Neonicotinoids, a type of insecticide, is one of the many factors responsible for the massive honeybee population decline. New evidence, however, shows that honeybees are not the only important pollinators this class of insecticide harms. Researchers believe that they are also harming butterflies and wild bees.
Oilseed rape is a flowering crop that is beneficial to pollinating insects, but farmers treat the seeds with neonicotinoids so the entire plant, including the pollen, will contain the insecticide. A study published in “Nature Communications” examined populations of wild bees and determined that those populations that fed on the rape seeds treated with insecticide declined three times faster than those that were fed untreated seeds. The study suggested that neonicotinoids were a factor for the bees’ decline, among habitat loss, pathogens, and other insecticides.
Another study conducted by Matthew Forister at the University of Nevada found a correlation between the dramatic decline of butterfly species in lowland Northern California and use of neonicotinoids in the region. Farmers began using these insecticides in 1995, and butterflies began declining in the late 1990s. The higher amount that was applied, the fewer butterflies there were in the area.
German researchers in Mainz found that the chemicals in the insecticides reduce the amount of acetylcholine, an important chemical found in royal jelly bees produce to feed their larvae, therefore causing bee reproduction rates to decrease. A German neurobiologist and bee researcher, Randolf Menzel, found that neonicotinoids are responsible for orientation and memory loss in bees, preventing them from finding their way back to their colonies. They may also lower sperm counts of male bees.
Manufacturers of insecticides, however, insist that their products do not harm bees and other important pollinators, as long as farmers use proper doses of insecticides. They are quick to turn blame on other factors for mass insects deaths, pointing at habitat loss, air pollution, and the parasitic varroa mites. Bayer and other companies claim that neonicotinoids are essential to maintain modern agriculture. Bayer, Syngenta, and Valent, all producers of the insecticide, commissioned a study that claimed neonicotinoid insecticides are able to increase crop yields by up to 70 percent.
Neonicotinoids are designed to kill sucking insects including aphids and soil insects such as root weevils. One positive attribute of this particular class of insecticide is that they are relatively less toxic to birds and mammals than other insecticides. They became widely used in the late 1990s to the early 2000s. Farmers apply the insecticide on corn, canola, cotton, and the vast majority of fruits and vegetables.
The EU partially banned neonicotinoids in 2013. The ban prohibits its non-commercial use and stipulates that it may only be applied to crops after blossom to prevent excess contact between pollinators and the substance. The US has no restrictions on the use of neonicotinoids, and the EPA will not even review them until 2018.