Application of carbon dioxide and nitrogen to control the greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) in stored combs

The greater wax moth (Galleria mellonella) is a significant pest that damages stored wax combs, leading to major losses for beekeepers globally. This study explored a safe method for protecting wax without leaving harmful residues. The effects of modified atmospheres (MAs) with varying concentrations of CO₂ (60 %, 70 %, 80 %) and N₂ (97 %, 98 %) were tested on different life stages of the wax moth (eggs, larvae, and pupae) at 25 °C. The study also evaluated the treatment on a larger scale using a 100 L barrel, with LT₅₀ values determined for 80 % CO₂ and 98 % N₂ over different storage periods (10, 20, and 30 days). Results showed that a 6-day exposure to all treatments killed 100 % of eggs, larvae (4th-6th instars), and pupae, except for the 60 % CO₂ treatment, which required 7 days for full mortality of fourth instar larvae and pupae. Additionally, 98 % N₂ took 7 days, and 97 % N₂ took 9 days to kill all pupae. Sensitivity to MAs varied by life stage: eggs were most sensitive to CO₂, while larvae were most sensitive to N₂. On a large scale, CO₂ treatment resulted in 100 % reduction in treated larvae after 10 days, while N₂ treatment reached 80.64 % after 10 days, increasing to 90.32 % after 30 days. Wax weight reduction was minimal in CO₂-treated samples (0.28 % after 10 days and 1.24 % after 30 days) compared to N₂-treated samples (5.36 % after 10 days, 12.28 % after 30 days). The results suggest that MAs are a viable alternative to toxic gases for protecting wax combs from G. mellonella infestation while preserving wax quality.