2012 Annual Report
Field surveys across four major Hawaiian Islands were conducted to determine populations of gall forming, shoot-tip feeding, and flower-head feeding native tephritid flies. Results of the field surveys were integrated with the data available from all accessible museum specimens and published documents to create a database of fly distribution that is both current and historical.
In collaboration with an entomologist at the Grinnell College, Iowa, 4 new species of native Hawaiian tephritid flies were described and reported. In addition, there were new island or host records for several other species. Using the maximum entropy Ecological Niche Modeling approach, spatial distribution models were constructed for 10 most common species of endemic Hawaiian tephritids. The models were presented as .kmz files to allow readers to have access to detailed distribution maps using the readily available software in Google Earth.
A multi-gene molecular based phylogeny for the genus, Bactrocera, has been developed to enhance the understanding of its systematics. By producing a robust phylogenetic framework for this quarantine significant fruit fly, all countries known to be plagued by Bactrocera will have an opportunity to understand which species currently occur in their countries, which species are causing damage, and how to improve their quarantine systems to keep the pest species out of their respective countries. Using methyl eugenol, cuelure and Torula yeast, a total of 4,500 specimens of fruit flies were collected from Thailand, Cambodia, Laos, and Malaysia in 2011 and then in Yunnan and Guangxi, China, in 2012. The data showed that 74% of the flies collected in 2011 belonged to Bactrocera dorsalis complex and 17 flies were categorized as undescribed, new species as they were distinctively dissimilar to those described species.
For the phylogenetic relationship study, DNA was extracted from fruit fly samples and sequenced 790 base pairs of the mitochondrial gene COI. Of these, 175 were selected for an in-depth study. The results showed that B. dorsalis complex is paraphyletic and B. dorsalis, B. papaya, B. philippinensis, B. carambolae and B. invadens are genetically similar with less than 1.5% differences. Results of the study also showed that inbreeding depression could arise in biological control agents, and that the fitness of the agents could be reduced when a laboratory strain of an insect species was crossed with a wild strain of the same species, which often occurred in augmentative releases of biological control agents. This finding warns against flooding of wild fruit fly populations with biological control agents, which were bred in captivity.