Canadian Forest Service employee directory

Larry Gringorten

Research Scientist, Physiological Interactions
Great Lakes Forestry Centre
1219 Queen Street East
Sault Ste. Marie, Ontario, P6A 2E5

Tel.: (705) 541-5674


Study Summary:

The study conducts research on the physiological effects and mode of action of insect pathogens and natural products on their hosts, with special emphasis on Bacillus thuringiensis (Bt) delta-endotoxins and secondary plant compounds. Current projects include the following:

1. Determining the extent to which Bt causes the release of protein-bound potassium in the midgut of susceptible insects. Finding ways to increase the release as means of enhancing the toxemia.

2. Testing pathogens and their cloned gene products against economically important forest defoliators with the aim of identifying novel products for commercial development against specific insect pests.

3. Development of a cell assay to evaluate the cytolytic activity of secondary plant compounds in vitro, determining their mode of action and determining whether the compounds interact synergistically or antagonistically with Bt.

4. Identification of gut-juice factors involved in potentiating the insecticidal activity of secondary leaf compounds and the factors causing their detoxification.

5. Development of a lawn assay for Bt toxins using midgut brush border membrane vesicles.

Study Objectives:

1. To determine how Bt and other pathogens interfere with the normal physiolgy of susceptible insects, particularly how insects respond to and recover from sublethal doses of toxins, and to use the information to devise ways of enhancing pathogen toxicity.

2. To identify cloned gene products of Bt and other pathogens that exhibit high activity against specific target insects.

3. To develop a cell assay for assessing toxicity of secondary plant metabolites in vitro and determine the degree of interaction with Bt toxins.

4. To determine how secondary metabolites of leaves are detoxified in the insect midgut and devise ways of interfering with the detoxification mechanism.

5. To provide a high throughput assay system for testing Bt insecticidal activity in vitro.