Biology subjects

Allan, B.

Publications and source records attributed to Allan, B..

3 recordsLinked to original sources

bioRxiv2024

Mechanistic pathways of tick exposure risk in native and invaded plant communities

Plant invasions may alter disease vector abundance by several mechanistic pathways, including modifying microclimates that influence vector survival or changing habitats to influence host use. Here, we used a field experiment and observational data to evaluate multiple mechanistic pathways (tick survival and host abundance) by which plant invasions may alter vector-borne disease risk using the common disease vector lone star tick (Amblyomma americanum), its preeminent host white-tailed deer (Odocoileus virginianus), and the widespread invasive cogongrass (Imperata cylindrica) in the southeastern USA. In the field experiment, ticks survived over 50% longer in areas dominated by the invasive plant compared to those with only native plant species. Invaded areas had lower temperatures and higher relative humidity, yielding a lower vapor pressure deficit (VPD) that likely reduced tick desiccation. The observational study showed similar average tick abundance in native and invaded plant communities and no difference in wildlife host (white-tailed deer) activity between plant communities. However, there was a positive relationship between tick abundance and white-tailed deer activity, but only in native areas. Together, these results suggest that more favorable microclimate conditions resulting in greater tick longevity are the dominant driver of tick abundance in invaded areas, while tick abundance in native-dominated areas may be promoted, at least in part, by white-tailed deer activity. Our results demonstrate that plant invasions can affect multiple, potentially counteracting mechanistic pathways that contribute to tick exposure risk. The complexity of these relationships highlights the need for better understanding of how invasive species and other global change drivers influence disease vectors and, ultimately, disease transmission.

ecology↗

bioRxiv2021

Animal lifestyle changes acceptable mass limits for attached tags

O_LIAnimal-attached devices have transformed our understanding of vertebrate ecology. To minimize tag-related harm for these studies, researchers have long advocated that tag masses should not exceed 3% of the animals body mass. However, this proposition ignores tag forces generated as a result of animal movement. C_LIO_LIUsing data from collar-attached accelerometers on diverse free-ranging terrestrial animals, we detail a tag-based acceleration method (TbAM) in which we quantify animal athleticism in terms of fractions of animal movement time devoted to different collar-recorded accelerations. The varying accelerations are converted to forces imposed on the animals based on the acceleration and tag mass and allow derivation of defined force limits, including those amounting to 3% of the animals mass, for specified fractions of any animals active time. C_LIO_LIWe demonstrate how species athleticism is the principal determinant of tag forces, whereas body mass is of little importance. Forces exerted by 3% tags were mostly equivalent to 4-19% of the animals masses during moving, with a maximum of 54% in a hunting cheetah. Cumulative frequency curves of tag acceleration for periods when animals were active, all showed a characteristic sigmoid pattern, which was displaced further to the right as higher acceleration activities accounted for an increasing proportion of any animals time. Specifying that tags should exert forces that are less than 3% of the animals body mass for 95% of the time led to corrected tag masses constituting between 1.6% and 2.98% of our study animals masses, with values depending on animal athleticism. C_LIO_LIRecognition that animal athleticism affects tag forces of their carriers fundamentally changes how acceptable tag mass limits should be determined by ethics bodies. In order to have a scientifically robust acceptable threshold to limit the forces experienced by an animal carrier, we suggest practitioners derive a similar cumulative acceleration profile for their study species and use a minimum of the 95% limits on the plot (although higher limits may be more appropriate). C_LI

zoology↗

bioRxiv2020

Culex pipiens L. and Culex restuans egg rafts harbor diverse bacterial communities compared to their midgut tissues

BackgroundThe bacterial communities associated with mosquito eggs are an essential component of the mosquito microbiota, yet there are few studies characterizing and comparing the microbiota of mosquito eggs to other host tissues. MethodsWe sampled gravid female Culex pipiens and Culex restuans from the field, allowed them to oviposit in the laboratory, and characterized the microbiota associated with their egg rafts and midguts for comparison through MiSeq sequencing of the 16S rRNA gene. ResultsBacterial richness was higher in egg rafts than in midguts for both species, and higher in Cx pipiens L. than Cx. restuans. The midgut samples of Cx. pipiens and Cx. restuans were dominated by Providencia. Culex pipiens L. and Cx. restuans egg rafts samples were dominated by Ralstonia and Novosphingobium, respectively. NMDS ordination based on Bray-Curtis distance matrix revealed that egg raft samples, or midgut tissues harbored similar bacterial communities regardless of the mosquito species. Within each mosquito species, there were distinct clustering of bacterial communities between egg raft and midgut tissues. ConclusionThese findings expand the list of described bacterial communities associated with Cx. pipiens L. and Cx. restuans and the additional characterization of the egg raft bacterial communities facilitates comparative analysis of mosquito host tissues, providing a basis for future studies seeking to understand any functional role of microbiota in mosquito biology.

microbiology↗