Influence of water extracts from the surface of two yew (Taxus) species on mites (Tetranychus urticae).

Taxus cuspidata and Taxus media var. Hicksii contain paclitaxel, among other taxoids, on the surface of the needles. These compounds were removed by 5-s dipping of the needles in water just below its boiling point at 96 degrees C and at 60 degrees C and 40 degrees C. Taxus cuspidata contained a fourfold higher concentration of paclitaxel than Taxus media var. Hicksii. The extract with the higher concentration of paclitaxel was more harmful to the mites Tetranychus urticae Koch, increasing their mortality 150%, prolonging development by ca. 20% and lowering the average fecundity from 112 in the control to 16.13 after treatment with Taxus cuspidata; also, the net reproductive rate dropped from 70.24 to 6.70, which is more than a tenfold reduction.