Medical and Veterinary Entomology

BackgroundThe invasive mosquito Aedes koreicus has established populations in several European countries during the past decade, raising increasing public health concerns due to its potential role as a vector of pathogens. While species identification is primarily based on morphological characters, Ae. koreicus exhibits distinct morphological variants originating from mainland Korea and Jeju Island, which complicates surveillance and may lead to misidentification, particularly in regions where closely related species co-occur. To date, the genetic basis and population-level relevance of these morphological forms in Europe remain poorly understood. MethodsWe investigated the co-occurrence of two morphological forms of Ae. koreicus in Hungary, representing the first confirmed European location where both forms were detected sympatrically and even within the same breeding sites. Adult mosquitoes were morphologically characterised using diagnostic traits, and individuals representing both morphotypes were subjected to comprehensive genetic analyses. We sequenced multiple mitochondrial markers (COX1, COX2, COX3, ATP6, ND1, ND3) and the nuclear ITS2 region using Oxford Nanopore long-read sequencing. Phylogenetic reconstructions and haplotype network analyses were applied to assess genetic differentiation between morphotypes and to compare them with Aedes japonicus as a closely related reference species. ResultsAcross all analysed mitochondrial and nuclear markers, no genetic differentiation was detected between specimens identified as the "mainland" or "Jeju-do" morphological forms of Ae. koreicus. Phylogenetic and haplotype network analyses consistently grouped individuals independently of their morphotype, indicating a shared genetic background at the population level. In contrast, Ae. japonicus formed a clearly distinct genetic lineage, confirming the robustness of the applied markers for interspecific discrimination. ConclusionsOur results demonstrate that the observed morphological variability in Ae. koreicus populations are not underpinned by detectable genetic differentiation using commonly applied mitochondrial and genomic markers. These findings highlight the limitations of using morphology alone to infer population origin or structure and emphasise the need for heightened awareness of intraspecific variability in routine surveillance. Accurate morphological identification remains critical, particularly in citizen science-based monitoring programmes and AI-based automatization platforms, such as Mosquito Alert, to avoid confusion with morphologically similar invasive species. Further studies integrating genomic and ecological approaches are required to elucidate the mechanisms underlying morphological variability in this emerging vector species.

BackgroundAnopheles gambiae sensu lato (s.l.) is the primary vector of malaria in sub-Saharan Africa. Although insecticide-based vector control has been central to prevention, the widespread emergence of insecticide resistance poses a serious biological threat to control efforts. Effective resistance monitoring is essential for sustaining vector control but remains highly limited in malaria-endemic hotspots. Here, we assessed pyrethroid and DDT resistance intensity and the frequency of the L1014F knockdown resistance (kdr) mutation in Anopheles gambiae s.l. populations from Sokoto, north-western Nigeria. MethodologyResistance status and intensity to five insecticides were determined in adult Anopheles reared from larvae collected in 2021 and 2022 using the World Health Organization (WHO) tube test and Centers for Disease Control and Prevention (CDC) bottle bioassay, respectively. A subset of resistant mosquitoes was analyzed using PCR-based diagnostic assays to identify species within the Anopheles gambiae complex and to genotype for the West African kdr mutation (L1014F). ResultsHigh knockdown times (KDT) were observed, with KDT50 ranging from 38 to 91 minutes and KDT95 from 104 to 678 minutes, indicating increased resistance levels across all insecticides. In 2021, resistance was detected to DDT, lambda-cyhalothrin, and permethrin, while susceptibility to alpha-cypermethrin (98%) and suspected resistance to deltamethrin (91%) were recorded. In 2022, a general increase in resistance to all insecticides was observed, with mortality rates ranging from 41% to 81%. High resistance intensity was observed against DDT, while permethrin and alpha-cypermethrin exhibited low resistance intensity in both years, failing to reach 10x the diagnostic dose. Deltamethrin and lambda-cyhalothrin showed low to moderate resistance intensity. The 1014F kdr mutant genotype was widely distributed (68.1%) across species and years. Allele frequencies were higher in An. gambiae s.s. (0.83) than in An. arabiensis (0.71), with significant deviations from Hardy-Weinberg equilibrium (p < 0.05), except for An. gambiae s.s. in 2021 (p = 0.7). ConclusionThese findings reveal a concerning increase in key insecticide resistance among Anopheles populations in Sokoto, underpinned by strong genetic mechanisms. This underscores the urgent need for integrated vector management strategies to sustain effective vector control efforts in the region.

