A Combination Treatment Using Ethyl Formate and Phosphine to Control Planococcus Citri (Hemiptera: Pseudococcidae) on Pineapples

Citrus mealybug, Planococcus citri (Risso), is a known quarantine pest that is difficult to control with phosphine (PH) or low concentrations of ethyl formate (EF), particularly at low temperatures. Methyl bromide (MB) is a fumigant used for quarantine and preshipment (QPS) that can eradicate target pests with short fumigation periods. However, MB, which is an ozone-depleting substance, is scheduled to be phased out in South Korea over the next decade. There is no ideal alternative fumigant to replace MB for QPS of perishable commodities. A laboratory study was conducted to compare the individual effects of EF and PH individually, and the effects of EF mixed with PH as an MB alternative for the control of P. citri adults, nymphs, and eggs. In comparison to treatments with EF and PH individually, EF mixed with PH resulted in high toxicity to all stages of P. citri. The eggs were more tolerant than the nymphs and adults. A mixed treatment of EF and PH achieved complete control of eggs infesting pineapples at concentrations of 25.1/1.0 (EF/PH) mg/liter at 8 °C for 4 h of exposures. This new combined EF/PH fumigation technology could offer shorter exposure times and less damage to perishable commodities at low temperatures, and could potentially be extended to controlling other quarantine pests as a replacement treatment for fruit and vegetables in which methyl bromide is currently being used.