Insects and microorganisms, ubiquitous organisms in the natural world, have developed intricate relationships throughout their evolutionary histories. However, most studies have concentrated on specific time points or life stages, but some limited studies have investigated the dynamics of microbial diversity within insects across life stages. Here, 16S rDNA sequencing technology was used to investigate the gut bacterial community across the life stages of Sarcophaga peregrina (Robineau-Desvoidy) (Diptera: Sarcophagidae). The results revealed that the gut bacterial diversity of S. peregrina varied with life stage and showed similarity in the nearby life stages. Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were the dominant phyla in S. peregrina. Genera such as Providencia, Ignatzschineria, and Myroides are implicated in potentially pivotal roles during the developmental processes of this flesh fly. Furthermore, the effects of amikacin on the growth and development of S. peregrina were not statistically significant. However, we did observe significant changes at the protein level, which suggests a close association between protein-level alterations and growth and development. Additionally, we speculate that S. peregrina regulates its nutritional status during nonfeeding stages to meet the demands of eclosion.This study represents the first comprehensive examination of the intestinal bacterial composition across various life stages of S. peregrina. Our findings deepen our understanding of the gut microbiota in this flesh fly and lay the groundwork for further exploration into the intricate interactions between microorganisms and insects.

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Triatomine bugs are vectors for the Trypanosoma cruzi Chagas parasites, the etiological agent for Chagas disease. This study evaluated 6 epidemiologically significant behaviors (development time, number of blood meals required for molting to the next instar, mortality rate, aggressiveness, feeding duration, and defecation delay) across 4 populations of Triatoma mexicana Herrich-Schaeffer (Heteroptera: Reduviidae), a major T. cruzi vector in Central Mexico. We collected triatomines from areas characterized by high (HP), medium (MP), medium-high (MHP), and low (LP) prevalence of human T. cruzi infection.The MHP population had the shortest development time, <290 days. Both the HP and MP populations required the most blood meals to molt to the next instar, with a median of 13. Mortality rates varied across all populations, ranging from 44% to 52%. All of the tested populations showed aggressive behavior during feeding. All populations shared similar feeding durations, with most exceeding 13 min and increasing with each instar. Quick defecation, during feeding, immediately after or less than 1 min after feeding, was observed in most nymphs (78%–90%) from the MP and MHP populations and adults (74%–92%) from HP, MP, and MHP populations.Though most parameters suggest a low potential for T. mexicana to transmit T. cruzi, unique feeding and defecation behaviors in 3 populations (excluding the LP group) could elevate their epidemiological importance.These population-specific differences may contribute to the varying prevalence rates of T. cruzi infection in areas where T. mexicana is found.

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Predicting the potential distribution and coexistence of suitable geographic areas for Chagas disease vectors in the Americas is a crucial task for understanding the eco-epidemiological dynamics of this disease. The potential distribution and coexistence of 3 species—Rhodnius prolixus (Hemiptera: Reduviidae), Cavernicola pilosa (Hemiptera: Reduviidae), and Rhodnius pictipes (Hemiptera: Reduviidae) were modeled. Presence records were obtained and environmental variables were selected based on correlation analysis, Jackknife analysis and knowledge of the biology and natural history of the species. The MaxEnt algorithm included in the kuenm package of R software was used for modeling the potential distribution, and various scenarios of the BAM diagram (Biotic, Abiotic, and Movement variables) were evaluated. The variables contributing to the final models were different for each species. Rhodnius pictipes showed a potential distribution in South America, particularly in Brazil, Bolivia, Peru, Colombia, Venezuela, Guyana, and Suriname. Areas with environmentally suitable conditions for R. prolixus were located in southern Brazil, Peru, Colombia, southern Mexico, Guatemala, El Salvador, and Honduras, whereas for C. pilosa they were in southeastern Brazil, southeastern Central America, Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname, and French Guiana. Co-occurrence analysis revealed distinct patterns in the neotropical region, with some areas indicating the potential distribution of 1 or more species. In Brazil, occurrence and co-occurrence areas were concentrated in the northwest and southeast regions. Overall, this study provides valuable information on the potential distribution and coexistence of vectors, which can inform targeted vector control strategies and contribute to global efforts in combating Chagas disease.

