New study suggests having multiple hives in close proximity does not contribute to colony collapse disorder
BERKELEY – Bees are the most prolific pollinators on the planet, making them an essential part of agriculture operations. Unfortunately, there is a mysterious disease killing off bee hives and scientists can’t seem to agree on what causes it.
Colony Collapse Disorder (CCD), a phenomenon that occurs when the majority of worker bees disappear, leaving behind a queen, food, nurse bees and baby bees, is a major issue facing beekeepers and apiaries since it was first identified in 2006. Without worker bees to bring nectar and pollen back to the hive, the colony of bees dies.
Scientists are still studying and debating the cause of CCD but agree there are many factors that play a role in it, including the overuse of pesticides and attacks from parasites such as varroa mites and pests such as small hive beetles and wax moths.
In order for a lost hive to be considered for colony collapse disorder, the USDA requires that they meet four criteria: 1) Little to no build-up of dead bees in the hive or at the hive entrance; 2) rapid loss of adult population despite the presence of queen; 3) absence or delayed robbing of the food reserves; and 4) that the loss was not caused by mites or pests.
Recent data from the USDA suggests the number of hives in close proximity to one another may be a cause of CCD. Six percent of bee colonies (about 70,000 colonies) in California were lost between April and June of 2018, the most recent numbers available from the USDA. However, state apiaries were able to renovate 21%, or about 254,000 colonies. The rate of colony collapse increased by 15% in the first quarter of 2018 over the same period in 2017, for operations with more than five colonies but was down 9% for those with less than five colonies.
But new research suggests that more “intensive” beekeeping does not raise the risk of diseases that harm or kill the insects. Intensive agriculture – where animals or plants are kept crowded together in very high densities – is thought to result in higher rates of disease spreading.
But researchers from the University of Exeter and the University of California, Berkeley found this is not the case for honeybees. Their study modeled the spread of multiple honeybee diseases and found that crowding many colonies together was “unlikely to greatly increase disease prevalence”.
However, the research only applies to existing honeybee diseases – and the findings suggest intensive beekeeping could accelerate the spread of new diseases.
“Crowding of animals or crops – or people – into minimal space usually increases rates of disease spread,” said Lewis Bartlett, of the University of Exeter and Emory University. “We carried out this study because beekeepers were worried about this – especially given the many threats currently causing the decline of bees.”
Bartlett said honeybees live in close proximity to each other naturally, and the study’s models show that adding more bees does little to raise disease risk.
“So, beekeepers don’t need to worry about how many bees they keep together as long as there is enough food for them,” Bartlett said. “The key is not whether they encounter a disease – it’s whether they are fit and healthy enough to fight it off.”
Although the paper says intensification of beekeeping does not boost diseases among honeybees, Bartlett points out that intensive agriculture – especially use of pesticides and destruction of habitats – harms bee species including honeybees.