Abstract
Biting midges are globally distributed pests causing significant economic losses and transmitting arbovirus diseases to both animals and humans. Current biological and chemical control strategies for biting midge target destruction of adult forms, but strategies directed at immature stages of the insect have yet to be explored in Australia. In the present study, coastal waters of Hervey Bay region in Queensland, Australia were screened to detect the habitats of biting midge at immature stages. These results were then correlated to local environmental conditions and naturally occurring entomopathogenic fungal flora, in particular the Oomycete fungi, to determine their reducing effect on insect immature stages in the search for biological control agents in the region. The dominant species of biting midge found within this study was Culicoides subimmaculatus occuring between mean high water neaps and mean high water spring tide levels. Within this intertidal zone, the presence of C. subimmaculatus larvae was found to be influenced by both sediment size and distance from shore. Halophytophthora isolates colonized both dead and alive pupae. However, the association was found to be surface colonization rather than invasion causing the death of the host. Lack of aggressive oomycete fungal antagonists towards midge larvae might correlate with increased incidences of biting midge infestations in the region.
Highlights
Biting midges are common pests, found in many different countries and regions such as the USA, the Caribbean, Africa, Mexico, Canada, Scotland and Australia [1,2,3]
The study reported here is a further investigation into the presence of naturally occurring entomopathogenic oomycete fungi against biting midge larvae within Hervey Bay, Queensland, in order to assess their potential as biological control agents and a safe alternative to chemical control in the region
Species of oomycete fungi in particular Halophytophthora were targeted for isolations in this study as they were reported to occur within the marine intertidal environment [28] and belong to the Family
Summary
Biting midges are common pests, found in many different countries and regions such as the USA, the Caribbean, Africa, Mexico, Canada, Scotland and Australia [1,2,3]. Adult insecticidal fogging is the application of aerosol particles against flying insects [20] This method is usually ineffective and short-term [15] due to rapid re-infestation, limited accessibility to treat large areas, and the significant costs involved [20]. The majority of insect orders are susceptible to pathogenic fungi [24] with populations commonly affected by extensive epizootic disease events [25]. The study reported here is a further investigation into the presence of naturally occurring entomopathogenic oomycete fungi against biting midge larvae within Hervey Bay, Queensland, in order to assess their potential as biological control agents and a safe alternative to chemical control in the region
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