Fig nbsp xA Relationship between toxicity

Chlorpyrifos concentrations were below levels of concern with respect to both H. azteca and C. dilutus (96-h EC50s of 96 and 510 to 750 ng/l, respectively; Weston and Lydy, 2010a and Pape-Lindstrom and Lydy, 1997). Similarly, imidacloprid 'Radotinib(IY-5511)' concentrations at creek sites (typically < 70 ng/l; maximum 1462 ng/l) were below reported toxicity thresholds for the two Radotinib(IY-5511) tested and were unlikely to have played a role in observed effects. C. dilutus is a relatively sensitive species, with an imidacloprid 96-h LC50 of 5750 ng/l, with concentrations about half of endosymbiosis reported to inhibit growth ( Stoughton et al., 2008; though those tests were done with a specific commercial formulation, making comparisons to our data difficult). The reported H. azteca imidacloprid 96-h LC50s are 65,430 and 526,000 ng/l ( Stoughton et al., 2008 and England and Bucksath, 1991 as reported by Stoughton et al.), with a 96-h EC50 (immobilization) of 55,000 ng/l, and growth effects with as little as 2220 ng/l ( Stoughton et al., 2008; using a specific commercial formulation).