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Beyond the Bale : March 2015
ON FARM 43 similar breech wrinkle, breech cover and a slight difference in dag score (0.1 score). Joe has used these samples in a test specifically designed to see whether they attract (or repel) flies. Joe placed the wool samples from a resistant sire and a susceptible sire in two separate glass flasks and blew air over them and then through a Y-shaped glass apparatus towards a single opening. He released gravid flies at that opening and they were given the option of walking up the stem and then choosing either the direction of the resistant or susceptible wool when they reached the Y junction. 90 flies have been tested, some coming from Mt Barker WA and others from Queensland. All 90 flies that walked down the glass Y tube chose to walk in the direction of the susceptible wool when they reached the Y junction (see photos on p42). Wool samples were rotated and switched between the left and right hand arms of the Y tube and the equipment was washed thoroughly (or changed completely) between runs to make sure there weren’t any anomalies occurring. It took quite some time to set up a sustainable fly colony to produce adequate numbers of gravid female flies, to optimize a range of variables and measures, such as airflow speed, light, measures of fly behavior and timing for each test run. Wool samples have been taken from all the 2012, 2013 and 2014 drop animals at both sites. These samples are now being tested using Gas Chromatography, a technology that is used in analytical chemistry to separate and evaluate a wide range of chemicals, including ones linked to odour. While only part way through the 2012 samples, 12 volatile odour chemicals appear to stand out as being different between the wool samples from resistant and susceptible sheep. The next step that Joe is about to embark on will involve the use of an antennogram, where single compounds are ‘passed by’ a single fly’s smell antennae to measure their brain’s reaction to these components. It is a slow process and could take 2-3 years to find the needle in the hay stack, but given that we know there are some compounds that appear to be very different between resistant and susceptible sheep, we have a way of targeting the antennogram studies increasing the chances of finding that needle. Similar type of work is being conducted on other insects (mosquito, tsetse fly) from a human health point of view as well as investigations into plant propagation (eg smoke compounds that lead to germination of eucalypts and compounds that attract insects for fertilisation). In 2014 Joe Steer was awarded the prestigious University of WA, Mike Carrol Travelling Fellowship. Joe will spend a month with Dr Mike Burkett at his Olfactory Research unit at the renowned Rothamsted Research facility in the UK to further his studies on fly attractant compounds. The practical end to this work is a test that could be used on wool samples in a lab (like micron testing) to get a resistance/ susceptibility measure that will lead to reduced breech strike and reduced reliance on chemicals. The genome of the sheep blowfly has been sequenced which will help provide researchers with unique insights into the fly’s molecular biology, interactions with the host animal, and insecticide resistance. Dr Robin Gasser, Dr Philip Batterham and Dr Claire Anstead from the University of Melbourne and their collaborators, including the Human Genome Sequencing Centre at the Baylor College of Medicine in Houston Texas, have sequenced the genome of the sheep blowfly Lucilia cuprina and submitted a paper for publication. They found 14,554 genes, 2062 of these being unique to the sheep blowfly Lucilia cuprina. The Baylor team created the 458 million piece jigsaw and the Melbourne team painstakingly put it together. A follow on project with the University of Melbourne will develop the new “CRISPR” technology for use in blowflies. An eye colour gene will be knocked out to produce a fly with white eyes, an easily observed marker to show that the technique is working. Then a gene that controls olfaction will be knocked out so that the blowflies produced will have no sense of smell. These flies could then be assessed using Joe Steer’s choice test. Further analyses of the blowfly genome will provide unique insights into the fly’s molecular biology, interactions with the host animal and insecticide resistance. These insights will have broad implications for designing new methods for the prevention and control of flystrike. The unique genes will have special attention, particularly those active in the early larval stage. Having known and unique gene targets will make formulation and registration of new chemicals easier. It will also help determine exactly how existing chemicals are impacting on the fly and provide information about which chemicals are more likely to lose efficacy early in their life. PhD student Joe Steer (second right) with his three PhD supervisors Dr Gavin Flematti, Dr Johan Greeff and Professor Phil Vercoe. Dr Robin Gasser and Dr Philip Batterham from the University of Melbourne. SKINTRACTION® INTRADERMAL The APVMA’s decision whether to allow the registration of the SkinTraction® intradermal is expected in the next few months. Further development and commercialisation of the product has been on hold pending the registration decision. LIQUID NITROGEN Liquid Nitrogen has shown in an early scoping study to successfully remove excessive breech and tail wrinkle and reduce breech wool cover. Development work continues to make the technique practical in the field, reducing the volume of Liquid Nitrogen required by engineering the delivery system to have a continuous Liquid Nitrogen flow and the number of head processed per day high enough in line with animal husbandry practices. MORE INFORMATION The AWI 2014 National Wool R&D Technical Update on Breech Flystrike Prevention is on the AWI website at www.wool.com/flystrikeRnDupdate FLY GENOME ALTERNATIVES TO BREECH MODIFICATION