In laboratory assays simulating field conditions, tunneling and mortality of Reticulitermes flavipes (Kollar) workers were evaluated in sand treated with aqueous solutions of formulated chlorpyrifos, isofenphos, and disodium octaborate tetrahydrate. Chlopyrifos and isofenphos were evaluated at concentrations of 500 and 1000 ppm (weight of active ingredient / weight of sand), and disodium octaborate tetrahydrate at 2500 and 5000 ppm. No tunneling was observed in sand treated with chlorpyrifos, and high termite mortality suggested vapor and/or high contact toxicity. Tunneling was initiated in isofenphos-treated sand, and termites subsequently died in the tunnels from contact toxicity. At both concentrations, termite mortality from isofenphos exposure was equivalent to that with chlorpyrifos, but the shorter tunnel length at the higher isofenphos concentration (1000 ppm) indicated a concentration-dependent rate of mortality. Greatest tunneling was observed in sand treated with disodium octaborate tetrahydrate. Low and variable mortality with this compound at 2500 ppm are attributable to its slow toxic action and, possibly, difficulty in obtaining an homogenous distribution. Tunneling was not inhibited at 5000 ppm, but mortality was comparable to that observed with 1000 ppm chlorpyrifos, although slightly less than with 1000 ppm isofenphos. Termiticides having different repellency/mortality profiles are potentially useful in termite control.

Download document (377 kb)
free for the members of IRG. Available if purchased.

Purchase this document