We know that parasites and infectious agents can have a large effect on the populations and distributions of terrestrial insects. What effect do they have on aquatic insects? This question is more difficult to study in aquatic insects due to difficulties in sampling and rearing. Parasites of many terrestrial insects have been characterized, especially those of economic importance. What about the parasites of aquatic insects?
New molecular techniques are making the identification of parasites faster, more accurate and more tractable. In a study by Daniel Grabner*, 10 species of aquatic insects and 2 species of aquatic crustaceans were collected from a stream and investigated as parasite hosts. DNA was collected from the arthropods and screened for the parasites using primers specific to microsporidian, nematode, trematode and cestode parasites. Microsporidians were found in all 12 species with infection rates from 20 to 100%. Also found were a nematode species and 6 trematode species. DNA evidence suggests that some of the parasites are previously unknown species.
The numbers of parasites found and the frequency with which aquatic insects are infected suggests that parasites can be important agents in regulating populations and occurrence of aquatic insects.
*DANIEL S. GRABNER. Hidden diversity: parasites of stream arthropods. Freshwater Biology (2017) 62, 52–64