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Leishmaniasis is a zoonoses caused by protozoan parasites belonging to the Leishmania genus that is transmitted to humans through the bite of previously infected phlebotomine sandflies (Diptera:Psychodidae: Phlebotominae). In Brazil, 2 types of leishmaniasis are endemic, tegumentary leishmaniasis (TL) and visceral leishmaniasis (VL). In Baldim, a municipality in the Espinhaço Range Biospere Reserve (ERBR), 5 autochthonous cases of TL, and one autochthonous case of VL were reported from 2017 to 2022. Owing to the lack of data on entomological fauna, we surveyed the occurrence and distribution of phlebotomine sandflies that could act as Leishmania vectors, as well as natural Leishmania infection. During 1 year, 918 sandfly specimens belonging to 12 species were collected. The predominant species was Lutzomyia longipalpis (Lutz & Neiva, 1912) (32.0%), a proven VL agent, followed by Evandromyia evandroi (Costa Lima & Antunes, 1936) (20.7%), Evandromyia cortelezzii (Brèthes, 1923) (17.0%), Nyssomyia whitmani (Antunes & Coutinho, 1939) (12.2%), and Nyssomyia intermedia (Lutz & Neiva, 1912) (10.5%), all putative or proven TL agents. Seasonal fluctuations and endo-exophilic behavior were delineated for the main phlebotomine sandflies. The population of Lu. longipalpis was higher during the coolest and driest months, although different profiles were noted for the other species. Natural Leishmania infection was not detected in any of the 197 phlebotomine sandfly females analyzed. The results were compared with those previously obtained in other municipalities belonging to the ERBR. The presence of Leishmania vectors and human cases of leishmaniasis indicate a risk of Leishmania transmission in the region.

In Diptera, reproductive strategies vary according to the stage of development of the newly deposited offspring and their abundance. The aim of our study is to establish connections between the reproductive strategies of flies (larviparous or oviparous) and the prevailing local conditions (sun or shade) as well as landscape attributes (low or high urbanization) in an urban setting. We collected flies using 2 baited traps (in the sun or shade) at each of the 13 study sites with varying levels of urbanization. We used generalized linear mixed models to examine the impact of landscape and local characteristics on the diversity (abundance and richness of larviparous and oviparous Diptera) of sarcosaprophagous flies. Our findings indicate that while the abundance and diversity of both larviparous and oviparous flies are affected by urbanization, larviparous flies would be less sensitive to more urbanized environments. Larviparous also exhibit a preference for resources under sun exposure, while the responses of oviparous seem more species-dependent.The observed patterns can be explained by the known biology of the studied groups.

Microenvironmental factors affect ovipositional choices and behavior in ticks. In this study, engorged female Amblyomma maculatum Koch were released in an observation arena covered with garden soil. The arena was evenly split into wet and dry sides, each containing 5 different types of structures (totaling 10). Upon release, observations at particular time points were made over 2 days as to speed, distance, actual paths traveled, and ultimate site selection, presumably for oviposition. In addition, time-lapse videography was utilized to record the track of each individual tick. This scenario was replicated 3 times with different cohorts of ticks (n = 5 per replicate). Of the total 15 ticks released in the arena, all attained a final site selection by 24 h. These final sites were 7/15 (47%) edge of arena; 2/15 (13%) under bark; 2/15 (13%) open soil; 2/15 (13%) at or near release point; 1/15 (7%) tunnel with animal fur; and 1/15 (7%) tunnel with chicken feathers. At final site selection, 11/15 (73%) subsequently burrowed into the soil, 3 of which were completely buried.Time-lapse videography revealed that most ticks (80%) explored the arena in a “looping back” fashion. Overall, engorged Gulf Coast ticks moved at an average speed of 0.09 mm/s, and the total distance traversed by the ticks averaged 2.37 m.

