Evaluation of methyl eugenol-supplemented diet as pre-release treatment for simultaneous application of male annihilation and sterile insect techniques against Bactrocera dorsalis

Abstract

Bactrocera dorsalis is a highly invasive fruit pest of economic and quarantine significance. The males are strongly attracted to methyl eugenol (ME). After consumption, ME is converted to metabolites that act as sex pheromones, which increase mating success. ME lure is instrumental in male annihilation technique (MAT) and sterile insect technique (SIT) applications to suppress or eradicate fruit fly populations. A simultaneous MAT-SIT concept is proposed to reduce operational costs and time-to-eradication. However, sterile males released to the field may respond to MAT’s ME-baited traps, reducing the efficacy of SIT. Here, we developed a ME-supplemented diet that reduces males’ response to ME without compromising mating efficiency and survivorship. We offered sugar-yeast diet supplemented with ME (0–5%) to 5-day-old males for 48 h and evaluated their response to ME, mating performance and pheromone production at 3-, 7-, 11- and 15-days post-treatment (DPT), while observing mortality for 60-DPT. Our results indicate that consuming a ME-supplemented diet reduces response to ME lures and enhances mating success, with the 5% ME diet showing the most promising results. The trend of pheromone production at different DPT after consuming various ME-supplemented diets corroborated with those of reduced lure response and mating enhancement. Although diet containing 3 and 5% ME affected males’ survival probability over 60-DPT, the treatment does not impact the survival of all treated males for at least 25-DPT. This finding suggests that pre-release feeding on a 5% ME-supplemented diet by 5-day-old B. dorsalis males is a feasible solution for implementing simultaneous MAT-SIT.