Think about you favorite fruit or vegetable. In fact, picture most of the food you eat. If you are not a complete junk food addict, a majority of your daily diet comes from bee-pollinated plants. The amazing honeybee, though tiny in comparison to many creatures, has a huge impact on our everyday lives. As it busily buzzes around from flower to flower collecting nectar to later convert to honey, it unintentionally promotes plant reproduction ultimately sustaining modern day agriculture.
Such a big task obviously requires an equally large task force to carry it out. Thus, it is incredibly alarming that beekeepers and farmers are slowly seeing honeybees disappear in all parts of the world. What mysterious phenomenon could cause such a disturbance in honeybee hives? Are the bees on vacation or something? Well the answer is starting to become more apparent and does not involve a pleasant trip to the tropics. A team of Italian researchers believes that global losses of honeybee colonies are a result of the increasing prevalence of insecticides used to protect crops.
They think that a harmful type of insecticide used for pest control called neonicotinoids could be hurting honeybee immunity, keeping the bees from recovering after they get sick. To confirm this theory, the scientists led by Dr. Gennaro Di Prisco first tested their hypothesis on fruit flies because, after all, honeybees are nowhere to be found (actually fruit flies are model organisms which are easier to deal with in the lab). They slathered the flies with insecticide and waited to see what would happen. Indeed the neonicotinoid insecticide caused the flies to lose some of their immune capabilities.
After measuring the negative effects of this insecticide on flies, the scientists were ready to test actual honeybees. They exposed some of the bees to small doses of the insecticide and then purposely infected them with a virus. The poor bees that came in contact with the harmful chemicals lost their ability to fight off the infection, while their other bee friends who did not receive a dose of the insecticide were able to regain their health.
The researchers also found that the insecticide-exposed bees were more likely to develop a condition known as deformed wing virus, which renders their wings useless. Without functioning wings, the bees cannot carry out their job of flying through meadows collecting nectar and pollen to bring back to their hive, and in turn they are unable to pollinate our crops, much less survive. This problem is thought to be one of the major causes of disappearing bee colonies throughout the globe.
So the scientists in Italy seem to be on to something. However, showing that insecticides hurt bees in the lab is not enough to prove that this is also what’s happening in the field. Thus, the final component of the experiment was to test the destructive effect of insecticides in a more natural setting. This time the bees had the freedom to roam around and take sips of sugary nectar spiked with various amounts of neonicotinoid insecticide, while the scientists observed the unassuming pollinators. The bees still didn’t stand a chance! Even in this “habitual” condition where the bees determined how much they ingested, the exposed bees lost immune functions and had more active cases of deformed wing virus.
Several countries are starting to become suspicious of neonicotinoids and have restricted their use in agriculture. The looming problem is that farmers need a way to protect their crops from harmful pests without hurting helpful pollinating insects such as honeybees. Luckily, some types of insecticides have not shown as disastrous of an effect on bee health and longevity. This study also looked at an additional insecticide variety known as chlorpyrifos, which showed no impact on fly and bee immunity. We still need to be careful though because even if other insecticides do not affect bee immunity, they may still undermine other aspects of bee vitality.
There is no doubt that the issues behind large-scale agriculture are complex and interdependent. Nevertheless, change in farming practices and the development of a more sustainable agricultural model is crucial not only for the livelihood of the honeybee, but also for our own livelihoods as well.
Modern Post by Shireen Usman
Prisco, G. D., and Cavaliere, V., et al. (2013). Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees. PNAS early edition, 1-6.