Lethal and behavioral effects of Glyphosate and 2, 4-D based pesticides on Rhinella arenarum larvae

AGUSTINA FURIÓ LANUZA; ARONZON C.M

Congreso; SETAC Latin America 11th Biennial Meeting "The role of science in environmeantal decision-making"; 2015

Given the increasingdevelopment of agriculture as main activity in Latin America, along with theadvance of transgenic cultures, the use of agrochemicals is increasingly common.Pesticides reach water bodies causing serious consequences for wild biota. The aimof the present study was to asses acute (up to 96h), short-chronic (168h) andchronic (336h) toxicity of glyphosate (Gli) (Atanor®) and 2,4-dichlorophenoxyaceticacid (2,4-D) (Asi Max®) based pesticides on the larvae (S.25) of the autochthonousRhinella arenarum amphibian. To thisend, groups of 10 larvae were exposed in triplicate batches to pesticides concentrationsranging between 45 and 78 mg acid equivalent (ae) Gli/L and 150-450 mg ae 2,4-D/Lprepared in AMPHITOX solution (AS). Bioassays were semi-static, with renewal ofmedium every 48 h. The lethal effects of the Gli and 2,4-D were reported every24 h. Behavior was analyzed at 168 h by means of video-tracking software ?EthovisionXT7? Noldus®. The behavioral endpoints as distance moved, swimming activity andmean speed were calculated, and Dunnet contrast-tests were used to assess eachtreatment against controls (AS). LC50s-96h were 59 mg ae Gli/L and 539,63 mg ae2, 4-D/L. Alterations in behavior were observed at 96h from 54 mg ae Gli/L and300 mg ae 2,4-D/L. LC50s-168h were 48,17 mg ae Gli/L and 418,69 mg ae 2,4-D/L. LC50s-336hwere 45,2 mg ae Gli/L y 294,37 mg ae 2,4-D/L. Larvae exposed from 45 mg aeGli/L and 350 mg ae 2,4-D/L showed a signicant different pattern behaviorrespect to controls (AS). Larvae exposed to Gli traveledshorter distances and presented less swimming activity, whereas larvae exposed from350 to 500 mg ae 2,4-D/L traveled larger distances and presented higher meanswimming speed, which might be an overstimulation related to the first symptomsof a neurotoxicity. But, larvae exposed to concentrations of 550 and 600 mg ae2,4-D/L presented a similar pattern than those exposed to Gli, travelingshorter distances, presented less swimming activity and a reduction of the meanswimming speed. 1) Gli was 8.5 times more toxic than 2,4-D. 2) there was asignificant increase on the toxicity of the two pesticides over time, whichhighlights the importance for chronic tests 3) Video tracking is very useful in ecotoxicologicalresearch for assess sublethal toxicity. The reduced performance of tadpoles exposed to Gli and2,4-D makes them more vulnerable to predation and higher probability of amortality event later in life.