RESEARCH & EVENTS
Development of ecofriendly selective pesticides to safeguard honeybees
By Shahnaz Sultana 1 , Emily Remnant 1 , Ron Hill 1 , Joel Mackay 1
1
School of Life and Environmental Sciences , The University of Sydney
OF the 100 crop varieties that provide 90 % of the world ’ s food , 71 are pollinated by bees1 . However , the recent invasion of Varroa destructor , a mite that parasitises honeybees , is threatening the productivity of horticultural industries2 . As part of an effective strategy to deal with this incursion , more specific and effective pesticides would be a valuable weapon . However , most pesticides currently used in agricultural applications work nonselectively against both pests and beneficial arthropods . A selective pesticide that is harmful to Varroa but safe for honeybees would therefore provide a valuable weapon in our arsenal and might also be a starting point for the development of pesticides that target other harmful mites . In order to design pesticides that display significant selectivity , a target-based approach can be employed . This strategy leverages protein biochemistry , genomics , structural biology , toxicology and chemistry to identify molecules that interact with specific biological targets . In this context , a hormone binding protein in the Varroa mite known as the ecdysone receptor protein is a promising target for pesticide development . This protein interacts with the pest hormone ecdysone to regulate mite development , reproduction and behaviour 3 . Disruption of this interaction by designed chemicals would significantly impair mite development and reproduction , 4 meaning that such chemicals could be potent pesticide candidates . Also , because this receptor is absent from vertebrates and is also subtly different between insects , chemicals targeting this receptor would be safe for farm workers , consumers and also beneficial insects such as honeybees . Such chemicals can also be applied in conjunction with current insecticides to improve potency and reduce the development of resistance .
Our research at The University of Sydney , led by Prof Joel Mackay , Prof Ron Hill and Dr Emily Remnant and funded by Hort Innovation and a generous philanthropic donation , aims to develop such a selective insecticide . Already , we have made considerable progress on this quest . We have identified and purified significant quantities of the Varroa ecdysone receptor protein and also the corresponding protein from the honeybee through a laboratory-based protein production process . We have used an array of experimental methods to demonstrate that these lab-generated receptor proteins can interact with the ecdysone hormone and can therefore be used as targets for pesticide development . With our target in hand , we have recently commenced the search for chemicals that can hit that target . Our strategy is to search collections of thousands of commercially available chemicals to find that needle in the haystack – a chemical that potently interferes with the Varroa ecdysone receptor but does not interfere with the equivalent target in the honeybee ( and so is safe for our beloved pollinators – see figure ). Excitingly , we have already discovered several ‘ hits ’ – chemicals that are starting points on that journey . Time will tell whether these starting points can be honed to yield our holy grail : a pesticide that can be deployed against Varroa without harming honeybees . Concurrently , we are using this strategy to target another pollinator pest – the small hive beetle . To date , we have already purified and characterised the hormone receptor protein from the beetle and are on track to follow in the footsteps of our Varroa work . We hope that this new approach to pesticide design offers a competitive route to the identification of safer , more selective and environmentally friendly agents for the control of insect and arachnid pests , thereby helping to protect global agricultural systems . “ Development of Ecofriendly Selective Pesticides to Safeguard Honeybees ” is funded by the Hort Frontiers strategic partnership initiative developed by Hort Innovation , with co-investment from the University of Sydney and contributions from the Australian Government .
References :
1 . Nabhan , G . P ., & Buchmann , S . L . ( 1997 ). Services provided by pollinators . Nature ’ s Services : societal dependence on natural ecosystems , 133-150 .
2 . Goulson D , Nicholls E , Botías C , & Rotheray EL ( 2015 ) Bee declines driven by combined stress from parasites , pesticides , and lack of flowers . Science . 347 ( 6229 ): 1255957 .
3 . Jack CJ , Kleckner K , Demares F , Rault LC , Anderson TD , Carlier PR , Bloomquist JR & Ellis JD ( 2022 ) Testing new compounds for efficacy against Varroa destructor and safety to honeybees ( Apis mellifera ). Pest Manag Sci . 78 ( 1 ): 159-165 .
4 . Hamaidia , K ., & Soltani , N . ( 2016 ). Ovicidal activity of an insect growth disruptor ( methoxyfenozide ) against Culex pipiens L . and delayed effect on development . Journal of Entomology and Zoology Studies , 4 ( 4 ).
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