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dc.contributor.authorOvermyer, Jay Paul
dc.date.accessioned2014-03-03T20:21:28Z
dc.date.available2014-03-03T20:21:28Z
dc.date.issued2002-12
dc.identifier.otherovermyer_jay_p_200212_phd
dc.identifier.urihttp://purl.galileo.usg.edu/uga_etd/overmyer_jay_p_200212_phd
dc.identifier.urihttp://hdl.handle.net/10724/20640
dc.description.abstractUrban and suburban watersheds have the potential to be highly impacted by chemicals, especially insecticides used to control insect pests on lawns, ornamental plants, and home gardens. Three of the most common lawn-care insecticides detected in urbanized watersheds, carbaryl, chlorpyrifos, and malathion, have been evaluated in the laboratory to determine their acute toxicity, joint-toxicity as mixtures, bioavailability in the presence of organic matter, and effects on survival, growth and development to black fly larvae, Simulium vittatum cytospecies IS-7. An acute orbital shaker toxicity test was used to determine the 48 hr LC50 value of the three insecticides for S. vittatum IS-7 larvae. Results of the 48 hr LC50 tests showed chlorpyrifos to be the most toxic (LC50 = 0.28 µg/L) followed by carbaryl (LC50 = 23.72 µg/L), and malathion (LC50 = 54.2 µg/L). These insecticides were also tested as mixtures using a toxic unit (TU) approach. Toxicity was greater than additive for the ternary mixture of chlorpyrifos-carbaryl-malathion (LC50 = 0.56 TU), and the binary mixtures of chlorpyrifos-malathion (LC50 = 0.72 TU), and carbaryl-malathion (LC50 = 0.78 TU). The binary combination of chlorpyrifos and carbaryl was additive (LC50 = 0.98 TU). Bioavailability of the three insecticides to S. vittatum IS-7 was significantly altered in the presence of a laboratory diet. Chlorpyrifos bioavailability decreased whereas carbaryl and malathion bioavailability increased when diet concentrations were =150 mg/L. Natural seston had little effect on the bioavailability of these insecticides except in carbaryl dosed larvae where mortality was significantly increased when seston concentrations reached 150 mg/L in the flasks. Multiple pulse-exposures of chlorpyrifos, carbaryl and malathion individually and as mixtures in a trough flow-through dosing system had little effect on survival, growth and development of S. vittatum IS-7. Survival in black flies exposed to chlorpyrifos was significantly lower than survival in malathion and carbaryl exposed insects. However, this effect was not significant compared to controls. No significant differences in growth or development were detected between insecticide-exposed and control larvae.
dc.languageeng
dc.publisheruga
dc.rightspublic
dc.subjectToxicity
dc.subjectToxic Units
dc.subjectInsecticide Mixtures
dc.subjectChlorpyrifos
dc.subjectCarbaryl
dc.subjectMalathion
dc.subjectBlack Fly
dc.subjectSimulium vittatum
dc.subjectSuburban Watersheds
dc.subjectBioavailability
dc.subjectLaboratory Diet
dc.subjectSeston
dc.subjectLife History
dc.subjectSurvival
dc.subjectGrowth
dc.subjectDevelopment
dc.subjectPulse-Exposure
dc.subjectFlow-Through
dc.titleUtilization of black fly larvae (Diptera: Simuliidae) in biomonitoring and aquatic toxicity testing : assessing the effects of lawn-care chemicals in suburban streams
dc.typeDissertation
dc.description.degreePhD
dc.description.departmentEntomology
dc.description.majorToxicology
dc.description.advisorRaymond Noblet
dc.description.committeeRaymond Noblet
dc.description.committeeKevin Armbrust
dc.description.committeeMarsha Black
dc.description.committeeJoseph McHugh
dc.description.committeeJ. Bruce Wallace


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