Color vision in hematophagous insects is a core sensory mechanism that enhances the detection of contrast during host seeking, oviposition site, and substrate selection. Understanding the effects of visual cues on black fly oviposition behavior can be a useful tool for control in field settings. This study evaluated the modulatory role that substrate color plays in oviposition behavior of laboratory-reared Simulium vittatum (Zetterstedt) (Diptera: Simuliidae) gravid females. We conducted multi-choice oviposition assays to examine the effects of color treatment (white, yellow, green, and grey egg sheets) on oviposition behavior and egg-laying densities. Results revealed a highly significant effect of color treatment on egg deposition (F3, 15 = 33.58, p < 0.001, η[2] = 0.898), which explained 89.80% of the total variance in egg distribution. White egg sheets resulted in significantly higher egg percentages (50.75 ± 7.33%) compared to yellow (18.20 ± 2.47%), green (15.95 ± 2.52%), and grey (15.07 ± 5.58%), representing a 2.5-fold difference between white and grey options. These results highlight the importance of visual cues in shaping oviposition behavior in S. vittatum and offer actionable insights for optimizing egg collection efficiency as a control measure under field settings. These findings can be further explored to enhance the design of gravid traps, decoy substrates or push-pull tools for black fly control.

There are many invasive alien insect species, several of these species can affect human health by causing disease. These include vectors of vector-borne diseases, such as the triatomines that transmit Chagas disease. Triatoma longipennis Usinger (Hemiptera: Reduviidae) is one of the most epidemiologically important vector species of Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae) in Mexico. This study reports the third collection of T. longipennis from the state of Hidalgo, Mexico, where the prevalence of T. cruzi infection in humans has historically exceeded 3.38%. This study evaluates several biological parameters of T. longipennis related to the egg-to-adult development time, number of blood meals to molt, and mortality for each instar, of two populations of the invasive species T. longipennis, recently detected in Hidalgo, as well as fecundity and fertility of females at the end of the cycle. Similar results were observed in the two populations for parameters studied, such as median egg-to-adult development time (162, 174 days), number of blood meals at each nymphal instar (7, 8 meals), total mortality (56%, 61%), fecundity (2.8 eggs/female/day) and fertility (83.3, 84.2%). These observed parameters suggest that both populations of the invasive T. longipennis detected in Hidalgo could be important transmitters of T. cruzi and could replace key triatomine species within their new distribution area.

Dermacentor ticks are widespread in eastern Washington and are known vectors of bacterial pathogens and harborers of endosymbionts belonging to the genera Francisella and Rickettsia. Some Dermacentor species can become infected with Ehrlichia chaffeensis Anderson et al. (Rickettsiales: Ehrlichiaceae); it remains unclear if any are competent vectors for this bacterial pathogen. This study reports the abundance of Dermacentor species and prevalence of select tick-borne bacterial pathogens collected from two conservation areas popular among hikers in Spokane County, Washington. In total, DNA from 599 adult ticks was analyzed using PCR; 87.8% (526/599) were identified as Dermacentor andersoni Stiles and 12.2% (73/599) as D. similis Lado, Glon and Klompen (Ixodida: Ixodidae). Ticks were also screened for the presence of bacterial DNA using genus- or species-specific primers targeting Rickettsia spp., Francisella spp., and E. chaffeensis. Rickettsia endosymbionts, R. peacockii Niebylski et al. or R. rhipicephali (Burgdorfer et al.) Weiss and Moulder (Rickettsiales: Rickettsiaceae), were found in 4.0% (21/526) of D. andersoni. Francisella-like endosymbionts were detected in 65.9% (395/599) of all ticks. No species known to be pathogenic belonging to either Rickettsia or Francisella were detected. However, E. chaffeensis was detected in 15.3% (12/73) of D. similis, which to our knowledge is the first report of ticks harboring this species of bacteria in Washington state. These findings contribute to understanding the microbial ecology of ticks in the Inland Northwest.

Mortality events can affect populations in counterintuitive ways leading to compensation or overcompensation when density-dependent effects are present. These phenomena occur in a variety of taxa and are particularly important to understand for the management of commercial species, the conservation of endangered species, and the control of arthropod pests. Using a mesocosm experimental design, we simulated different levels of adult control by altering larval densities (i.e. via the simulated mortality event) to assess mortality effects in Aedes aegypti L. (Diptera: Culicidae). Various larval densities were placed in containers with 500 mL water and given the same amount of food per container, resulting in different food to larvae ratios. A segmented liner analysis approach was used to determine the response of the mosquitoes to starting larval densities. We found that overcompensation occurred with the most adults produced at medium levels of mortality. Adult production and development had a non-linear relationship with food per larvae. Wing length and percent survival showed significant variation from linear relationships across starting larval densities. Our results suggest that medium densities of Ae. aegypti larvae, simulating medium levels of control, will produce the most adult females with a relatively large body size. Control efforts for Ae. aegypti should take the potential of density-dependent effects into account in planning and analysis stages to ensure overcompensation does not result.