Wolbachia pipientis (Hertig, 1936), also referred as Wolbachia, is a bacterium present across insect taxa, certain strains of which have been demonstrated to impact the fitness and capacity to transmit viruses in mosquitoes, particularly Aedes aegypti (Linnaeus, 1762). Most studies examine these impacts in limited sets of environmental regimes. Here we seek to understand the impacts of environmentally relevant conditions such as larval density, temperature, and their interaction on wAlbB-infected A. aegypti. Using a factorial design, we measured wAlbB stability (relative density, post-emergence in females, and in progeny), the ability for wAlbB to induce cytoplasmic incompatibility, and bacterial effects on mosquito fitness (fecundity, fertility, and body mass) and performance (adult survival and time to pupation) across 2 temperature regimes (fluctuating and constant) and 2 initial larval densities (low and high). Fluctuating daily regimes of temperature (27 to 40 °C) led to decreased post-emergence wAlbB density and increased wAlbB density in eggs compared to constant temperature (27 °C). An increased fecundity was found in wAlbB-carrying females reared at fluctuating temperatures compared to uninfected wild-type females. wAlbB-carrying adult females showed significantly increased survival than wild-type females. Contrarily, wAlbB-carrying adult males exhibited a significantly lower survival than wild-type males. We found differential effects of assessed treatments (Wolbachia infection status, temperature, and larval density) across mosquito sexes and life stages. Taken together, our results indicate that realistic conditions may not impact dramatically the stability of wAlbB infection in A. aegypti. Nonetheless, understanding the ecological consequence of A. aegypti-wAlbB interaction is complex due to life history tradeoffs under conditions faced by natural populations.

Wolbachia pipientis (Hertig, 1936), también referida cómo Wolbachia, es una bacteria ampliamente presente en el mundo de los insectos, algunas de sus cepas han demostrado impactos sobre el fitness y la capacidad de transmitir virus de algunos mosquitos, particularmente de Aedes aegypti (Linnaeus, 1762). Sin embargo, la mayoría de los estudios han examinado estos impactos en un conjunto limitado de regímenes ambientales. En este estudio buscamos entender los impactos de condiciones ambientales relevantes cómo la densidad larval, la temperatura ambiental y su interacción en A. aegypti infectados con wAlbB. Utilizando un diseño factorial, medimos la estabilidad de wAlbB (densidad relativa; hembras y progenie), la capacidad de wAlbB de inducir incompatibilidad citoplásmica, y los efectos de la bacteria en el fitness de los mosquitos (fecundidad, fertilidad, masa corporal) y desempeño (supervivencia adulta, tiempo de pupación) en dos regímenes de temperatura (fluctuante y constante) y dos densidades larvales iniciales (baja y alta). El régimen diario de temperatura fluctuante (27-40°C) condujo a una disminución en la densidad post-emergencia de wAlbB y un aumento en la densidad de wAlbB en los huevos en comparación con la temperatura constante (27°C). Se encontró un aumento en la fecundidad en las hembras portadoras de wAlbB criadas en temperaturas fluctuantes en comparación con las hembras no infectadas. Las hembras adultas portadoras de wAlbB mostraron una supervivencia significativamente mayor que las hembras silvestres. Por el contrario, los machos adultos portadores de wAlbB exhibieron una supervivencia significativamente menor que los machos silvestres. Encontramos efectos diferenciales de los tratamientos evaluados (estado de infección de Wolbachia, temperatura, densidad larval inicial) en los sexos y estadios de vida del mosquito. En conjunto, nuestros resultados indican que es posible que las condiciones realistas no impactan drásticamente la estabilidad de la infección wAlbB en A. aegypti. Sin embargo, es complejo entender las implicaciones ecológicas de la interacción A. aegypti-wAlbB debido a efectos compensatorios sobre la historia de vida del mosquito bajo condiciones enfrentadas por poblaciones naturales.

