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We evaluated the oral and dermal toxicity of 18 chemicals to brown tree snakes (Boiga irregularis). Chemicals that produced mortality when dosed orally were rotenone, propoxur, natural pyrethrins, allethrin, resmethrin, diphacinone, warfarin, and aspirin. The lowest oral doses that gave 100% mortality were: rotenone, 2.5 mg kg-1; pyrethrins, 40 mg kg-1; propoxur, 40 mg kg-1; diphacinone, 80 mg kg-1; and aspirin, 1280 mg kg-1. Allethrin, resmethrin, and warfarin produced 80% mortality at 40 mg kg-1, the highest dose tested. Materials given orally that produced little mortality were permethrin, fenvalerate, and carbaryl; those giving no mortality were phenothrin, tetramethrin, piperonyl butoxide, propylene glycol, and cholecalciferol. Chemicals that produced mortality when applied dermally at doses of 40 mg kg-1 were rotenone, nicotine, propoxur, natural pyrethrins, allethrin, and resmethrin; those that gave no mortality were permethrin, fenvalerate, phenothrin, tetramethrin, piperonyl butoxide, and diphacinone. Rotenone, at 10 mg kg-1, and nicotine, at 40 mg kg-1, were the most toxic dermally, killing all tested snakes. Piperonyl butoxide enhanced the oral toxicity of allethrin and resmethrin and the dermal activity of resmethrin; it did not enhance the activity of natural pyrethrins either orally or dermally.

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To determine whether a resistant chemotype to the white pine weevil, Pissodesstrobi Peck, could be identified, the relative composition of monoterpenes in weevil-susceptible Sitka spruce, Piceasitchensis (Bong.) Carr., was compared to that in apparently resistant trees. Foliar and cortical analysis of trees from Green Timbers Nursery in Surrey, Nootka Island, Sayward, and the Nass River Valley, B.C., revealed significant differences between 38 resistant and 60 susceptible trees. The foliage of resistant trees, compared with that of susceptible trees, had significantly lower amounts of isoamyl isovalerate at three sites and lower amounts of isopentenyl isovalerate at one site. Amounts of a α-pinene, β-pinene, camphene, and camphor were significantly higher in some resistant trees, but these differences were not consistent between sites. Myrcene, β-phellandrene, and limonene levels were much higher in the cortex of susceptible trees than the resistant trees from the Nass River and Green Timbers Nursery. Thus none of the monoterpenes, singly or in combination, is a consistent indicator of resistance to the white pine weevil. The two isovalerates could possibly be used as indicators of resistance. However, a broader spectrum of resistance characteristics should be employed if breeding for resistance is desired.