New insecticides to target honey bee enemies

University of Sydney scientists are developing insecticides that target two major pests of honey bees but are completely safe for the bees and other animals.

Today, after a state-wide emergency order has been issued to control the movement of bees across NSW and stop the spread of Varroa mite, the scientists plan to combat this pest, as well as the small hive beetle, which are leading causes of colony losses worldwide.

The Varroa mite is rampant worldwide, though thankfully not yet endemic in Australia. On the other hand, small hive beetles are a major problem on the east coast of Australia. Thriving in warm, humid conditions, they feed on hive products like pollen, honey and bee larvae, causing hives to become ‘slimed out’.

Not only are honey bees worth saving in themselves, thirty percent of global agricultural systems are reliant on pollination, and honey bees are our most valuable commercial pollinators. In Australia, for example, honey bees contributed an estimated $14.2 billion to our agricultural economy in 2017. The gross value of Australian agriculture in 2018-19 was $62.2 billion, so honey bees could have contributed to almost a third of this.

Dr Emily Remnant of the BEE Lab is co-leading the project that builds on over a decade of work by Honorary Professor Ron Hill, one of her research partners. She explained how the new insecticides will work: “They will contain molecules that exploit differences in a protein found in honey bees, Varroa mites and small hive beetles. In the pests, they will inhibit the operation of the protein – which is a receptor for the essential insect hormone ecdysone – while leaving the corresponding protein in honeybees unaffected.”

The protein isn’t found in vertebrates, so the insecticides won’t pose a threat to animals such as birds, cats and dogs. Variations in structure between the ecdysone receptors of different arthropods (invertebrates including insects) means that it is possible to design specific molecules that target pests while leaving beneficial insects unharmed.

The team, which also includes Professor Joel Mackay from the School of Life and Environmental Sciences, is currently working to identify active molecules in the ecdysone receptors to use in the insecticides.

Their work was initiated by a philanthropic donation to the University and has recently been awarded additional funding by Horticulture Innovation Australia.