Medical and Veterinary Entomology最新文献

The active dispersal of triatomines has great epidemiological importance as it constitutes the main mechanism of colonization and reinfestation. Walking dispersal and its locomotor system have been little studied in triatomines. The aim of this study was to characterize the locomotor activity of fifth-instar nymphs of T. infestans and link it to morphometric characteristics of the body, legs and their articles. For locomotor activity, each insect was placed on a circular arena and was filmed while walking freely for 10 min. The variables analysed were distance travelled (TD), movement time (TM) and effective speed (ES). Photographs were then taken of the body, the right legs and their articles, and morphometric tools were used to obtain linear, size and shape metrics. On average, a nymph walked 470 cm and moved for 5 min at an ES of 98 cm/min. Positive correlations were observed for TD-TM and TD-ES. Body and leg lengths correlated mainly with ES. Linear measurements showed the same pattern for each leg: TD correlated with femur and tibia length, and coxa width; TM did not show correlation; and ES correlated with femur and meron length, and coxa width. Size variables showed different associations for each leg. Shape variables revealed the associations of the meron with TD for foreleg and of the femur with TD for mid and hind leg. The locomotor activity of fifth-instar nymphs of T. infestans was highly variable in time and distance, with a relatively constant speed. The results suggest that linear dimensions are not linked to the function of each leg, but rather the size and shape of the articles. Thus, the specific function of the foreleg during walking would be linked to the size and shape of its proximal part, while that of the hind leg would be linked to the size and shape of its distal part. Our results provide a solid understanding of how the form of the locomotor structures is linked to walking performance.

The Aedes (Stegomyia) aegypti mosquito is the main vector of arboviruses such as dengue, urban yellow fever, chikungunya and Zika. The extensive use of insecticides to control this vector has led to the selection of resistant populations, compromising the effectiveness of control programmes. Insecticide resistance is often related to the integration of transposable elements (TEs) in specific genes. TEs can also contribute to the regulation of gene expression in response to insecticides. In this paper, we performed transcriptome analysis of the mosquito Ae. aegypti using bioinformatics tools to identify and characterize TEs. We also evaluated the relative expression of these mobile elements in susceptible strains and resistant strains exposed to the organophosphate insecticide malathion. In total, 6915 transcripts showed significant similarity with TEs and/or characteristic domains. Retrotransposons (Class I) accounted for 67% (4604 sequences) of the elements identified, while DNA transposons (Class II) were less abundant, with 2311 annotations (33%). TEs were classified into 39 superfamilies, with Gypsy and MITEs being the most abundant. Expression data of mobile elements showed both up- and downregulated elements in resistant strains challenged with the organophosphate insecticide malathion compared to susceptible strains. Mobile element expression data showed both upregulated and downregulated elements in resistant strains challenged with the insecticide compared with susceptible strains. These data contribute significantly to knowledge about the expression of some groups of mobile elements present in the genome of this species. Therefore, TE insertions may have a potential role in the resistance observed in this species, and suggest the role of stress on their expression. Such results provide insights into understanding molecular and cellular mechanisms that can be used in strategies to control mosquitoes.

Bovine theileriosis is a vector-borne disease poised to become one of the most economically significant diseases of cattle in the United States. The hemoparasite Theileria orientalis Ikeda genotype causes bovine theileriosis (Piroplasmida: Theileriidae), which is primarily transmitted by Haemaphysalis longicornis Neumann (Acari: Ixodidae) (longhorned tick, Asian longhorned tick). Since its initial detection in New Jersey in 2017, H. longicornis has rapidly spread to 24 states and Washington, DC, as of July 2025. Given the exotic and invasive nature of this vector and its unique biological characteristics, cattle producers face a lack of effective management guidelines. This study documents our first response to a T. orientalis Ikeda-positive herd in Maury County, Tennessee (USA). Before our arrival and detection of H. longicornis on the property, we advised the producer to maintain a closed herd, use on-animal chemical control, and reduce overgrown vegetation. Upon arrival, we identified sampling areas where cattle primarily resided or previously had been and targeted these areas using timed tick dragging methods, checking the drag for ticks every 10 meters for a mean of 352 min per visit (~6 h). Collections occurred once in July 2022 and every other week in 2023 (June-November). In total, 166 H. longicornis larvae and 45 nymphs were collected. Nymphs were screened for T. orientalis, and 4.5% (2/44) were positive for T. orientalis Ikeda a year after the herd was initially confirmed positive. This study contributes to the long-term goal of developing first response plans for farms facing H. longicornis infestations and bovine theileriosis infections, thereby limiting the spread of this tick and pathogen.

