Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Chemical Taxa/species
carbofuran
carbofuran
1 h average 85 μg/L and
declined to 0.100 μg/L by 96 h
in 1991;
2 h average 12 μg/L L and
declined to 5.14 μg/L by 96 h in
1993;
No detectable differences in
AChE inhibition at 24 h, low
statistical power (0.82 and 1);
Note: AChE is expected to
recover by 24 h;
Increase in coefficient of
variation of drift measure from
day 1and 2 post application
compared to reference site drift
in 1991; Similar increase on day
2 in 1993; drift composed
primarily of live mayflies
(Emphemeroptera)
Aquatic invertebrate community
in rice fields:
ostracada, copepod, cladocera,
mosquito larvae, chironomid
larvae
Assessment
measures
Taxa abundance
and biomass
Abundance of
ostracada, copepod,
cladocera, mosquito
larvae, chironomid
larvae
Concentrations tested
5 μg/L
25 μg/L
Note: pH of 9 in
experimental pond
reduced persistence of
carbofuran by
increasing the rate of
hydrolysis (Chapman
and Cole 1982)
0.1 kg carbofuran/ha-
applied once
0.3 kg carbofuran/ha
applied in two regimes:
3, 52, 85, 97 days; 16,
57, 69 days
355
Exposure
duration
Taxa
assessed at
5, 11, 32, 55
days post
application
variable
application
intervals and
frequencies
Effects
No detectable reductions to
abundance or biomass of taxa
from 5 μg/L;
H azteca: 10% reduction in
abundance; 6% reduction in
biomass
Chironominae: 77% dead in
48-72 h dip net samples
compared to 0% dead in
control and 5 μg/L treatment;
biomass reduced by 17% at 55
d; evidence that younger
larvae were less sensitive than
older larvae;
No detectable reductions in
remaining taxa
Ostracada: timing and
magnitude of peak
abundances not affected by
carbofuran, multiple
application regimes of 0.3 k/ha
significantly reduced
abundance compared to one
application of 0.1 kg/ha
Copepods: significant
reductions at 45 and 57 d at
0.3 kg/ha.
Cladoceran: rate of population
growth significantly affected
from 52 and 85 days at 0.3
kg/ha. Abundance lower at 0.1
kg/ha compared to 0.3 kg/ha.
Chironomid larvae: isolated
significant differences in
abundances were found
(P