Entomopathogenic Nematodes (Steinernematidae and Heterorhabditidae): Origin, Classification, Species Diversity, and Prospects for Study in Central Asia and Uzbekistan

Entomopathogenic nematodes (EPNs) are soil-dwelling parasitic worms that kill insects within one to two days with the help of symbiotic bacteria. This article examines the origin, phylogeny, species and clade (evolutionary branch) diversity, structure, life cycle and distribution of the families Steinernematidae and Heterorhabditidae on the basis of publications from open sources. By the end of 2023, 113 Steinernema and 21 Heterorhabditis species had been identified and described, whereas in the late 1980s this number was only 13. The symbiotic bacteria belong to the genera Xenorhabdus (32 taxa) and Photorhabdus (30 taxa). The two families lie on distant branches within the order Rhabditida: they acquired the habit of parasitizing insects independently of one another, by separate routes (convergence). Data for Central Asia are very scarce: the publications report local isolates only from Northern Kazakhstan, and no confirmed record was found for Uzbekistan. The literature analysis showed that data on classification are reliable, whereas regional data and evidence of efficacy are weak. Drawing on the biological characteristics of families, clades and species, the article proposes possibilities for their use under the conditions of Uzbekistan and a plan for studying the local fauna.