Decline of wild bee populations is linked to the use of toxic, systemic neonicotinoid (neonic) pesticides used on oilseed rape (canola), according to new research done by a team of scientists at the Centre for Ecology and Hydrology in the United Kingdom. In addition to corn and soybeans, canola is one of the main crops treated with neonicotinoids worldwide. Neonic pesticides have long been identified as a major culprit in bee decline by independent scientists and beekeepers, yet chemical manufacturers like Bayer and Syngenta have focused on other issues such as the varroa mite. As Beyond Pesticides put it in the spring 2014 issue of Pesticides and You, the issue of pollinator decline is No Longer a Big Mystery, and urgent action is needed now to protect pollinators from these toxic pesticides.

Neonics are associated with decreased learning, foraging and navigational ability, as well as increased vulnerability to pathogens and parasites as a result of suppressed bee immune systems. In addition to toxicity to bees, pesticides like neonicotinoids have been shown to also adversely affect birds, aquatic organisms and contaminate soil and waterways, and overall biodiversity.

The study, Impacts of neonicotinoid use on long-term population changes in wild bees in England, published in the journal Nature Communications, analyzed 18 years of UK national wild bee distribution data for 62 different species, and related it to amounts of neonicotinoid use. Researchers focused on figuring out which species of wild bees had been observed in different plots of land, and which of those species had disappeared over the course of the study (1994-2011).  The results of the study show the decline of species that forage on the neonicotinoid-treated canola is on average three times more than that of species that forage on other plants. By comparing the locations of these bees and their changing populations with growing patterns of canola fields across England, researchers are able to attribute half of the total decline in wild bees to the use of neonics.