Ethyl formate and nematicidal dip treatments as methyl bromide alternative treatments for the longtailed mealybug (Pseudococcus longispinus) and the root-lesion nematode (Pratylenchus penetrans) on imported nursery plants

Authors: KIM, DONG-BIN - Kyungpook National University; KIM, KYEONGNAM - Orise Fellow; KWON, TAE-HYUNG - Orise Fellow; Cha, Dong; LEE, BYUNG-HO - Kyungpook National University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2025
Publication Date: 6/19/2025
Citation: Kim, D., Kim, K., Kwon, T., Cha, D.H., Lee, B. 2025. Ethyl formate fumigation and nematicidal dip treatments as methyl bromide alternative treatments for the longtailed mealybug (Pseudococcus longispinus) and the root-lesion nematode (Pratylenchus penetrans) on imported nursery plants. Journal of Economic Entomology. Article toaf092. https://doi.org/10.1093/jee/toaf092.
DOI: https://doi.org/10.1093/jee/toaf092

Interpretive Summary: Mealybugs and root-lesion nematodes are major pests and key trade barriers of imported nursery plants. Methyl bromide fumigation (MB) has been used to disinfest imported nursery plants. However, severe phytotoxicity has been reported. As a first step to develop MB alternative treatment for imported nursery plants, researchers at the USDA-ARS and Kyungpook National University and Chungbook National University in South Korea are testing whether ethyl formate (EF) fumigation and nematicidal dip treatments are effective for the disinfestation of longtailed mealybug and a root-lesion nematodes from imported nursery plants. EF fumigation was effective at controlling longtailed mealybug with much lower phytotoxicity than MB fumigation. Nematicidal dip treatment was effective at controlling root-lesion nematode without negative impact on treated plants, suggesting EF fumigation and nematicidal dip as potential disinfestation treatments for imported nursery plants.

Technical Abstract: The increase in nursery plant trade has heightened the risk of invasions of exotic pests such as mealybugs and nematodes. In this study, we (1) compared the efficacy of methyl bromide (MB) and ethyl formate (EF) fumigation treatments against the longtailed mealybug, Pseudococcus longispinus Targioni-Tozzetti, (2) tested two nematicides against the root-lesion nematode, Pratylenchus penetrans Cobb, and (3) evaluated the impacts of these treatments on the quality of tested imported nursery plants. During commercial trials at an importing port in Korea, the approved MB treatment of 40 g/m³ for 2 h for imported nursery plants did not result in complete control of P. longispinus. Moreover, the MB treatment caused severe and irreversible damage to the treated plants. In contrast, the suggested dose of EF (35 g/m3 for 4 h) caused significantly less phytotoxicity on the treated plants than did MB, and 66% of tested species that suffered moderate to severe treatment damage recovered within the 30 d post-fumigation period. The efficacy of EF was also confirmed in a commercial-scale trial, suggesting that EF is a feasible alternative to MB, showing similar efficacy on P. longispinus but much lower phytotoxicity. For P. penetrans, dipping plant roots in Allstar or Nemakick at 0.5 ml/L for 1 h or 4 ml/L for 10 min resulted in complete control of P. penetrans with no apparent phytotoxicity on the treated nursery plants. Together, our results suggest that EF fumigation and a nematicidal dip treatment are two feasible phytosanitary measures for use on imported nursery plants.