Acris Research Articles

Skittering locomotion in cricket frogs: a form of porpoising.

Multiple species of frogs in the Ranidae family have been observed to 'skitter' across the water surface, but little is understood about the biomechanical or physical mechanisms that underlie this behavior. All documented descriptions are anecdotal, asserting simply that the frogs can cross the water surface without sinking. To study this form of interfacial locomotion, we recorded high speed video of the northern cricket frog Acris crepitans and quantified its kinematics. We also compared its semi-aquatic behavior with the frogs' terrestrial locomotion. Contrary to expectations based on anecdotal knowledge, we found that cricket frogs do not maintain an above-surface position throughout the locomotor cycle. Instead, the frogs are completely submerged during both the launching and landing phase of a jump cycle, similar to porpoising in other animals. It is possible that leg-retraction time constrains these frogs from performing true surface-only locomotion.

Potential effects of traffic noise on anuran call characteristics in Louisiana, USA during winter.

Urban environments expose wildlife to levels of anthropogenic noise they would not experience in rural areas (e.g., traffic noise), and research suggests that many species adjust their acoustic signals for optimal transmission in urban soundscapes. However, our understanding of anuran (order Anura) responses to noise pollution in urban environments of the southeastern United States is limited, particularly for species that can breed during winter. Our goal was to examine how vocal anuran advertisement call characteristics during winter varied with increasing distance from roadways in bottomland hardwoods of Louisiana, USA. We deployed acoustic recording units at two sites (i.e., rural and urban) perpendicular to Interstate 10 at 200-, 400-, and 600-m intervals (i.e., close, middle, and far) from November 2019 to January 2020. We detected Cajun Chorus Frogs (Pseudacris fouquettei) and Cricket Frogs (Acris spp.) at our rural site, and only detected Cricket Frogs at our urban site. At the rural site, Cajun Chorus Frogs produced longer duration notes at the far location compared to the middle location. At the urban site, Cricket Frogs produced higher dominant frequency calls at the close location compared to the far and middle locations and longer duration notes at the far location compared to the close location. We were unable to account for additional factors in our models (e.g., temperature, noise levels), but our results generally align with previous research. Our study provides baseline data for future research to examine the potential effects of traffic noise on winter advertisement calls in locations with similar environmental conditions and species.

Comparing skin swabs, buccal swabs, and toe clips for amphibian genetic sampling, a case study with a small anuran (Acris blanchardi).

Multiple methods for collecting genetic samples from amphibians exist, each with their own implications for study design, animal welfare, and costs. Toe clipping is one common method, but there is ongoing debate regarding its potential detriment. Less invasive methods should be implemented, if efficacious, as amphibians are a particularly vulnerable vertebrate group. Skin and buccal swabbing are less invasive methods for genetic sampling, but the potential for contamination and a lower yield of DNA may exist. To compare these methods, we gathered skin swabs, buccal swabs, and toe clips from the same individuals of a relatively small anuran species, Blanchard's Cricket Frog (Acris blanchardi). We then compared DNA yield, DNA purity, amplification success rate, and genotypic data quality among sample types. We found toe clips and buccal swabs generated similar DNA yield and purity, with skin swabs yielding significantly less DNA of significantly lower purity than the other sample types. Amplification success rate was significantly higher using toe clips compared to the other sample types, though buccal swab samples amplified more readily than skin swabs. Genotypic data from toe clips and buccal swabs did not differ significantly in quality, but skin swab data quality was significantly lowest among sample types. Thus, skin swabbing could produce erroneous data in some situations, but buccal swabbing is likely an effective substitute to toe clipping, even for small species. Our results can help future researchers select which genetic sampling method might best suit their research needs.

Atrazine and estradiol effects on development of Acris blanchardi (Blanchard's cricket frog) exposed in outdoor enclosures.

