Area-wide control of buffalo fly and prevention of southward spread using Wolbachia

Buffalo flies (BF) are ranked as a major health concern by northern cattle producers in many areas. In addition, BF are invasive, and have increased their range southward by 1000 km in the last 40 years with infestations seen as far south in NSW as Maitland, Dubbo and Narromine, west to Bourke and Alice Springs in NT. Climate change will result in increased economic and welfare impacts in BF-endemic areas and even more rapid spread into new areas. Modelling suggests that persisting populations of BF could establish as far south as South Australia and south-western WA by 2030.

BF survives winter in localised areas as very low numbers of adult flies which build up and spread when weather becomes favourable. This is the weak link in the BF life cycle. This project will investigate a novel approach using Wolbachia, an insect-infecting bacterium, in area-wide approaches targeting overwintering foci of BF to reduce the effects of BF in already infested areas and to arrest the southerly spread of BF. A technique using Wolbachia is currently showing good results in northern QLD in the control dengue fever vectored by Aedes mosquitoes.

Project objectives

• To transfect laboratory populations of buffalo flies with strains of Wolbachia by June 2017.
• To assess the effect of presence of Wolbachia on reproduction and survival/fitness traits of BF by June 2018.
• To evaluate the potential for use of Wolbachia in regional eradication programs and to arrest the southerlyspread of BF and to recommend strategies for practical implementation, by June 2019.

It was recently estimated that BF cost the beef industry $99m p.a. in an average year (MLA final report B.AHE.0010). This estimate does not take account of the very considerable costs that will result if BF spreads through the southern cattle industries or the increased impact of BF expected as a result of climate change in endemic areas. It also does not account for welfare impacts, thought to be considerable in some quarters. Control of BF is increasingly compromised by the development of resistance to control products and there are rapidly growing markets for meat and milk produced in low- chemical systems. The move towards a greater proportion of Bos taurus genes in northern cattle herds to raise beef quality will increase susceptibility to BF and potentially the industry cost of BF.

This project focuses on direct control of BF populations rather than through application of insecticides. Wolbachia once released has the ability to drive itself through an insect population. In addition, use of a biological control agent, focused on the pest population rather than cattle, avoids potential disadvantages associated with chemical treatments such as the cost of product and application, loss of effectiveness due to the development of resistance, potential for residues and occupational health and safety issues.

When: 22 April 2015 to 1 July 2018

Where: Ecosciences Precinct, Dutton Park

Contact: Geoffrey Brown E: Geoff.Brown@daf.qld.gov.au

Collaborators: QAAFI, Meat & Livestock Australia (MLA)