Impact of imidacloprid on the common toad (Rhinella arenarum) physiology.

GUIÑAZU. JJ; BACH N; CHEDIACK, J. G.; CID F.

San Juan

Congreso; XLI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2023

SBCuyo

The present study focused on studying theeffects of the neonicotinoid insecticide imidacloprid on Rhinella arenarum physiology;evaluating effects at biochemical and morphological levels. According to ourknowledge, there is a lack of information on this topic. Fourteen animals werecollected from the Juan Martín de Pueyrredón and Coronel Pringles Department inSan Luis province. The animals were acclimated to the laboratory conditions andsubsequently exposed to Imidacloprid through exposure bioassays undercontrolled conditions. A realistic exposure scenario was tested evaluating thesoil application dose of the commercial formulation GlacoXAN IMIDA. To do this,a solution of the insecticide was prepared and sprayed in a standardized manneron a soil bed (fertile soil) every 24 hours, without the presence of theanimal, which was placed in the experimental enclosure immediately after theapplication of the insecticide. In addition, a control group was used, on whichthe same procedure was carried out, without the insecticide. The experimentaldesign was in randomized blocks, with a duration of 48 hours of exposure. Atthe beginning of the exposure period, body mass and snout-vent length wererecorded. After the exposure period, animals were weighed and anesthetized in abenzocaine solution (20%). Subsequently, the individuals were euthanized andblood was extracted by cardiac puncture and organ ablation. In this way, thecorresponding samples were collected to determine the morphometric indices andblood biochemical parameters in R. arenarum. Concentration of differentbiochemical parameters were determined using a CM200 Automatic BiochemistryAnalyzerWiener Lab, like albumin, alkaline phosphatase, cholinesterase,glucose, GOT, GPT, total proteins, triglycerides, urea, and uric acid. The datawere analyzed using a student's t test, with a significance value of 0.05.Regarding the results, scaled liver index, scaled gonad index and scaled massindex, showed no significant variations. Blood biochemical parameters showed asignificant decrease (p < 0.05) in hematocrit and total blood proteinconcentration in the treated toads respect to controls. These results representthe first report of the imidacloprid effects on adult native amphibians andhighlight the potential harmful effects of the insecticide on a native speciesphysiology, since it has been proved the relationship between hematocritdecrease and alterations in hematopoietic processes.