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Context: Organisms living in small, isolated populations with very restricted ranges are at high risk of extirpation due to various direct and indirect forces than mainland populations. Roatán spiny-tailed iguanas (Ctenosaura oedirhina) are endemic to the 146-km2 island of Roatán, Honduras. Harvesting for consumption, fragmentation of habitat and predation by domestic animals threaten the existence of this lizard. This species is federally protected in Honduras; however, enforcement is rare. These iguanas are also listed as Endangered by the International Union for Conservation of Nature (IUCN) and are on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This species is geographically and genetically isolated into small subpopulations that are declining in density. Aims: To estimate the population size of Roatán spiny-tailed iguanas (Ctenosaura oedirhina) on the island of Roatán, Honduras. Methods: Distance sampling surveys have been used to monitor this species since 2012, and have been used to determine population density at five study sites. Estimates of density at those sites and across the island were used to calculate the population size of this species. Key results: The present study elucidates that the high-density populations remaining are declining. The current population size is estimated to be 3759 (95% CI = 1406–12 616) individuals within the study sites, with 730 additional iguanas potentially outside of the study sites. Conclusions: If the current level of decline continues, this species may become extirpated from some locations on Roatán, and go extinct in the wild. Although Honduras does have laws protecting this species and other wildlife, enforcement must be enhanced. Implications: Lack of enforced protection for this species allows poaching for consumption to continue, which has been shown to alter its distribution and cause increased adult mortality. Local customs value the consumption of this species, creating a delicate management situation. Recommendations include strategies that mitigate the threat posed by consumption and increase enforcement of the current laws, while acknowledging cultural traditions. Roatán spiny-tailed iguanas (Ctenosaura oedirhina) are found only on the island of Roatán, Honduras, and are threatened by overharvesting, fragmentation of habitat and predation by domestic animals. Using systematic survey techniques, the population of this species within the surveyed protected areas was estimated at 3759 (95% CI = 1406–12 616) individuals within the study sites and up to 730 outside of these protected areas. This species is in decline and may become extirpated from some locations on Roatán. Photograph by Ashley B. C. Goode. [ABSTRACT FROM AUTHOR]

Pistia stratiotes L. is an invasive floating plant that alters native habitats in Florida by forming thick mats that shade out submerged vegetation and obstruct navigation. Multiple genotypes of this plant have been identified from locations across its native and adventive ranges including types from throughout the Americas, the Caribbean, Asia, and Australia. We investigated the performance of a known monophagous insect, Lepidelphax pistiae, on nine P. stratiotes haplotypes (from four clades) in no-choice experiments and found that while L. pistiae performance varied on different haplotypes, there was considerable overlap in fitness and impact among haplotypes. Lepidelphax pistiae did not distinguish between purported 'native' and 'non-native' haplotypes and did not perform better or cause more damage to South American haplotypes specifically, which would have supported its utility as a biocontrol agent on the exotic haplotypes found in Florida. While L. pistiae is monophagous on P. stratiotes, it was not specific enough to differentiate consistently among the tested haplotypes and thus, may not be suitable as a biological control agent because of the potential threat they pose to native haplotypes of P. stratiotes in Florida. [ABSTRACT FROM AUTHOR]

The Roatán Spiny-tailed Iguana (Ctenosaura oedirhina) is an endangered species endemic to only two islands in the Bay of Honduras and a few of its surrounding cays. Ctenosaura oedirhina is currently threatened by different impacts, including habitat modification, invasive predators, and illegal collection and harvesting. Although previous work has monitored population numbers, animal distributions, and genetic variation, very little is known about the reproductive ecology and physiology of the species. Physiological indicators provide valuable information regarding the health of animals and populations. Commonly used metrics include circulating hormone concentrations, energetic indicators, and immunological indices. However, the aforementioned physiological measures can also be difficult to interpret because they are not static but rather vary according to sex, season, reproductive state, and body condition. Therefore, to understand the health status of an individual better, it is important to concomitantly measure multiple related and relevant physiological systems, and to examine these responses under different individual and environmental contexts (e.g., reproductive state, site). In the current study, we measured circulating plasma oxidative stress markers and energy metabolites in five populations of Roatán Spiny-tailed Iguanas during the prenesting season. We found significant physiological variation in females according to breeding state, and males according to population. Understanding the natural variation in the physiology of free-living animals will allow us to determine the significance of physiological measures such as health indicators in the future and thus better manage these threatened populations. [ABSTRACT FROM AUTHOR]

