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Carl E. Crisp
the following insecticides are toxic to western spruce budworm by feeding action:
chlorpyrifos-methyl, chlorpyrifos, bioethanomethrin, diflubenzuron, permethrin,
aminocarb, and mexacarbate. Similar results have been reported for feeding
action to Douglas fir tussock moth larvae, where the most toxic insecticides were
permethrin, diflubenzuron, bioethanomethrin, DDT, mexacarbate, carbaryl, and
acephate (Gillette et ai., 1978). Nigam (1978) reports that the most effective
insecticides to spruce budworm are decamethrin, cypermethrin, NRDC-I60
(± cis analog of cypermethrin), chlorpyrifos-methyl, permethrin, and acephate.
The feeding toxicity of diflubenzuron to larvae of introduced sawfly [Diprion
similis (Hartig)] was evaluated by Valovage and Kulman (1977), who dipped
cut branches of white pine [Pinus strobus (L.)] in various concentrations of
diflubenzuron. Dipping permits uniform coverage of the substrate. Concentrations greater than 25 ppm gave effective control.
7.6.1.5. Spray Chamber Tests
Application of insecticides to potted trees or directly onto insects placed in
the Moellman spray chamber (Robertson et ai., 1979) permits assessment of
toxicity under laboratory conditions. Direct, indirect, and residual toxicities of
insecticide sprays to western spruce budworm were evaluated (Robertson and
Rappaport, 1979). Permethrin was one of nine insecticides tested in the Moellman
spray chamber. It was more toxic when sprayed directly on sixth instar larvae
than when first sprayed on foliage. All other insecticides were more toxic when
sprayed on foliage.
The residual toxicity of several insecticides to fourth instar Douglas fir
tussock moth larvae caged on 2-year-old potted Douglas fir seedlings was determined (Robertson and Boelter, 1979b). Bioethanomethrin and permethrin
were substantially more toxic than DDT both by contact and by ingestion.
Diflubenzuron, though not as toxic as pyrethroids, was consistently more toxic
than DDT.
Spray chamber tests were used to evaluate some selected insecticides for
toxicity to western black-headed budworm [Acleris gioverana (Walsingham)].
The most toxic insecticides were chlorpyrifos-methyl, methomyl, mexacarbate,
malathion, and aminocarb (Robertson, 1976). Using similar techniques, Page
and Lyon (1975) investigated the effectiveness of some selected insecticides to
the cottonwood leaf beetle (Chrysomeia scripta F.) and report that mexacarbate,
resmethrin, chlorpyrifos, phoxim, and propoxur were the most toxic compounds.
7.6.1.6. Toxicity Tests on Different Species and Populations
The toxicologist needs to know if significant differences in toxicity exist
between species of the same genus. The response of six species of Choristoneura
to insecticides was tested (Robertson et ai., 1978b). These results showed that
Carl E. Crisp
the following insecticides are toxic to western spruce budworm by feeding action:
chlorpyrifos-methyl, chlorpyrifos, bioethanomethrin, diflubenzuron, permethrin,
aminocarb, and mexacarbate. Similar results have been reported for feeding
action to Douglas fir tussock moth larvae, where the most toxic insecticides were
permethrin, diflubenzuron, bioethanomethrin, DDT, mexacarbate, carbaryl, and
acephate (Gillette et ai., 1978). Nigam (1978) reports that the most effective
insecticides to spruce budworm are decamethrin, cypermethrin, NRDC-I60
(± cis analog of cypermethrin), chlorpyrifos-methyl, permethrin, and acephate.
The feeding toxicity of diflubenzuron to larvae of introduced sawfly [Diprion
similis (Hartig)] was evaluated by Valovage and Kulman (1977), who dipped
cut branches of white pine [Pinus strobus (L.)] in various concentrations of
diflubenzuron. Dipping permits uniform coverage of the substrate. Concentrations greater than 25 ppm gave effective control.
7.6.1.5. Spray Chamber Tests
Application of insecticides to potted trees or directly onto insects placed in
the Moellman spray chamber (Robertson et ai., 1979) permits assessment of
toxicity under laboratory conditions. Direct, indirect, and residual toxicities of
insecticide sprays to western spruce budworm were evaluated (Robertson and
Rappaport, 1979). Permethrin was one of nine insecticides tested in the Moellman
spray chamber. It was more toxic when sprayed directly on sixth instar larvae
than when first sprayed on foliage. All other insecticides were more toxic when
sprayed on foliage.
The residual toxicity of several insecticides to fourth instar Douglas fir
tussock moth larvae caged on 2-year-old potted Douglas fir seedlings was determined (Robertson and Boelter, 1979b). Bioethanomethrin and permethrin
were substantially more toxic than DDT both by contact and by ingestion.
Diflubenzuron, though not as toxic as pyrethroids, was consistently more toxic
than DDT.
Spray chamber tests were used to evaluate some selected insecticides for
toxicity to western black-headed budworm [Acleris gioverana (Walsingham)].
The most toxic insecticides were chlorpyrifos-methyl, methomyl, mexacarbate,
malathion, and aminocarb (Robertson, 1976). Using similar techniques, Page
and Lyon (1975) investigated the effectiveness of some selected insecticides to
the cottonwood leaf beetle (Chrysomeia scripta F.) and report that mexacarbate,
resmethrin, chlorpyrifos, phoxim, and propoxur were the most toxic compounds.
7.6.1.6. Toxicity Tests on Different Species and Populations
The toxicologist needs to know if significant differences in toxicity exist
between species of the same genus. The response of six species of Choristoneura
to insecticides was tested (Robertson et ai., 1978b). These results showed that