Borate protection of hoop pine (Araucaria cunninghamii) sapwood from attack by subterranean termites (Coptotermes spp., Isoptera: Rhinotermitidae)

Abstract

Field bioassays were conducted with two Australian Coptotermes species to determine protection of hoop pine sapwood afforded by borate compounds. Coptotermes lacteus (Froggatt) was examined in winter and Coptotermes acinaciformis (Froggatt) in winter, spring and late summer at two localities in the state of Queensland. Sapwood blocks were placed in plastic containers and attached to termite mounds or infested trees. Termite response was determined by mass loss over five weeks and modelled. C. lacteus was relatively benign in winter and for 1.0 and 2.5% mass loss, mean borate retentions of 0.20 and 0.06% m/m boric acid equivalent (BAE), respectively, were derived. With C. acinaciformis, for 1.0 and 5.0% mass loss, mean borate retentions ranged from 0.49 and 0.25% BAE. respectively, in winter, to 0.76 and 0.47% BAE. respectively, in late summer. These results support conclusions from earlier laboratory studies conducted elsewhere. Total prevention of damage by field populations of termites was not achieved. Marked intercolony variation in response to borate compounds was demonstrated, highlighting the usefulness of this rapid technique. The need for long term field exposure trials, which will facilitate technology transfer to industry, is indicated.