Tunisia is considered a high-risk country for arboviral transmission, and the re-emergence of malaria. Vector control programs predominantly rely on insecticide-based interventions, however knowledge on the insecticide resistance status of local vectors is limited. Here, we determined the mosquito species composition and investigated the resistance status of disease vectors to insecticides, collected from two distinct ecological settings; urban setting and rural setting. Known insecticide resistance loci were molecularly analysed. A total of 210 mosquitoes were collected, representing three main genera: Culex (n = 119), Aedes (n = 79), and Anopheles (n = 1). Within the Culex genus, Cx. pipiens pipiens and Cx. pipiens hybrids were the predominant species in Monastir and Kairouan respectively. Amongst Aedes, Ae. albopictus was the most abundant species in Monastir, while Ae. caspius predominated in Kairouan. The knockdown (kdr) mutation L1014F was detected at both sites across the three Cx. pipiens biotypes. In contrast, Cx. perexiguus showed no kdr mutation in Kairouan and a low frequency in Monastir. Among Aedes species, kdr mutations were detected exclusively in Ae. albopictus, restricted to domain III (mutation I1532T). No mutations in the chs gene were identified in both populations. Aedes albopictus collected in Monastir exhibited a moderate copy number variation for both carboxylesterases 3 and 6. No mutations were detected in the Anopheles labranchia. Our study results indicate the suitability of diflubenzuron for Culex and Ae. albopictus control in central Tunisia, emerging pyrethroid resistance in both vector species, and possibly reduced organophosphate efficacy against Ae. albopictus.

Diapause is a critical adaptive strategy that enables temperate mosquito species to survive adverse environmental conditions and maintain population persistence across seasons. In Culex pipiens, diapause plays a key role in overwintering and influences the seasonal dynamics of arbovirus transmission. However, diapause expression is often assessed using single traits, limiting our understanding of its integrated physiological basis and variation among populations. In this study, we investigated the behavioural, morphological, and reproductive signatures of diapause across three laboratory strains of Culex pipiens (Mogden, Pirbright, and Pirbright Hybrid) reared under diapause-inducing (10 {degrees}C), cold (14 {degrees}C), and control (26-27 {degrees}C) conditions. We quantified blood-feeding behaviour, wing size as a proxy for somatic growth, and spermatheca size as an indicator of reproductive development. Diapause-inducing conditions resulted in a coordinated phenotype characterised by strong suppression of blood-feeding, increased somatic size, and marked inhibition of reproductive development. Mosquitoes reared at 10 {degrees}C exhibited near-complete feeding inhibition and significantly reduced spermatheca size, consistent with reproductive arrest, while those reared at 14 {degrees}C showed intermediate phenotypes. In contrast, control mosquitoes displayed active feeding and fully developed reproductive structures. Wing size increased progressively with decreasing temperature, with the largest individuals observed under diapause-inducing conditions. When analysed together, wing size and spermatheca development exhibited opposing responses across temperature treatments, revealing a strong negative association and indicating a trade-off between somatic growth and reproductive investment. This integrated response supports the interpretation of diapause as a coordinated life-history strategy involving resource reallocation towards survival. Additionally, diapause expression varied among strains, with the Mogden strain showing reduced sensitivity compared with Pirbright and hybrid populations, highlighting the role of genetic background in diapause plasticity. These findings demonstrate that diapause in Culex pipiens is a multi-trait, plastic phenotype with important implications for overwintering success and the seasonal dynamics of arbovirus transmission in temperate regions.

A parasitic mite of honey bee brood (Tropilaelaps mercedesae), is spreading through populations of Apis mellifera honey bees in new regions and poses a major threat to honey bee health. Despite its clear threat, the biology of this mite is poorly understood, with gaps on such fundamental issues as how fast its populations can grow. This leaves the beekeeping world underprepared to plan for its arrival and management. In this study, we documented the growth of T. mercedesae populations in untreated A. mellifera colonies in Thailand and South Korea, and did the same for another parasitic mite (Varroa destructor) when possible. We found that the population growth of T. mercedesae was variable but could reach high levels (daily r of 0.010, 0.036, and 0.057), while the population growth of V. destructor (r = 0.021) matched previous estimates. Our results indicate that T. mercedesae populations can grow rapidly but they do not always attain this potential. Based on our results, humidity should be studied as a potential driver of population growth. If future work can reveal key drivers of T. mercedesae population growth, this would help predict infestations and help design management strategies that exploit the pest's biological vulnerabilities.