The distribution of container mosquitoes in relation to distances from forests was studied in temperate Japan. Mosquito larvae were collected between May and September in 4 years from tree holes, bamboo stumps, riverine rock pools, and artificial containers; sampling ranged spatially from the mountain forest across the deforested plain developed as agriculture and urban areas to the seacoast. Although tree holes, bamboo stumps, and artificial containers existed throughout the deforested plain area, 10 container species of 6 genera were found virtually only within 5 km from the nearest forest edge. Worldwide invasive Aedes albopictus (Skuse) and Aedes japonicus (Theobald) of Asian origin showed unique occurrence patterns different from other container species and from each other. Ae. japonicus was dominant in artificial containers in and near the forest but minor in forest natural containers and only occurred within 5 km from the forest. Ae. albopictus was minor in the forest irrespective of container types but not bound to the forest and dominant in natural and artificial containers throughout rural and urban areas.The 5-km range was designated as the circum-forest zone for container mosquitoes (except Ae. albopictus) in Japan, and an expanded concept, circum-boundary zone, is proposed.The widths of these zones primarily depend on the dispersal traits of mosquitoes. Whether the relation of Ae. albopictus and Ae. japonicus to forests we observed are common in the native and invasive ranges is discussed. The study of across-ecosystem dispersal is important for mosquito management under anthropogenically changing environments due to either deforestation or green restoration.

Factory-treated permethrin uniforms are the primary method used by the US Army to prevent arthropod bites and transmission of arthropod-borne diseases. In this study previously worn uniforms were collected from cadets at the United States Military Academy in West Point, NY to determine the amount of permethrin remaining after prolonged wear and subsequent effects on ticks. Six trousers were collected from cadets in the sophomore, junior, and senior classes. A new, unwashed uniform served as a positive control and an untreated maternity uniform served as a negative control. Fabric samples were removed from each trouser and used in bioassays with laboratory-reared Ixodes scapularis Say nymphs. Contact irritancy bioassays measured the nymphs' ability to remain in contact with fabric for a period of 5 min.Toxicity bioassays measured tick survival at 1 and 24 h after contacting uniform samples. liquid chromatography-mass spectrometry was used to quantify the permethrin content (mg/cm²) in each uniform after the bioassays were complete. The results showed significant amounts of permethrin were lost after extended wear and it was related to the cadet year group.The contact irritancy assays found uniforms with less permethrin did not irritate ticks and cause them to dislodge. Mortality was also affected by permethrin levels, with less ticks dying at 24 h on older uniforms. The results from this study show older uniforms lose most of their permethrin and no longer provide the same levels of protection.

In the last 2 decades, there has been an increase in the geographic range and frequency of vector-borne diseases. Management of mosquito populations has become challenging due to increasing rates of resistance to existing insecticidal products and formulations. Several alternative tools have emerged to suppress or replace mosquito populations. One of these tools is the In2Care Mosquito Station (In2Care station). This dual-action station contains the insect growth regulator pyriproxyfen which disrupts the development of immatures and the entomopathogenic fungus Beauveria bassiana (B. bassiana) strain GHA which kills exposed adult mosquitoes. The In2Care stations have previously been shown to effectively control Aedes aegypti in field settings at a density of 6 stations/acre rather than the label-recommended 10 stations/acre. To further test the efficacy of low station density deployment, we deployed In2Care stations in the Pleasant Street Historic District of Gainesville, Florida, at a density of 3 stations/acre over a period of 2 years in the presence or absence of ground larvicidal applications.The deployment of stations resulted in no measurable impact on Ae. aegypti and Culex quinquefasciatus adult or immature abundance suggesting that the low-density deployment of In2Care stations is insufficient to reduce Ae. aegypti and Cu. quinquefasciatus abundance within treatment areas.

