4 research outputs found
Insecticide Effects on Normal Development and Hatch of Embryos of \u3ci\u3eParatanytarsus Parthenogeneticus\u3c/i\u3e (Diptera: Chironomidae)
Simple, low cost methods are needed to determine the effect of pesticides on non-target aquatic organisms. In this report, embryos of Paratanytarsus parthenogenetic us were exposed from deposition to hatch to five pesticides. Four of the five pesticides affected development or hatch only at concentrations which exceeded 96-h LC50 values of other non-target invertebrates. One pesticide, fenitrothion, affected hatch at 13 Ilgll which is similar to 96-h LC50 values for other aquatic invertebrates. Because of the low sensitivity of the embryo to pesticides, this method may not be a useful pesticide screening test for non-target invertebrates
Insecticide Effects on Normal Development and Hatch of Embryos of \u3ci\u3eParatanytarsus Parthenogeneticus\u3c/i\u3e (Diptera: Chironomidae)
Simple, low cost methods are needed to determine the effect of pesticides on non-target aquatic organisms. In this report, embryos of Paratanytarsus parthenogenetic us were exposed from deposition to hatch to five pesticides. Four of the five pesticides affected development or hatch only at concentrations which exceeded 96-h LC50 values of other non-target invertebrates. One pesticide, fenitrothion, affected hatch at 13 Ilgll which is similar to 96-h LC50 values for other aquatic invertebrates. Because of the low sensitivity of the embryo to pesticides, this method may not be a useful pesticide screening test for non-target invertebrates
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Ration and toxicant preexposure influence dieldrin accumulation by rainbow trout
Whole body accumulation and tissue distribution of dieldrin
(HEOD1) in rainbow trout was studied through oral dose disposition
tests and subchronic exposures via water (0.04 and 0.08 jig dieldrin/l)
and/or diet (0.087 jig dieldrin/g fish/day). Growth and maintenance
rations of 4 and 2% body weight/day were employed. Subchronic testing
produced apparent steady state residue concentrations dependent on
ration and exposure concentration after eight weeks exposure. At 16
weeks, mean whole fish residue concentrations ranged from 120 to 1400
ng dieldrin/g fish. Exposure through food and water under conditions
of growth produced the highest values (1300-1400 ng dieldrin/g fish).
Maintenance rations apparently limited accumulation to a maximum of
360 ng dieldrin/g fish. Whole body dieldrin concentration calculated
on the basis of total lipids greatly reduced the differences in
residue levels due to ration.
Disposition tests were conducted on fish administered dieldrin via
the diet for 2, 4 and 6 weeks and naive fish (no pretreatment). The
1 HEOD: endo exo isomer of 1,2,3,4,10,10-hexachloro-6,7-expoxy-1,4,4a,
5,6,7,8,8a-octahydro-1,4,5,8-dimethanonaphthalene
disposition of a single oral dose of radiolabelled dieldrin was
determined 48 hours following administration.
Retention of the dose was relatively constant at 0, 2, and 6 weeks
with a downward trend for most tissues and a 2 and 5 fold increase in
retention of label in the bile of fish receiving maintenance and
growth treatments, respectively. After 4 weeks pretreatment, label
concentrations in all tissues except the bile, gut, and gut contents
increased 3 to 30 fold compared to label retained by naive fish