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

Citrus mealybug, Planococcus citri (Risso), is a known quarantine pest that is difficult to control with phosphine (PH₃) 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 PH₃ individually, and the effects of EF mixed with PH₃ as an MB alternative for the control of P. citri adults, nymphs, and eggs. In comparison to treatments with EF and PH₃ individually, EF mixed with PH₃ 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 PH₃ achieved complete control of eggs infesting pineapples at concentrations of 25.1/1.0 (EF/PH₃) mg/liter at 8 °C for 4 h of exposures. This new combined EF/PH₃ 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.