THE EFFECT OF DIET QUALITY ON GROWTH AND DEVELOP- MENT OF RECENTLY HATCHED LARVAE OF Chironomus gr. plumosus

Recently hatched larvae of two egg-masses of Chironornus gr. plumosus were used in feeding experiments lasting for 12 days. Three diets were selected to test the effect of food quality and feeding mechanism on growth and development of larvae: detached benthic algae and leaf debris in the form of leaf disks of 1.S cm diameter (CPOM) and leaf particles of size less than 250 pm (FPOM). Significant effects of diet were observed for growth and development of larvae of both egg-masses. Benthic algae, more properly algae derived detritus, proved to be the food of higher quality, producing a higher rate of growth than did the CPOM diet. In the FPOM diet, no significant growth was obtained over the experiment, and after 12 days no larvae were found alive on this diet. On the CPOM diet the larvae were observed to ingest mostly fungal biomass, scraping the surface of leaf disks. However, on the FPOM diet the leaf tissue was ingested in higher proportion possibly because of the impossibility of microbial selection due to the small particle size. These results suggest that leaf tissue itself was of poor nutritional value for larvae, unlike fungal biomass