Eliminating Macchiademus diplopterus (Hemiptera: Lygaeidae) and Siculobata sicula (Acari: Oribatulidae) From Export Fruit Using Ethyl Formate

Abstract

South African fruit is sometimes rejected for export for the presence of live arthropods that are not considered pests of the fruit concerned. Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae) is a cereal pest but may aestivate on fruit of some tree crops in the Western Cape province of South Africa and occasionally results in rejections of export fruit. Ethyl formate in the form of the commercial product Vapormate (a patented combination of ethyl formate and carbon dioxide) was evaluated as a fumigant against M. diplopterus at a dosage of Vapormate 250 g/m3 or ethyl formate 1.29% and carbon dioxide 10.76% (both by volume) and when applied for 4 h gave complete control. Confirmatory trials with >35,000 M. diplopterus using the same treatment, resulted in no survivors. The arboreal mite Siculobata sicula (Berlese) (Sarcoptiformes: Oribatulidae) at times reaches high numbers on citrus in orchards if few pesticides are used and may result in export rejections. A small-scale trial using the same ethyl formate treatment also killed these mites. This treatment-time combination did not appear to have phytotoxic effects on pears or oranges, unless they had prior mechanical injuries that were accentuated. Ethyl formate therefore holds promise for disinfesting fruit before it is packed.

Keywords: Macchiademus diplopterus, Blissus, Siculobata sicula; disinfestation; fumigation.