Anopheles stephensi (Diptera: Culicidae), a primary malaria vector native to south Asia and the Arabian peninsula, has recently spread to Sri Lanka and the Horn of Africa (HOA). Its arrival poses a serious challenge to malaria control initiatives, particularly in the rapidly urbanized African settings because it can transmit both Plasmodium falciparum (Haemosporida: Plasmodidae) and Plasmodium vivax (Haemosporida: Plasmodidae). This threat is compounded by the vector's growing resistance to insecticides, particularly pyrethroids, the backbone of indoor residual spraying (IRS) and insecticide-treated nets (ITNs). The use of dichlorodiphenyltrichloroethane (DDT), which exhibits a comparable mode of action to pyrethroids, significantly increases the likelihood of cross-resistance development. This review presents the first regionally integrated synthesis of An. stephensi susceptibility to pyrethroids and DDT. The analysis encompasses phenotypic resistance and underlying molecular mechanisms across the World Health Organization (WHO) Eastern Mediterranean Region, the Indian subcontinent and the HOA regions where the species is either native or invasive. Twenty-one studies published over the past two decades were identified through searches in five electronic databases. The findings revealed confirmed resistance to multiple pyrethroid compounds such as permethrin, deltamethrin, lambdacyhalothrin, alpha-cypermethrin, and cyfluthrin, as well as DDT, while susceptibility to etofenprox varied by location. Geographic variability was observed in intensity of resistance and allele distribution across Iranian sites. Mechanistically, resistance was linked to both target-site knockdown resistance (kdr) mutations (L1014F and L1014S) and metabolic detoxification pathways involving cytochrome P450s, glutathione S-transferases (GSTs), and esterases. These findings underscore the escalating menace that insecticide resistance poses to malaria vector control, particularly in newly invaded regions characterized by inadequate surveillance infrastructure and pronounced reliance on pyrethroid-based interventions. This review advocates for the establishment of comprehensive global monitoring frameworks and the formulation of evidence-based resistance management strategies tailored to local vector ecologies and resistance mechanisms.

Hippobosca equina, a common ectoparasite of horses, poses a significant challenge to equine health worldwide. This study provides a molecular characterization of H. equina and examines its impact on host immune responses and oxidative stress. Genetic analysis of samples from various regions revealed notable homogeneity, indicating limited genetic variation among populations. Phylogenetic analysis demonstrated close genetic relationships among sequences from Egypt, France, Kazakhstan and Portugal, while also showing comparable but more distant identities to sequences from China, Denmark, Finland and other countries. Infested horses exhibited elevated levels of pro-inflammatory cytokines, including IL-6, TNF-α and IFN-γ, relative to uninfested control horses, indicating a strong immune response to the parasite. Additionally, there was a significant increase in oxidative stress markers, including malondialdehyde, catalase, glutathione peroxidase and nitric oxide, indicating substantial cellular damage. These findings highlight the dual impact of H. equina infestations on horse health, prompting both immune activation and oxidative stress. This study emphasizes the importance of targeted pest management strategies that consider the genetic uniformity of parasites and host physiological responses. By providing valuable insights into the complex host–parasite interactions between H. equina and equine hosts, this research enhances our understanding of equine ectoparasites and suggests potential avenues for improving horse health and welfare.

Leishmaniasis comprises a group of vector-borne neglected tropical diseases caused by species of the obligatory intracellular parasite Leishmania, transmitted by the bite of dipteran sand flies. Infected dogs serve as the primary domestic reservoir of Leishmania parasites and are often found in close association with various arthropods, such as fleas and ticks. There have been recent reports of Leishmania infections occurring in areas non-endemic for sand fly species, leading to reconsideration of the hypothesis that other arthropods, such as ticks, may also play a significant role in the natural history and epidemiology of leishmaniasis. Here, we used a tick cell line as a tool to study Leishmania infantum and tick interaction. The results showed that L. infantum can bind to and proliferate inside Ixodes scapularis IDE8 tick cells. The infection did reduce tick cell viability and induce reactive oxygen species (ROS) production. Lipid profile analysis showed that the presence of L. infantum increased oxysterol in tick cells and influenced tick cell lipid biosynthesis, since an increase in glycerolipids and esterified cholesterol was observed in infected cells at 48 h. Further experiments are necessary to elucidate whether Leishmania can overcome the various biochemical and tissue barriers within ticks and be transmitted to the host.

This study reported hard tick (Ixodida: Ixodidae) infestation in sheep of Samara city, north of Baghdad, from June to December 2023. A total of 480 ticks were manually pulled out from the sheep with an ethanol-soaked tissue and preserved in plastic containers containing 70% ethyl alcohol. All samples were counted and examined individually under a light microscope to identify the genus. Preliminary microscopic examination revealed that the majority of the collected ticks were Hyalomma, with 91.4%, followed by Rhipicephalus (6.8%) and Ixodes (1.8%). Furthermore, Hyalomma was dominant across all months, with a peak relative abundance in October (100%). The peak relative abundances for Rhipicephalus (16%) and Ixodes (4.3%) occurred in July. Under further microscopic evaluation, morphological features demonstrated three species, namely, Hyalomma detritum (Koch), Hy. anatolicum (Koch) and Rhipicephalus sanguineus sensu lato (Latreille). To confirm genera and species, molecular diagnosis was performed, based on the COX1 gene, resulting in the identification of five species, namely, Hy. detritum, Hy. anatolicum, Hy. excavatum (Koch, 1844), Rh. sanguineus sensu lato and an unidentified Ixodes sp. While the Ixodes scapularis isolation unexpectedly revealed genetic resemblance to North American samples, indicating a wider geographical spread, the Hyalomma and Rhipicephalus isolates shared ancestry with other Middle Eastern strains, demonstrating regional genetic stability. These results showed the comprehensive diversity of tick species in sheep, including Hyalomma, Rhipicephalus and Ixodes, and also provided good epidemiological data to support the preventative procedures of tick-borne infections in Samarra city.

