Postharvest CO2 treatment and cold storage for Drosophila suzukii (Diptera: Drosophilidae) fruit infestation control

Abstract

The invasive pest, spotted wing drosophila (Drosophila suzukii (Matsumura, 1931) or SWD), damages various soft-skinned fruits, severely impacting orchards and vineyards economically. Current sorting practices in commercial production may overlook early-stage SWD infestations, as visible signs take a few days to appear. Our study focused on managing SWD infesting fruits (blueberry, cherry, and raspberry) without visible signs using an artificial atmosphere with elevated CO2 and low temperature. We hypothesized that these factors affect SWD survival and possibly interact, with potential variations among different soft- or stone-fruit species or varieties. High CO2 concentrations and cold storage both negatively affected SWD development. A 24-h 100% CO2 fumigation, without cold storage, significantly reduced SWD infestations in all 3 fruit species studied. On the other hand, 10% CO2 without cold storage did not cause a significant infestation reduction in cherries. Cold storage alone was too slow to be considered effective. Concurrent low-temperature treatment and CO2 treatment reduced the insecticidal efficacy of CO2 fumigation. Optimal fruit sanitation was achieved with a 3-h 100% CO2 treatment at ambient temperature before cold storage. Raspberries were the most suitable host for SWD development, with over a 5-fold higher SWD development compared to blueberries and over 50 times more than in cherries. We discussed the observed interactions between CO2 fumigation and chilling and suggested a simple postharvest SWD management protocol using optimal CO2 levels, exposure times, and chilling periods-achievable without complex equipment.

Keywords: fruit infestation; fruit sanitation; integrated pest management; post-harvest treatment; spotted wing drosophila.

Fig. 1.

Effect of different concentrations of CO2 and different times of cold storage on the survival and development of Drosophila suzukii in blueberries (A), cherries (B) and raspberries (C). Data presented are averages ± standard error from 2 pooled experiments, each performed with 5 replicates per treatment (n = 10). Bars not sharing the same lower-case letter(s) are significantly different (P < 0.05) according to Tukey’s HSD post-test.

Fig. 2.

Effect of different times of fumigation of infested blueberries in a 100% CO2 atmosphere at ambient temperature and effect of cold storage on survival and development of Drosophila suzukii. Data presented are average ± standard error from 3 pooled experiments (n = 15). Bars not sharing the same lower-case letter(s) are significantly different (P < 0.05) according to Tukey’s HSD post-test.

Fig. 3.

Average number of flies developed in various treatments in the verification experiment. Results presented are average values ± standard error, calculated from 5 replicates per treatment. The experiment was performed once (n = 5). Bars not sharing the same lower-case letter(s) are significantly different (P < 0.05) according to Tukey’s HSD post-test.