What Is Colony Collapse Disorder? Research Update 2024

A frame with very few bees indicating signs of colony collapse disorder

Colony Collapse Disorder (CCD) occurs when most worker honey bees abruptly disappear from their hive. After the collapse, little or no dead bees remain near the entrance. The developing bee brood, queen bee, and a small number of adult bees usually remain.

Initial reporting of CCD came from American beekeepers around 2005. The exact cause of the phenomenon is not fully understood, but it poses a significant threat to honeybee colonies globally.

What are the symptoms of CCD?

The most noticeable sign of colony collapse disorder is the absence of adult bees in the colony, with minimal dead bees nearby. Hives with piles of dead bees inside or nearby have another problem.

Despite the absence of adult worker bees:

  • The colony often still has capped brood.
  • The queen bee continues to lay eggs.
  • A bounty of food reserves may exist, although robbing is uncommon.

Hives affected by CCD often show signs of a recent healthy population. A young queen and developing brood suggest a rapid colony decline.

How to identify a collapsing colony

As a colony collapses, beekeepers will notice the reduction in adult worker bee numbers over a few weeks. While a few scattered dead bees may lie outside the entrance, often, there will be no sign of death.

The queen continues laying eggs, and a dwindling cluster of workers may continue their work inside the hive.

A collapsing colony:

  • Still has a queen.
  • Won’t typically eat supplemental food provided by the beekeeper.
  • Has an insufficient adult bee population to maintain the brood.
  • Has mostly young adult bees doing the work. 

What is the difference between CCD and a bee kill incident?

CCD and bee kill incidents both cause the mass death of bees.

A bee kill incident results from pesticide overexposure, swiftly killing the colony en masse with deceased corpses piled outside the hive. In contrast, colony collapse disorder is a slower killer, and no evidence of dead bees remains.

Piles of dead bees as the result of pesticide overexposure.

Causes of colony collapse disorder

While scientists haven’t reached a consensus on the cause of CCD, various potential contributing factors exist. It likely results from a combination of these factors rather than one.

1. Pesticides

Insecticides like Neonicotinoids imidacloprid, Thiamethoxam, and Clothianidin are potential factors in bee population declines. These chemicals can weaken bee immunity and act as a catalyst for preexisting pathogens like deformed wing virus. They may also impair the honey bee’s ability to navigate and communicate.

2. Pathogens

Diseases are common in colonies affected by CCD. Researchers are trying to decipher which infections are the main offenders.

Scientists often discover the following diseases in hives impacted by colony collapse disorder:

3. Parasites

The Varroa mite (Varroa destructor) is a significant threat to honeybee colonies worldwide. These mites feed off adult bees and their brood while transmitting viruses.

The phorid fly (Apocephalus borealis) is an emerging threat to bees and may also contribute to CCD. They are increasingly found in dead bees with pathogens and may help transmit sickness amongst the hive’s population.

4. Malnutrition

Bees need a suitable food source to maintain good health. Poor nutrition becomes a stressor in areas where pollen and nectar are in short supply. Without supplemental feeding from beekeepers, colonies become prone to disease.

Urbanization, changes in habitat, and global warming impact foraging sources, making colonies more vulnerable to CCD.

5. Stress

Transportation of colonies for commercial pollination services causes bee stress. Factors like over-inspecting and over-harvesting hives may also play a role in collapsing hives.

Other useful reading:

A beekeeper inspecting a colony for potential issues.
The beekeeper inspects the hive for issues like colony collapse disorder.

Latest colony collapse disorder research

We looked at the latest research on CCD and summarized some of the work.

Research 1: Israeli Acute Bee Paralysis Virus Prevalence in Apiaries With Colony Loss in Türkiye

Authors: Dilek Muz, Mustafa Necati Muz

The research aimed to determine the prevalence of Israeli acute paralysis virus (IAPV) in apiaries experiencing sudden bee deaths and colony collapse. It examined samples from affected apiaries for coexistence with IAPV and other bee pathogens.

Key Findings:

  • 52.5% of the apiaries tested positive for IAPV.
  • 97.5% of the sampled apiaries had at least one pathogen present.
  • The presence of IAPV in apiaries suffering from CCD was higher than previous reports indicated.
  • In addition to IAPV, Nosema disease and Varroa mites were frequently detected in the sampled apiaries.

This research suggests the combined effects of various pathogens might play a significant role in bee colony losses.

Read more>

Research 2: Can the examination of different types of hive samples be a non-invasive method for detection and quantification of viruses in honey bee (Apis mellifera L.) colonies?

Authors: Eliška Čukanová, Jana Prodělalová, Miroslava Palíková, Kristýna Kováčová, Petr Linhart, and Ivana Papežíková

Viruses like DWV, BQCV, and SBV have been detected in bee food sources, such as pollen and honey. These sources may serve as non-invasive ways to monitor viral infections.

Studies discovered most of the selected viruses in all pooled bee samples. BQCV and SBV showed high concentrations, while DWV and ABPV showed variability.

  1. Viruses were detected in non-invasive hive materials, with honey and pollen providing the most consistent results.
  2. All non-invasive hive materials contained honey bee viruses, though none are routinely used for virus detection in beekeeping operations.
  3. Honey and pollen stood out as practical materials for non-invasive monitoring due to their ease of processing and high detection rates.

Detection in hive debris was less successful due to its heterogeneous nature. Notably, viruses in pollen might not always translate to infected bees, as the forager bees consume less pollen, and it has antiviral properties.

Honey bee viruses can be detected in non-invasive hive materials, with honey and pollen providing promising results. Further refinement and broader testing are needed to confirm their reliability as monitoring tools.

Read the research>

Commonly asked questions

What can beekeepers do about CCD?

Beekeepers identifying a collapsing colony should never combine it with a healthy hive. Following beekeeping best practices and maintaining an integrated pest management system for mite control will help reduce the potential for collapse.

Has there been any improvement or decline in CCD occurrences in recent years?

According to EPA data, reported cases have declined in recent years.

Is it safe to eat honey from CCD-affected hives?

CCD appears limited to adult bees, with no current evidence that it affects honey. Source via University of Delaware pdf>

Are native bees and other pollinators also affected by CCD?

Although some native bees are experiencing reduced numbers, they are unaffected by colony collapse disorder. Source.

Want to learn more?

To learn more about some common issues bees face, read our guide on cloudy wing virus or discover the small hive beetle symptoms to look out for.

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