Methoxychlor alters the predator-prey relationship between dragonfly naiads and salamander larvae

The effects of methoxychlor on the startle response of larvae of the salamander, Ambystoma macrodactylum, and on dragonfly naiad feeding, as well as on their interaction, were studied. Results indicated that exposure of free-swimming A. macrodactylum larvae for 3 d to greater than or equal to 0.1 mu M methoxychlor caused a significantly attenuated startle response, as did exposure of larvae in ovo. Exposure of naiads to elevated concentrations of the pesticide resulted in a reduced ability to feed on Tubifex worms. At lower concentrations, however, feeding and perching of naiads were not impacted significantly, which suggested that naiads, upon exposure to low concentrations of methoxychlor, could be effective predators of A. macrodactylum larvae exposed to the same low concentrations.