Toxic effects of pyrethroids in tadpoles of Physalaemus gracilis (Anura: Leptodactylidae).

Pyrethroid insecticides are one of the most commonly used pesticide groups, but these compounds have brought risks to non-target species, such as amphibians. This study evaluated the toxicological effects (mortality, swimming activity and oral morphology) caused to a South American species of anuran amphibian, Physalaemus gracilis, exposed to the pyrethroids cypermethrin and deltamethrin. Total spawnings of this anuran were collected in the natural environment and transported to the laboratory where they were kept under controlled conditions. Chronic assays were defined between 0.1 and 0.01 mg L-1 of cypermethrin, and 0.009 and 0.001 mg L-1 of deltamethrin. For cypermethrin, a further chronic toxicity test was performed at 0.05 and 2.0 mg L-1, with hatchlings at stages S.20-S.25. Cypermethrin and deltamethrin were lethal enough to kill over 70% of exposed tadpoles in 1 week at concentrations that can be found in nature (0.01-0.1 mg L-1). The exposure effects also influenced swimming activity and caused changes in oral morphology, which would make it difficult for the animals to survive in their natural habitat. Both pyrethroids presented a risk for P. gracilis, so they should be re-evaluated for non-target wild species.

BRAZIL ROAD-KILL: a data set of wildlife terrestrial vertebrate road-kills.

Mortality from collision with vehicles is the most visible impact of road traffic on wildlife. Mortality due to roads (hereafter road-kill) can affect the dynamic of populations of many species and can, therefore, increase the risk of local decline or extinction. This is especially true in Brazil, where plans for road network upgrading and expansion overlaps biodiversity hotspot areas, which are of high importance for global conservation. Researchers, conservationists and road planners face the challenge to define a national strategy for road mitigation and wildlife conservation. The main goal of this dataset is a compilation of geo-referenced road-kill data from published and unpublished road surveys. This is the first Data Paper in the BRAZIL series (see ATLANTIC, NEOTROPICAL, and BRAZIL collections of Data Papers published in Ecology), which aims make public road-kill data for species in the Brazilian Regions. The dataset encompasses road-kill records from 45 personal communications and 26 studies published in peer-reviewed journals, theses and reports. The road-kill dataset comprises 21,512 records, 83% of which are identified to the species level (n = 450 species). The dataset includes records of 31 amphibian species, 90 reptile species, 229 bird species, and 99 mammal species. One species is classified as Endangered, eight as Vulnerable and twelve as Near Threatened. The species with the highest number of records are: Didelphis albiventris (n = 1,549), Volatinia jacarina (n = 1,238), Cerdocyon thous (n = 1,135), Helicops infrataeniatus (n = 802), and Rhinella icterica (n = 692). Most of the records came from southern Brazil. However, observations of the road-kill incidence for non-Least Concern species are more spread across the country. This dataset can be used to identify which taxa seems to be vulnerable to traffic, analyze temporal and spatial patterns of road-kill at local, regional and national scales and also used to understand the effects of road-kill on population persistence. It may also contribute to studies that aims to understand the influence of landscape and environmental influences on road-kills, improve our knowledge on road-related strategies on biodiversity conservation and be used as complementary information on large-scale and macroecological studies. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper.

Lethal and Sublethal Effects of the Herbicide Atrazine in the Early Stages of Development of Physalaemus gracilis (Anura: Leptodactylidae).

Water sources used as reproductive sites by crying frog, Physalaemus gracilis, are extensively associated with agroecosystems in which the herbicide atrazine is employed. To evaluate the lethal and sublethal effects of atrazine commercial formulation, acute and chronic toxicity tests were performed in the embryonic phase and the beginning of the larval phase of P. gracilis. Tests were started on stage 19 of Gosner (Herpetologica 16:183-190, 1960) and performed in 24-well cell culture plates. Acute tests had a duration of 96 h with embryo mortality monitoring every 24 h. Chronic assays contemplated the transition from the embryonic to larval stages and lasted 168 h. Every 24 h the embryos/larvae were observed for mortality, mobility, and malformations. The LC50 of atrazine determined for P. gracilis embryos was 229.34 mg L-1. The sublethal concentrations did not affect the development of the larvae but were observed effects on mobility and malformations, such as spasmodic contractions, reduced mobility, malformations in mouth and intestine, and edema arising. From 1 mg L-1 atrazine, the exposed larvae began to have changes in mobility and malformations. The atrazine commercial formulation has caused early life effects of P. gracilis that may compromise the survival of this species but at higher concentrations than recorded in the environment, so P. gracilis can be considered tolerant to this herbicide at environmentally relevant concentrations.

Seasonal, daily activity, and habitat use by three sympatric pit vipers (Serpentes, Viperidae) from southern Brazil.

