The hypothesis that spores of terrestrial and aquatic microsporidia differ
in their utilization of sugars was tested by evaluating the sugars in germi
nated and ungerminated spores of several species in each category. The aqua
tic species tested were Vavraia culicis, Edhazardia aedis, and Nosema alger
ae and the terrestrial species were Vairimorpha necatrix, Nosema disstriae,
Nosema apis, Vairimorpha lymantriae, and Nosema spp. from Spodoptera exigu
a and Plutella xylostella. The percentage germination varied between specie
s, ranging between 40 and 92%. Total sugars (anthrone reactive) and reducin
g sugars (Nelson's test) remained unchanged through germination in the thre
e terrestrial species tested; however, reducing sugars increased significan
tly in the aquatic species. High-performance liquid chromatography and gas
chromatography revealed a preponderance of trehalose in all species and lar
ge quantities of sorbitol in all species except N. algerae and E. aedis. Ot
her sugars were present in some species in much lower concentrations. After
germination no changes in sugar content were observed in terrestrial speci
es; however, all aquatic species lost trehalose with a concomitant increase
in fructose and/or glucose concentrations. Increased osmotic potential fro
m breakdown of trehalose has been postulated to induce germination of the a
quatic species, but another explanation must be found for the terrestrial s
pecies.