The herbicide atrazine has been proposed as a potential endocrine disrupting compound (EDC) for amphibians. Using atrazine concentrations below or at those typically found in surface waters (0.5, 5.0, 50 μg/L), we exposed Acris blanchardi (Blanchard's cricket frog) larvae throughout development until metamorphosis (i.e. Gosner stages 26-45). An additional 50 μg/L treatment (50s μg/L) was utilized where supplemented algae was added to control for indirect atrazine effects from reduced food sources. In addition to atrazine, experimental groups also included a negative control and two positive controls, 17β-estradiol (E2) at 2.3 and 25 μg/L. At 60 days post-metamorphosis, A. blanchardi metamorphs were euthanized for analysis of gross and histopathological development. Atrazine did not significantly influence mortality (mean recovery of 54% across treatments), sex ratio, body mass (BM), snout-vent length (SVL), gonad size, nor gonad development of A. blanchardi. Females exposed to 50sμg/L atrazine had 29% less mass, were 10% shorter, and had a 29% lower mean ovary area (mm2 ) as compared to negative controls, suggesting algae enrichment had a significant negative effect. Males exposed to estradiol (25 μg/L) showed an increased level of oviduct development. Ovary area was also significantly influenced by estradiol treatment at 2.3 and 25 μg/L. Overall, estradiol had much less effect than predicted based on other model species (e.g. Xenopus laevis). Development of A. blanchardi, overall, was not affected by long-term exposure to environmentally relevant concentrations of atrazine. However, this species also was largely insensitive to exogenous estradiol in this test system. © 2022 Society of Chemical Industry.

Larval development and survival of pond-breeding anurans in an agricultural landscape impacted more by phytoplankton than surrounding habitat.

The destruction of freshwater habitat is a major contributor to biodiversity loss in aquatic ecosystems. However, created or restored wetlands could partially mitigate aquatic biodiversity loss by increasing the amount of available habitat across a landscape. We investigated the impact of surrounding terrestrial habitat and water quality variables on suitability for two species of pond-breeding amphibians (bullfrogs [Lithobates catesbeianus] and Blanchard's cricket frogs [Acris blanchardi]) in created permanent wetlands located on an agricultural landscape. We examined tadpole growth and survival in field enclosures placed in ponds surrounded by agricultural, forested, or grassland habitats. We also evaluated the potential for carryover effects of the aquatic environment on terrestrial growth and overwinter survival of cricket frog metamorphs. We found that habitat adjacent to ponds did not predict tadpole growth or survival. Rather, phytoplankton abundance, which showed high variability among ponds within habitat type, was the only predictor of tadpole growth. Cricket frogs emerged larger and earlier from ponds with higher phytoplankton abundance; bullfrogs were also larger and at a more advanced developmental stage in ponds with higher levels of phytoplankton. Overwinter survival of cricket frogs was explained by size at metamorphosis and there were no apparent carryover effects of land use or pond-of-origin on overwinter growth and survival. Our results demonstrate that created ponds in human-dominated landscapes can provide suitable habitat for some anurans, independent of the adjacent terrestrial habitat.

Interspecific amplexus between a Bangladeshi Cricket Frog, Minervarya ornata (Bolkay, 1915), and a male Ornate Narrow-mouthed Frog, Microhyla ornata (Microhylidae), from Bangladesh

Interspecific amplexus between a Bangladeshi Cricket Frog, Minervarya ornata (Bolkay, 1915), and a male Ornate Narrow-mouthed Frog, Microhyla ornata (Microhylidae), from Bangladesh

A new record of the Banladeshi Cricket Frog, Minervarya asmati (Howlader, 2011), from Manipur State, with comments on the occurrence of the Paddy Frog, Fejervarya multistriata (Hallowell, 1861) (Anura: Dicroglossidae), in Mizoram, India

A new record of the Banladeshi Cricket Frog, Minervarya asmati (Howlader, 2011), from Manipur State, with comments on the occurrence of the Paddy Frog, Fejervarya multistriata (Hallowell, 1861) (Anura: Dicroglossidae), in Mizoram, India

COMPLEX ASSOCIATIONS OF ENVIRONMENTAL FACTORS MAY EXPLAIN BLANCHARD'S CRICKET FROG, ACRIS BLANCHARDI, DECLINES AND DRIVE POPULATION RECOVERY

