BIOASSAYS OF EXTRACTS FROM WHITE CYPRESS PINE (CALLITRIS-COLUMELLARIS F MUELL) AGAINST SUBTERRANEAN TERMITES

White cypress pine (Callitris columellaris F. Muell.) is known for its high resistance to termite attack. Extracts of white cypress pine bark and heartwood were exposed in the laboratory on filter papers to workers of Coptotermes acinaciformis Froggatt, Nasutitermes exitiosus (Hill) and on filter papers and wood blocks to Mastotermes darwiniensis Froggatt. A spoked-arena multichoice bioassay was developed to overcome the limitation of low volumes of petroleum ether extractives available for testing, and provided repeatable and consistent results in screening fractions of extracts repellent to workers of M. darwiniensis. The bioassays indicate that the petroleum ether soluble extractive from the heartwood was more toxic to M. darwiniensis than the diethyl ether or methanol soluble extractives and that the neutral fraction of the petroleum ether soluble extract from the heartwood was significantly more repellent to this termite. In addition, acid and neutral fractions were found to be toxic to both N. existiosus and C. acinaciformis, though acting at a slower rate on the latter species. The acid fraction was found to produce faster knockdown and mortality than the neutral fraction. © Copyright by Walter de Gruyter & Co.