Viperid snakes are widely distributed in the South America and the greater distribution range of the family is found at the Crotalinae subfamily. Despite the abundance of this snakes along their geographic distribution, some ecological aspects remain unknown, principally at subtropical areas. In the present study, we evaluated the activity (daily and seasonal) and the use of the habitat by Bothrops diporus, B. jararaca and B. jararacussu, in an Atlantic Forest area at southern Brazil. We observed higher incidence of viperid snakes during the months with higher temperatures, while no snakes were found during the months with lower temperatures. The data suggest the minimum temperature as environmental variable with the greatest influence on the seasonal activity of this species. Considering the daily activity, we observed a tendency of snakes to avoid the warmest hours. Bothrops jararacussu tend to avoid open areas, being registered only inside and at the edges of the forest. We compared our results with previous studies realized at tropical areas and we suggest the observed seasonal activity as an evolutive response, despite the influence of the different environmental variables, according to the occurence region.

Cypermethrin- and fipronil-based insecticides cause biochemical changes in Physalaemus gracilis tadpoles.

Insecticides used for agricultural pest control, as cypermethrin-based insecticide (CBI) and fipronil-based insecticide (FBI), are constant threats to non-target aquatic organisms. This study aimed to investigate the effect of different concentrations of cypermethrin and fipronil on neurotoxicity and oxidative stress in Physalaemus gracilis. Physalaemus gracilis tadpoles were exposed to five insecticide concentrations and a control treatment, with six replicates. During the experimental period, the tadpole mortality rate was evaluated and after 168 h, the neurotoxic enzyme activity and metabolite quantification related to the antioxidant system were measured. Tadpoles reduced acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities when exposed to 20 µg L-1 CBI and at all FBI concentrations, respectively. Glutathione S-transferase (GST) and superoxide dismutase (SOD) activities showed an increase from concentrations of 6 µg L-1 and 20 µg L-1 of CBI, respectively. After exposure of P. gracilis tadpoles to FBI, inhibitions of AChE and BChE were observed at the highest concentrations evaluated (500 and 1500 µg L-1). SOD activity decreased from 50 µg L-1 of FBI; however, catalase (CAT) and GST activities and carbonyl protein levels increased, regardless of the evaluated dose. We observed that both insecticides promoted oxidative stress and neurotoxic effects in P. gracilis tadpoles. These results suggest that biochemical biomarkers can be used for monitoring toxicity insecticides for the purpose of preservation of P. gracilis.

Morphological and biochemical traits and mortality in Physalaemus gracilis (Anura: Leptodactylidae) tadpoles exposed to the insecticide chlorpyrifos.

Organophosphate insecticides such as chlorpyrifos are commonly detected in surface waters around the world, where they are highly toxic to many organisms. The frog Physalaemus gracilis uses water sources located in open fields as reproductive sites, where it is exposed to insecticides. The study aimed to evaluate the lethal and sublethal effect of a commercial chlorpyrifos formulation on P. gracilis tadpoles (Anura: Leptodactylidae). In acute toxicity tests, five chlorpyrifos concentrations between 750 and 2,000 µg L-1 were tested. Chronic toxicity, swimming activity, morphological and enzymatic changes, as well as levels of non-protein thiols (NPSH), carbonyl proteins and lipid peroxidation were evaluated at five insecticide concentrations between 11 and 500 µg L-1. The highest mortality rate of P. gracilis tadpoles occurred at 24 and 48 h, with an LC50 of 893.59 µg L-1. At all chlorpyrifos concentrations, tadpoles displayed reduced mobility and spasms. Morphological anomalies were observed in the mouth and intestine, especially at the highest concentrations used. Acetylcholinesterase activity decreased at 250 and 500 µg L-1, catalase activity increased at all concentrations, and superoxide dismutase and glutathione S-transferase increased from 90 µg L-1 to 30 µg L-1, respectively. We also observed increases in NPSH levels at chlorpyrifos concentration starting at 30 µg L-1 and increases in carbonyl proteins from 90 µg L-1 of pesticide. Taken together, these data suggest that the insecticide chlorpyrifos presents acute and chronic risks for P. gracilis, causing neurotoxic effects and oxidative damage, culminating in high risk for this species.

Toxicity of cypermethrin and deltamethrin insecticides on embryos and larvae of Physalaemus gracilis (Anura: Leptodactylidae).

It is important to establish the toxicity pesticides against non-target species, especially those pesticides used in commercial formulations. Pyrethroid insecticides are widely used in agriculture despite their toxicity to aquatic animals. In this study, we determine the toxicity of commercial formulation of two pyrethroid insecticides, cypermethrin and deltamethrin, in two life stages of Physalaemus gracilis, a frog that breeds in agricultural ecosystems and has potential contact with pyrethroid pesticides. The acute toxicity test (96 h) was carried out with embryos of stage 17:18 and larvae of stages 24:25. Embryos were more resistant to both pesticides than larvae. In embryo mobility assays, we found that both pesticides caused spasmodic contractions, suggestive of neurological effects. In acute toxicity assays, we found that P. gracilis is more resistant to these insecticides than other studied species.