Blanchard’s Cricket Frog, Acris blanchardi, is a small hylid frog that was once among the most common amphibians in any part of its range. Today, it remains abundant in much of the southern portion of its range, but is now disappearing elsewhere. Our analysis of habitat characters observed across several states revealed interesting relationships of these factors with the abundance or presence of Blanchard’s Cricket Frog. Further, we later established two ½ acre ponds based on these relationships that led to immediate colonization of the ponds by cricket frogs followed by explosive production of juveniles less than a year later. Our findings suggest that habitat management for this species should specifically manage the shoreline grade and especially the aquatic floating vegetation to maximize population growth and sustenance.

Batrachochytrium dendrobatidis in Kansas

Batrachochytrium dendrobatidis (Bd) has been implicated in the decline of amphibians worldwide and was first noted in Kansas in 2014 in Kingman and Sedgwick Counties. The objectives of this study were to further assess the presence of Bd throughout the state. We sampled anurans at 25 locations throughout the state and Bd was detected at six sample locations: Marais Des Cygnes National Wildlife Refuge, Farlington Fish Hatchery, Hadley Ranch, Quivira National Wildlife Refuge, Tuttle Creek Wildlife Area, and Jamestown Wildlife Area and across six species: Gray Treefrogs, Boreal Chorus Frogs, Woodhouse's Toads, Blanchard's Cricket Frogs, Plains Leopard Frogs, and American Bullfrogs. We did not find evidence that Bd was negatively impacting populations at this time. We suggest continued monitoring of anuran populations to ensure population survival into the future.

Faunal diversity of an insular crepuscular cave of Goa, India

This study is the first attempt to document troglofaunal diversity of crepuscular cave ecosystem from the state of Goa. Twelve faunal species (seven invertebrates and five vertebrates) have been documented from an insular crepuscular cave which measures 18.62m in floor length and shows a transition of light and hygrothermal profile between its entrance and dead end. Absence of primary producers, thermal constancy, high humidity, poor ventilation, and competitive exclusion due to limited food resources restricts the faunal diversity of this cave; though trophic linkages are interesting yet speculative, as is typical of subterranean ecosystem. Among the macro-invertebrates, cavernicolous Whip Spider is a significant species here; whereas the important vertebrates encountered are the Fungoid frog and the Indian Cricket frog, besides roosts of the Rufous Horseshoe bat. Eco-energetic subsidy, possibly offered by crickets and bats that regularly feed outside this oligotrophic cave ecosystem is discussed. The need to document the unique and vulnerable troglofauna of this sensitive ecosystem from the conservation perspective is highlighted.

Evaluating a developmental endocrine toxicity assay for Blanchard's cricket frog (Acris blanchardi) in outdoor enclosures

A developmental toxicity testing design was evaluated for larval and post-metamorphic Blanchard's cricket frogs (Acris blanchardi) raised in outdoor enclosures. Larvae were chronically exposed to 17β-estradiol (0.0–2.3 μg/L E2) from free swimming (Gosner stage 26) until metamorphosis. Juvenile frogs were allowed to mature within the enclosures for 60 days to assess effects of larval exposure on development, including body mass, snout-vent length (SVL), sex ratio, gonad size, and gonadal histopathology. Forty-eight percent of the initial 600 animals were recovered at the end of the study. Recovery was not influenced by E2 exposure, but larval losses were negatively impacted by unusually high spring rain events that flooded some larval tanks, and heat-related mortality of late stage larvae during summer. All surviving larvae completed metamorphosis within an average of 47 days. Overall, E2 exposure did not influence sex ratio, or the body mass, SVL, or gonad size of either males or females. Development of testes was not influenced by E2 exposure, but oviduct development in males was 4.5-fold greater in the highest treatment. Oviduct and ovary development in females exposed to the two highest E2 treatments were half that of control females. Although not treatment related and despite ad-lib feeding, variation in terminal body mass and SVL within enclosures was pronounced, with minimum – maximum differences ranging from 207 to 1442 mg for body mass and 1 mm to 15 mm for SVL. This design allowed us to assess the effects of larval exposure to a contaminant on post-metamorphic development of a native amphibian in a semirealistic field environment. With modifications to decrease flooding or overheating, this enclosure design and species is a good test system for assessing contaminant effects on development of an amphibian from early larval stages through reproductive maturity.

