No evidence that a common pesticide impairs female mate choice in a freshwater amphipod.
Sublethal concentrations of pesticides may drastically alter the evolutionary trajectories of populations by interfering with mating behaviors. We used a median lethal concentration (LC50) experiment to test the sensitivity of three amphipod (Hyalella sp.) classes (females, small males, and large males) to five concentrations [10.4, 1.52, 0.16, 0.05, none detected (ND) microg/L] of the most commonly applied pesticide (malathion) in the United States. We then tested the sensitivity of female mate choice to sublethal concentrations (0.55, 0.38, and 0.05 microg/L) of malathion using a dichotomous choice test. Mortality was relatively high at low concentrations for all three amphipod classes with LC50s ranging from 0.06 microg/L in females to 0.19 microg/L in small males. There was overlap in the 95% CI of these estimates across amphipod classes suggesting no class-specific differences in sensitivity to malathion. We found no evidence that malathion interferes with female choice in this species, suggesting that mating behavior may not always be a good indicator of sublethal pesticide contamination.
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA. rdc28@pitt.edu
Rickey D
RD
Cothran
Raymond L
RL
Greco
Rick A
RA
Relyea
D033304:Amphipoda / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005618:Fresh Water / Q000737:chemistry*; D007928:Lethal Dose 50; D008294:Malathion / Q000633:toxicity*; D008297:Male; D010575:Pesticides / Q000633:toxicity*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D010575:Pesticides; D014874:Water Pollutants, Chemical; D008294:Malathion