Exposure to ticks (Acari: Ixodidae) puts humans and their companion animals at risk of tick bites and potential pathogen transmission. Bites often occur when humans encounter ticks outdoors, but there may also be a risk in the home given the propensity of ticks to hitchhike on clothes and pets. We assessed survival of two tick species widely distributed across the southeastern United States, Amblyomma maculatum Koch and A. americanum Linnaeus, on different types of flooring commonly found in residential homes. We placed ticks individually onto one of five different types of flooring (tile, wood, vinyl, short pile carpet, and long pile carpet; n = 180 total, 36 ticks per species per floor type). Ticks were contained in plastic cups fixed in place on each floor type to reduce movement and/or escape and promote tick contact with the flooring. Survival was assessed as a function of the interaction between species and floor type. We found that A. maculatum ticks survived for significantly longer periods of time than A. americanum (median survival/mean survival) on vinyl (22.5/25.4 vs. 11.5/10.4 d), wood (18.5/16.1 vs. 11.0/12.2 d), tile (21.0/20.4 vs. 6.5/7.33 d) and short pile carpet (20.0/20.8 vs. 10.5/10.8 d), but A. americanum lived longer overall on long pile carpet (13.0/10.4 vs. 13.0/14.9 d). Our findings help clarify expected tick survival following entry into the home, and how floor type can mediate in-home tick exposure. Furthermore, this work emphasizes the necessity of performing tick checks, wearing protective clothing, and applying appropriate acaricides to people and pets to prevent tick transportation into the home.

Ticks (Ixodida: Ixodidae) encounter ash after wildfires or controlled burns-either directly or via wildlife that bathe in ash. Despite its use to control ectoparasites in traditional ethnoveterinary practices, the effects of plant-derived ash remain unstudied. We evaluated ash from three tree species that grow in California-coast redwood (Sequoia sempervirens (D.Don) Endl.; Cupressaceae), California bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.; Lauraceae), and non-native Tasmanian blue gum eucalyptus (Eucalyptus globulus Labill.; Myrtaceae)-on survival and behavior of four ixodid tick species: Ixodes pacificus Cooley & Kohls (larvae, adult females), Dermacentor occidentalis Marx (larvae, adults), D. similis Lado, Glon & Klompen (adults), and D. albipictus Packard (larvae). Treatments included ash, two commercial acaricidal dusts (diatomaceous earth and kaolin clay), and a negative control. Eucalyptus ash significantly reduced survival in I. pacificus larvae and females and D. occidentalis larvae, with effects comparable to positive controls. Bay ash showed moderate lethality in I. pacificus females and D. occidentalis larvae. Redwood ash had strong effects only on D. albipictus larvae. Dermacentor species showed low overall susceptibility; larvae were more affected than adults, which showed no lethal effects. Our findings suggest that ash type, tick species, and life stage influence outcomes. This is the first laboratory study to show the effects of plant ash on ticks, supporting ash as a potential alternative for tick control and highlighting fire's indirect role in tickborne disease dynamics.

Dermacentor reticulatus is a widely distributed tick species in Europe, whose rapid range expansion and importance as a vector of multiple pathogens have increased scientific interest in its genetic diversity and population structure. The Baltic States region, which has been experiencing D. reticulatus tick migration into northern areas over the last two decades, with its unique ecological and climatic conditions, could offer valuable insights into tick distribution patterns and their genetic structure in northern European ranges. This study aimed to investigate the genetic variation of D. reticulatus across its European range, including new data from the Baltic States. Genetic variability of 83 D. reticulatus tick samples from 42 locations across the Baltic states, central, western, and southeastern Europe was assessed using mitochondrial (12S rRNA, 16S rRNA) and nuclear (ITS2) markers. The study revealed low genetic variability in D. reticulatus populations across Europe, characterized by a dominant haplotype present in the Baltic states as well as central and western Europe. Unique haplotypes discovered in the Baltic region may be associated with environmental factors and the recent range expansion of the species. The presence of unique haplotypes and genetic variability among northern D. reticulatus populations suggests ongoing local adaptation driven by environmental pressures, including regional climate and landscape heterogeneity in newly colonized habitats.

