New self-marking device for dispersal studies of black flies (Diptera: Simuliidae).

An effective and inexpensive device is described for marking newly emerged black flies with fluorescent dust. Survival of marked adults of Simulium venustum s.l. and Stegopterna mutata s.l. did not differ significantly from unmarked individuals over a 5-day period. Marked individuals were attracted to human hosts in landing biting tests, and the portions of the self-marking trap lying just above the water surface did not appear to significantly hamper black fly emergence success.

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.