* Parasite species with multiple host species are anomalous *

Certainly if we have gotten this far into taxonomy, we should point
out that before DNA testing, parasites were typically named for their
association with their hosts. The first nosema species was discovered
by Pasteur in the silkworm (Bombyx mori) and named Nosema bombycis.

> At the beginning of the 20th Century, the great German bee scientist Zander first described Nosema apis as the 'microsporidium responsible for Nosema disease'. Subsequently, all reports of microsporidia in honey bees, in both the western hive bee Apis mellifera and the eastern hive bee Apis cerana, were attributed to Nosema apis.

> In 1995, Professor Ingemar Fries of the Swedish Agricultural University, Uppsala and an expert on Nosema in bees, visited China where he described a new microsporidium, Nosema ceranae, in indigenous honey bees Apis cerana. The differences between the two microsporidia, Nosema apis and Nosema ceranae, lie in their ultrastructure and genetics. (Robert J Paxton)

Parasites seemed to have co-evolved with their hosts so it is fairly
uncommon for them to leapfrog onto other species. In many cases, they
simply cannot survive or at least they fail to do any harm to their
new host. Occasionally, as with varroa, they wreak havoc in their new
environment, finding even more suitable to their development than the
original host.

However, with the new techniques of genetic testing (PCR) the old way
of classifying species on the basis of external characteristics and
behavior has been challenged. In some cases, the genetic underpinning
confirms species distinctions and some cases it casts doubt. It must
be remembered that a species is not a hard and fast distinction. In
some cases it is obvious like "dog" and "cat" and in others, not so
easy like "dog" and "coyote". Even more so with parasites. There are
specific dog and cat parasites and ones they share, so it should be no
surprise that bees may share parasites with other insects but this is
rare. For example:

> Bacillus thuringiensis is a soil dwelling bacterium of the genus Bacillus. It also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well as on the dark surface of plants. B. thuringiensis was discovered 1901 in Japan by Ishiwata and 1911 in Germany by Ernst Berliner, who discovered a disease called Schlaffsucht in flour moth caterpillars. B. thuringiensis was discovered 1901 in Japan by Ishiwata and 1911 in Germany by Ernst Berliner, who discovered a disease called Schlaffsucht in flour moth caterpillars." (Wikipedia)

Bt has been used as a treatment against wax moths and has not been
shown to infest honey bees, although it was implicated in early
speculation about CCD.

> Parasite species with multiple host species are *anomalous* as, under a codivergence paradigm, speciation by the hosts should cause speciation of their parasites. We discuss situations such as cryptic parasite species, recent host switching or failure to speciate that may generate multi-host parasites. We suggest methods to identify which of the mechanisms have led to multi-host parasitism. Applying the suggested methods may allow multi-host parasites to be integrated more fully into cophylogenetic studies." (Jonathan C. Banks)

> What an interesting investigation would be the comparison of the parasites of the closely allied and representative birds of the two countries." (Darwin)

I am not so sure anyone but Darwin and a few others will find the
comparison of the parasites all that interesting so I shall rest my
keyboard.

-- 
Peter L Borst
Danby, NY USA
42.35, -76.50
http://picasaweb.google.com/peterlborst

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