Comparative assessment of four steinernematidae and three heterorhabditidae species for infectivity of larval diabrotica virgifera virgifera

Authors: Geisert, Ryan; CHERUIYOT, DOROTHY - Tulane University; Hibbard, Bruce; Shapiro Ilan, David; Shelby, Kent; Coudron, Thomas

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2017
Publication Date: 1/20/2018
Citation: Geisert, R.W., Cheruiyot, D.J., Hibbard, B.E., Shapiro Ilan, D.I., Shelby, K., Coudron, T.A. 2018. Comparative assessment of four steinernematidae and three heterorhabditidae species for infectivity of larval diabrotica virgifera virgifera. Journal of Economic Entomology. 111(2):542-548. https://doi.org/10.1093/jee/tox372.
DOI: https://doi.org/10.1093/jee/tox372

Interpretive Summary: The western corn rootworm has developed resistance to most control tactics used to manage it including the use of insecticides and transgenic corn varieties that express insecticidal Bt proteins. Because of this it is important to look for alternative methods for rootworm control. One method that shows promise involves the use of beneficial insect-specific nematodes that infect and kill the immature stage of rootworm. More studies are needed to identify highly infective species and strains of nematodes before formulation trials begin. For this experiment we tested the nematode species Heterorhabditis bacteriophora, H. megidis, Steinernema feltiae, S. carpocapsae, S. diaprepesi, S. riobrave and a Missouri wild type H. bacteriophora for their ability to infect and kill larval rootworms. Rootworms were exposed to either 60 or 120 nematodes for six days. Results showed that H. bacteriophora, H. megidis, and S. diaprepesi caused significantly higher rootworm death than the non-infested control. This is the first time S. diaprepesi has been tested against rootworm. Results from this experiment show it has potential for rootworm control. Both researchers and industry will find these results to be important for the development of nematodes as biological control agents targeting rootworms.

Technical Abstract: Larval Diabrotica virgifera virgifera LeConte 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, H. megidis Poinar, Jackson & Klein, Steinernema feltiae Filipjev, and S. carpocapsae Weiser were tested in a concerted experiment alongside S. diaprepesi Nguyen & Duncan, S. 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 larvae for six days. Following exposure, mortality was recorded and larvae were dissected 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; morality data indicated a similar trend. Stinernema rarum showed almost no infectivity in laboratory experiments.