>> >Given the amount of work done so far on CCD and comb contamination,
>> presumably someone has been checking for N ceranae spores?

I would ask, why wouldn't there be? The idea that a hive that was sick with
nosema would leave the equipment covered with spores is consistent with
logic and common sense. The following refers to N. apis but no doubt applies
to N. ceranae with the difference that it persists in the summer

> Nosema disease is probably the most widespread of the diseases of adult
bees. White (1919) cited reports of the presence of nosema in Australia,
South America, North America and Europe. The disease has been reported on
every continent (Furgala and Mussen, 1990). Considerable variation has been
reported in its incidence in different countries. but this is probably a
function of the scale and timing of investigations. The true incidences are
probably considerably greater than the values that have been reported. These
range from less than 2% of colonies infected in Italy to more than 60% in
the Black Forest regions of Germany (Bailey and Ball, 1991). 

> Doull (1961) carried out a study of N. apis in hives in South Australia.
He determined that N. apis was *present in all hives at all times*. He
concluded that no hive is likely to be completely free from either spores or
infected bees for any appreciable length of time. Langridge (1961) reported
that during the summer months colonies in Victoria generally carry a few
infected bees (usually a small fraction of 1%). [referring to N. apis]

> N. apis spores are ingested by susceptible worker bees via contaminated
water or food, by food exchange with other bees or in their duties of
cleaning contaminated combs. The spores are passed quickly into the midgut
by the proventriculus. A single spore of N. apis can cause infection.
However, the mean infective dose is reported to be between approximately 20
and 90 spores per bee. When they enter the mid-gut they each extrude their
hollow polar filament and inject the germ through it onto an epithelial cell
(Kramer, 1960b; Morganthaler, 1963). Adult worker bees, adult queen bees and
adult drones are all susceptible. 

© 2008 Rural Industries Research and Development Corporation.
All rights reserved.
ISBN 1 74151 595 5
ISSN 1440-6845
Nosema Disease: Literature review and three year survey of beekeepers - Part 2
Publication No. 08/006
Project No. DAN-228A

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