Laboratory bioassay and field trial on imidacloprid and cypermethrin as glueline treatments for softwood plywood

IRG/WP 06-30405

J W Creffield, D K Scown

The effectiveness of imidacloprid and cypermethrin as glueline treatments for protecting phenol formaldehyde (PF)-bonded Pinus radiata (radiata pine) plywood from attack by subterranean termites was evaluated both in the laboratory and field. Imidacloprid was evaluated in two plywood constructions (19 ply x 1.6 mm-thick veneers and 5 ply x 3.2 mm-thick veneers) whereas cypermethrin was evaluated in only one (19 ply x 1.6 mm-thick veneers). There was a strong correlation between the results obtained from the laboratory bioassay and the subsequent field trial. Results of both the laboratory bioassay and field trial demonstrated that imidacloprid at the retention of 20 g a.i./m3 failed to adequately protect test specimens of radiata pine plywood (19 ply x 1.6 mm-thick veneers) from attack by both Coptotermes acinaciformis and Mastotermes darwiniensis. However, it was noted that imidacloprid only marginally failed against attack by C. acinaciformis in the field. In contrast, imidacloprid at the retention of 20 g a.i./m3 was successful in protecting test specimens of radiata pine plywood (5 ply x 3.2 mm-thick veneers) from significant attack by C. acinaciformis, but comprehensively failed against M. darwiniensis. Cypermethrin at the retention of 420 g a.i./m3 was successful in protecting test specimens of radiata pine plywood (19 ply x 1.6 mm-thick veneers) from significant attack by C. acinaciformis. The same retention of cypermethrin performed well in protecting radiata pine plywood test specimens from attack by M. darwiniensis, even though it marginally failed in the laboratory. It is hypothesised that the longer hot pressing time used for the manufacture of plywood test panels of 19 ply x 1.6 mm-thick veneers may have caused more degradation of the imidacloprid active than in panels of 5 ply x 3.2 mm-thick veneers.


Keywords: laboratory bioassay, aboveground field trial, imidacloprid, cypermethrin, Pinus radiata, termites, plywood, correlation, Coptotermes acinaciformis, Mastotermes darwiniensis

Conference: 06-06-18/22 Tromsoe, Norway


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