Since 2009, more than 80 research projects have been conducted in the USA to determine the cause of CCD. These projects can be subdivided into four categories as follows:
- Survey and sample data collection (5 projects)
- Analysis of existing samples (19 projects)
- Research to identify factors affecting honeybee health, including attempts to recreate CCD symptomology (21 projects)
- Mitigation and management preventive measures (39 projects)
Based on the scientific publications about CCD at the end of 2012, the research has not resulted in a precise understanding of the cause of CCD. This is notable, as the principle of CCD was already demonstrated in scientific experiments in 2004.
One of the key findings from research on the theme of CCD and microbiology is the change in types of bacteria in the bees' intestines. It was reported that in the event of CCD, the groups bifidobacteria and alphaproteobacteria decreased. At the same time numbers of bacteria from the group gammaproteobacteria group increased.
Of the range of viruses, there was just one (KBV, Kashmir Bee Virus), which was always found in the bee colonies affected by CCD, but that was not present in other colonies. KBV is closely related to several other viruses commonly present in bee colonies, such as ABPV and IAPV. Furthermore, certain combinations of viruses were found to be more common in CCD cases.
Genome analyses have provided a great deal of information. The gap between this specialized area and practical beekeeping is probably too large for this knowledge to be applied in the correct manner in practice.