1In 2024-2025 a multi-centre study involving seven international laboratories was conducted with the support of the World Health Organization (WHO). The aim of the study was to establish and validate discriminating concentrations (DCs) in WHO bottle bioassays for monitoring susceptibility to broflanilide and isocycloseram in Anopheles gambiae s.s., An. funestus, An. stephensi and Aedes aegypti. The following values are recommended for adoption as DCs for broflanilide: 10 {micro}g/bottle for An. gambiae and Ae. aegypti, 15 {micro}g/bottle for An. funestus, and 25 {micro}g/bottle for An. stephensi. The recommended DCs for isocycloseram are 15 {micro}g/bottle for Ae. aegypti, 30 {micro}g/bottle for An. gambiae, 50 {micro}g/bottle for An. stephensi, and 60 {micro}g/bottle for An. funestus. Based on the experiences of conducting this study, which represents the application of a generic protocol for establishing discriminating concentrations produced by the WHO, technical recommendations are made on the generation and analysis of DC data for insecticides in future.

IntroductionProgress against malaria has stalled since 2015, with insecticide resistance a key driver. Spatial emanators release volatile insecticides into the air, exposing mosquitoes through a route distinct from the tarsal contact used by treated nets, indoor residual spraying, and standard bioassays. Transfluthrin is currently monitored using the WHO bottle bioassay, which combines contact and vapour exposure and cannot isolate airborne effects. A scalable, vapour-only method is needed to characterise susceptibility to volatile pyrethroids. MethodsWe adapted the WHO tube bioassay to deliver non-contact transfluthrin vapour exposure without contacting treated papers. Non-blood-fed female Anopheles were exposed to acetone control or transfluthrin papers at 0.005, 0.1 and 2 mg/paper. Knockdown was recorded over 60 minutes and mortality at 24 hours. Testing spanned three laboratories (LSTM, AIRID and KEMRI) using susceptible reference and resistant lab colonies. Dose response models estimated EC{square}{square} for knockdown (EC{square}{square}KD) and mortality (EC{square}{square}Mort), with resistance ratios (RR) against the local susceptible reference. ResultsThe assay generated clear concentration- and time-dependent responses. At LSTM, Kisumu gave an EC{square}{square}KD of 0.052 and EC{square}{square}Mort of 0.054 mg/paper; Siaya was comparable (RR{square}{square}KD 1.17, RR{square}{square}Mort 0.89), whereas Tiassale 13 and KDR showed reduced susceptibility (RR{square}{square}KD 2.42 and 2.85; RR{square}{square}Mort 5.56 and 6.65). At AIRID, the resistant Cove strain did not reach 50% knockdown or mortality. At KEMRI, Siaya showed reduced susceptibility (RR{square}{square}KD 3.36/RR{square}{square}Mort 5.65). Kisumu at AIRID and KEMRI was comparable to LSTM (EC{square}{square}KD 0.007/EC{square}{square}Mort 0.030; EC{square}{square}KD 0.044/EC{square}{square}Mort 0.023). Despite inter-laboratory variation, susceptible strains remained distinguishable from resistant ones. Lower RRs than for contact pyrethroids suggest contact-based phenotypes may not predict vapour susceptibility. ConclusionThe assay provides a practical benchtop method using standard WHO hardware, distinguishing susceptible from resistant strains across three laboratories. Twenty-four-hour mortality is the recommended endpoint, 60-minute knockdown secondary. Not yet validated, it provides a foundation for further validation and adaptation to other actives.

