The venom from a deadly Australian spider offers promise of a new bio-pesticide that kills key insect pests but leaves honey bees unharmed.
The insect-specific Hv1a/GNA fusion protein bio-pesticide is a combination of a natural toxin from the venom of the funnel web spider and snowdrop lectin.
Researchers at Newcastle University in the United Kingdom says feeding acute and chronic doses to honeybees – beyond the levels they would ever experience in the field – had only a very slight effect on the bees’ survival and no measurable effect at all on their learning and memory.
Publishing their findings in the journal Proceedings of the Royal Society B, the researchers say the insect-specific compound has huge potential as an environmentally-benign, bee-safe bio-pesticide and an alternative to the chemical neonicotinoid pesticides which have been linked to declines in pollinator populations.
Prof. Angharad Gatehouse of the Newcastle’s School of Biology says the university’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.
The Commonwealth Scientific and Industrial Research Organization lists 14 deaths from funnel web bites since 1927, but there have been none since antivenom was developed in the 1980s.
The spiders are medium-to-large in size, with body lengths ranging from 1 cm to 5 cm (0.4″ to 2″). Their primary range is the east coast of Australia and they are found in New South Wales, South Australia, Victoria, and Queensland. The only Australian states or territories without funnel-webs are Western Australia] and the Northern Territory. During the research, involving scientists from Newcastle and Durham Universities and the Food and Environment Research Agency, the bees were exposed to varying concentrations of the spider/snowdrop bio-pesticide for seven days.
During this time the research team carried out a series of memory tests and recorded any changes in behavior.
Unlike many other pesticides, Hv1a/GNA is not absorbed through the exoskeleton and had to be ingested by the insects.
It is also different from other pesticides in that it affects an underexplored insecticidal target – calcium channels. These are more diverse than commonly targeted insecticide receptors, such as sodium channels, and 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 … does not interfere with this process,” says research lead Erich Nakasu, a PhD student at Newcastle University.
“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 are also unaffected by the Hv1a/GNA, as they are able to break it down in their gut.
Dr. Geraldine Wright, one of the authors on the paper who heads up Newcastle University’s Honeybee Lab, last year led the research highlighting the damaging effect of neonicotinoids on bees’ ability to learn and remember and subsequently communicate to their hive mates.
“There is now substantial evidence linking neonicotinoid pesticides to poor performance and survival in bees and what we need now is a clear directive from government to develop and introduce bee-safe alternatives,” she says
Gatehouse says Hv1a/GNA isn’t going to be one silver bullet.
“What we need is an integrated pest management strategy and insect-specific pesticides will be just one part of that,” he says.