Limnological relations of insects to plants of the genus Potamogeton

TitleLimnological relations of insects to plants of the genus Potamogeton
Publication TypeJournal Article
Year of Publication1949
AuthorsBerg CO
JournalTransactions of the American Microscopical Society

1. Limnological relations of insects to plants representing 17 species of Potamogeton were studied in five counties in the Lower Peninsula of Michigan. 2. Insects of 42 species reared from Potamogeton are listed and the host plants of each recorded. Approximately 64 per cent of this fauna is phytophagous; the remainder includes parasites, insects protected by living within Potamogeton tissues, and insects which draw oxygen from these plants. 3. The identified insects directly related to Potamogeton belong to 32 species, including 17 species of Diptera (chiefly Chironomidae and Ephydridae), six species of Trichoptera, four of Lepidoptera, three of Coleoptera, and two species of Homoptera. Odonata (Zygoptera and Anisoptera) unidentified beyond suborder and representing an unknown number of species hatched from eggs found within the plants. 4. Parasitic Hymenoptera of 10 species, at least six of which remain undescribed, were reared from the insects directly related to Potamogeton. 5. Including parasites, the total number of species found associated with each plant is as follows: P. alpinus, 13; P. amplifolius, 25; P. epihydrus, 6; P. filiformis, 0; P. foliosus, 2; P. Friesii, 1; P. gramineus, 10; P. illinoensis, 5; P. natans, 23; P. nodosus, 6; P. Oakesianus, 3; P. pectinatus, 1; P. praelongus, 10; P. pusillus, 0; P. Richardsonii, 18; P. Robbinsii, 6; P. zosteriformis, 7. 6. Various degrees of aquatic adaptation are illustrated by Potamogeton insects. 7. Representatives of most of the species studied hibernate as larvae, on or within host plants living beneath the ice. 8. Plants of the genus Potamogeton suffer injuries of various types due to infestation by insects. The phytophagous species mine, channel, skeletonize, or entirely consume leaves; mine, or gnaw away superficial patches of stems, roots, or flowering peduncles; or suck plant juices. Injuries from insects seeking shelter within plant tissues include stem-burrows of Chironomidae larvae, punctures from ovipositors of Odonata, and defoliation by case-making larvae of Lepidoptera and Trichoptera. Larvae of Ephydridae (Diptera) and of Donaciinae (Coleoptera) pierce the epidermis when they insert their respiratory spines to obtain oxygen. 9. Striking differences in local population densities of the insect fauna are presented. 10. Potamogeton species support a large and heterogeneous assemblage of insects which are directly, intimately, and in some instances probably obligatorily related to these plants.