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Ongoing project

Protecting pollinators from pesticides: Developing safer, selective pesticides targeting Varroa mite and small hive beetle hormone receptors (PH20003)

Key research provider: The University of Sydney

What's it all about?

This investment is investigating safer, environmentally-friendly pesticides that target the hormone receptors of varroa mite and small hive beetle without negatively impacting honey bees.

The hormone ecdysone regulates many major developmental processes in insects and other arthropods. Ecdysone acts by binding to the ecdysone receptor, a protein that controls the expression of thousands of genes underlying insect reproduction, development and behaviour.

Ecdysone receptors (ECRs) vary subtly in structure between insect groups. This variation provides an opportunity for selective pesticide design, with the aim of developing molecules that selectively bind to and interfere with pest receptors. Furthermore, these receptors are absent from vertebrates, making pesticides that target ECRs particularly safe for farm workers, consumers of agricultural products and other beneficial animals in the environment.

The research team will apply their knowledge of ecdysone receptor biology and biochemistry to discover compounds that they can develop into a commercial pesticide that is selectively toxic to Varroa mite and small hive beetle but safe for bees and humans.

The project team have used publicly available databases to identify the DNA sequences of expressed ecdysone receptor genes in the honeybee, small hive beetle, and Varroa mite.

Each of these genes has now been synthesised and inserted into a DNA vector that can be used to manufacture the two halves of the ECR protein (EcR and USP) in cultured cells.

The team have designed this system in such a way that each of the two proteins that make up the ECR will be produced with a unique ‘handle’ that will allow the research team to isolate them from every other protein inside the cells, resulting in a pure ECR protein sample that can be used for high throughput screening assays and further analysis.

This project aims to discover molecules that are toxic to one of two major honeybee pests - Varroa mites and the small hive beetle (SHB) - but at the same time are safe for honeybees themselves.  Such molecules will be starting points for the development of safer, more selective insecticides that support the pollination industry.

These molecules will be designed to interfere with the activity of a protein (known as EcR) that is essential for the survival all insects and mites, but the project team predict is subtly different in shape in honeybees, Varroa and SHB. These differences should allow molecules with specific shapes to selectively interfere with the protein in the pests but not the honeybee.

To execute this project, the project team need to make purified samples of the EcR protein from each of the three species above. The first step in this process is to obtain the DNA sequences from the three species that encode the EcR protein in each case. These sequences then need to be genetically engineered to ultimately allow the project team to produce the protein from each species.

Over the last six months, the project team have successfully identified the EcR sequence from honeybee, Varroa and SHB and have carried out genetic manipulations that will enable the production of the three versions of the EcR protein.