The unfortunate fact is that bees are in danger. Many U.S. beekeepers are experiencing losses of 40 to 50 percent or more over the winter, substantially more than is considered normal or sustainable. Of the over 4,000 species of native bees, more than half are declining in population. And in 2017, the United States listed a species of bumble bee as endangered for the first time.
With how important bees are to the lives of human beings, there’s no doubt that this is beyond alarming. So what could be at the cause of all of this trouble? While there are many factors that play a part, the three major causes for declines in bee populations are pesticides, mites and diseases, and loss of habitat.
While no one investigating declining bee populations is suggesting that pesticides are the sole cause of the issue, no single pathogen or parasite, appears to sufficiently explain the current rate of hive collapse. Some studies have indicated that neonicotinoids - a widely used type of pesticide - can lead to a sharp decline in queen bees in colonies and can also interfere with the ability of bees to navigate back to their hives. Other research shows that pesticides may suppress the immune system of bees, thus allowing mites and pathogens an easier way to attack their host.
Mites and Disease
Varroa mites are external parasites that attack both honey bees and brood. They suck the blood from both the adults and developing brood, especially drone brood. This weakens and shortens the bee’s life. While varroa mites have been known about since the 1980’s, they are still a major cause for the collapse of many beehives.
When a varroa mite attacks a bee, it weakens the immune system of the bee and make it susceptible to a number of diseases. Some of these diseases are bacterial, like American and European Fouldbrood, while others are viral, like the cloudy wing virus or the sacbrood virus.
Loss of Habitat
As humans have continued to build more and more highways, office spaces, houses, strip malls, and industrial parks, we’ve also removed and/or fragmented more and more bee habitat. The removal of bee habitat means that we are replacing land that used to have forage for bees with structures that have no forage at all, and the fragmentation of bee habitat means that we are increasing the distance bees must travel to get to one source of food from another.
Furthermore, changing temperature and weather conditions due to climate change have restricted the area where bees can survive, and the pollinators have struggled to adapt. A number of bee species are experiencing a diminishing range in which they can travel to find shelter and/or food.