Predictions of Disease Risk in Space and Time Based on the Thermal Physiology of an Amphibian Host-Pathogen Interaction

Emerging infectious diseases have been responsible for declines and extinctions in a growing number of species. Predicting disease variables like infection prevalence and mortality and how they vary in space and time will be critical to understanding how host-pathogen dynamics play out in natural environments and will help to inform management actions. The pandemic disease chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been implicated in declines in hundreds of amphibian species worldwide. We used field-collected measurements of host body temperatures and other physiological parameters to develop a mechanistic model of disease risk in a declining amphibian, the Northern cricket frog (Acris crepitans). We first used a biophysical model to predict host body temperatures across the species range in the eastern United States. We then used empirically derived relationships between host body temperature, infection prevalence and survival to predict where and when the risk of Bd-related declines is greatest. Our model predicts that pathogen prevalence is greatest, and survival of infected A. crepitans frogs is lowest, just prior to breeding when host body temperatures are low. Taken together, these results suggest that Bd poses the greatest threat to short-lived A. crepitans populations in the northern part of this host’s range and that disease-related recruitment failure may be common. Furthermore, our study demonstrates the utility of mechanistic modeling approaches for predicting disease outbreaks and dynamics in animal hosts.

Spatial and temporal dynamics of exuberant colour polymorphism in the southern cricket frog

ABSTRACT Intraspecific variation in colour pattern is widespread across multitudinous amphibian species. In some species, many distinct colour patterns are maintained within populations, a phenomenon referred to as exuberant colour polymorphism. The underlying causes of exuberant colour pattern polymorphism are poorly understood but are likely explained by selection, rather than neutral processes like genetic drift. Nevertheless, empirical data are needed to understand the selective drivers of this phenomenon, but such data are currently lacking for most polymorphic species. We studied frequency, spatial, and linkage dynamics of colour pattern across nine populations of the southern cricket frog (Acris gryllus) from southeastern Georgia, USA. Using 233 individuals, we combined direct field observations with examination of natural history specimens to look at colour pattern characteristics as they relate to space, time, and sex over a 30-year time frame. We found evidence of spatial and temporal variation in colour pattern across populations. We also discovered associations among colour pattern traits and between two colour pattern traits and sex. Our results suggest that the exuberant colour polymorphism of A. gryllus may involve correlations between traits and be caused by spatial and/or temporal variation in selection. However, similar studies in other species are necessary to allow us to discriminate among different drivers of colour pattern in exuberantly polymorphic frogs. Collectively, such systems offer important opportunities for understanding the evolution of colour and phenotypic diversity.

Phenotypic divergence in large sized cricket frog species that crossed the geographical barriers within peninsular India.

A good number of new species are being described and included in the genus Fejervarya / Minervarya from South Asia and Southeast Asia in the recent past. But, the classification or consideration of the genus Fejervarya / Minervarya is only phylogenetic, where it is difficult to morphologically identify the genus in the overlapping range of geographical distribution. Recently a large sized new species of cricket frog Fejervarya kalinga has been described, which is thought to be endemic to the Eastern Ghats (a unique geographical landscape running parallel to the East Coast of India). Here we report a morphologically variable and distinct population of F. kalinga from the Western Ghats (an amphibian diversity hotspot running parallel to the West Coast of India). We discuss the importance of genetic studies in handling such morphologically highly variable populations of the species and their adaptation to different habitats and their implications in taxonomic identity.

