Ethyl Formate Fumigation for Control of the Scale Insect Asiacornococcus kaki, a Quarantine Pest on Sweet Persimmon, Diospyros kaki: Efficacy, Phytotoxicity and Safety

SIMPLE SUMMARY: The aim of this study was to evaluate the effectiveness the fumigant of ethyl formate (EF), an alternative to methyl bromide, in controlling the pest Asiacornococcus kaki on sweet persimmon fruit. The study assessed the hatching rate of eggs and the survival rates of nymphs and adults of A. kaki at low temperatures as well as the lethal concentration of EF required to kill 50% and 99% of its population. Large-scale tests were conducted in a 20 ft reefer container at 5 ± 1 °C for 6 h to confirm the efficacy of EF on different life stages of A. kaki. Our results indicated that EF is an effective pesticide for A. kaki without causing phytotoxic damage to persimmon fruit. However, at the egg stage, which was the most tolerant, the A. kaki population was not completely controlled in linear low-density polyethylene (LLDPE)-packaged fruit. Overall, EF is a promising fumigant for the quarantine pre-treatment of sweet persimmon fruit before it is packed with LLDPE film, specifically to control A. kaki located beneath the calyx of the fruit. ABSTRACT: Sweet persimmons are a valuable export commodity. However, the presence of live insects such as Asiacornococcus kaki limits their access to many export markets. Methyl bromide, traditionally used for pest control, is damaging to human health and the environment. Ethyl formate (EF) is a viable alternative; however, its effectiveness against A. kaki on sweet persimmon fruit is unknown. We evaluated the effectiveness of EF fumigation in controlling A. kaki present under the calyx of persimmon fruit. The hatching rate of eggs and the survival rates of nymphs and adults of A. kaki at low temperatures, its LCt(50) and LCt(99) after EF exposure, and phytotoxic damage caused by EF were evaluated in laboratory-scale and commercial-scale tests. The dose–response tests showed that the EF LCt(99) at 5 °C was 9.69, 42.13, and 126.13 g h m(−3) for adults, nymphs, and eggs, respectively. Commercial-scale tests demonstrated EF efficacy against all A. kaki stages without causing phytotoxic effects on persimmons, though the eggs of A. kaki were not completely controlled in linear low-density polyethylene (LLDPE)-packaged fruit. This study demonstrated that EF is a potential fumigant for quarantine pretreatment, especially before persimmon fruit is packed with LLDPE film, to control A. kaki infesting sweet persimmon fruit.