Acute Toxicity and Etho-toxicity of Three Insecticides Used for Mosquito Control on Amphibian Tadpoles

Among the measures used to manage mosquito populations and prevent human diseases, the application of pesticides is the global strategy mostly employed. To investigate the lethal and sublethal effects of insecticides used to control mosquitoes on amphibians (Rhinella arenarum, Rhinella fernandezae, and Physalaemus albonotatus), tadpoles were exposed to commercial formulations of temephos (Abate®), Bacillus thuringiensis var. israelensis (Introban®), and permethrin (Depe®). Their acute toxicity in terms of median lethal concentration (LC50) and no- (NOEC) and lowest-observed-effect concentrations (LOEC) was evaluated. To assess the sublethal effects on behavioral endpoints, tadpoles were exposed to the NOEC-24-h value of each insecticide. After that, tadpoles were recorded and video-streaming data were processed by Smart® software. Based on LC50, permethrin was the most toxic insecticide, followed by temephos and B. thuringiensis var. israelensis. Also, intraspecific and interspecific susceptibilities of tadpoles to insecticides were observed. Regarding behavior, the exposure of R. arenarum to the three insecticides had a significant effect on all behavioral endpoints. Two of the three swimming parameters evaluated for R. fernandezae were affected by permethrin, and in the end, only one behavioral pattern was altered in P. albonotatus after exposure to temephos. These results showed that tadpoles’ species were affected differently depending on the chemical properties of the pesticide and on a dose-response effect of the insecticides. Overall, our study suggests that further research is needed to quantify the potential damage of pyrethroid insecticides used for mosquito control on non-target aquatic organisms, mainly due to etho-toxic effects.Fil: Junges, Celina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Maglianese, M. I.. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Lajmanovich, Rafael Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Peltzer, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Attademo, Andres Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentin

First evidence of the effects of agricultural activities on gonadal form and function in Rhinella fernandezae and Dendropsophus sanborni (Amphibia: Anura) from Entre Ríos Province, Argentina

The relationship between male gonadal abnormalities and habitats with different degrees of agricultural activities was quantified in two anuran species, Rhinella fernandezae and Dendropsophus sanborni. The study sites were selected along a gradient of increasing agricultural land use in south-western Entre Ríos province (Argentina): an agroecosystem, a natural wetland (a non-agricultural site adjacent to monoculture zones), and a natural forest (not associated with agriculture). Rhinella fernandezae and D. sanborni were manually captured from each environment during field surveys. A scaled mass index (MI) was evaluated for each animal. Specimens of R. fernandezae from the agroecosystem and the natural wetland site presented poorly developed seminiferous tubules, lower testicular volume, and a lower number of seminiferous tubules, primary spermatogonia, and spermatids than specimens from the natural forest site. Additionally, we observed fewer primary spermatocytes in the agroecosystem group than in the natural forest group. Individuals of D. sanborni from the agroecosystem and the natural wetland site presented poorly developed tubules, higher proportions of irregularly shaped testes, and a reduced number of primary and secondary spermatogonia compared with specimens from natural forest sites. Consequently, the affected anurans are likely to have reduced reproductive success. We suggest that agrochemical use may be associated with decreased testicular development and function in both R. fernandezae and D. sanborni occurring in agroecosystems and nearby environments. Buffer zones are needed to prevent contamination, preserve wildlife, and enhance the conservation value of pristine natural forests

First evidence of the effects of agricultural activities on gonadal form and function in <em>Rhinella fernandezae</em> and <em>Dendropsophus sanborni</em> (Amphibia: Anura) from Entre Ríos Province, Argentina

