Summary

Summary
This paper describes a very large body of research that was conducted over several years between scientists at The Centre for Animal Biotechnology, The University of Melbourne and the CSIRO Division of Animal Production into the feasibility of developing a recombinant sheep blowfly vaccine. A total of 12 individual antigens were evaluated as potential vaccine candidates for use in a sheep blowfly vaccine. The results indicated that 80% of the larval antigens evaluated could significantly inhibit larval growth (P <0.05) in an in vitro growth assay using sera from vaccinated sheep. While reductions in biomass of up to 60% were recorded in some in vivo trials the variation in the response within groups of vaccinated sheep meant that this protection was not statistically significant. It was found that many of the larval antigens were glycosylated that posed specific problems in the expression of these molecules. The use of alternative expression systems in conjunction with recent improvements in carbohydate synthesis technologies may enable the production of more efficaious antigens and thereby improve protection.
 
 

Summary
Vaccination against the sheep blowfly represents an alternative approach to controlling this important ectoparasite. In order for vaccination to be effective appropriate target molecules must be identified and evaluated. Insect hormones represent potential targets for vaccination due to their importance in larval development. A vaccine trial was therefore undertaken in which sheep were vaccinated with the hormone 20-hydroxyecdysone (20-HE) and subsequently challenged with blowfly larvae. There was a 27% reduction in the weight and a 23% reduction in the number of larvae recovered from the vaccinated sheep compared to the controls. This difference was not statistically significant at the 5% level due to the variation in the response between sheep. Vaccinated sheep mounted a humoral response to the hormone as assessed by ELISA. In addition, electron microscopy studies of larvae recovered from vaccinated sheep indicated that new cuticle formation appeared to have been disrupted. These effects were not observed in larvae recovered from control sheep. The potential for hormones to be used as targets for vaccination will be discussed.
 
 

Summary
The Lucilia cuprina genetic control program conducted by members of CSIRO Entomology is reviewed. A strategy for reviving interest in area-wide control of this pest is suggested through the development of mass-rearing abilities, leading to the application of SIRM to eradicate the pest from Tasmania. Genetic control methods could be integrated in the SIRM program if appropriate strains could be developed, particularly sexing strains. The potential exists to gain synergy with other SIRM programs within Australia if a multi-species SIRM facility capable of producing sterile L. cuprina and other pest species is constructed.
 
 

Summary
We propose a new method for the control of flystrike. This method would utilise live bacteria to deliver insecticidal proteins and/or dsRNA to fly larvae, thus killing the larvae. Live vectoring has been widely used to deliver vaccine antigens and there are some reports of this type of delivery system being used to deliver other biologicals. The adaptation of this technology to flystrike will require the choice of suitable vector bacteria. A review of the literature indicates a number of possible choices. A variety of insecticidal biological molecules are discussed.
 
 

Summary
Wolbachia are obligate intracellular bacterial parasites that infect an extremely wide range of invertebrates. In their insect hosts, Wolbachia induce a diverse range of effects on host reproduction, many of which lead to production of non-viable offspring and skewing of sex ratios. These reproductive parasites infect a significant number of the major insect pests of livestock and crops and also insects responsible for the spread of human infectious diseases. It has been proposed that the changes in host reproduction induced by these bacteria could be exploited to control such insect pests and disease vectors. We believe that research on Wolbachia could lead to new biological control strategies for flystrike. Our understanding of the molecular biology of Wolbachia is set to escalate with the complete genome sequence, providing an opportune time to study Wolbachia. We aim to use genomics to identify Wolbachia genes that encode proteins with the potential to be developed as insecticides.
 
 

Summary
A range of aminopeptidase inhibitors were screened for activity against L. cuprina in in vitro and in vivo assays. Two classes of inhibitors were identified with significant effects on these insects in culture and in sheep trials. Several specific molecules were identified and are now undergoing field trials. Combinations of these molecules with other protease inhibitors or other insecticidal molecules suggests significant potential for new control protocols and products.
 
 

Summary
The identification of novel targets for controlling the sheep blowfly is an important process for discovering new generation compounds that are safer and more environmentally friendly. Experiments in our laboratory have indicated a role for serine proteases in influencing egg hatching in the sheep blowfly. Isolation of the proteases involved using Benzamidine affinity chromatography identified a group of molecules with homology to both trypsin and chymotrypsin-like proteases. These proteases represent potential new targets for controlling egg hatching in the sheep blowfly.

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