The Passionate Gardener: Spider Venom — Good News for Bees?
Evidence is accumulating that commonly used pesticides are linked to the decline of pollinator populations. Several reports of adverse effects on beneficial pollinating insects from the class of chemicals known as neonicotinoids have recently resulted in a controversial ban on their use by the European Commission. “Neonics” currently make up 24 percent of the world insecticide market; 90 percent of the world’s plants are directly reliant on pollinators to survive.
Protecting crops often means using synthetic insecticides, sometimes with collateral damage to humans and other non-target animals. Even newer pesticides that are safe for mammals are killing helpful pollinators, like bees.
Insect pollination is an important ecosystem service and is essential for fruit set in many crop species, contributing to 35 percent of global food production in approximately 70 percent of crops.
Developing insecticides that pose negligible risks to beneficial organisms such as honeybees is desirable and needed now.
Scientists have discovered that the venom of the world’s deadliest spider will kill pests but won’t harm bees. This strategy uses certain neuro-active proteins linked to a “carrier” protein that allows the “poison” to act orally. One such oral biopesticide, effective against various insect pests, is a combination of an insect-specific spider venom linked to material from Galanthus nivalis — the common snowdrop. The spider is an Australian funnel web spider, an eight-eyed, three-clawed spider that runs, swims and bites!
The spider venom acts as a calcium-channel blocker. Tests suggest that this material is unlikely to cause detrimental effects on honeybees and support the possibility that “biotoxins” targeting calcium channels are a potential alternative to conventional pesticides. Another study showed that it attacks the central nervous system of agricultural pests such as aphids and caterpillars without harming bees.
Proteins from the spider venom, when combined with carrier protein (lectin, from the snowdrop mentioned above), can cross the insects’ gut wall. The calcium channels that carry ions into the nerve cells are disrupted and this disruption kills the bugs.
One of the tests to see if this pesticide would harm bees was performed in 2014 by Newcastle University in England. Calcium channels are linked to learning and memory in honeybees, who must remember various floral traits to help them find food and return to their hives. Honeybees in this test were exposed to varying doses of the spider venom through ingesting it in a sugary solution. Some consumed it just once and others ate massive amounts over the course of seven days. Some were actually injected directly with the solution.
The spider venom had only a slight effect on the honeybee survival, probably because of the differences in channel receptors among various insect species.
On the down side, this pesticide has not been tested on a wide variety of non-target species such as native bees, lady beetles, lacewings and hover flies. Also, these substances are “recombinant fusion proteins” which means they are created artificially genetically by DNA technology (no deadly spiders are “milked”), and it’s unknown what the effect of these substances could be in the future to our environment.
While humans have not ingested the pesticide, the scientific evidence suggests that there is absolutely no danger to humans; the toxins affect the central nervous system of insects, but not mammals.
After 11 years of research, Vestaron Corp., a spinoff of the University of Connecticut, has received approval from the U.S. Food and Drug Administration to start selling the venom-based pesticides. The products, produced in Kalamazoo, MI, will be sold under the brand name SPEAR (“Species at Risk”), currently only to farmers and greenhouse growers.