The following video of a bumblebee foraging on swamp milkweed is used with permission from Debra Palermo of fromweedstobees.org:
Wouldn’t it be terrible if the nectar this bee is collecting had somehow been poisoned so as to be toxic to the bee and the bee’s hive?*
Incredibly, this has become a real possibility with the worldwide increasing use of neonicotinoids, systemic pesticides that are absorbed into the plant vascular system and can accumulate in the plant’s nectar and pollen.
In 2014, Common Dreams reported that an examination by Friends of the Earth found that more than half the plants being sold at major garden retailers as “bee-friendly” have been treated with neonicotinoids. (*Deb contacted the Delaware Nature Society from whom she purchased the milkweed in the video above and they assured her it had not come into contact with any neonicotinoids.)
Neonicotinoids are applied by many methods including foliar spraying, soil drench, seed coating, and trunk injections for trees.
The following information comes from a report by the Xerces Society for Invertebrate Conservation:
As of 2012 neonicotinoid pesticides had been applied to hundreds of thousands of acres of farmland. They persist in the soil and plants for very long periods of time (months and years). Measurable amounts of residues are found in woody plants up to six years after application. Untreated plants may absorb residues in the soil from the previous year. Neonicotinoids applied to crops can contaminate adjacent weeds and wildflowers.
It has been suggested that seed treatments may be less harmful than other application methods because concentration of the insecticide decreases over time as the biomass of the growing plant increases. However…. studies examining repeated use of seed-treatments over time noted that untreated sunflowers absorbed residual imidacloprid from the previous year’s treated sunflower plantings. Based upon these findings, annual plantings of seed-treated crops may lead to increased residue levels that may pose more of a risk to bees, since residues from previous seasons remain.
Products approved for home and garden use may be applied to ornamental and landscape plants, as well as turf, at significantly higher rates (potentially 120 times higher) than those approved for agricultural crops.
Neonicotinoid residues found in pollen and nectar are consumed by flower-visiting insects such as bees. Concentrations of residues can reach lethal levels in some situations.
Direct contact with foliar sprays is hazardous to pollinators and foliar residues on plant surfaces remain toxic to bees for several days. Honeybees exposed to sublethal levels of neonicotinoids can experience problems with flying and navigation, reduced taste sensitivity, and slower learning of new tasks, which all impact foraging ability.
Laboratory studies demonstrate that the neonicotinoids imidacloprid and clothianidin are highly toxic to bumble bees. Bumble bees exposed to sublethal amounts of neonicotinoids exhibit reduced food consumption, reproduction, worker survival rates, and foraging activity.
Evidence has not been obtained for a direct link between neonicotinoids and Colony Collapse Disorder (CCD). However, research suggests these chemicals may make honey bees more susceptible to parasites and pathogens implicated as a causative factor in CCD.
In 2013, the European Union banned for a 2 yr. period the use of 3 neonicotinoids, imidacloprid, clothianidin, and thiamethoxan. The European Food Safety Authority found that these insecticides pose acute risks to bees.
The story of the EPA approval of clothianidin is illustrative and informative. In 2003 EPA granted a “conditional” registration to this chemical based on the contingency that a study be performed on its safety. The study was to be performed by none other than Bayer, the pesticide’s manufacturer. In 2010 a leaked memo indicated the study was fatally flawed.
According to beekeeper Jeff Anderson, who has testified before EPA on the topic, “The Bayer study is fatally flawed. It was an open field study with control and test plots of about 2 acres each. Bees typically forage at least 2 miles out from the hive, so it is likely they didn’t ingest much of the treated crops. And corn, not canola, is the major pollen-producing crop that bees rely on for winter nutrition. This is a critical point because we see hive losses mainly after over-wintering, so there is something going on in these winter cycles. It’s as if they designed the study to avoid seeing clothianidin’s effects on hive health.”
Even more troubling evidence is coming to light indicating that neonicotinoids are poisoning other species in addition to bees:
- A recent study published by Dutch scientists establishes an additional indirect link between neonicotinoid use and insect-eating birds. The report provides evidence that these pesticides are indirectly hurting larger creatures by reducing insect prey populations such as mosquitoes and beetles.
- Another report by the Task Force on Systemic Pesticides states that terrestrial invertebrates such as earthworms can be adversely affected by low or acute (i.e. ongoing) exposure to neonicotinoids, making them highly vulnerable at field realistic concentrations – i.e., the concentrations which can be found in agriculture.
- Still another meta-analysis of systemic pesticides by IUCN (the International Union for Conservation of Nature) confirms that they are causing significant damage to a wide range of beneficial invertebrate species, e.g. bees, butterflies and earthworms, and are a key factor in the decline of bees. They go on to state, “Neonics are a nerve poison and the effects of exposure range from instant and lethal to chronic. Even long term exposure at low (non-lethal) levels can be harmful. Chronic damage can include: impaired sense of smell or memory; reduced fecundity; altered feeding behaviour and reduced food intake including reduced foraging in bees; altered tunneling behaviour in earthworms; difficulty in flight and increased susceptibility to disease.”
Some of the retailers found to be selling neonicotinoid-tainted garden products are attempting to correct the situation. Thus, Home Depot has said they plan to ban or limit the use of neonicotinoid pesticides. They will require suppliers to start labeling any plants treated with these chemicals by the fourth quarter of 2014. They are also “running tests” to see if suppliers can eliminate these chemicals in their plant production.