Efficacy and phytotoxicity of sulfur dioxide fumigation for postharvest control of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on select fresh fruit and vegetables

Authors: Liu, Yong Biao

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2024
Publication Date: 2/14/2024
Citation: Liu, Y.-B. 2024. Efficacy and phytotoxicity of sulfur dioxide fumigation for postharvest control of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on select fresh fruit and vegetables. Agriculture. 14(2). Article 305. https://doi.org/10.3390/agriculture14020305.
DOI: https://doi.org/10.3390/agriculture14020305

Interpretive Summary: There is a need for safe and effective alternative fumigants to replace methyl bromide for postharvest pest control. Western flower thrips is a major pest on a wide variety of field crops and a quarantine pest on some exported fresh products to some overseas markets. Although sulfur dioxide (SO2) has a long history to be used as a pesticide, it has not been used widely for postharvest pest control. In this study, SO2 fumigation was evaluated for controlling western flower thrips and safety to four select fresh fruits and vegetables including broccoli, peppers, apples, and navel oranges. Complete control of thrips was achieved in 30- and 60-minute fumigations with 0.5% and 0.3% SO2 at 5'C. The 30-minute fumigations with 0.3-0.5% SO2 of fresh products resulted in complete control of thrips and no injuries to peppers and navel oranges. However, the treatment caused severe injuries to broccoli and minor injuries in form of darkened lenticles on green apples. This study demonstrated that SO2 fumigation has potential to be a safe and effective treatment to control western flower thrips and other susceptible pests on certain fresh fruit and vegetables.

Technical Abstract: Sulfur dioxide (SO2) fumigation was evaluated for efficacy against western flower thrips (Frankliniella occidentalis) and phytotoxicity to four select fresh fruit and vegetables. Western flower thrips were found to be very susceptible to SO2 fumigation. Fumigations of 30 and 60 minutes with 0.5 and 0.3% SO2 respectively at a low temperature of 5'C achieved 100% thrips mortality. Broccoli, bell peppers, apples, and navel oranges with thrips were subjected to 30-minutes fumigation with 0.3-0.5% SO2 to verify efficacy and determine potential phytotoxicity. The fumigation resulted in complete control of thrips. Its effects on visual quality of fresh product varied. The fumigation caused severe discoloration of broccoli. However, the treatment did not have significant effects on color of other products. No negative impact on visual appearance of bell peppers and navel oranges was observed. However, it caused darkened lenticels on green apples and, therefore, may potentially degrade apple postharvest quality. The lack of phytotoxicity of SO2 fumigation is likely due to well-developed wax layers on those fresh products. The results of the study suggest that SO2 fumigation has good potential to be used safely and effectively against sensitive pests on some fresh fruit and vegetables.