<p>The relationship between male gonadal abnormalities and habitats with different degrees of agricultural activities was quantified in two anuran species, <em>Rhinella fernandezae</em> and <em>Dendropsophus sanborni</em>. The study sites were selected along a gradient of increasing agricultural land use in south-western Entre Ríos province (Argentina): an agroecosystem, a natural wetland (a non-agricultural site adjacent to monoculture zones), and a natural forest (not associated with agriculture). <em>Rhinella fernandezae </em>and <em>D. sanborni</em> were manually captured from each environment during field surveys. A scaled mass index (MI) was evaluated for each animal. Specimens of <em>R. fernandezae</em> from the agroecosystem and the natural wetland site presented poorly developed seminiferous tubules, lower testicular volume, and a lower number of seminiferous tubules, primary spermatogonia, and spermatids than specimens from the natural forest site. Additionally, we observed fewer primary spermatocytes in the agroecosystem group than in the natural forest group. Individuals of <em>D. sanborni</em> from the agroecosystem and the natural wetland site presented poorly developed tubules, higher proportions of irregularly shaped testes, and a reduced number of primary and secondary spermatogonia compared with specimens from natural forest sites. Consequently, the affected anurans are likely to have reduced reproductive success. We suggest that agrochemical use may be associated with decreased testicular development and function in both <em>R. fernandezae</em> and <em>D. sanborni</em> occurring in agroecosystems and nearby environments. Buffer zones are needed to prevent contamination, preserve wildlife, and enhance the conservation value of pristine natural forests.</p

Wildlife vertebrate mortality in roads from Santa Fe Province, Argentina Mortalidad de vertebrados en caminos de la provincia de Santa Fe, Argentina

Mortality of vertebrates was monitored on 2 roads (National Road 168; NR168 and Provincial Road 1; PR1) in Santa Fe Province (Argentina) from October 2007 to August 2008. These roads differed in traffic volume and surrounding landscape management conditions. We also investigated the influence of environmental variables (mean monthly air temperature and monthly total rainfall) on the incidence of road kills. Two people monitored the roads on foot (1 000-m line transects), 3 times a month (36 samples per road). We found 2 024 vertebrate road killed specimens representing 61 species (7 amphibians, 15 reptiles, 32 birds, and 7 mammals). The toad Rhinella fernandezae was the most frequently killed species (n = 1307, 64.57%). NR168 had a higher incidence of vertebrate road kills, particularity for amphibians, whereas birds had a higher incidence of road kills on PR1. We found a positive correlation between precipitation and temperature with vertebrate road kills on PR1. We suggest that vertebrate road mortality is a very serious problem for the conservation of the biodiversity in Santa Fe Province-Argentina, therefore implementing mitigation measures will be necessary.Se estudió la mortalidad de vertebrados en 2 rutas (RP1: Ruta Provincial N° 1 y RN168: Ruta Nacional N° 168) de la Provincia de Santa Fe (Argentina) desde octubre de 2007 hasta agosto de 2008. Estas rutas diferían en el tránsito vehicular y obras de infraestructura. Además, se investigó la influencia de variables climáticas (temperatura media mensual y precipitación total mensual) con el atropellamiento de la fauna silvestre. Se realizaron de 2 a 3 transectos por mes de 1 000 m cada uno, los cuales fueron recorridos a pie por 2 observadores. Un total de 2 024 vertebrados fueron registrados distribuidos en 61 taxa (7 anfibios, 15 reptiles, 32 aves y 7 mamíferos). La especie más impactada fue el sapo Rhinella fernandezae (n = 1307, 64.57%). La RN168 presentó una alta abundancia de vertebrados particularmente de anfibios, mientras que las aves fueron más representativas en la RP1. Se encontró una correlación positiva entre las variables ambientales (precipitación y temperatura) con la mortalidad de vertebrados en la RP1. Sugerimos que la mortandad de vertebrados en la Provincia de Santa Fe, Argentina, es un problema serio para la conservación de la biodiversidad, siendo necesaria la implementación de medidas de mitigación

Hematología y citoquímica de las células sanguíneas de Rhinella fernandezae (Anura: Bufonidae) en Espinal y Delta-Islas del río Paraná, Argentina