A comparison on two discordancy tests to detect outlier in von mises (VM) sample

<span>This paper focuses on comparing two discordancy tests between robust and non-robust statistic to detect a single outlier in univariate circular data. So far, to the best author knowledge that there is no literature make a comparison between both tests of <em>RCDu Statistic</em> and </span><em><span>𝐺</span><sub><span>1</span></sub><span> Statistic</span></em><span>. The test statistics are based on the circular median and spacing theory. In addition, those statistics can detect multiple and patches outliers. The performance tests of <em>RCDu Statistic</em> and </span><em><span>𝐺</span><sub><span>1</span></sub><span> Statistic</span></em><span> are tested in outlier proportion of correct detection, masking and swamping effect. At the beginning stage, we obtained the cut-off points for the <em>RCDu Statistic</em> and </span><em><span>𝐺</span><sub><span>1</span></sub><span> Statistic</span></em><span> by applying Monte Carlo simulation studies. Then, generated sample from von Mises (VM) with the combination of sample size and concentration parameter. The estimating process of cut-off points for both statistics is repeated 3000 times at 10%, 5% and 1% upper percentiles. As a result, the <em>RCDu Statistic</em> perform well in detecting a correct single outlier. Moreover, the <em>RCDu Statistic</em> has a lower masking rate compared to </span><em><span>𝐺</span><sub><span>1</span></sub><span> Statistic</span></em><span>. However, the </span><em><span>𝐺</span><sub><span>1</span></sub><span> Statistic</span></em><span> is better than <em>RCDu Statistic</em> for swamping effect due to a lower swamping rate. Thus, <em>RCDu Statistic</em> performs better than </span><em><span>𝐺</span><sub><span>1</span></sub><span> Statistic</span></em><span> in detecting a single outlier for von Mises (VM) sample. As an illustration, both statistics were applied to the real data set from a conducted experiments series to investigate the northen cricket frogs homing ability.</span>

LETHAL AND SUBLETHAL AMPHIBIAN HOST RESPONSES TO BATRACHOCHYTRIUM DENDROBATIDIS EXPOSURE ARE DETERMINED BY THE ADDITIVE INFLUENCE OF HOST RESOURCE AVAILABILITY

Host species may differ in their responses to pathogen exposures based on host energy reserves, which could be important for long-term trends in host population growth. Batrachochytrium dendrobatidis (BD) is a pathogen associated with amphibian population declines but also occurs without causing mass mortalities. The impact of BD in populations without associated declines is not well understood, and food abundance could play a role in determining the magnitude of its effects. We exposed American toad (Anaxyrus americanus), northern leopard frog (Lithobates pipiens), and cricket frog (Acris blanchardi) metamorphs to BD under low or high food treatments. Overall, anuran species responded differently to BD exposure and the combined effect of BD exposure and food abundance was additive. American toad survival was lowered by BD exposure and low food availability. Based on these results, we developed a population model for American toads to estimate how reductions in survival could influence population growth. We found that BD could reduce population growth by 14% with high food availability and 21% with low food availability. In contrast, survival of northern leopard frogs was high across all treatments, but their growth was negatively impacted by the additive effects of BD exposure and low food availability. Cricket frog growth and survival were unaffected by BD exposure, suggesting that this species is not sensitive to the effects of this pathogen in terms of growth and survival across environments of different quality in the time period examined. Our results showed that low food availability additively increased the species-specific lethal and sublethal impacts of BD on hosts, which could have implications for long-term host population dynamics.

Effects of latitudinal, seasonal, and daily temperature variations on chytrid fungal infections in a North American frog

AbstractAs human activities alter environmental conditions, the emergence and spread of disease represents an increasing threat to wildlife. Studies that examine how host–pathogen relationships play out across seasons and latitudes can serve as proxies for understanding how natural and anthropogenic changes in climate may influence infection and disease dynamics. Amphibians are ideal host organisms for studying the impacts of climate on disease because they are ectothermic and threatened by chytridiomycosis, a recently emerged and globally important disease caused by fungal pathogens in the genus Batrachochytrium. Previous studies suggest that temperature affects the interaction between amphibians and Batrachochytrium pathogens. However, a clearer understanding of this host–pathogen–environment interaction is needed to predict how the risk of chytridiomycosis will vary in space and time. Here, we investigate how daily, seasonal, and latitudinal variations in temperature affect the incidence and impact of Batrachochytrium dendrobatidis (Bd) infection in a broadly distributed host, the northern cricket frog (Acris crepitans), using a combination of field and laboratory studies. In a four‐year field study conducted at three latitudes, we found that daily maximum air temperature over a 15‐d period prior to sampling best predicted patterns of Bd infection and that the lightest infection loads followed periods when these temperatures exceeded 25°C. In a laboratory exposure experiment, we found pathogen load and mortality to be greater at temperatures that mimic winter temperatures at the southern extent of this host's range than for scenarios that mimic temperature conditions experienced in other areas and seasons. Taken together, our findings suggest that changes in temperature across timescales and latitudes interact to influence the dynamics of infection and disease in temperate amphibians.

