Bees are critical to agriculture, there is no doubt about that. They fertilize various crops by spreading the pollen that they collect to meet their protein and fat needs. Recently there has been much concern about declining bee populations in some areas and speculation has focused on insecticides known as 鈥渘eonicotinoids.鈥� Many media reports have tried and convicted the 鈥渘eonics鈥� and urged that they be banned. But as is so often the case, media reports only scratch the scientific surface and deeper digging produces a different buzz. Neonics at a certain level of exposure can disorient or even kill bees, which comes as no surprise since they are insecticides, and bees are insects. The question is whether these chemicals can be used in a way that protects plants without harming bees.
Neonicotinoids, first introduced in 2004, are modeled on nicotine, the natural insecticide produced by the tobacco plant. One advantage is that instead of spraying, these chemicals can be applied to the seeds of crops such as corn, soybeans and canola. They then end up distributed throughout the plant as it grows and are ready to dispatch any insect that dares to dine on the foliage. Bees don鈥檛 do that, they go for the nectar in the flowers which has only traces of neonics. Yet bee deaths have been linked with neonic-coated corn and soy seeds, mostly in Ontario. But curiously, not with canola seeds in western Canada which are also treated with the same pesticides. So what is going on?
Mechanical planters use a jet of air to blow seeds into the soil. Commonly talc or graphite are added as lubricants to reduce friction between the seeds but these can rub off and can carry insecticide contaminated dust into the air, exposing flying insects such as bees to the neonics. The concern is that the tainted bees return to the hive where they can expose fellow bees to the neonics and wreak havoc. A novel polyethylene wax lubricant that can replace talc and graphite has shown a significant reduction in airborne insecticide during planting. There are also polymers being developed to help the insecticide stick to the seeds.
The planting of canola uses different technology and doesn鈥檛 produce comparable amounts of dust. Some 20 million acres of canola are planted in Canada with neonicotinoid treated seed and there has been no impact on bee health at all. So it seems the problem may not be the neonics as much as the seeding methodology. Neonics are also commonly used on cut flowers and on plants purchased from nurseries but whether these affect pollinators is an open question.
In any case, the neonics are only part of the picture when it comes to bee health. There are mites, parasites and viruses that can infect bees, and transporting hives, which is commonly done, also stresses them, as do harsh winters and long springs. Specifically, the Varroa mite can affect bee health significantly, and it is interesting to note that in Australia, which is free of these mites, no problems have been seen with bee populations in spite of extensive use of neonicotinoid coated seeds.
So while the neonicotinoids may be a factor in the decline of bee populations in some areas, they are not the only factor. Furthermore, loss of bee colonies has been observed in places where neonicotinoids are not used at all, and history records many cases of unusual deaths of honey bee colonies long before neonics were introduced.
Still, there are some troubling developments. A recent British study showed that bees are more attracted to a sugar solution laced with neonics than to one without, implying the bees may be getting some sort of a buzz from the chemicals and may be more likely to visit plants containing them and end up contaminating hives. And a study in Sweden showed a reduced density of wild bees, but not honey bees, in a field planted with neonic-coated seeds.
Because of the cloud hanging over neonics, Europe and Ontario have decided to greatly restrict their use. It will take a while to see the effect, not only on the bees, but also on crop yields which have steadily increased since the introduction of the neonicotinoids. If yields are to be maintained, it may be back to the insecticidal sprays which come with problems of their own, not only for pollinators, but for people as well. Of course in the western world we can forego insecticides and just pay more for our locally-grown food.
