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Title: Agar plate analysis of chitinase expression by pathogens of the Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae)

Author
item Wright, Maureen
item Lax, Alan

Submitted to: Journal of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2016
Publication Date: 3/1/2016
Citation: Wright, M.S., Lax, A.R. 2016. Agar plate analysis of chitinase expression by pathogens of the Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae). Journal of Entomological Research. 40(1):21-26.

Interpretive Summary: Subterranean termites cause several billion dollars in damage and prevention costs in the United States annually. The Formosan subterranean termite is responsible for a large and growing proportion of the cost. Novel chemicals which are non-repellant and slow-acting have been developed to control termite activity. This work reports the development of biological control agents, fungal enemies of termites, that will complement the chemicals in an Integrated Pest Management scheme. This manuscript reports the development of a method to detect the production of an enzyme that breaks down the outer surface of termites by fungi that kill termites. These results can lead to greater ease and speed in screening fungi that have had their ability produce this enzyme enhanced.

Technical Abstract: Strains of Paecilomyces fumosoroseus were grown on PDA plates containing chitin azure to determine whether their expression of chitinase could be correlated with their previously measured pathogenicity against the Formosan subterranean termite. Paecilomyces strains 3581 and 4491 both formed maximal zones of conversion of chitin azure that were significantly larger, 40.0 mm on day 12, than the zone formed by strain 92118, 36.8 mm on day 12. However in past studies, strain 4491 was less pathogenic than strain 92118. A strain of Metarhizium anisopliae was also tested for its ability to convert chitin azure. The zones formed by M. anisopliae strain 30905 were significantly smaller than those formed by all of the Paecilomyces strains, 7.0 mm on day 12, but this strain is known to exhibit pathogenicity against termites. To determine if the glucose in PDA inhibited chitinase expression the experiment was conducted on A&M plates supplemented with fructose instead of glucose. More variation was seen between strains 3581 and 4491 on A&M plates, but the general expression of chitinase was not enhanced on this medium. Analysis of fungal growth confirmed that, at least with strain 92118, the differential response between the media was not attributable solely to a reduction in growth on the A&M medium.