Hydroquinone is not a phagostimulant for the Formosan subterranean termite

It has been suggested that hydroquinone found in the labial glands of a number of termite species acts as a primary phagostimulating factor. We tested hydroquinone as a phagostimulant using workers from three colonies of the Formosan subterranean termite, Coptotermes formosanus, under both laboratory and field conditions. Hydroquinone at concentrations ranging from ca. 0.002-20.0 ng/cm2 did not increase visitation by C. formosanus workers to treated over control filter papers, and was actually repellent at a 20 ng/cm2 dose. No phagostimulant response to hydroquinone was observed in two colonies. In the third, there was a significant increase in feeding on filter paper treated with a 2 ng/cm2 dose, but was significantly lower at a 20 ng/cm2 dose. Furthermore, sand treated with a gradient of hydroquinone, did not evoke increased tunneling activity compared with controls. GC-MS analysis of C. formosanus workers indicated that hydroquinone was present at an average of 41 pg/worker. It was also determined that within one week about 11% hydroquinone in aqueous solution oxidized to 1,4-benzoquinone. Our findings indicate that hydroquinone alone does not act as a phagostimulant but instead may act as a repellent at higher concentrations. The attractant/arrestant of the Formosan termite may have multiple components of which hydroquinone, at low doses, could be one.