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Among approaches aimed at reducing Lyme disease risk in the environment, those targeting reservoirs of Borrelia burgdorferi Johnson are promising because they have the potential to reduce both the density of questing Ixodes scapularis Say (Acari: Ixodidea) ticks and the prevalence of B. burgdorferi in the tick population. In this 4-yr field study, we treated a population of wild small mammals with 2 densities of fluralaner baits and investigated the effect of the treatment on 3 parameters of the endemic cycle of B. burgdorferi: (i) the prevalence of infected Peromyscus mice (PIM), (ii) the density of questing nymphs (DON), and (iii) the prevalence of infected questing nymphs (NIP). We demonstrated that fluralaner baiting is effective at reducing tick infestation of Peromyscus mice, the main reservoir of B. burgdorferi in central and northeastern North America, in the laboratory and the field. Results from this study showed a significant decrease in B. burgdorferi infection in mice (odds ratio: 0.37 [CI95: 0.17 to 0.83]). A reduction in the DON between 45.4% [CI95: 22.4 to 61.6] and 62.7% [CI95: 45.9 to 74.2] occurred in treated area when compared with control areas. No significant effect was reported on the NIP.These results confirm the hypothesis that fluralaner baits have an effect on B. burgdorferi endemic cycle, with the potential to reduce the density of B. burgdorferi-infected ticks in the environment. Further studies performed in various habitats and public health intervention contexts are needed to refine and operationalize this approach for reducing Lyme disease risk in the environment.

Directly involved in the “suck-and-spit” physiology, female mosquito salivary glands (SGs) primarily imbibe blood for egg development and release anticoagulants to keep blood flowing. Indirectly involved, mosquitoes can uptake arboviruses during blood feeding from a viremic host.This research examined the presence of the filamentous cytoplasmic contractile protein (F-actin) and heparan sulfate proteoglycan (HSPG), in the female mosquito SGs. Immunofluorescent antibody labeling of actin molecules or HSPG combined with anatomy suggests that F-actin forms a network in the SG lobe parenchymal cells attached to intralobar ducts by HSPG. In addition, F-actin twists around intralobar SG ducts in a beaded manner, altogether involved in the expulsion of SG secretions.This arrangement in female Aedes aegypti SGs, suggests that F-actin structures are integrally involved in transmitting infectious agents into hosts.

The transmission and incidence of vector-borne diseases rely on vector distribution and life history traits such as survival, fecundity, and feeding. Since arthropod disease vectors are ectotherms, these vital rates are strongly influenced by temperature. Chagas disease is a neglected tropical disease caused by the protozoan parasite, Trypanosoma cruzi. This parasite is transmitted when the feces of the infected triatomine enter the bloodstream of the host. One of the most important vector-species of this disease in the Southern Cone region of South America is Triatoma infestans. In this study, we evaluated the role of constant and variable environmental temperature on the feeding behavior of T. infestans. Fifth-instar nymphs were acclimatized to 4 thermal treatments comprising 2 temperatures (27 °C and 18 °C) with and without diurnal thermal variability (27 ± 5 °C and 18 ± 5 °C). Individuals were fed weekly for 7 wk to quantify their feeding. Our results showed lower feeding frequency in nymphs acclimatized to cold temperature compared to those from warmer temperature treatments. However, treatments with thermal variability presented a nonlinear effect on feeding, with an increased feeding rate in the cold, variable treatment and a decreased feeding rate in the warm, variable treatment. Individuals maintained under cold treatments, the variable temperature exhibited a higher feeding rate and the lowest amount of ingested blood among all treatments. Thus, natural diurnal temperature variation cannot be ignored if we are to make more accurate T. cruzi transmission risk predictions now and in the future.

The Nísia Floresta National Forest, located in Rio Grande do Norte (RN), is an important remnant of the Atlantic Forest biome in Brazil. Bromeliad tanks in this forest offer suitable breeding sites for mosquito species that may act as viral vectors, thus posing an epidemiological concern. However, studies investigating the presence of immature Culicidae in natural breeding sites in RN have thus far been restricted to Caatinga vegetation.This study investigated mosquitoes and their natural breeding sites in bromeliads growing in the Nísia Floresta National Forest. From March 2013 to February 2014, monthly samples were collected from the tanks of five randomly selected bromeliads and larvitraps placed in each of the three forest management areas. Hohenbergia catingae Ule (Hohenbergia bromeliad) is an important shelter for immature mosquitoes. Culex (Microculex) was the predominant species, representing 86% of the immature mosquitoes collected. A rare occurrence of Aedes (Stegomyia) aegypti (Linnaeus, 1762) (generally associated with urban areas under high anthropogenic influence) was observed, highlighting the importance of investigating the presence of mosquitoes in different natural habitats. An analysis of species diversity revealed that species such as Culex imitatorTheobald, 1903 and Culex davisi Kumm, 1933, have a strong association with bromeliads. In tire traps (larvitraps) Aedes (Stegomyia) albopictus Skuse, 1894 was predominant. Environmental changes, such as deforestation, removal of bromeliads, and climate change in the area, can influence the migration of species and adaptation to new habitats in a peridomiciliary environment around the forest, consequently the possibility of transmission of virus and other pathogens.