La descripción de la hematología de los anfibios anuros es escasa, habiéndose realizado la mayoría de los trabajos en especies de Norteamérica, Asia y Europa. Con el propósito de obtener datos hematológicos para Rhinella fernandezae, fueron estudiados 23 especímenes provenientes de zonas protegidas de las provincias de Santa Fe y Entre Ríos. Se les extrajo sangre por punción cardíaca y se realizaron hemogramas. En los extendidos sanguíneos, se efectuaron la descripción morfológica y citoquímica de las células sanguíneas y búsqueda de parásitos. Se observaron cinco tipos de leucocitos, donde predominaron los linfocitos pequeños. Heterófilos y eosinófilos resultaron positivos para PAS, Sudan B y peroxidasa; contrariamente, los eritrocitos y sus precursores fueron negativos. Los puntajes de las reacciones citoquímicas fueron variables para basófilos, linfocitos, monocitos y trombocitos. Las frecuencias de micronúcleos y de alteraciones nucleares fueron escasas. No se observaron diferencias significativas (p>0.05) entre sexos en el hemograma ni en la morfología sanguínea. Los únicos hemoparásitos encontrados fueron microfilarias (Nematoda: Filaroidea), cuya prevalencia e intensidad de infección fueron bajas. Las características hematológicas estudiadas fueron semejantes a los valores reportados para otros anfibios, pudiendo inferir que los individuos de R. fernandezae estudiados se encuentran en un buen estado nutricional e inmunológico.<br>Hematology and blood cell cytochemistry of Rhinella fernandezae (Amphibia: Anura) from Espinal and Delta-Islands of Paraná River, Argentina. The description of amphibian hematology is scarce and most of these studies have been done in species from North America, Asia and Europe. With the purpose to obtain basic hematological information of Rhinella fernandezae, 23 blood samples from Santa Fe and Entre Ríos natural reserves were studied. Blood of each individual was extracted by cardiac puncture and hemograms were carried out. Morphological and cytochemical description of blood cells were analyzed in slides and were inspected for extra and intra cellular parasites. Five leucocytes types were observed, being lymphocytes the predominant ones followed by basophiles. Heterophils and eosinophils were positive to PAS, Sudan B and peroxidase. The erythrocytes and its precursors were negative for cytochemical reactions. Micronuclei and nuclear alterations frequencies were scarce. No significant differences (p>0.05) were observed between sexes neither in hemograms nor in blood cells morphology. Microfilarias were the only hemoparasites found with a relative low prevalence and infection intensity. The hematological characteristics studied were similar to those reported for other amphibians, suggesting that R. fernandezae individuals present optimal nutritional and immunological status. Rev. Biol. Trop. 59 (1): 17-28. Epub 2011 March 01

Hematología y citoquímica de las células sanguíneas de Rhinella fernandezae (Anura: Bufonidae) en Espinal y Delta-Islas del río Paraná, Argentina

La descripción de la hematología de los anfibios anuros es escasa, habiéndose realizado la mayoría de los trabajos en especies de Norteamérica, Asia y Europa. Con el propósito de obtener datos hematológicos para Rhinella fernandezae, fueron estudiados 23 especímenes provenientes de zonas protegidas de las provincias de Santa Fe y Entre Ríos. Se les extrajo sangre por punción cardíaca y se realizaron hemogramas. En los extendidos sanguíneos, se efectuaron la descripción morfológica y citoquímica de las células sanguíneas y búsqueda de parásitos. Se observaron cinco tipos de leucocitos, donde predominaron los linfocitos pequeños. Heterófilos y eosinófilos resultaron positivos para PAS, Sudan B y peroxidasa; contrariamente, los eritrocitos y sus precursores fueron negativos. Los puntajes de las reacciones citoquímicas fueron variables para basófilos, linfocitos, monocitos y trombocitos. Las frecuencias de micronúcleos y de alteraciones nucleares fueron escasas. No se observaron diferencias significativas (p > 0.05) entre sexos en el hemograma ni en la morfología sanguínea. Los únicos hemoparásitos encontrados fueron microfilarias (Nematoda: Filaroidea), cuya prevalencia e intensidad de infección fueron bajas. Las características hematológicas estudiadas fueron semejantes a los valores reportados para otros anfibios, pudiendo inferir que los individuos de R. fernandezae estudiados se encuentran en un buen estado nutricional e inmunológico