2.5. Perspectives on the taxonomy of Varroa spp.

More research is needed to clarify the taxonomy of varroa mites from A. cerana in the Philippines. This will require examinations of nuclear DNA sequences obtained from these mites, as their mtDNA sequences do not provide the resolution needed to determine their identity (Fig. 5). From published research, there are three distinct mite types in the Philippines, two from the northern island of Luzon and another from the southern island of Mindanao (Anderson and Trueman, 2000). These could well be distinct species. New varroa species may also yet be found on other Asian honey bees, particularly on A. nigrocincta in Sulawesi, A. nuluensis in Borneo and A. indica from southern India.

An interesting feature of varroa mites on Asia honey bees is that most of them lack the ability to reproduce on A. mellifera. This is not from lack of trying though, for when A. mellifera colonies are introduced to different regions of Asia female mites that are indigenous to the local Asian honey bee readily invade the introduced colonies and enter brood cells that are about to be capped, in preparation for reproduction. However, they do not go on to lay eggs or produce offspring. Since at least the middle of the last century, only a few mite types have been able to reproduce on A. mellifera, the most successful of which is the Korea type of V. destructor. This suggests that female varroa mites must recognize specific signals on the host bee in order to successfully reproduce. Even though these signals may be fundamentally the same between different honey bee types and species, they may vary between honey bee populations. Identifying these signals and the genes that control them, could lead to the genes being targeted for particular purposes, such as control. This kind of research will require a good understanding of both the parasite and host genomes. Even though our understanding of the honey bee genome has improved in recent years, studies have only recently commenced on sequencing the varroa genome (Cornman et al., 2010). As our understanding of the varroa genome improves, too will our understanding of varroa taxonomy and ways by which the mite can be controlled on European honey bees.