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Chiggers are larval mites that pose a significant health risk globally via the spread of scrub typhus. However, fundamental studies into the bacterial microbiome in North America have never been considered. In this investigation, chiggers were collected in the wild from two locally common rodent host species (i.e., Sigmodon hispidus and Peromyscus leucopus) in three different ecoregions of North Carolina (NC), United States to investigate the composition of their bacterial communities, including potential pathogens. DNA was extracted from the chiggers, and the V3-V4 regions of the bacterial 16S rRNA gene were sequenced using next-generation sequencing (NGS). Alpha diversity metrics revealed significant differences in bacterial diversity among different collection counties. Beta diversity metrics also revealed that bacterial communities across counties were significantly different, suggesting changes in the microbiome as the environment changed. Specifically, we saw that the two western NC collection counties had similar bacterial composition as did the two eastern collection counties. In addition, we found that the chigger microbiome bacterial diversity and composition differed between rodent host species. The 16S rRNA sequence reads were assigned to 64 phyla, 106 orders, 199 families, and 359 genera. The major bacterial phylum was Actinobacteria. The most abundant species were in the genera Corynebacterium, Propionibacterium, class ZB2, and Methylobacterium. Sequences derived from potential pathogens within the genera Orientia and Rickettsia were also detected. Our findings provide the first insights into the ecology of chigger microbiomes in the US. Further research is required to determine if the potential pathogens found detected in chiggers are a threat to humans and wildlife. [ABSTRACT FROM AUTHOR]

Simple Summary: The longhorned tick (LHT), Haemaphysalis longicornis, is an invasive species of public health and veterinary importance. Having invaded North America, Australia, and New Zealand from East Asia, the LHT also has the potential to inhabit and survive in Africa, South America, and Europe. Synthetic chemicals have been vital in controlling these ticks but at the risk of the development of resistant strains and sometimes affecting non-target species. There is also a popular demand for non-chemical approaches for pest control. The use of diatomaceous earth (DE) derived from fossilized diatoms to control LHTs was not considered. This study examined whether DE could kill nymphal LHTs. When ticks were dipped into DE powder for a few seconds and then incubated at 30 °C and 70% relative humidity, they began dying as early as 2.5 h and were all dead by 9 h. The movement by walking of DE-treated nymphs was significantly higher in the first two hours and then the same as the control up to death. A dose of 5 g DE/m2 spread on pine leaf litter killed all the ticks. SEMs after treatment showed the mineral on large areas of the tick surface. These results indicated that DE has the potential of being used as a novel acaracide for LHTs. The longhorned tick (LHT), Haemaphysalis longicornis Neumann (Acari: Ixodidae), is a serious invasive pest in North America where its geographical range is expanding with high densities associated with commercial animal production. There are only a few chemical pesticides available for LHT control, which can lead to the evolution of resistant strains. Diatomaceous earth (DE) was shown to be effective in killing some important tick species but was not examined for LHTs. When LHT nymphs were dipped for about 2–4 s into DE, transferred to Petri dishes (one tick/dish), and incubated at 30 °C and 70% relative humidity, the median survival time was 4.5 h. A locomotor activity assay showed that there was no difference in the overall distance traveled between the DE-treated and control ticks except during the first 2 h after exposure. In a field-simulated study in which a dose of 5.0 g DE/m2 was applied to pine needle litter infested with LHT, all the LHTs were dead at 24 h with no control mortality. Scanning electron micrographs showed the mineral adhering to all surfaces of the tick. The results indicated that DE is effective in killing nymphal LHTs and could be an alternative to the use of chemical acaricides with the advantage of managing pesticide resistance through the killing by a different mode of action and could be used for organically certified animal husbandry. [ABSTRACT FROM AUTHOR]

Scrub typhus, a rickettsial disease caused by Orientia spp., is transmitted by infected larval trombiculid mites (chiggers). We report the molecular detection of Orientia species in free-living Eutrombicula chiggers collected in an area in North Carolina, USA, to which spotted fever group rickettsiae infections are endemic. [ABSTRACT FROM AUTHOR]

Diatomaceous earth (DE) recently was shown to rapidly kill ticks. Proof of concept for use of DE to kill the American dog tick, Dermacentor variabilis, the most widely distributed native three-host tick in North America, has not been investigated. Unfed D. variabilis nymphs dipped into DE and incubated at 30 °C and 50 versus 70% relative humidity (RH) had an estimated median survival time of 5 h and 4 h, respectively, with mortality starting within 1 h. There was no difference in survival time at the 50 and 70% RH. In a two-choice assay at 30 °C and 50% RH, ticks walked freely onto DE treated surfaces; the estimated median survival time was 3 h, indicating that DE is not a repellent. There was no difference in locomotor activity between DE-treated nymphs and untreated controls. In simulated-field experiments, pine straw infested with nymphs and then treated with DE at 5.00, 2.50, 1.25, 0.63 and 0.31 g DE/m 2 resulted in 100% mortality and 81.40% (± 4.13%) mortality at 0.15 g DE/m 2 after 24 h. Scanning electron microscopy of the dead ticks in the 0.15 g DE/m 2 treatments showed most of the cuticle surface was devoid of DE except for the hypostome. The rapid time to first death by dipping, the no effect of RH on survival time, the small amounts of mineral on the tick body and no visible scarring on the tick cuticle questions the generally accepted mode of action for DE, that is, cuticle damage and dehydration., Competing Interests: Declarations. Competing interests: The authors declare no competing interests. Ethical approval: No approval of research ethics committees was required to accomplish the goals of this study because experimental work was conducted with an unregulated invertebrate species. Consent to participate: Not applicable., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Scrub typhus, a rickettsial disease caused by Orientia spp., is transmitted by infected larval trombiculid mites (chiggers). We report the molecular detection of Orientia species in free-living Eutrombicula chiggers collected in an area in North Carolina, USA, to which spotted fever group rickettsiae infections are endemic.

Wetland construction can mitigate the biodiversity and water quality losses associated with reduced natural wetland coverage. While beneficial effects of wetland construction for bats have been observed in natural and rural settings, the effects of wetland construction on bats in an urban ecosystem are less understood. We used passive acoustic monitoring to measure bat activity levels and diversity at two constructed wetlands and two control sites on the University of North Carolina Greensboro campus, in Greensboro, North Carolina, USA. We monitored all 4 sites before and after wetland construction. Pre-wetland construction, there were few differences in bat activity and community structure at our sites. After wetland construction, we observed greater activity, attributable to all species we recorded, at wetland sites compared to control sites. Species diversity and species richness were also higher at wetland sites compared to control sites. When comparing the same sites before and after wetland construction, both bat activity and species richness increased after construction, but the effects were seen in Winter and not Spring. Our results demonstrate that bats use constructed wetlands in urban ecosystems similarly to other habitat settings. Increases in bat activity, diversity, and species richness occurred within one year of wetland construction.