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Discarded vehicle tires serve as habitat for mosquito vectors. In New Orleans, Louisiana, discarded tires are an increasingly important public concern, especially considering that the city is home to many medically important mosquito species. Discarded tires are known to be associated with mosquito abundance, but how their presence interacts with other socioenvironmental gradients to influence mosquito ecology is poorly understood. Here, we ask whether discarded tire distribution could be explained by social factors, particularly median income, home vacancy and human population density, and whether these factors interact with urban heat islands (UHI) to drive mosquito vector assemblages. We surveyed tire piles across the city and adult mosquitoes in 12 sites, between May and October of 2020. We compared this data with the social indicators selected and UHI estimates. Our results show that median income and human population density were inversely related to tire abundance.Tire abundance was positively associated with Aedes albopictus abundance in places of low heat (LS) severity. Heat was the only predictor for the other monitored species, where high heat corresponded to higher abundance of Aedes aegypti, and LS to higher abundance of Culex quinquefasciatus. Our results suggest that low-income, sparsely populated neighborhoods of New Orleans may be hotspots for discarded vehicle tires, and are associated with higher abundances of at least one medically important mosquito (Ae. albopictus). These findings suggest potential locations for prioritizing source reduction efforts to control mosquito vectors and highlight discarded tires as a potential exposure pathway to unequal disease risk for low-income residents.

Similar to other states in the southeastern United States, human cases of tick-borne diseases in Alabama have risen steadily over the last 2 decades. Nevertheless, limited data have been published on ticks or tick-borne pathogen (TBP) distributions since the 1990s.To better understand the risk of tick andTBP exposure in eastern central Alabama, ticks were sampled repeatedly across 8 sites associated with recreational use during May and June of 2015 to characterize tick density and diversity. Although habitats were similar across sites, tick density varied among locations. Seven species were collected, but 97.7% of 1,310 samples were the lone star tick, Amblyomma americanum (L.), the primary vector of ehrlichial agents and the tick species most commonly linked to alpha-gal syndrome and southern tick-associated rash illness. To investigate pathogen prevalence among sites, we tested A. americanum by a multiplex qPCR assay for 5 bacterial species, including 3 Ehrlichia spp. and 2 Rickettsia spp. None of the specimens tested positive for Panola Mountain Ehrlichia or Rickettsia parkeri. However, causative agents of human ehrlichiosis, Ehrlichia chaffeensis and Ehrlichia ewingii, occurred at half of the locations with, respectively, 0.27% and 0.45% of A. americanum infected on average. In contrast, Rickettsia amblyommatis, a tick endosymbiont suspected to be nonpathogenic, was found in 54.5% of the 1119 A. americanum tested. Despite low infection rates of Ehrlichia spp. in A. americanum, high encounter rates with this species in recreational deciduous woodlands suggest a moderate risk of tick bite and a low-to-moderate risk ofTBP exposure in late spring.

Haemaphysalis longicornis (Neumann) was first established in New Jersey and has rapidly spread across most of the eastern United States. This tick has the potential to infest a wide variety of hosts and can reproduce quickly via parthenogenesis, presenting a new threat to animal health. Here we report the first record of a single H. longicornis tick in Mecklenburg County, Virginia, from incidental field collections of ticks. In addition to H. longicornis, we collected 787 Amblyomma americanum, 25 Dermacentor variabilis, 6 Ixodes affinis, 1 Haemaphysalis leporispalustris, and 1 Amblyomma maculatum using standard dragging and flagging techniques.The expansion of H. longicornis will have economic consequences for livestock producers in south-central Virginia, who must now manage this species. Enhanced surveillance is needed to fully understand its growing geographic distribution in the United States and the subsequent consequences of its spread.