Larvae of helminths of molluscs and insects in Karakalpakstan

Abstract

The work discusses some issues related to the species diversity of helminth larvae developing in the body of freshwater molluscs and insects distributed in the territory of Karakalpakstan, a vast region in Uzbekistan. A total of 42 species of parasites in larval form were identified in the region; 27 species were recorded in aquatic molluscs and 15 species in insects. 29 species were recorded for the first time in Karakalpakstan. We established that the class Gastropoda in the water bodies of Karakalpakstan is represented by 17 species; 9 of them belong to the family Lymnaeidae, 6 species to Planorbidae and 2 to Physidae. 3,477 mollusс individuals of 11 species were infected with larval stages of trematodes. The prevalence of infection in Lymnaeidae (Radix and Lymnaea) ranged from 1.7% to 25.5%. A similar prevalence was recorded in Planorbidae (1.6–25.4%). Physa fontinalis showed a prevalence of infection of 1.3%. 27 species of parasites in cercarial forms were identified in molluscs. The largest number of cercariae of trematode species was found in molluscs from the family Lymnaeidae (14 species). They were followed by representatives of Planorbidae (12 species). The fauna of cercariae identified in molluscs from water bodies in Karakalpakstan was from 12 families of trematodes. The most common were the cercariae of those species of trematodes that complete their life cycle in wetland birds (20 species). Cercariae of 6 species of trematodes turned out to be parasites of mammals, mainly ungulates. 1 species of trematodes in a larval stage was recorded in each of the fish and amphibian groups. The richest species composition in the studied region was shown by trematode cercariae representing Schistosomatidae (6 species), which were followed by Echinostomatidae (4 species). Cercariae of other trematode families were represented by one, two and three species. It was established that the studied molluscs do not play an equal role as intermediate hosts of trematodes. The richest species composition was shown by populations of Radix auricularia (14 species), Planorbis planorbis (12 species), Anisus spirorbis (9 species), and Lymnaea stagnalis (5 species). Populations of L. bactriana, Pl. tangitarensis were infected by only one species. The prevalence recorded in the studied insects infected with helminth larvae ranged widely from 1.1% to 14.4%. The identified larvae turned out to be representatives of Cestoda (3 species), Trematoda (1 species) and Nematoda (11 species). The largest number of species (4) of helminth larvae were found in beetles from the family Scarabaeidae – Gongylonema pulchrum, Spirura rytipleurites, Choanataenia infundibulum and Echinolepis carioca, and mosquitoes – Dirofilaria immitis, D. repens, Dipetalonema ewansi and Setaria labiatopapillosa. 2 species were recorded in flies – Stephamofilaria stilesi and Parabronema skrjabini. The recorded species belong to the classes Nematoda and Cestoda. The intensity of infection ranged from single to 11–17 individuals. The work provides original data on the morphology and biology of the larvae of the studied mollusсs infected with cercariae of trematodes and insects with metacercariae of trematodes, cysticercoids of cestodes and larvae of nematodes, and presents the structure of communities of larval forms of parasitic worms.