Toxicity and residual action of the photoactivated compound, cyano-alpha-terthienyl, and its efficacy for reducing pre-imaginal populations of mosquitoes.
The photoactivated compound, cyano-alpha-terthienyl (cyano-alpha-T), was highly toxic to pre-imagines of the mosquitoes Culex restuans, Cx. tarsalis and Culiseta inornata when synergized with piperonyl butoxide (PBO). Lethal concentrations for 50% mortality, determined during an outdoor trial using caged fourth-instar Culex spp. larvae, were 19.4, 15.4 and 12.9 g/ha at 24, 48 and 72 h after treatment, respectively. No residual activity of cyano-alpha-T was observed beyond 24 h following treatment. In artificial pool tests, greatest population reductions were achieved using dosages of 20 and 40 g/ha; statistically significant reductions were not observed following applications of 5 g/ha. Cyano-alpha-T plus PBO was more effective for reducing mosquito populations than alpha-terthienyl (alpha-T) plus PBO at comparable dosages, although it exhibited slightly lower insecticidal activity at a dosage of 20 g/ha than a formulation of Bacillus thuringiensis var. israelensis (Vectobac 12 AS, 0.12 ml/m2). Greatest effectiveness of cyano-alpha-T plus PBO was observed in pools with low organic content relative to pools high in organic content.
Alberta Environmental Centre, Vegreville, Canada.
L M
LM
Dosdall
M M
MM
Galloway
J T
JT
Arnason
D000818:Animals; D001681:Biological Assay; D003465:Culex; D009033:Culicidae; D005618:Fresh Water; D007306:Insecticides; D007814:Larva; D010882:Piperonyl Butoxide; D010944:Plants; D013876:Thiophenes
D007306:Insecticides; D013876:Thiophenes; C019101:alpha-terthienyl; D010882:Piperonyl Butoxide