Use of Ethyl Formate Fumigation to Control Adult Bean Thrips in Navel Oranges

: Shipments of California Navel oranges (Citrus sinensis) (Osbeck)) that are found to be infested with adult bean thrips (Caliothrips fasciatus (Pergande) (Thysanoptera: Thripidae)) upon arrival in Australia either undergo mandatory fumigation with methyl bromide (MeBr) to kill the thrips or are refused entry. Ethyl formate (EtF) mixed with carbon dioxide (CO₂) is an effective fumigant for control of various arthropods including but not limited to, thrips, aphids, Pacific spider mites, California red scale, and omnivorous leaf rollers. Dose-mortality curves at 5°C, 10°C, and 15°C were developed for control of adult bean thrips using EtF plus CO₂, with 5°C being more effective. In further testing, the efficacy of EtF plus CO₂ against adult bean thrips in Navel oranges and the impact on fruit quality after fumigation followed by 5 wk of storage at 5°C and shelf life at 20°C was determined. Fruit fumigated with 31 g/m3 EtF plus CO₂ at 5°C for 1 h showed no difference in quality compared with untreated control fruit. Ethyl formate plus CO₂ fumigation efficacy was confirmed in a 27.32 m3 sea freight container with eight pallets of packed Navel oranges (load factor 28.69%) and 10,000-15,000 adult bean thrips in each of three replications. Complete control of adult bean thrips was achieved with no negative effects on fruit quality.