The scope and complexity of interactions within community food webs necessitates their simplification to a community module scale for conducting empirical studies. An outdoor mesocosm study in the USA quantified the strengths of direct and indirect interactions between two herbivore congeners that fed on two aquatic plant species while sharing a parasitoid.Kalopolynema ema (Hymenoptera: Mymaridae) is a stenophagous native egg parasitoid that attacks the hemipteran species in this study, Megamelus davisi (Hemiptera: Delphacidae), a native herbivore that feeds on the native aquatic species Nuphar advena, and the introduced biological control agent Megamelus scutellaris (Hemiptera: Delphacidae) that feeds on the non‐native aquatic species waterhyacinth, Pontederia crassipes.The presence of M. scutellaris did not significantly increase parasitism of M. davisi indicating that apparent competition was not a factor in this community module. There was no evidence of any trophic cascades caused by these interactions based on the relative growth rates of biomass and leaf area for both plant species.Synthesis and applications. The relative strengths of community interactions varied with herbivore densities suggesting that should negative indirect effects with biological control agents occur they would likely be transient and closely linked to population dynamics as influenced by abiotic factors like temperature. Despite identifying potential negative interactions using path analysis, we saw no apparent competition following the insertion of a weed biological control agent into a community that contains an ecological analog. In this example, the primary negative interaction was biotic resistance to Megamelus scutellaris from attack by Kalopolynema ema. Adopting weed management tactics that emphasize efficacy, sustainability and environmental benevolence argue for the use of classical biological control when appropriate. [ABSTRACT FROM AUTHOR]

Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae) is monophagous on Pistia stratiotes L. (Araceae), an invasive floating plant in Florida. Temperature studies were conducted to determine the optimal temperature for development and reproduction for this potential biological control agent. Egg development time decreased as temperature increased from 17°C to 30°C. No eggs developed and no nymphs survived at 15°C. Adult females survived the longest at 15°C, indicating that they might be more resilient to cold temperatures. Optimal temperature for nymph development was 25°C with 29% surviving to adulthood in 18.2 ± 0.4 days. [ABSTRACT FROM AUTHOR]

Pistia stratiotes L. (Araceae) is a floating aquatic plant that has become invasive in Florida. It is primarily controlled with herbicides, but two biocontrol agents have previously been released to assist in management of this species. A new potential biocontrol agent from Argentina, Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae), has been evaluated comprehensively for specificity after initial host range studies done in its native range indicated that it is likely specific to P. stratiotes. Host range studies indicated that this insect is specific to P. stratiotes, with no survival or reproduction occurring on any of the 42 other plant species tested. Impact studies indicated that this insect can significantly damage P. stratiotes at medium and high population densities, which were comparable to those seen in its native range. Lepidelphax pistiae is sufficiently specific enough to warrant release and has a high probability of aiding management of P. stratiotes populations in Florida. [ABSTRACT FROM AUTHOR]

Biological experiments involving animals in K-12 classrooms can be time consuming or logistically difficult. Insects are small and easy to obtain, making them suitable for classroom use. We provide an experiment using insects that will teach students how to use the scientific method to formulate and test a hypothesis. The experiment is based on a case study involving an insect used as a biological control agent that targets an invasive weed, and the rigor of the experiment can easily be tailored to different grade levels. Using ~1 m² arenas set up in the classroom, students measure insect jumping or walking distances as a proxy for dispersal capabilities in the field, and more advanced classes can investigate variables that affect jumping or walking distance and direction. [ABSTRACT FROM AUTHOR]

A postsecondary institution partnered with several high schools in a large, urban and highly diverse school district in the southeast U.S. through a GK-12 program funded by the National Science Foundation. The main goal of the project was to investigate the potential impact of the GK-12 program on the ability of graduate students to communicate their scientific research and expertise to a non-technical audience comprised of high school chemistry, biotechnology, and environmental science students and teachers. The graduate student presentations about their research were videotaped before, during, and after their participation in the program. Applying a standardized communications rubric, analysis of the video presentations indicated significant improvement in the graduate students' communication skills during their participation in the program. In addition, graduate student perception of their improvement in communication skills was demonstrated through a qualitative survey. Implications for the training of graduate students in communication skills are discussed. [ABSTRACT FROM AUTHOR]

Abnormal colouration has been reported in both wild and captive reptile populations. In wild populations, piebaldism is a type of leucism where individuals have normal-coloured eyes, but exhibit white patches, giving them a blotched or mottled appearance. It is a common form of abnormal colouration. Some species show an ontogenetic shift in this patchy colouration, while others start life with a piebald appearance. We studied colouration across populations of Roatan Spiny-tailed Iguanas (Ctenosaura oedirhina), a species endemic to the island of Roatan, Honduras. In general this lizard exhibits an ontogenetic shift in colouration from grey with green mottling in hatchlings to dark grey/black with white or cream patches in adults; however, there is substantial colour variation among both adults and populations. Based on an ordinal regression analysis there is a significant positive trend between size (snout-vent length) and percentage of white colouration, suggesting an ontogenetic shift toward increasing piebaldism. Additional data, specifically recapture and genetic information, are needed to elucidate the mechanisms responsible for these patterns. [ABSTRACT FROM AUTHOR]