Page 49 - SA Fruit Journal VOLUME 14

FRUIT FLY SYMPOSIUM THAILANDReport on the Ninth International Symposium on Fruit Flies of Economic Importance held in Bangkok Thailand in May 2014It is always difficult deciding on what aspects of a symposium to report on, not due to lack of choice but rather the sheer volume of information that one is exposed to, writes Matthew Addison, Crop Protection Manager at HORTGRO Science. I have selected a number of presentations and discussions - all relevant to agriculture in southern Africa and specifically to fruit producers in the South Western Cape - on which to report.One of my motivations for attending the symposium was to gather informa- tion on Bactrocera invadens, the new inva-sive fruit fly that poses a significant threat to fruit production in southern Africa. The taxonomic status of B. invadens has drawn a lot of attention recently, the question being whether or not B. invadens is a separate spe- cies from the oriental fruit fly B. dorsalis.Prof. Tony Clarke (School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Bris- bane, Australia) presented research findings that confirm that B. invadens and a num- ber of other sibling species are in fact part of the same species, namely B. dorsalis. This is significant as the African fly is no longer regarded as a new species. The reclassifica- tion of B. invadens simplifies quarantine and other measures as there is no longer a need to develop information on a “new” species. The finding also allows for the application of cur- rent research findings to be applied locally in southern Africa, for example the develop- ment of sterile insect technique on B. dorsalis is advanced and could be applied locally.The rapid invasion of Africa by B. dor- salis and the economic impact of the fly on agriculture were discussed extensively. A number of delegates expressed their alarm at the sudden range expansion of the fly. South American entomologists were concerned and it was noted that if the fly established in South America it would be devastating for agriculture on the continent. I had the op- portunity to talk to Prof. Clarke and asked him if B. dorsalis would pose a threat to theSouth Western Cape. He noted that the insect is able to survive in a wide variety of environ- ments, that it is highly mobile and has a very wide host range. He predicted that it could establish in the South Western Cape, and if it did so it would pose a significant economic threat. Australia has had an incursion of B. dorsalis and managed to eradicate it. The eradication program was extensive and cost a significant amount. The discussion turned to B. tryonii, the Queensland fruit fly. Prof. Clarke noted that B. tryonii had moved into southern Australia and was having a signifi- cant impact on deciduous fruit production. He noted that the production of low chill stone fruit near Brisbane had declined due to the fly and orchards were being removed.Closer to home was a presentation on the population genetics of Natal fruit fly by Mi- nette Karstens (Ph. D student in the Depart- ment of Conservation Ecology and Entomol- ogy, University of Stellenbosch) and others. The industry funded research allowed for the detailed analysis of the genetics of Natal and Mediterranean fruit fly and the mobility of the flies within South Africa. The study revealed that there was little genetic structure within the country thus indicating that flies move around or are moved around the country. This has implications for any control program as the program would have to be applied on a much larger scale than originally thought.Shanmugam Vijaysegaran (Queensland University of Technology, School of Earth, Environmental and Biological Sciences, Bris- bane Australia) addressed the meeting on the subject of small-scale production of fruit flybait from waste brewer’s yeast. The method involves the heating of waste yeast to remove water and alcohol and then treating the yeast with enzymes. The mixture is then stabilized with a preservative to ensure shelf life. The bait contains 12 – 18 % protein and 18 – 25 % sugars. The method has been developed and is now being used in Malaysia, Cambodia and other countries to produce low volume fruit fly bait with good effect. In addition, the bait is also being applied in commercial orchards in conjunction with male annihilation technique. The use of locally produced bait by small-scale farmers is appealing as the method is effective and removes the need for cover sprays. The equipment needed for the manufacturing pro- cess is relatively simple and low cost.The control of Bactrocera in Africa using male annihilation technique was presented by Dr Aruna Manrakhan (Citrus Research Inter- national, Nelspruit) and others. She reported that Bactrocera populations can be effectively suppressed by using a method known as male annihilation technique (MAT). The method involves the use of small absorbent blocks containing an attractant (methyl eugenol) and a toxin. It was reported that the use of MAT in combination with conventional (protein) bait applications and strict orchard sanitation effectively controlled B. dorsalis populations in the north of the country. It was noted that other MAT technologies are becoming avail- able within South Africa.The early detection and rapid eradication of B. dorsalis is the ultimate aim of any ento- mologist working on the insect. Preeaduth Sookar (Ministry of Agro Industry and FoodTEGNOLOGIE 46 FEB | MAART 2015