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Varroa mite pesticide now in development

THE South Australian bee industry will benefit from a world-first hormone-based pesticide that is safe for honey bees but fatal to the destructive varroa mite. 

Amid Australia’s first varroa mite outbreak, the grower-owned research and development corporation Hort Innovation has joined forces with the University of Sydney to develop the hormone-based pesticide that is fatal to varroa mite, but will not affect honey bees. 

As part of the initiative, scientists will create molecules that selectively bind and interfere with hormone receptors of varroa mite and fellow honey bee pest, the small hive beetle, interfering with reproduction, development and behaviour.

The target receptors are absent from vertebrates, making the pesticide safe for other beneficial animals in the environment. 

Hort Innovation chief executive Brett Fifield said the project aims to help safeguard Australian honey bees and will have positive impacts on horticulture production.

“Thirty per cent of global agricultural production is reliant on pollination by honey bees,” he said.

“Across the board, this production is currently under threat from pests including the varroa mite and the small hive beetle.”

Mr Fifield said pesticides are a crucial aspect of sustainable agriculture and disease control, but underlined the pressing need for more environmentally-friendly pesticides that have selective action against “bad” versus “good” insects.

“The development of a commercial pesticide that is fatal to varroa mite and small hive beetle, but not honey bees, will lead to a worldwide market opportunity to export Australian-based technology,” he said.

“It will also offer a significant step toward protecting global agricultural systems that are reliant on honey bee pollination.”

Until recently, Australia was the last known inhabited continent in the world unaffected by varroa mite, which causes weakness in honey bee colonies by feeding on larvae and pupae, but can also live on adult honey bees, transmitting viruses.

Chemical control methods exist but research shows varroa mites globally are building up tolerances and some treatments are unsuitable for the Australian environment.

University of Sydney project lead Professor Joel Mackay said insecticides that target varroa mite, as well as small hive beetle receptors, have not been successfully created before.

“There has been international recognition of the potential value of insect hormone receptors as targets for safer selective control agents,” he said.

“Several companies have tried and encountered technical difficulties largely because these proteins are challenging to express, purify and characterise.

“However, our team has had over a decade of experience tackling and overcoming technical challenges, and we have one of only two laboratories in the world that have determined atomic structures of the hormone proteins of the receptors we ae targeting.

“We have also developed a unique receptor-based chemical library screen for discovery of new pesticide leads molecules.”

La Trobe University and the Walter and Eliza Hall Institute are also contributing to the five-year project.