Amphibian Monitoring in Hardwood Forests: Optimizing Methods for Contaminant-Based Compensatory Restorations.

Amphibians such as frogs, toads, and salamanders provide important services in aquatic and terrestrial ecosystems and have been proposed as useful indicators of progress and success for ecological restoration projects. Limited guidance is available, however, on the costs and benefits of different amphibian monitoring techniques that might be applied to sites restored in compensation for contaminant injury. We used a variety of methods to document the amphibian communities present at 4 restored bottomland hardwood sites in Indiana, USA, and to compare the information return and cost of each method. For 1 method-automated recording units-we also modeled the effect of varying levels of sampling effort on the number of species detected, using sample-based rarefaction and Bayesian nonlinear (Michaelis-Menten) mixed effects models. We detected 13 amphibian species across the restored sites, including 2 species of conservation concern in Indiana-northern leopard frogs (Lithobates pipiens) and Blanchard's cricket frogs (Acris blanchardi). Sites across a range of restoration ages demonstrated encouraging returns of amphibian communities. Although more mature sites showed greater species richness, recently restored sites still provided important habitat for amphibians, including species of conservation concern. Among the 4 methods compared, amphibian rapid assessment yielded the highest number of species detected and the greatest catch per unit effort, with the lowest per-site cost. Our analysis of level-of-effort effects in the rarefied acoustic data found that number of nights sampled was a better predictor of observed species richness than the number of hours sampled within a night or minutes sampled within an hour. These data will assist restoration practitioners in selecting amphibian monitoring methods appropriate for their site characteristics and budget. Integr Environ Assess Manag 2019;00:1-15. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Individual and combined effects of organophosphate and carbamate pesticides on the cricket frog Fejervarya limnocharis.

Many amphibians use water bodies associated with agro-ecosystem for breeding and thus are exposed to multiple chemicals. Fejervarya limnocharis is a common frog occurring in rice paddy fields. The timings of pesticide application generally coincide with the tenure of the occurrence of tadpoles in shallow waters of paddy fields. Malathion and carbaryl are frequently used in rice paddy fields to control leafhoppers and rice bugs, respectively. Therefore, effects of mixtures of malathion and carbaryl insecticides on the survival of tadpoles and emergence of froglets of Fejervarya limnocharis were studied in the laboratory using combinations of three concentrations of carbaryl (0, 25, 50µgl-1) with four concentrations of malathion (0, 100, 250, 500µgl-1). Both malathion and carbaryl were found to be toxic to tadpoles. A reduction in tadpole survival and froglet emergence was recorded with increasing concentrations of carbaryl and malathion. We found significant interaction between carbaryl and malathion on tadpole survival and froglet emergence. Tadpoles exposed to combination of pesticides showed early emergence as froglets compared to control. The extent of toxicity and pesticide interactions are varied when mixed in different concentrations. The reduction in survival, froglet emergence and delay in emergence of metamorphs can occur in rice paddy field as both pesticides are used simultaneously. Therefore, combinations of pesticides may have significant negative effects on the frog population of agro-ecosystems, which requires further confirmation through appropriate field experiments.

A new locality record of Orissa Cricket Frog, Fejervarya orissaensis (Dutta, 1997) from Purba Medinipur District, West Bengal State, India

Orissa Cricket Frog Fejervarya orissaensis was first describe by Dutta (1997). Later this species reported from only few pockets of eastern India and recently reported from some countries of South-east Asia. Here, we provide the first occurrence report for this species from State West Bengal, India.