Effects of the synthetic pyrethroid insecticide, esfenvalerate, on larval leopard frogs (Rana spp.)

Abstract

Leopard frog (Rana spp.) tadpoles exposed to esfenvalerate in the laboratory experienced a decrease in activity at concentrations as low as 1.3 μg/L and exhibited a convulsive, twitching response at concentrations of 3.6 μg/L. The 96‐h median lethal concentration was 7.29 μg/L. Temperature influenced amphibian mortality; the mortality concentration‐response slope at 22°C was significantly greater than at 18°C. Tadpoles exposed in a pond showed the same responses (inactivity, convulsive actions, and death) at similar concentrations as laboratory test organisms. Surviving tadpoles from laboratory tests resumed normal behavior 1 week after being placed into clean water, but most of those tadpoles that exhibited convulsive behavior during initial exposure eventually died. Tadpoles surviving pond exposures showed no later mortality, but rather exhibited a negative density‐growth relation. Measured pyrethroid concentrations in ponds and streams adjacent to sprayed fields do not exceed levels associated with convulsive twitching or mortality in larval amphibians; however, they do exceed concentrations associated with inactivity and fish and invertebrate mortality, which may indirectly affect larval amphibians.

Low temperatures lead to higher toxicity of the fungicide folpet to larval stages of Rana temporaria and Bufotes viridis

“…Our results are in contrast to most studies that investigated the effect of temperature on pesticide toxicity for amphibian larvae in acute toxicity studies. In Materna et al [ 20 ] leopard frog larvae ( Lithobates sp. ; former R .…”

“…Our results are in contrast to most studies that investigated the effect of temperature on pesticide toxicity for amphibian larvae in acute toxicity studies. In Materna et al [20] leopard frog larvae (Lithobates sp. ; former R. pipiens complex) showed higher mortalities in 96-h acute toxicity tests for the pyrethroid insecticide esfenvalerate at 22˚C than at 18˚C.…”

“…However, studies on the combined effects of temperature and pesticides on amphibians reveal contrasting results. Some observed that higher temperatures increased toxicity [19][20][21], while others showed a reduced toxic effect of pesticides on exposed amphibians [22][23][24]. For Oligosoma polychroma, a skink (reptile) and thus also an ectothermic vertebrate species, heat-seeking behaviors were observed, that can be interpreted as response to increase the metabolism to better deal with stress after exposure to a glyphosate formulation [25].…”

Low Temperatures Lead to Higher Toxicity of the Fungicide Folpet to Larval Stages of Rana temporaria and Bufotes viridis

“…However, studies on the combined effects of temperature and pesticides on amphibians reveal contrasting results. Some observed that higher temperatures increased toxicity [19][20][21], while others showed a reduced toxic effect of pesticides on exposed amphibians [22][23][24]. For Oligosoma polychroma, a skink (reptile) and thus also an ectothermic vertebrate species, even a heatseeking behavior was observed, that can be interpreted as response to increase the metabolism to better deal with stress after exposure to a glyphosate formulation [25].…”