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 pg/L and exhibited a convulsive, twitching response at concentrations of 3.6 pg/L. The 96-h median lethal concentration was 7.29 pg/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.

Apoptotic cell death in the central nervous system of Bufo arenarum tadpoles induced by cypermethrin

“…Fresh water can accumulate pesticides and toxic products from cultivated land where pesticides are applied. Moreover, amphibian larval development occurs in spring-summer contemporaneously with increase in pesticide applications (Materna et al, 1995). In Argentina, the application rates of insecticides in cultivated lands are between 1.5 and 120 g CY active ingredient per hectare (CASAFE, 1995).…”

Pyrethroid Insecticides: Use, Environmental Fate, and Ecotoxicology

“…Leopard frog tadpoles exhibited convulsions and twitching following sublethal (1.3 µg/L) esfenvalerate exposure, with behavioral homeostasis re-established only one week after removal to clean systems (Materna et al, 1995). These behavioral aberrations, though not lethal alone, may increase predation of affected amphibians and fish.…”

“…For instance, although exposure to either permethrin or fenvalerate at 0.01 to 2 ppm for 22 to 96 hours caused no increase in mortality, green frog (Rana clamitans) embryonic development was stunted at pyrethroid concentrations greater than 1 ppm, and operculum growth was also adversely affected (Berrill et al, 1993). Exposure to pyrethroids also causes reductions in tadpole biomass production 24 days following esfenvalerate exposures of 3.6 to 10 µg/L (Materna et al, 1995). When exposed in a mesocosm study, amphibian fitness may actually improve as a result of decreased competition from invertebrate species.…”

The toxicology of climate change: Environmental contaminants in a warming world

“…However, others have observed increased pyrethroid toxicity at elevated temperatures in leopard frogs (Rana spp.) (Materna et al,1995) and water fleas (Daphnia magna) (Ratushnyak et al, 2005), illustrating the species-specific response to increased temperatures and toxicant exposures. Temperature-dependent changes in metabolism appear to be one important mechanism modulating the biotransformation and enhanced toxicity observed under elevated temperature conditions.…”