Culicoides midges are vectors of bluetongue virus (BTV), an arbovirus affecting wild and domestic ruminants. Bluetongue distribution generally overlaps with vector range, so understanding the vector's ecology is necessary for predicting BTV risk. Culicoides require moist substrate for development, and C. sonorensis, the primary recognized vector in the western United States, is classically associated with livestock wastewater ponds. However, it is well-known that BTV can be found outside of livestock areas, with transmission occurring in natural settings. To better classify development habitat, we conducted a broad biweekly survey of moist and wet habitats from June to September of 2022 in northern Colorado at ten sites, including large livestock operations, non-commercial domestic operations, and natural spaces. Samples were maintained in the insectary for 11 weeks and monitored for emergence of adult midges. Standing water substrates displayed higher presence and abundance of midges than running or transient habitats, though all microhabitats showed emergence. Additionally, livestock sites did not produce more midges than other site types, and in fact more midges were observed in natural spaces per sample and overall. Livestock spaces did, however, show significantly higher proportions of C. sonorensis midges, which are thought to be the most competent vectors of BTV in this region, as opposed to other Culicoides species. These results suggest that development sites in natural areas may play an important role in maintaining vector populations in the western U.S. outside of previously implicated livestock operations, and that differences in larval habitat lead to differences in vector species composition.

In Peru, since the beginning of the 20[th] century, 18 mosquito species (Diptera: Culicidae) and three forms have been discovered by previous authors: Anopheles acanthotorynus, An. calderoni, An. peruvianus, Chagasia ablusa, Ae. (Howardina) Iquitos form, Aedes epinolus, Haemagogus obscurescens, Hg. (Conopostegus) Peruvian highland form, Hg. (Con.) Peruvian lowland form, Culex archegus, Cx. debilis, Cx. diplophyllum, Cx. escomeli, Cx. raymondii, Onirion aenigma, On. celatum, Sabethes idiogenes, Trichoprosopon hyperlecum, Tr. subsplendens, Wyeomyia baltae, and Wy. paucartamboensis. Of these, seven species were later synonymized under the name of other species, the rest remain as valid species, one of them is placed in Nomen dubium, and the forms continue retained without specific status. With the intention of updating the checklist of mosquito species in Peru, historical and recent species-records were reviewed and mosquito collections were conducted in specific sites of Peru, resulting in the confirmation of the presence of Hg. anastasionis, Hg. capricornii, Psorophora dimidiata, Ps. cilipes, Cx. usquatissimus, Cx. dunni, Mansonia wilsoni, Johnbelkinia leucopus, Limatus pseudomethysticus, Tr. compressum, and Uranotaenia socialis. Additionally, Ae. aurivittatus, Ae. terrens/zavortinki, Cx. acharistus, Cx. dolosus, and Cx. surinamensis are reported for the first time in Peru, while An. apicimacula, An. mediopunctatus, Ae. condolescens, Cx. bihaicolus, and Sa. tarsopus are removed from the Peruvian mosquito fauna. An updated list of 198 nominal species and four forms of mosquitoes from Peru is presented.

Tick-borne pathogens pose an ongoing threat to human health in the southeastern United States, where tick and host abundances are high. In North Carolina, several medically important tick species are present, but in the Piedmont region, Amblyomma americanum is particularly abundant and associated with multiple human pathogens, including Rickettsia amblyommatis, a hypothesized human pathogen. In this study, we build on recent tick surveillance efforts across several North Carolina counties by screening A. americanum for Ehrlichia ewingii, Ehrlichia chaffeensis, and R. amblyommatis while also analyzing tick abundance, pathogen prevalence, and county-level human disease case data from the North Carolina Department of Health to assess potential correlations. Our results reveal variation in pathogen prevalence across counties, with Chatham County consistently emerging as a high-risk area due to high tick abundance and elevated infection rates. However, we did not observe a strong correlation between tick abundance or pathogen prevalence and reported human disease cases at the county level. These findings highlight counties of elevated risk in a region experiencing an increasing burden of tick-borne disease and contribute to our understanding of ongoing public health trends.

