16
Mar
Study Finds Bees’ Pollination Skills Impaired by Pesticides
(Beyond Pesticides, March 16, 2016) Another study, this time from researchers at the University of Guelph, finds that at very low levels the neonicotinoid pesticide thiamethoxam affects the foraging behavior of bumble bees, changing their floral preferences, hindering their ability to learn and extract nectar and pollen. This study is one of many that detail the negative effects of pesticides on bees’ learning behavior and ability to pollinate essential crops. Pesticides, like the neonicotinoid class of insecticides, have been implicated in the global decline of pollinator populations, while advocates call for limiting pesticide exposures to reverse population declines.
According to the authors of this Canadian study, “Chronic exposure to a neonicotinoid pesticide alters the interaction between bumblebees and wild plants, “published in the journal Functional Ecology, it is the first to explore how pesticides may impact the ability of bumble bees to forage from common wildflowers that have complex shapes such as white clover and bird’s foot trefoil. The researchers found that bumble bees exposed to environmental levels of thiamethoxam (10ppb) took longer to collect pollen than unexposed bees, as well as foraged from different flowers. Importantly, this study reports that bumble bees that were not exposed to thiamethoxam are able to learn how to manipulate complex flowers to access pollen and nectar after only a few visits, while exposed bees were not.
Nigel Raine, PhD, the Rebanks Family Chair in Pollinator Conservation at the University of Guelph and senior author of the paper, notes, “If exposure to low levels of pesticide affects their ability to learn, bees may struggle to collect food and impair the essential pollination services they provide to both crops and wild plants. Our results suggest that current levels of pesticide exposure could be significantly affecting how bees are interacting with wild plants, and impairing the crucial pollination services they provide that support healthy ecosystem function.” Co-author Dara Stanley, PhD, of Royal Holloway University of London, said, “Bumble bees exposed to pesticide initially foraged faster and collected more pollen. However unexposed (control) bees may be investing more time and energy in learning. Our findings have important implications for society and the economy as pollinating insects are vital to support agriculture and wild plant biodiversity.”
Previous studies have found that pesticides, especially the neonicotinoids, impair bees’ ability to learn, forage, navigate as well as communicate. These pesticides, which are highly toxic to bees, have also been found to impair bee’s immune systems, leaving them more susceptible to parasites and disease. Other studies detail impairments in the brains of exposed bees, specifically in the areas associated with learning and memory. The science has become increasingly clear that pesticides, either working individually or synergistically, play a critical role in the ongoing decline of honey bees.
Just last week a U.S. Government Accountability Office (GAO) report concluded that U.S. regulatory agencies are falling short in addressing the multiple threats contributing to declining pollinators. The GAO report recommends that the U.S. Department of Agriculture (USDA) increase the monitoring of wild, native bees, while the U.S. Environmental Protection Agency (EPA) efforts thus far regarding pesticides (label amendments and restrictions) have done little to change pesticide exposure patterns to pollinators. GAO identified the need for EPA to develop a plan to assess pesticide risks to a range of bee species beyond honey bees, as current EPA evaluations only use honey bees a surrogate for other wild bee species. Further, the report finds that the impact from exposure to chemical mixtures also needs to be investigated.
At the start of the year, EPA released its long awaited pollinator risk assessment for the widely used neonicotinoid imidacloprid. The assessment confirms the pesticide’s toxicity to bees and that its presence in the pollen and nectar of various crops can put bees at risk. Imidacloprid, like others in its class are systemic pesticides, meaning they are taken up by the vascular system of the plant and then expressed through pollen, nectar, and guttation droplets, exposing all that come into contact. The other neonicotinoids, including thiamethoxam, are still under EPA review. Similarly, in February, a United Nation’s assessment of pollinations and the global food supply warned that many species of wild bees, butterflies and other pollinators are on a dangerous path toward extinction, further threatening the food supply if the causes of these declines, many of them human-made, are not halted. The assessment found that an estimated sixteen percent of vertebrate pollinators are threatened with global extinction. Meanwhile, the European Union, numerous retailers, and local cities and towns have adopted policies that stop or restrict their use. Beyond Pesticides points to a thriving organic industry as the alternative to neonicotinoids.
Join us at Cultivating Community and Environmental Health, the 34th National Pesticide Forum, April 15-16, 2016 in Portland, ME to discuss pollinators and other local and national environmental concerns. Jonathan Lundgren, Ph.D., a senior USDA entomologist will join other top scientists and leaders who have stood up to protect human and environmental health, despite facing industry backlash and scientific suppression. Dr. Lundgren’s research on the harm neonicotinoids pose to monarch butterflies reflects a growing scientific consensus that these chemicals present significant risks to declining pollinator populations. Registration, which includes access to all sessions as well as organic food and beverages, is $45 for grassroots activists, and $25 for students. Register online today.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: News Release
Photo Source: Susan J, WI
