast, ozone dissolved in distilled water at 18.52 ppm (mg/L) did not provide any mortality after total immersion of subjects for 30 s. While gaseous ozone may have some utility as a fumigant for D. suzukii in closed vessels where concentrations could be maintained, we did not identify any insecticidal potential for ozone dissolved in aqueous solution when simulating a preharvest treatment under optimal laboratory conditions.