Microplastic pollution differentially affects development of disease-vectoring Aedes and Culex mosquitoes.

Plastic in the form of microplastic particles (MPs) is now recognized as a major pollutant of unknown consequences in aquatic habitats. Mosquitoes, with aquatic eggs, larvae, and pupae, are likely to encounter microplastic, particularly those species that are abundant in close proximity to human development, including those that vector human and animal disease. We examined the effects of polyethylene MPs, the most common microplastic documented in environmental samples, on the development and survival of the mosquitoes Aedes albopictus and Culex quinquefasciatus. In laboratory egg-laying and larval development container environments similar to those used by both species in the field, a mix of 1-53 µm MPs at concentrations of 60, 600, and 6000 MP ml-1 increased early instar larval mortality in both species relative to control treatments. A significant difference was found in the response of each species to microplastic at the lowest microplastic concentration tested, with Cx. quinquefasciatus survival equivalent to that in control conditions but with Ae. albopictus larvae mortality elevated to 37% within 48 h. These results differ from those of previous studies in which larvae were only exposed to MPs during the last aquatic instar stage and from which it was concluded that microplastic was ontogenically transferred without negatively affecting development. Increasing plastic pollutant concentrations could therefore act as selective pressures on aquatic larvae and ultimately influence outcomes of ecological interactions among mosquito vector populations.

Relative response to digital tablet devices and painting as sensory enrichment in captive chimpanzees.

Digital devices, including tablet computers and other touchscreens, can potentially serve as flexible and convenient means for providing behavioral enrichment activities to captive primates. Despite increased interest in incorporating technology into enrichment programs, no direct quantitative comparison has previously been made between the effectiveness of typical tactile enrichment activities and enrichment activities on digital devices. One way in which these activities differ is in the degree of controllability afforded the animals in interacting with the enrichment objects, since digital devices will be limiting to varying degrees based on the particulars of software and the interface format. This study compared the effects of painting with brush on paper to those of a painting application on a digital tablet device (iPad™) in eight group-living chimpanzees at the Honolulu Zoo. Observations were analyzed across baseline, enrichment, and post-enrichment periods to measure significant differences in the reduction of displacement and stereotypic behaviors. We found that the digital tablet device running an application that permits production of semi-automated visualizations, was as effective as painting with brush on paper in reducing some stereotypic and displacement behaviors, including yawning and self-picking. However, the digital tablet was not as effective in reducing other displacement behaviors, nor was it as effective in retaining the chimpanzee's attention. These results confirm a useful role for digital devices in enrichment programs but suggest a need to assess individual device applications in their capacity to promote greater controllability and sensory breadth of the enrichment experience.

Incubation temperature modifies neonatal thermoregulation in the lizard Anolis carolinensis.

The thermal environment experienced during embryonic development can profoundly affect the phenotype, and potentially the fitness, of ectothermic animals. We examined the effect of incubation temperature on the thermal preferences of juveniles in the oviparous lizard, Anolis carolinensis. Temperature preference trials were conducted in a laboratory thermal gradient within 48 hr of hatching and after 22-27 days of maintenance in a common laboratory environment. Incubation temperature had a significant effect on the upper limit of the interquartile range (IQR) of temperatures selected by A. carolinensis within the first 2 days after hatching. Between the first and second trials, the IQR of selected temperatures decreased significantly and both the lower limit of the IQR and the median selected temperature increased significantly. This, along with a significant incubation temperature by time interaction in the upper limit of the IQR, resulted in a pattern of convergence in thermoregulation among treatment groups. The initial differences in selected temperatures, as well as the shift in selected temperatures between first and second trials, demonstrate plasticity in temperature selection. As a previous study failed to find environmentally induced plasticity in temperature selection in adult A. carolinensis, this study suggests that this type of plasticity is exclusive to the period of neonatal development.