The
Australian sheep blowfly, L. cuprina,
is a major pest of the Australian Wool Industry.This pest causes sheep myiasis (flystrike),
where adult flies lay eggs on a sheep’s body that hatch and the resulting
larvae begin feeding on the flesh of live sheep, often resulting in sheep
death. Currently there are two common methods of control. The first is the use
of insecticides, but their effectiveness has been severely hampered by the
development of insecticide resistance to a large number of commonly used
insecticides. The second is the practice of mulesing, where the wool and skin
around a sheep’s backside, including its tail, are cut away with shears.The Australian Wool Industry has, however,
promised to phase out the practice of mulesing by 2010.Currently there are no viable alternatives to
mulesing as a control option against sheep blowfly strike.
This
project aims to investigate the possible use of the intracellular bacterium Wolbachia as a method to suppress
populations of the sheep blowfly in Australia.To implement such a strategy, a thorough
understanding of the population dynamics of both host (L. cuprina) and symbiont (Wolbachia)
is needed. To determine the population structure of L. cuprina in Australia,
six microsatellite markers and four EPIC (exon primed intron crossing) markers
have been developed. Eighteen populations (> 20 individuals) have now been
collected from Victoria, NSW, Western Australia and South Australia during spring and summer of
2007/2008 and individuals will are currently being assessed for their genotype
at the ten genetic marker loci. Three sites have also been sampled on a
temporal timescale (over 2 years) in Victoria
to determine population structure through time. These samples will also be used
to assess Wolbachia infection
frequencies in L. cuprina in the
field. Further experiments are planned this year to determine the effects of Wolbachia infection on L. cuprina in both the laboratory and
the field so that a thorough assessment of a Wolbachia based strategy for the suppression of populations of L. cuprina can be made.