Surveillance and diagnostics are critical for the early detection, containment and eradication of exotic pests. For the screwworm fly, this is usually via targeted surveillance and exclusion testing of trap-caught flies, as well as the identification of larvae associated with myiasis wounds. We present a specific and sensitive real-time polymerase chain reaction (PCR) assay for the detection of the New World screwworm fly, Cochliomyia hominivorax Coquerel (Diptera: Calliphoridae). The assay targets the cytochrome oxidase subunit 1 (cox1) gene from adult flies or larvae and retains high analytical sensitivity when multiplexed with an existing assay for the Old World screwworm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), achieving a limit of detection of less than 1 copy per microlitre of reaction. To assess its utility for surveillance and diagnostics, a novel non-destructive DNA extraction method was performed on spiked trap catches of field-caught flies, and on boiled and unboiled specimens of larval instars. The multiplexed assay detected 95% of spiked flies, and all screwworm flies from positive samples were retrieved and morphologically identified. Results from larval instars confirmed that the assay can be used for larvae, with higher sensitivity observed for unboiled larval instars. This molecular assay enables the simultaneous detection of Co. hominivorax and Ch. bezziana, offering a reliable alternative to existing single-target and destructive methods of bulk fly testing. It also holds potential for broader application in the identification of larval stages.

Rhipicephalus sanguineus Latreille (Ixodida: Ixodidae) has an economic impact as it is a blood-feeding ectoparasite transmitting numerous pathogens to humans and animals. The present study evaluated the acaricidal effect of eucalyptus essential oil (EO) with the concentrations (40%, 30%, 20%, 10%, 5% and 2.5%), eucalyptus nano-emulsion (ENE) with the concentrations (30%, 20%, 15%, 10%, 5%, and 2.5%), ENE combined with silver nanoparticles (ENE & SNPs) with the concentrations (5%, 4%, 3%, 2% and 1%) and SNPs with the concentrations (5%, 4%, 3%, 2% and 1%) on unfed adults of R. sanguineus sensu lato using the adult immersion test. There were two controls, one with tween 80 and the other without tween 80, while Bravecto® was used as an acaricidal reference. The nanoformulations were analysed by particle size, UV-visible spectroscopy, and transmission electron microscopy (TEM). The mortality of treated R. sanguineus was recorded daily for 7 days. The mortality of ENE and SNPs, EO and SNPs at 7 days was 96.6%, 90% and 80%, at concentrations of 5%, 40% and 5%, respectively. The lethal concentration to 50% mortality (LC₅₀) of EO, ENE, ENE and SNPs, and SNPs at 7 days was 6.65, 9.49, 2.23 and 4.08%, respectively. The particle size of nanoformulations was (83.08, 10.59 and 223.4 nm) for ENE, a mixture of SNPs, and ENE and SNPs, respectively. Scanning electron microscopy of treated adult R. sanguineus revealed numerous alterations in aeropyles of spiracular plates, anal grooves and mouthparts. The histopathological examination of the treated adult R. sanguineus showed degeneration in the cuticle, midgut and salivary gland. These findings demonstrate that eucalyptus oil could be used as part of an integrated pest management program for the control of R. sanguineus.

This study analysed the presence of Rickettsia (Rickettsiales: Rickettsiaceae) in fleas (Siphonaptera) associated with cricetid rodents in periurban localities of Gran La Plata, Argentina. Rodents were captured in three localities and fleas were collected directly from their fur. After DNA extraction, fleas were prepared for microscopic identification. PCR amplification of gltA and ompB genes was performed on each individual flea to detect and identify Rickettsia. The OmpB gene was sequenced and compared using nBLAST to initially identify its similarity with other sequences from GenBank. A phylogenetic tree was constructed to evaluate the relationships of the sequences obtained with others deposited in GenBank. Out of the 253 cricetids (seven species) captured, 87 fleas (four species) were collected. Of them, 10 fleas (11.5%) tested positive for Rickettsia. According to nBLAST and the phylogenetic tree results, sequences of this study were identified as R. felis Bouyer et al. Those sequences were obtained only from five of the seven cricetid species and from two of the three localities, as follows: from Street 143 and Diagonal 630, Arana neighbourhood, La Plata District: Polygenis (Polygenis) axius (Jordan and Rothschild) (n = 3) and Polygenis (Neopolygenis) atopus (Jordan and Rothschild) (n = 1); and from Balneario La Balandra, Berisso District: Polygenis (Polygenis) axius (n = 4), Polygenis (Neopolygenis) atopus (n = 1) and Craneopsylla minerva minerva (Rothschild) (n = 1). Our results confirm the presence of R. felis in fleas parasitizing cricetids in the periurban area of Gran La Plata, which could represent a risk to public health.