Comparative Assessment of Four Steinernematidae and Three Heterorhabditidae Species for Infectivity of Larval Diabrotica Virgifera Virgifera

Abstract

Larval Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) were exposed to seven different entomopathogenic nematode species to test their potential infectivity in a laboratory setting. Known D. virgifera-infecting nematode species Heterorhabditis bacteriophora Poinar, Heterorhabditis megidis Poinar, Jackson & Klein, Steinernema feltiae Filipjev, and Steinernema carpocapsae Weiser were tested in a concerted experiment alongside Steinernema diaprepesi Nguyen & Duncan, Steinernema riobrave Cabanillas, Poinar & Raulston, and a Missouri wild-type H. bacteriophora which have not been previously tested on D. virgifera. The species S. rarum Doucet was tested separately for D. virgifera infectivity. Third-instar D. virgifera were exposed to either 60 or 120 nematodes per larva for 6 d. Following exposure, mortality was recorded and larvae were examined to determine the presence of active nematode infections. Results indicated a significantly higher proportion of larvae with active infections from the Heterorhabditidae species and S. diaprepesi than the other Steinernematidae species for both exposure rates; mortality data indicated a similar trend. Steinernema rarum showed almost no infectivity in laboratory experiments.

Entomopathogenic nematodes from Mexico that can overcome the resistance mechanisms of the western corn rootworm

“…The potential of H. bacteriophora as a biological control agent of WCR has been widely recognized and studied, and commercial products based on this EPN are registered in a number of European countries. It is considered (a) www.nature.com/scientificreports www.nature.com/scientificreports/ as one of the most effective EPN species in the biological control of WCR larvae, particularly in light of the recent phase-out of neonicotinoid-based seed coatings and highly toxic soil pesticides such as tefluthrin [49][50][51] . Nevertheless conventional EPN application methods have various limitations such as being knowledge-intense for the farmer 52 , or sometimes not cost-effective for low-value crops like maize.…”

Characterization of pyrethroid resistance in the western corn rootwormDiabrotica virgifera virgiferaLeConte

“…The use of entomopathogenic nematodes like Heterorhabditis and Steinernema species have been the most promising WCR biological control so far (Ellsbury et al 1996, Pilz et al 2009, Hiltpold et al 2010, 2012, Toepfer et al 2010, Kahrer et al 2014, Geisert et al 2018. However, many of these techniques, performed either in the laboratory or in small plots, have not been cost effective when compared to insecticides or transgenic maize on a large commercial field scale.…”

An improved bioassay for the testing of entomopathogenic nematode virulence to the western corn rootworm (Diabrotica virgifera virgifera) (Coleoptera: Chrysomelidae): with focus on neonate insect assessments

“…One such method is the use of subterranean entomopathogenic nematodes which utilize insect hosts to feed and reproduce. Previous studies have been conducted to determine the virulence of a wide variety of entomopathogenic nematode species against larval and adult western corn rootworm in both the United States and Europe (Toepfer et al 2005, 2008, 2010, Geisert et al 2018). Nematode virulence experiments can be conducted in simplified arenas consisting of petri plates lined with filter paper that have been inoculated with nematodes suspended in water.…”