A novel bio-pesticide created using spider venom and a plant protein has been found to be safe for honeybees, despite being highly toxic to a number of key insect pests, according to a study by UK-based Newcastle University.
The new research tested the insect-specific Hv1a/GNA fusion protein bio-pesticide – a combination of a natural toxin from the venom of an Australian funnel web spider and snowdrop lectin.
Feeding acute and chronic doses to honeybees – beyond the levels they would ever experience in the field – the team found it had only a very slight effect on the bees' survival and no measurable effect at all on their learning and memory.
Publishing their findings last week, the authors say the insect-specific compound has huge potential as an environmentally-benign, 'bee-safe' bio-pesticide and an alternative to the chemical neonicotinoid pesticides.
Though research prepared by the USDA and the U.S. EPA have determined there are several causes for declines in bee and pollinator populations, some studies have linked neonicotinoids to the declines. The EU has already authorized a ban on neonicotinoid seed treatments.
By pollinating some key crop species, honeybees make a vital contribution to food security. The decline of these insects raises significant concerns about farmers' ability to feed a growing population.
Newcastle professor Angharad Gatehouse, one of the supervisors on the project, says the study's findings suggest that Hv1a/GNA is unlikely to cause any detrimental effects on honeybees.
"Previous studies have already shown that it is safe for higher animals, which means it has real potential as a pesticide and offers us a safe alternative to some of those currently on the market," he says.
During the study, the bees were exposed to varying concentrations of the spider/snowdrop bio-pesticide over a period of seven days. Throughout the study period, the team carried out a series of memory tests and recorded any changes in behavior.
Honeybees naturally perform sophisticated behaviors while foraging that require them to learn and remember floral traits associated with food. Disruption to this important function has profound implications for honeybee colony survival, because bees that cannot learn will not be able to find food and return to their hives.
"This is an oral pesticide so unlike some that get absorbed through the exoskeleton, the spider/snowdrop recombinant protein has to be ingested by the insects," explained research lead Erich Nakasu, a PhD student at Newcastle University.
Unlike other pesticides, Hv1a/GNA affects an underexplored insecticidal target, calcium channels. These are more diverse than commonly-targeted insecticide receptors, such as sodium channels, and therefore offer the potential for more species-specific pesticides.
"Calcium channels are linked to learning and memory in bees so it's vital that any pesticide targeting them does not interfere with this process," Nakasu says.
"Although Hv1a/GNA was carried to the brain of the honeybee, it had no effect on the insect which suggests the highly selective spider-venom toxin does not interact with the calcium channels in the bee."
The larvae were also unaffected by the Hv1a/GNA, as they were able to break it down in their gut.
"Around 90% of the world's plants are directly or indirectly reliant on pollinators to survive," says Dr. Geraldine Wright, one of the authors on the paper.
"If we destroy the biodiversity of pollinators then it will be irrelevant how effective our pesticides are because we won't have any crops to protect."
This research was funded by the UK'sTechnology Strategy Board.