|Shapiro Ilan, David|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2006
Publication Date: 11/1/2006
Citation: Brown, I.M., Shapiro Ilan, D.I., Gaugler, R.R. 2006. Entomopathogenic nematode infectivity enhancement using physical and chemical stressors. Biological Control. 39:147-153. Interpretive Summary: Entomopathogenic nematodes are tiny round worms that kill many important insect pests, but do not harm humans, other animals, or the environment. In some cases these nematodes are not being used commercially because production methods are too expensive. This paper describes improved methods for infecting insects during mass production of nematodes. We discovered that nematode infection is increased by stressing the insects (mealworms) through exposure to heat. Other methods of stressing the insects prior to infection were also investigated such as exposure to various chemicals and cold temperatures, but none of these stressors caused increases in nematode infection comparable to heat exposure. Use of heat stress to increase nematode infection will enhance the efficiency of mass producing beneficial nematodes in insects.
Technical Abstract: Heterorhabditis bacteriophora (hb strain) infection for in vivo mass production in the host, Tenebrio molitor, is optimized by stressing the host. Physical and chemical stressors used included hot and cold temperature, insecticidal oils, metal ions Mg2+ and Mn2+ and the insecticide imidacloprid. Dry heat treatment at 40 degrees C for 30 minutes, increased control infection from 56% to a consistent 97% infection after immersion in 21000IJ/ml inoculation. Yields were unaffected by the dry heat treatment. Immersion in hot water (60-70 degrees C) also produced more than 90% infection, although infection levels and yields fluctuated. None of the chemical stressors produced infection levels acceptable for use in vivo production. The dry heat treatment makes possible the optimal use of the H. bacteriophora vs T. molitor infection system in the automated LOTEK in vivo production system.