Hort Innovation is partnering with researchers at The University of Sydney to develop environmentally-friendly pesticides that selectively target varroa mite.

Pollination is crucial to the long-term sustainability of Australia’s $16 billion horticulture industry. As we move from an eradication to management approach, measures to combat the pest have never been more critical.

Hort Innovation spoke to Dr Emily Remnant and Prof Joel Mackay from The University of Sydney who is developing a pesticide to control varroa mite without harming honeybees and the environment.

Q: What are the challenges of managing Varroa mite with pesticides?

Prof Joel Mackay: One of the biggest challenges in handling the varroa mite is the close relationship between the mite and the honeybee. Even though bees and mites are different evolutionarily, they are still closely linked.

Finding molecules that can affect one but be safe for the other one is a real challenge. The fact that they are both locked up in a small box together really makes it that much bigger a problem to deal with compared to other organisms interacting in an open environment.

Q: Tell us more about this pesticide.

Dr Emily Remnant: We are designing a pest-specific molecule that targets varroa mite without having any effect on other organisms like honeybees, or any other beneficial insects in the environment. The objective is to target a hormone called the ecdysone receptor that is present among all insects, tick, mites and spiders. By doing so we can exploit the differences in the way that this hormone acts between that of the varroa mite and the honeybee.

Q: How could this pesticide change the way we manage varroa mite?

Dr Emily Remnant: The main way that our pesticide will change the way we manage varroa mite is we will not need to use chemicals in the hive that harm bees and the environment. By targeting a molecule specific to the pest, it means that our honeybees will not suffer any negative consequences.

It may mean that we can use this pesticide in more situations than we currently can. A number of pesticides that currently target mites can only be used when there is no honey in the hive.

This is due to the damaging residues the pesticide can leave, harming the honey as well as the pollinators. Using a pesticide that does not leave residues in honey or cause any damage to the bees will prevent these problems from occurring in the future and allow for more extensive use of such pesticides in the management of varroa mite.

Q: How will this research benefit Australian growers?

Dr Emily Remnant: This research will benefit Australian growers by providing another alternative to broad spectrum pesticides that we commonly use on our pests. It will eventually provide growers with an extra pesticide that they can use to target the varroa mite.

This is critical at the moment due to the rapid spreading of varroa mite around Australia. There are a number of pesticides that we can currently use on varroa mite, however the mites are becoming more and more resistant to these molecules. This new approach could revolutionise the way in which we deal with varroa mite on a global scale.

Q: What are the benefits of partnering with Hort Innovation?

Prof Joel Mackay: Partnering with Hort Innovation is really an exciting opportunity. They have allowed our team to pursue a relatively early-stage project through the funding that they have provided. We have confidence in the success of the project, but to see that from a financial investment perspective is truly valuable.

What I love about partnering with Hort Innovation is how we are connected with the growers, the producers and the industries who are potentially going to make the most use of the research that we carry out.