Ethyl Formate as an Alternative Quarantine Treatment to Control Insect Pests in Navel Oranges (Citrus sinensis L. Osbeck), Lemons (Citrus limon) and Sweet Cherries (Prunus avium L.)

Methyl bromide fumigation may soon not be available for the control pests on harvested citrus and sweet cherry fruit due to restrictions on use and cost of this ozone depletor chemical. Ethyl formate is a natural volatile that has been used to control pests in dried fruits and could be used as an alternative to methyl bromide for postharvest insect control. The mortality of third instar California red scale [Aonidiella aurantii (Maskell)], western flower thrips adults [Frankliniella occidentalis (Pergande)], and third instar codling moth [Cydia pomonella (Linnaeus)], as well as the quality of navel oranges (Citrus sinensis L. Osbeck), lemons (Citrus limon), and sweet cherries (Prunus avium L.) were determined after ethyl formate fumigation. California red scale, western flower thrips and codling moth were fumigated with a range of ethyl formate concentrations at 20°C to determine the dose required to reach Probit 9 level of control for these pests. Fruit were subsequently treated with the dose required to reach Probit 9 control to evaluate fruit tolerance. Citrus fruit were treated at 20°C for 1 h with 37.8 g m-3 ethyl formate and sweet cherries were treated for 1.5 h with 85.8 g m-3 ethyl formate. The quality of oranges and lemons was evaluated after simulated overseas shipping, storage and shelf-life and the quality of sweet cherries was evaluated after simulated overseas air and sea shipment. No significant effect of ethyl formate fumigation on the quality of navel oranges and lemons was observed. Sweet cherries subjected to simulated air shipment had acceptable quality for most of the attributes, with only slight stem browning. However, ethyl formate treatment at 85.8 g m -3 was not suitable for cherries that will be sea-shipped due to reduced overall acceptability with severe stem browning and pitting. Results indicate that ethyl formate is a promising substitute for methyl bromide for the control of California red scale and western flower thrips and for the control codling moth in sweet cherries shipped overseas by air.