Many farmers house livestock in open pens or sheds that offer no physical protection against biting flies, with protection relying heavily on the use of residual or on-animal insecticides. Insecticidal barriers can offer an alternative or additional option to managing pestiferous biting flies near livestock but they need to be evaluated in the field. We assessed the efficacy of a deltamethrin-incorporated net to reduce contact of Culicoides and mosquitoes with livestock. On cervid farms, reduction of biting-midges in light traps was assessed for traps surrounded by deltamethrin-treated nets, untreated nets, or no-net controls. Significantly fewer Culicoides were collected in pens surrounded by untreated nets compared to no-net, and further significant reductions were achieved with deltamethrin-treated nets. Similar results were observed on a subsistence poultry and swine farm. Total Culicoides and mosquito abundance and abundance of blood-fed females was significantly reduced in light-trap collections after surrounding livestock units with a deltamethrin-treated net. These results suggest the use of insecticidal nets at a 2 m height can reduce contact between livestock and some biting flies in open areas or sheds.

Lutzia vorax Theobald (Diptera: Culicidae) is a ferocious predator of small container habitats in the forests and rural areas of the eastern Palearctic and Oriental regions. Owing to its consumption of various invertebrates, including mosquito larvae, it is considered a potential biological control agent of vector species. However, studies on the general biology of Lt. vorax are scarce; thus, our understanding of its role in natural habitats is limited. To elucidate its ecological role with regard to its interaction with vector species populations, we conducted field monitoring surveys in two different deciduous forests in South Korea, using tire traps for larvae in 2023. Community samples of mosquito larvae were collected every three weeks (July to September, 2023) from each trap, which replicated the natural container environment in forest areas. Then, community structures were compared based on the presence or absence of Lt. vorax. Communities with Lt. vorax larvae exhibited distinct structures characterized by lower species richness, diversity, and vector species density. Furthermore, non-metric multidimensional scaling results showed that the group structure differed depending on the presence of Lt. vorax larvae. Gut content analysis of the predaceous larvae supported the evidence of top-down regulation of Lt. vorax with considerable predation rates on other mosquito larvae in each habitat: 63.92 ± 30.72% in Site A and 72.85 ± 18.03% in Site B (mean ± SD). Thus, we suggest that Lt. vorax serves as both a significant natural enemy and key predator species in container habitats in the forested areas of Korea.

The subtropical coastal plain of Deep South Texas provides a wildlife corridor for hosts of disease-transmitting ixodid species, including the southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini). Wind tides and storm surges push hypersaline Lower Laguna Madre water inland on occasion, creating substantial areas of saline soil dominated by sea ox-eye daisy, Borrichia frutescens (L.) DC, and inhabited by numerous mud flat fiddler crabs, Uca rapax (Smith). Ixodid populations, especially larvae, in the saline areas are mostly negligible because of saltwater toxicity to eggs, desiccation, and predators. Soil salinity, U. rapax populations, and ant foraging activity were determined for areas dominated by B. frutescens, areas with intermediate stands, and areas without the plant. Borrichia frutescens density and U. rapax populations were moderately correlated with soil salinity, but predatory ant foraging was not correlated with soil salinity, B. frutescens density, and U. rapax abundance. Borrichia frutescens stand density, however, was strongly correlated with numbers of U. rapax holes, hence, the plant is an indicator of negligible ixodid activity. GIS mapping of high-Borrichia habitats might be useful for refining surveillance of ixodid populations, particularly one-host ixodids, such as R. (B.) microplus.

In 2021, Japanese encephalitis virus (JEV) reverse transcription quantitative RT-qPCR testing of mosquitoes was used for the first time in the Northern Territory (NT) in an attempt to determine the presence of circulating JEV and identify probable vector mosquito species. All test results for 2021 and 2022 returned negative for JEV. Testing resumed in January, 2023, with mosquitoes also tested for Murray Valley encephalitis virus (MVEV) following an outbreak resulting in eight confirmed human cases. Mosquito pools tested positive by RT-qPCR for both viruses on several occasions, confirming the suitability of this method for flavivirus surveillance. Culex annulirostris (Skuse) and Cx. gelidus (Theobald) tested RT-qPCR positive for both viruses in 2023, incriminating them as JEV and MVEV vectors in the NT. Aedes normanensis (Taylor) also tested positive for JEV and MVEV, identifying this species as a probable vector species for both viruses in the NT. While Cx. annulirostris is known to be the principal MVEV vector in the NT, the fact that all three vector mosquito species potentially play a part in the JEV transmission cycle is of major public health concern. While Cx. tritaeniorhynchus (Giles) did not test positive to JEV in 2023, this species is the principal JEV vector in SE Asia and could potentially play a role in JEV transmission in the NT. Genotyping of viruses from the NT mosquitoes confirmed the continued circulation of genotype IV JEV and showed that both genotypes 1A and 2 of MVEV were co-circulating in the NT in 2023.