TOXICITY OF INSECTICIDES TO FIRST-INSTAR LARVAE OF THE SPRUCE BUDMOTH, ZEIRAPHERA CANADENSIS MUT. AND FREE. (LEPIDOPTERA: TORTRICIDAE): LABORATORY AND FIELD STUDIES

Abstract

Laboratory tests with selected carbamate, organophosphorus, and pyrethroid insecticides demonstrated that the pyrethroid permethrin has the best potential for controlling newly hatched larvae of Zeiraphera canadensis Mut. and Free. Permethrin possessed high crawling contact toxicity (toxicity of insecticide deposits on foliage when contacted by crawling larvae) and direct contact toxicity to first-instar larvae and exhibited long residual effectiveness on potted, white spruce trees. Chlorpyrifos, fenitrothion, mexacarbate, and methomyl had high crawling contact toxicity but short residual activity. Azinphos-methyl appeared to possess long residual effectiveness but relatively low crawling contact toxicity. Aminocarb and thiodicarb exhibited short residual effectiveness and relatively low toxicity. In field trials, an aerial application of permethrin (70 g/ha) at egg hatch resulted in an 81% population reduction and limited the destruction of tree leaders to 9%. Leader destruction was greater than 19% after treatments of permethrin at 35 g AI/ha or aminocarb at 180 g AI/ha or aminocarb twice at 90 g AI/ha. Leader destruction in an untreated plantation was 51%.

Status of research on the development of management tactics and strategies for the spruce bud moth in white spruce plantations

“…Using a bioassay where first-instar larvae were allowed to crawl on treated twigs, the toxicity and residual activity of eight chemical insecticides were assessed under laboratory and greenhouse conditions. These tests demonstrated that permethrin, a pyrethroid, was the only insecticide with a high potency and a long residual activity (Table I), thus offering the best potential for success under field conditions (Helson et al 1989). Among the insecticides tested under field conditions, only applications of permethrin at 70 g/ha with fixed wing aircraft provided an acceptable level of leader protection with < than 10% of leaders destroyed (Helson et al 1989).…”

“…These tests demonstrated that permethrin, a pyrethroid, was the only insecticide with a high potency and a long residual activity (Table I), thus offering the best potential for success under field conditions (Helson et al 1989). Among the insecticides tested under field conditions, only applications of permethrin at 70 g/ha with fixed wing aircraft provided an acceptable level of leader protection with < than 10% of leaders destroyed (Helson et al 1989). Although this experiment was not replicated, an aerial application of 70 glha of permethrin with helicopter and a ground application with a backpack mist blower supported these results (B. Helson, Forestry Canada, Forest Pest Management Institute, pers.…”

“…A new unit may have to be developed because a variable amount of within tree redistribution of second-instar larvae takes place each year (Turgeon 1985). Helson et al (1989) used a 45-cm branch sample, which provided less variation in pre-and post-spray samples, but took much longer to process. Sequential sampling plans with one (Turgeon and RCgnikre 1987) and two (RCgnikre et al 1988) critical levels of larval density have also been developed.…”

Role of physical factors on pesticide performance in forestry: An overview

“…If, however, the active material is a solid or associated with solid fillers, as in the case of highly concentrated aqueous formulations containing wettable powders and clays, or Bacillus thuringiensis agent, the evaporated droplet becomes a solid particle. While a 100 or 50 /jm droplet shrinking to a 50 or 25 //m droplet is still capable of retention on the target, the one which becomes a solid particle is virtually useless since its adhesion capabilities would be drastically impaired (Sundaram, 1989 When penetration of forest canopy is required to provide residual contact on stem parts and undergrowth, as in the control of Zeiraphera canadensis in plantation forests (Helson et al, 1989), the problem becomes much more complex, because we want to avoid high canopy but reach similar surfaces in lower layer. Granules would avoid both and produce poor contact effect on insects.…”