Control of the sheep blowfly in Australia and New Zealand--are we there yet?

The last 50 years of research into infections in Australia and New Zealand caused by larvae of the sheep blowfly, Lucilia cuprina, have significantly advanced our understanding of this blowfly and its primary host, the sheep. However, apart from some highly effective drugs it could be argued that no new control methodologies have resulted. This review addresses the major areas of sheep blowfly research over this period describing the significant outcomes and analyses, and what is still required to produce new commercial control technologies. The use of drugs against this fly species has been very successful but resistance has developed to almost all current compounds. Integrated pest management is becoming basic to control, especially in the absence of mulesing, and has clearly benefited from computer-aided technologies. Biological control has more challenges but natural and perhaps transformed biopesticides offer possibilities for the future. Experimental vaccines have been developed but require further analysis of antigens and formulations to boost protection. Genetic technologies may provide potential for long-term control through more rapid indirect selection of sheep less prone to flystrike. Finally in the future, genetic analysis of the fly may allow suppression and perhaps eradication of blowfly populations or identification of new and more viable targets for drug and vaccine intervention. Clearly all these areas of research offer potential new controls but commercial development is perhaps inhibited by the success of current chemical insecticides and certainly requires a significant additional injection of resources.

Trapping the flies that cause myiasis: their responses to host-stimuli

A critical phase in the life cycle of the fly species that cause myiasis is host location by the adult females, whether by direct location of and contact with the host, or by indirect location through the selection of sites frequented by hosts. The stimuli to which these flies respond in host location, principally visual and olfactory, are discussed here in the context of their use to enhance the performance of trapping systems used in research, monitoring and control. The three major families of flies encountered in myiasis can be divided into two groups for comparison of host-location strategies: (1) Oestridae; and (2) Calliphoridae and Sacrophagidae. The former are all obligate parasites, the latter include obligate and primary facultative parasites. In the Oestridae, the majority of Cuterebrinae deposit their eggs at sites likely to be visited by the host, whereas the majority of Oestrinae, Hypodermatinae and Gasterophilinae deposit their eggs or larvae directly onto the host. It is presumed that most host location is, like that of haematophagous insects, by response to olfactory and visual cues released by healthy hosts, but the subject is very under-researched. In the Calliphoridae and Sacrophagidae, most species that cause myiasis deposit their eggs or larvae directly onto the host at some predisposing site, such as those caused by wounding, necrosis and/or bacterial contamination. Healthy hosts are much less attractive, even for obligate species such as Wohlfahrtia magnifica, which can invade undamaged tissues. The last decade has seen a renewed interest in the potential for using traps in control of myiasis, leading to significant advances in trap and bait efficiency. However, there is great potential for further research and development, particularly on the general responses of Oestridae to hosts and in the precise identification of the olfactory cues for Calliphoridae and Sarcophagidae.