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Within the rotational scheme developed by the Programme to fight the resistance of Simulium damnosum to chemical larvicides, there was an operational gap at discharges between 5 and 70 m3 s−1 for the treatment of rivers where resistance to organophosphates was present. The use of permethrin and carbosulfan was precluded because of risk of environmental impact and, Bacillus thuringiensis ser. H-14 treatments were not envisageable due to cost and logistics constraints. Among the possible complementary groups of larvicides tested, the pseudo-pyrethroids, held promise, because of a mode of action similar to that of pyrethroids, but along with a usually lower toxicity for fish. Etofenprox, one of the pseudo-pyrethroids tested, shows a global detachment of non-target insects in 24 h close to that of pyraclofos, an organo-phosphorus compound (27 against 23%). In laboratory conditions, six times the operational dose which is 0.03 mg l−1 10 min, is needed to cause 50% mortality of Caridina sp. (a small shrimps species) and 30 times this same dose for 95% mortality. For fish species, a safety margin of 400–800 times the operational dose is observed for Oreochromis niloticus and 200–400 times for Tilapia zillii. 相似文献
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Within the rotational scheme developed by the Programme to fight the resistance of Simulium damnosum to chemical larvicides, there was an operational gap at discharges between 5 and 70 m3 s−1 for the treatment of rivers where resistance to organophosphates was present. The use of permethrin and carbosulfan was precluded because of risk of environmental impact and, Bacillus thuringiensis ser. H-14 treatments were not envisageable due to cost and logistics constraints. Among the possible complementary groups of larvicides tested, the pseudo-pyrethroids, held promise, because of a mode of action similar to that of pyrethroids, but along with a usually lower toxicity for fish. Etofenprox, one of the pseudo-pyrethroids tested, shows a global detachment of non-target insects in 24 h close to that of pyraclofos, an organo-phosphorus compound (27 against 23%). In laboratory conditions, six times the operational dose which is 0.03 mg l−1 10 min, is needed to cause 50% mortality of Caridina sp. (a small shrimps species) and 30 times this same dose for 95% mortality. For fish species, a safety margin of 400–800 times the operational dose is observed for Oreochromis niloticus and 200–400 times for Tilapia zillii. 相似文献
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Multinational,Freshwater Biomonitoring Programs in the Developing World: Lessons Learned from African and Southeast Asian River Surveys 总被引:2,自引:1,他引:1
Resh VH 《Environmental management》2007,39(5):737-748
Biomonitoring programs are widely used in developed countries. They also offer many advantages in assessing ecological consequences
of perturbations in developing countries, including reducing the equipment-operation, maintenance, and training costs associated
with physicochemical monitoring. Three case histories of river biomonitoring using freshwater organisms (fish, benthic macroinvertebrates,
diatoms, zooplankton) are described that involve (1) documentation of environmental effects from long-term, large-scale applications
of insecticides to control insect-vectors of river blindness (onchocerciasis) in 11 West African countries; (2) water quality
assessments and restoration planning in and around national parks in three East African countries; and (3) evaluation of overall
ecological health of the Lower Mekong River in four Southeast Asian countries. As in developed countries, benthic macroinvertebrates
are the organisms most widely used in biomonitoring in developing countries. Conflicting opinions of system resilience and
whether expected changes are within natural variation may result in differences in underlying hypotheses proposed, study designs
implemented, and study execution; each may lead to uncorrectable bias. Direct transfers of approaches used from developed
to developing countries are often appropriate; however, techniques dependent on pollution-tolerance values are often region
specific and not transferable. Typically expressed concerns about applications of biomonitoring in developing countries include
poor coordination among agencies; lack of legislation, identification keys, and trained personnel; and incomplete information
on how tropical rivers function. Problems are real but solvable, as evident from accomplishments in several multicountry programs
in developing countries. Developed countries requiring coordinated monitoring of international rivers may benefit from examining
successful programs under way in developing countries. 相似文献
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