Eastern subterranean termite (Reticulitermes flavipes) chitinase activity in response to two chitinase inhibitor treated diets

The objective of this research was to examine total chitinolytic enzyme activity within the eastern subterranean termite in response to chitinase inhibitor treated diet.  Termites were fed a filter paper diet treated with one of two chitinase inhibitors, pentoxifylline or psammaplin A. Five pentoxifylline and four psammaplin A concentrations of treated diet were tested. An untreated filter paper diet was used as a control treatment. Termites were allowed to feed on the diet for 5 weeks. Three biological replicates were sampled from each treatment concentration at weekly intervals. Each biological replicate was then assayed for glucosaminidase activity (exo-chitinase activity) and triacetylchitotriase activity (endo-chitinase activity) colorimetrically. Assays within each biological replicate were performed in triplicate. Mean exo- and endo-chitinase activity in response to both treatment chemicals and control diets are reported at 1, 2, 3, 4, and 5 weeks after initial feeding. In terms of total chitinolytic inhibition, both chemicals even at the lowest concentrations tested, significantly inhibited endo-chitinase activity when compared to control treatments at each sampling interval over five weeks. Similar trends in exo-chitinase inhibition were observed between both chemical treatments. Considerable differences of inhibition levels between the two treatments were observed when comparing endo- and exo-chitinase activity in vitro and in vivo.  Mean diet consumption and percent test population mortalities in response to treatment over time are also reported.