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Published Studies Assessing the Effects of Multiple Applications of ULV Mosquito A

ND = Not Detected. 

Active 

Ingredient 

Product Sample 

Type 

Time 

sampled 

Results Notes 

Pyrethrins and PBO 

Pyrenone 25-5 

Sediment within 12 

hrs after 

the 5th

and 11th

spray 

events 

No evidence for accumulation. In 6 treated tanks sampled after 5 biweekly sprays pyrethrins levels were ND in 4 tanks, 23.1 & 33.1 ppb in 2 others, after 11 sprays: pyrethrins ND in 4 tanks, 4.03 and 34.5ppb in 2 others, 

6 stock tanks under 11 biweekly ULV applications Sediment in tanks sampled for pyrethrins and PBO after 5th & 11thbiweekly spray events eventsa

Pyrethrins and PBO 

Evergreen 6-60 

Water mid depth 10 sites under an aerial application 

12-16 

hours 

8 days 

Pyrethrins were ND 16 h post app at any site. In “next day” samples, PBO incr in conc at 2 sites, but decr or was ND at 8 sites. Decrease to ND 8 days after spraying ceased 

3-4 consecutive spray events occurring every 2nd day 

PBO Pyrenone 

25-5 

Sediment within 12 

hrs of the 

5th and 

11th spray 

events 

No evidence for accumulation. In 2 out of 6 treated tanks after the 5th and 11th spray: 

PBO ND to 14.9 11th spray: PBO ND to 

2.55 

Sediment in 2 out of 6 treated tanks after 5th & 11th spray eventsa

PBO was detected less frequently as the number of biweekly sprays increased

PBO Pyrenone Water + 12 h Under RL 1 wk after 8th 8 spray events 
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25-5 sediment 1 wk spray event Sampled 1 wk after last treatmentb

Notes: a Lawler et al. (2008) found no accumulation of pyrethrins or PBO in sediment after multiple spray events by truck mou

Pyrethrins were not detectable in sediment in 4 of 6 treated tanks after 5 and 11 biweekly spray events. After 5 sprays, pyrethrins were present in 2 of the 6 treated tanks, at 23.1 and 33.1 ppb, respectively. After 11 sprays, pyrethrins were detected at 4.03 and 34.05 ppb in 2 of 6 treated tanks. Concentrations of pyrethrins in sediment were not higher after the 11th spray event than after the 5th one, and in some ca

the 11th event. 

PBO was detected less frequently as the number of biweekly sprays increased. Five of six tanks had detectable PBO aft

tanks were found to have PBO after 11 biweekly spray events. Concentrations of PBO were lower after the 11th event than after only 5 events. 

After the 11th spray, four of 6 tanks had no detectable PBO. 

PBO-synergized pyrethrin had no detectable effect on the survival of Daphnia or mayfly larvae held in tanks in the spray 

spray events 

bAmweg et al. (2006) reported that levels of Pyrethrins and PBO in water or sediment were below reporting limits when 

last of 8 weekly spray events. 

References 

Amweg, EL, DP Weston, CS Johnson, J You and MJ Lydy. 2006. Effect of piperonyl butoxide on permethrin toxicity in 

azteca. Environmental Toxicology and Chemistry 25 (7):1817-1825 

Larry Walker and Associates 2006. SYMVCD Pyrethrin Water Quality Monitoring Data Summary. Larry Walker and A

Lawler, S.P., D.A. Dritz, C.S. Johnson, and M. Wolder. 2008. Does synergized pyrethrin applied over wetlands for mosq

magna zooplankton or Callibaetis californicus mayflies? Pest Manag Sci 64: 843-847.