Postharvest control of western flower thrips (Thysanoptera: Thripidae) and California red scale (Hemiptera: Diaspididae) with ethyl formate and its impact on citrus fruit quality.

The postharvest control of arthropod pests is a challenge that the California citrus industry must overcome when exporting fruit overseas. Currently, methyl bromide fumigation is used to control postharvest pests on exported citrus, but it may soon be unavailable because of use restrictions and cost of this health-hazard ozone-depleting chemical. Ethyl formate is a natural plant volatile and possible alternative to methyl bromide in postharvest insect control. The objectives of this study were 1) to evaluate the mortality of third instar California red scale [Aonidiella aurantii (Maskell)] (Hemiptera: Diaspididae) and adult western flower thrips [Frankliniella occidentalis (Pergande)] (Thysanoptera: Thripidae) under a wide range of ethyl formate concentrations, 2) to determine the ethyl formate concentration required to reach a Probit 9 level of control for both pests, and 3) to test the effects of ethyl formate fumigation on the quality of navel oranges [Citrus sinensis (L.) Osbeck] and lemons [Citrus limon (L.) Burman f.] at 24 h after fumigation, and at different time periods to simulate shipping plus storage (5 wk at 5 degrees C), and shipping, storage, handling, and shelf-life (5 wk at 5 degrees C, plus 5 d at 15 degrees C, and 2 d at 20 degrees C). The results indicate that ethyl formate is a promising alternative to methyl bromide for the California citrus industry, because of successful control of adult western flower thips and third instar California red scale and no deleterious effect on fruit quality at any of the evaluated periods and quality parameters.