March 24, 2017
The Genome of T. mercedesae
Researchers have been looking into the genome sequence of mites, specifically the Tropilaelaps mercedesae, to understand their interaction with honeybees and how to best mitigate their ability to harm honeybee colonies. By studying their genomes, researchers are trying to discover how these mites control their hosts. Understanding this mite's genome could help protect honeybee populations since, as recent studies suggested, the current methods of fighting colony collapse disorder (CCD) appear to be ineffective, according to GigaScience, which published these genome findings.
The T. mercedesae is a parasite that is most densely populated in Asian countries, with many honeybee colonies in those countries at risk by these mites. It is similar to the Varroa mite, a tiny parasite that feeds on adult bees as well as pupae and larvae. However, the worldwide trade of honeybees and flowers could still leave the rest of the world susceptible to these mites. If left untreated, a colony invasion could affect crops and affect crop productivity. However, the hope is that the proper use of organic pesticides could avoid any potential threats if this mite spreads across oceans.
Previous studies that took place at Jiaotong-Liverpool University compared the genome of the T. mercedesae to that of free-living mites. When compared to free-living mites, researchers found that the T. mercedesae needed hosts that were part of a balanced colony. Its genome is shaped by its interaction with honey bees and the environment.
In the process of the researchers' discovery, the mites showed a resistance to the miticide used to kill most pests. They have detoxifying enzymes, which help them resist the toxins used to get rid of them. Instead of focusing on the use of miticides, researchers elected to target bacteria, specifically Rickettsiella grylli, as it commonly infects T. mercedesae mites. Studying the bacteria could be a better alternative regarding the control of T. mercedesae mites.
The R. gyrylli bacteria were involved in the horizontal gene transfer of Wolbachia genes to the mite's genome. The Wolbachia genus usually infects arthropods but not the T. mercedesae. The authors of this study noted that this example is the first horizontal gene transfer in ticks and mites. Since T. mercedesae is unaffected by Wolbachia bacteria, researchers believe that T. mercedesae and Wolbachia may have coexisted. It’s also been suggested that Wolbachia bacteria were the ancestors of T. mercedesae but were replaced by the R. grylli bacteria during the course of evolution.
Moreover, combating declining honeybee populations around the world is a difficult fight, with the biggest concern being crop production and economic damage. Understanding the dynamic of pests that invade honeybee colonies is a step in the right direction. Furthering research could help beekeepers maintain bee colonies, which are responsible for pollinating a third of our crops and contributing to much of our survival.
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