Susceptibility of Ripe Avocado to Invasive Alien Fruit Flies (Tephritidae) on the Island of Hawaii

Abstract

The Avocado Growers Association on the island of Hawaii requested that the USDA-APHIS reconsider the possibility of approving the export of untreated avocado to the continental USA. In response, as part of the Hawaii Area Wide Pest Management Program, the Agricultural Research Service undertook a survey to supplement the original survey conducted by Liquido et al. (1995). This consisted of deploying traps baited with male lures for the three invasive species (Bactrocera dorsalis (Hendel), B. cucurbitae (Coquillett), and Ceratitis capitata Wiedemann)) and protein bait traps for general detection of females within orchards. The survey was concentrated in the Kona District, and the orchards were mapped using a geographic information systems approach. In addition, between 9 August 2006 until 22 May 2007, 519 avocado fruits were collected from the ground and held individually to determine the presence of fruit fly larvae. Because male lure trap captures varied with locality and season and attracted flies from large distances, they are probably of limited value in predicting numbers of fruit flies within small avocado orchards. On the other hand protein bait traps, because they captured females and attracted flies from short distances, were a better indication of female flies found within orchards. C. capitata was the most prevalent species year round (0.456 ± 0.130 ♀ flies/trap/day). B. dorsalis was captured considerably less frequently (0.096 ± 0.068 ♀ flies/trap/day). B. cucurbitae was the least prevalent species in avocado orchards, averaging 0.034 ± 0.006 ♀ flies/trap/day. Adult fly emergence from the ground fruit sample was 1.25 x 10–05 ± 8.89 x 10–6 B. dorsalis flies/g of fruit and no C. capitata emerged from any fruit sample. That is a fruit infestation rate of 0.385% and a rate of 0.771% larvae per fruit. All of the fruits sampled had some damage that would have excluded them from shipment by previous export criteria.