Ecological characterization of Heterorhabditis sonorensis (Caborca strain) (Nematoda: Heterorhabditidae), an entomopathogenic nematode from the Sonoran Desert

Abstract

Heterorhabditis nematodes are parasites of a wide range of soil-dwelling insect species. Although these nematodes have been exploited as biological control agents since the last half of the 20th century, much research remains to be done to understand how these organisms function in agricultural and other ecosystems. In this study, we present some ecological traits of Heterorhabditis sonorensis, a natural parasite of the cicada Diceroprocta ornea, from the Sonoran Desert. Specifically, we evaluated its infectivity across a diverse panel of insect groups and assessed its fitness (infectivity and reproduction) considering different temperatures, and soil moisture levels. Three other Heterorhabditis species served as points of comparison for temperature and soil moisture assays. Host range experiments indicate that H. sonorensis, although isolated from seasonal cicada nymphs, is more virulent and reproductively fit in the lepidopteran hosts tested. This nematode has an optimum temperature range at 25–30 °C but can also successfully reproduce at temperatures ranging from 15 to 35 °C. Additionally, this nematode is adapted to a variety of soil moisture conditions with successful infections across the tested moisture range (3%–20%). Finally, we demonstrate that H. sonorensis infective juveniles have a high survival rate (over 80%) at various storage temperatures (10–25 °C) after 24 weeks of storage and remain infective as revealed by the post-storage infection assays.