Dispersal of Algae, Protozoans, and Fungi by Aquatic Hemiptera, Trichoptera, and Other Aquatic Insects1

Abstract

Fifteen of 16 species of aquatic insects studied, including 5 aquatic Hemiptera, 5 caddisflies, 1 stonefly, 2 dobsonflies, and 2 mayflies, were found to be transporting 27 genera of viable small aquatic organisms. Three corixids carried 5 genera of blue-green algae, 11 green algae, 1 yellow-green alga, 2 protozoans, and fungi. Eudorina, representing colonial volvocalean algae, was found for the 1st time on field-exposed aquatic insects. The suitability of the Corixidae and Notonectidae as passive dispersal vehicles for small organisms is discussed. Only 1 of 6 caddisflies studied carried algae and protozoans, but that species, Hydropsyche orris Ross, carried 10 genera. Organisms taken in casual samplings of Plecoptera, Megaloptera, and Ephemeroptera are indicated. Excluding fungi, Chlorella was the most common viable form being carried, followed by Bodo, Nannochloris Chloroccoccum, and Microcystis, in order of frequency of occurrence. Unidentified fungi and Fusarium were carried by more than 75% of the 16 insects sampled and occurred in more than 50% of the 112 culture samples.