Neonicotinoid Pesticides Still Bad for Bees: Two Studies in Nature Journal Add to the Evidence

Two scientific articles published in the prestigious journal Nature add to the growing mountain of scientific evidence linking neonicotinoid pesticides (neonics) with bee declines (see for example review article by Pisa et al 2015).

The study by Kessler et al (2015) published this week in Nature journal, set up a feeding experiment that showed that bees preferentially eat sugar-water spiked with field-realistic levels of neonic pesticides, even though they can't taste it. Instead, the bees seem to prefer it because of its nicotine-like effect on the brain cells! This study is in agreement with previous studies reporting that honeybees will preferentially collect sugar solution spiked with low levels of nicotine, and also caffeine (Singaravelan et al 2005).bees smoking.png

So, basically it seems like bees really enjoy a sugary-nicotine-caffeine buzz to get their day off to a start - doesn't sound so bad, right? But, unfortunately, it isn't a healthy habit for bees or people. Scientific studies have shown that chronic exposure of honeybees to field-realistic levels of neonics can impair learning and memory, making their pesticide habit a dangerous one (Decourtye and Devillers 2010; Williamson and Wright 2013).

Moreover, a study by Rundlöf et al (2015) published in the same issue of Nature journal, reported that wild bees that foraged in fields of crops grown from neonic-coated seeds had reduced nesting and failed to build brood cells for new larvae. The results of this field study are in agreement with earlier reports from laboratory studies that found chronic exposure to one of the most widely used neonicotinoid pesticides (imidacloprid) was associated with reduced brood production, reduced colony growth, and an 85% reduction in the production of bumblebee queens (Gill et al 2012; Whitehorn et al 2012).

This is an especially dangerous effect in wild bees that nest in small colonies of only ten to one hundred bees, or solitary bee species that live alone, and may not be able to survive a reduction in their numbers. For example, bumblebees only live one year. The queens produced at the end of the season will hibernate through winter, and then they alone are responsible for laying the brood to start a new colony in spring. In contrast, a commercial honeybee colony can contain ten thousand bees or more and may therefore be able to weather more losses and still survive winter. Thus, the authors suggest that studies on honeybees may not accurately predict risk to more vulnerable wild bee species.

Following an NRDC legal petition and pressure from NRDC and coalition partners, earlier this month EPA announced that it will no longer approve new outdoor uses of the most widely used and most bee-toxic neonic pesticides until the pesticide manufacture submits new data on impacts to bees (EPA April 2015). EPA is requiring industry to submit data on a pesticide product's potential impact on young bees, toxicity from eating contaminated pollen and nectar, and long-term impacts on whole colony health and survival. EPA's announcement is a complete reversal from its practice of allowing the pesticide products on the market while giving industry time - often years - to submit the required data, a loophole called a "conditional registration" that NRDC uncovered. While this is a good start, it does nothing about the neonic pesticide products already approved.

Meanwhile, we are still awaiting the overdue report of the White House Task Force on Pollinator Health that is expected to lay out the recommendations of EPA and other federal agencies to address pollinator decline. Will it be too little, too late? In our option, at the very least it should recommend the following:

NRDC recommendations for EPA and USDA to take action:

  • Speed up the review of neonics. EPA's current leisurely timetable stretches to 2019. Given the rapidly accumulating scientific evidence against neonics, that's far too slow. Immediate intervention is needed.
  • Close the conditional registration loophole. Under current EPA rules, harmful pesticides can be put on the market with a "conditional registration" without being fully tested for toxicity. That's how many neonics got approved. The process has been abused and must be stopped. (see our Conditional Registration report)
  • EPA should cancel the use of neonics. An NRDC legal petition asks EPA to initiate cancellation proceedings for all neonicotinoid pesticide products, beginning with those for which safer alternatives are available. Systemic and persistent pesticides like the neonics pose too much risk to non-target and beneficial wildlife. (NRDC July 2014)
  • USDA should cancel pesticide seed treatments. The overuse of pesticides as seed treatments, including fungicides and insecticides, is creating a chronic hazard to bees, butterflies, and other wildlife. Seed treatments should be cancelled, particularly where they have little or no economic benefit for growers.
  • EPA and USDA should track the production, sale, use, and environmental movement of pesticides. This would include data on bee deaths, waterway contamination, and industry sales and usage of neonics, including uses to treat seeds.

How neonicotinoids are used in U.S. agriculture, including on what crops, can be found at the US Geological Survey (USGS) website of pesticide use maps, and summarized below:

US neonic use in ag.png

About the Authors

Jennifer Sass

Senior Scientist, Federal Toxics, Health and Food, Healthy People & Thriving Communities Program

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