Global distribution of entomopathogenic nematodes, Steinernema and Heterorhabditis

Abstract

Entomopathogenic nematodes (EPNs) in the families' Steinernematidae and Heterorhabditidae are obligate insect parasites. Their easy multiplication, broad host range, compatibility with chemical pesticides, and ease in application has grabbed interest among research practitioners to work on these beneficial microorganisms. Till date, around 100 valid species of Steinernema and 21 species of Heterorhabditis have been identified from different countries of the world. Extensive surveys have been conducted across the globe to isolate locally adapted EPN species and exploit them to suppress soil-dwelling and foliar insect pests in agricultural fields. Most of the new species have been described from Asia, whereas research in some Asian countries are still at infancy. Some new species have been recorded from Australia but very few surveys have been conducted in New Zealand. Likewise, less information about these tiny creatures is from Central America; however, in North America many new species have been described, some of which have been commercialized for insect pest control, whereas in South America, several native nematode species have been described and exploited as biological control agents. European countries have also been explored for EPN diversity and new species have been reported, exploited under field condition, and commercialized. Many new species and other previously described species have been reported from Africa. Despite frequent surveys in different continents of the world, number of sites touched are low and, therefore, further surveys are still needed to explore untouched geographic areas and climatic conditions, both in plantations and indigenous forests with an aim to identify and exploit additional EPN species.

Survey and identification of entomopathogenic nematodes in the province of Cotabato, Philippines, for biocontrol potential against the tobacco cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

“…These native EPN populations have mainly gained an increasing attention due to its beneficial attributes like better adaptation to local biotic and abiotic conditions (Stock et al 2008 andCampos-Herrera et al 2012). At present, about 100 Steinernema and 16 Hetererhabditis have been described worldwide (Bhat et al 2020). These EPNs are broadly applied as biopesticides against insect pests (Lacey et al 2015).…”

Functional Diversity of Soil Nematodes in Relation to the Impact of Agriculture—A Review

“…EPN occur in soils both in natural and agricultural ecosystems in all continents, except Antarctica. Some species from tropical and subtropical regions show potential for practical exploitation in banana crops [149][150][151].…”

“…Species from five insect orders (Coleoptera, Hymenoptera, Diptera, Lepidoptera and Orthoptera) have been found naturally infected by EPN [154]. Nevertheless, the majority of EPN species/populations have been isolated from soils, using Galleria mellonella as bait [149,154]. EPN epizootics appear uncommon in nature.…”

Opportunities and challenges of entomopathogenic nematodes as biocontrol agents in their tripartite interactions

“…Symbiotic association of EPN-bacteria is specific. Each species of Steinernema associates with only one species of Xenorhabdus, but Xenorhabdus may be associated with more than one Steinernema species (Bhat et al 2020). Xenorhabdus bovienii bacteria have been found symbiotically associated with 14 species of Steinernema, which signifies broad host range of this bacterial species.…”

“…However, based on what has already been done in many related EPN surveys, it is clear that the percentage of samples positive for EPN is relatively low (Glazer 2015). This general decline in the positive samples demonstrates the desperate need to increase the number of nematode-positive samples whenever possible, and also by exploring untouched geographical areas and climatic conditions (Bhat et al 2020). Hence, a hypothesis of rational sampling was recently tested (Abd-Elgawad 2020).…”