J. Frouz et al., The effect of bibionid larvae feeding on the microbial community of litterand on reconsumed excrements, PEDOBIOLOG, 43(3), 1999, pp. 221-230
The effect of larval bibionid feeding on microbial respiration (CO2 product
ion and O-2 consumption), fluorescein diacetate activity (FDA), direct coun
ts of bacteria and composition of the microbial community were studied. Lea
f litter and larval excrement (1-3 days old) were used as food. Two species
of bibionid larvae and two types of leaf litter (Bibio marci feeding on Ca
rpinus betulus litter and Bibio pomonae on Populus nigra) were used. Gut pa
ssage resulted in an increase of microbial O-2 consumption, total microbial
metabolic activity, direct counts of bacteria and number of actinomycetes
in the fresh excrement. This effect was only short term. Reduction of bacte
rial counts and shift in composition of microbial communities were observed
during both the first and second gut passages. Passaging induced decrease
in the C and N contents of the substrate, the C/N ratio and the amounts of
water soluble carbohydrates. Animal - microbial interactions differed betwe
en the first and the second gut passage. During the second gut passage high
er numbers of bacteria in the gut content were found. This appears to be du
e to the higher counts of bacteria in the food and a higher proportion of b
acteria which could survive gut passage. The effect of gut passage was depe
ndent on the species of bibionid larvae and on the food that was consumed.
CO2 production responded differently than O-2 consumption and most of the m
icrobial parameters suggesting that CO2 production is influenced not only b
y microbial activities but also by other factors (aeration status, pH).