NEW YORK (GenomeWeb) – An international team, led by researchers from Xi'an Jiaotong-Liverpool University in China, has sequenced the genome of the Asian honey bee mite, Tropilaelaps mercedesae.
Honey bee populations in developed countries across the world have been on the decline in recent years. While there are many potential causes, parasites are considered one of the major threats to honey bee colony health, with T. mercedesae contributing to Asian honey bee decline in most Asian countries. The researchers, who published their findings this week in GigaScience, produced a genome sequence of these parasites with the goal of gaining an understanding of their biology and use that information to identify gene-based strategies to prevent future mite infestations.
The team collected adult male, female, and nymph T. mercedesae from a beekeeper in Jiangsu Province, China. They extracted DNA from the mite samples using Qiagen's DNeasy Blood and Tissue kit, then created whole-genome sequences for a single male and single female T. mercedesae on an Illumina shotgun platform. The researchers reassembled the "cleaned" reads from the male mite to produce a draft genome.
They then compared the genome and transcriptome sequences of T. mercedesae and other internal mite species with free-living mites, and found that the T. mercedesae mite had evolved unique biological features that was shaped by its interaction with honey bees and the colony environment.
One significant finding was that the mite lacks genes for olfactory and chemical sensing and therefore does not rely on this to direct its behavior. This indicates that any control methods that targets these types of receptors are not effective. The study also indicated that the T. mercedesae mite is enriched with detoxifying enzymes and pumps for toxic xenobiotics, making it very easy for the mite to acquire miticide resistance to current chemical control methods.
However, one finding showed that a new strategy to control mite infestations may be more effective than previous methods. The researchers discovered that the T. mercedesae is closely associated with a symbiotic bacterium (Rickettsiella grylli-like) and DWV, the most prevalent honey bee virus. They noted that manipulating the symbiotic bacteria in female mites may offer one way to limit T. mercedesae infestations.
Although the researchers recognize that there is still more research to be done, they concluded that the "T. mercedesae datasets, alongside published [Verroa] destructor genome and transcriptome sequences, not only provide insights into mite biology, but may also help to develop measures to control the most serious pests of the honey bee."