Medical and Veterinary Entomology最新文献

Some species of the genus Chrysomya, known as hairy maggot blowflies (Diptera: Calliphoridae), are medically and forensically important insects worldwide. However, identifying these species can be challenging due to morphological characteristics overlapping. In this study, we investigated morphological and molecular differences among three hairy maggot blowflies: Chrysomya rufifacies Macquart, 1843, Chrysomya albiceps (Wiedemann, 1819), which are widely distributed throughout the Old World, respectively; and Chrysomya villeneuvi Patton, 1922, which is restricted to Asia. Morphological analysis revealed overlapping characters in larval and adult stages of C. rufifacies and C. albiceps based on traditional diagnostic characters, confirming phenotypic polymorphism in both species. Due to the global spread of these species, likely by human activity and climate change, a morphological and phylogenetic investigation was underway. A revision of the established morphological keys was proposed, and the phylogenetic analysis supported a sister relationship among the three species, with C. rufifacies more closely related to C. albiceps (genetic distances of 2.42%-3.13%) than to C. villeneuvi (3.49%-4.40%). Notably, C. albiceps differed from C. villeneuvi (3.31%-3.48%), suggesting that C. albiceps, occupies an intermediate evolutionary position between C. rufifacies and C. villeneuvi.

Houseflies (Musca domestica L.), a widespread pest in livestock facilities, have developed resistance to commonly utilized insecticides, including pyrethroids, organophosphates and carbamates. However, the genetic status of insecticide resistance in Japanese housefly populations remains largely elusive. We used hybridization probe capture and next-generation sequencing (NGS) to examine the mutations across the entire coding sequence of two insecticide target genes, voltage-gated sodium channel (VGSC) and acetylcholinesterase (AChE), from 240 individual M. domestica collected from 14 livestock facilities in Japan between 2013 and 2024. This study is the first to utilize these molecular methods to examine insecticide resistance in houseflies collected from the field. Resistance-related mutations in VGSC (e.g., super-kdr [M918T + L1014F], kdr-His [L1014H] and L1014F) were detected in most wild populations, with differing allele frequencies. Notably, super-kdr was widespread (12/15 populations) with frequencies ranging from 0.06 to 1.00, whereas kdr-His was observed in 8/15 populations with 0.03-0.70 frequencies. For AChE, three known resistance mutations (V260L, G342A/V and F407Y) were observed in all populations, with at least one resistance allele present at 0.65-1.00 frequencies. An elevation in NGS read counts for AChE was noted in several populations, along with the presence of three distinct alleles at amino acid position 342, suggesting AChE gene duplication. These duplications may help in mitigating the fitness costs linked to AChE resistance. Our results show the widespread presence and complexity of insecticide resistance mutations in Japanese M. domestica populations and underscore the use of NGS-based probe capture techniques for monitoring the evolution of resistance.

Heavy metal exposure represents a substantial health risk to humans and other animals, in some cases leading to death. However, detecting these metals in decaying corpses can pose a considerable challenge. In such situations, the eventual presence of necrophagous insects feeding on the remains may serve as a valuable tool for detecting and measuring these toxic substances. Nonetheless, heavy metals might affect insect development and survival rates. This study explored the effects of increasing concentrations of arsenic, mercury, cadmium and lead compounds on the survival and development rate of Calliphora vicina (Robineau Desvoidy, 1830) (Diptera: Calliphoridae) larvae. Additionally, the research investigated the possibility of tracing these metals in the developed larvae and whether bioaccumulation occurred. The larvae were reared in a dog food matrix infused with varying concentrations of these heavy metal compounds, ranging from 0.0 (control) to 60 mg/kg. The results showed that all tested metals increased mortality rates in a non-linear dose-dependent manner. Higher concentrations of each metal limited larval growth, as evidenced by lower length and weight than the control group. This growth inhibition could lead to inaccurate post-mortem estimations based on entomological evidence collected in heavily contaminated substrates. All metals were successfully detected in the larvae; however, bioaccumulation was only confirmed for cadmium at low concentrations. Therefore, C. vicina larvae can serve as a valuable toxicological indicator for these elements, especially when larvae are found in the corpses of individuals chronically exposed to the assessed heavy metals.

The 'core Guimaraesiella' comprise a morphologically rather homogeneous group of avian chewing lice (Phthiraptera), most of which remain undescribed. Based on an integrative approach combining morphological characters and analyses of COI barcoding sequences, we here describe two new species within this group: Guimaraesiella impiger new species and Guimaraesiella stellana new species. Both species were collected from hippoboscid flies in Singapore, suggesting that they are capable of moving phoretically between hosts. In at least G. impiger, this was confirmed as louse specimens from another 30 host species that were found to be conspecific with the holotype of G. impiger in our mOTU analysis. This, together with limited morphological variability between species, highlights the need to combine genetic and morphological data when identifying 'core Guimaraesiella' species from southeast Asia. Moreover, both louse species appear to be able to cross vast geographical distances. Guimaraesiella impiger is known from across southeast Asia as well as in Malawi, despite none of the known hosts occurring in both Asia and Africa. Guimaraesiella stellana is known from two host species, one in Singapore and one in Australia, separated by several known biogeographical barriers, which seem to have limited the range of all known closely related species to the Australo-Papuan region; how G. stellana arrived in Singapore on a nonmigratory host is presently unknown. These cases highlight that comparisons with only locally occurring louse species may not be a valid identification method for this group. As both species described here are morphologically similar, identification of cryptic species of lice in this group within Guimaraesiella may need to rely on COI barcodes or other molecular markers.

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.

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.