Despite extensive efforts to understand the population biology and ecology of the African malaria mosquitoes questions regarding their movement pattern, survival, and population size persist, reflecting methodological limitations. Site fidelity, in which mosquitoes return to feeding sites, resting sites, or oviposition sites remain debated. Mark release recapture (MRR) studies are vital to address such questions. Using locality- and date-specific DNA tags in fluorescent spray, we carried out a continuous MRR in a Malian village from September to December 2019 with three days interval between capture and release across seven zones. A total of 12,937 Anopheles gambiae s.l. (7,455 females) were captured during 35 indoor collections. Handling related mortality was 3.4%., A. coluzzii predominated (89.7%), followed by A. gambiae (9.4%), and A. arabiensis (0.9%). Overall recapture rate was 1.05% (N=129). Contrary to the site-fidelity hypothesis, the distribution of recaptured mosquitoes across zones (regardless of their zone of release) was similar to the distribution of the captured mosquitoes (r=0.97, P<0.001), with 70% recaptured in a different zone. There was no difference in distance moved between sexes, but males average distance increased over time since release, whereas females distance remained unchanged. Simulated movements (across released points), with equal probability to reach any of the village houses predicted actual distance moved by mosquitoes. The regression of observed distance from each zone over predicted had a slope of 1 (r2=94%, P=0.006), suggesting that the layout of the capture area greatly affected the results. The average days post release (minimum age of wild captured mosquitoes) for recaptures was 6.4 d with the longest being 30 d. No seasonal and sex related difference in minimum age were detected. The corrected probability of daily survival (PDS) was 94% and the daily increase in sporozoite rate was 4.9%. Limiting the recapture duration period showed that PDS increased with recapture duration from 74% to 86% (12 to 30 d, uncorrected). Thus, larger recapture area and longer recapture duration are needed to obtain accurate estimates of movement range and of daily survival.

Mosquitoes transmit diverse pathogens through repeated blood feeding, a process that subjects the midgut to significant mechanical stress and cellular damage. While hemocyte association with the midgut is known to occur following injury, the mechanisms promoting their recruitment remain poorly defined. Given the conserved roles of eicosanoid signaling in injury responses, we hypothesized that thromboxane A2 (TXA2) mediates hemocyte recruitment to the damaged midgut. Here, we demonstrate that chemically induced midgut damage significantly increases both the number of hemocytes attached to the midgut and those in circulation. Pharmacological inhibition of cyclooxygenase suppresses hemocyte recruitment whereas supplementation with a stable TXA2 analog restores the response, indicating that TXA2 signaling is required for this process. To identify candidate enzymes involved in TXA2 biosynthesis, we performed in silico docking analyses and identified two cytochrome P450 (CYP) candidates. Among these, CYP6D3 was shown to be strongly upregulated in hemocyte populations following midgut damage. RNA interference-mediated knockdown of CYP6D3 significantly reduced both hemocyte recruitment to the midgut and systemic TXB2 levels, supporting its role in the eicosanoid-mediated immune response. Together, our findings demonstrate that TXA2 signaling drives hemocyte recruitment to the damaged mosquito midgut and suggest a conserved lipid-mediated mechanism underlying insect tissue-associated immune responses that may influence vector competence.

Gastropods are a highly diverse and often overlooked taxonomic group of significant ecological and economic importance. Some terrestrial gastropods are critical pests of commercial agriculture and home gardens worldwide. Malacopathogenic nematodes offer an effective biological control method of managing pest slugs and snails as a natural enemy. Pellioditis (syn. Phasmarhabditis) hermaphrodita and Pellioditis (syn. Phasmarhabditis) californica are two species of biocontrol nematodes that have been commercialized, sold as Nemaslug(R) and Nemaslug(R) 2.0 respectively on three continents. Although there is interest in bringing Nemaslug(R) products to the US, they are currently not permitted due to limited knowledge on their North American distribution and effects on non-target and native species. In this study, we investigated the impact of P. hermaphrodita and P. californica on Ariolimax columbianus across two slug-host life stages, in laboratory infectivity assays. The objectives were to 1. determine whether P. hermaphrodita and P. californica nematodes impact survival of A. columbianus, and 2. evaluate whether there are differential effects on survival in juvenile and adult life stages of A. columbianus, in laboratory infectivity trials. We found that P. hermaphrodita caused significant mortality in A. columbianus with 100% mortality observed in both juvenile and adult slug hosts. The P. californica treatment had significant effects on the juvenile A. columbianus group only, with 80% mortality. By contrast, only 16% of unexposed control juveniles and 4% of control adult slugs died during the experiment. These results indicate that P. hermaphrodita and P. californica are lethal to the native, non-target Pacific banana slug (A. columbianus) under laboratory conditions, with mortality differing between juvenile and adult host life stages. Given the ecological importance of A. columbianus, these findings raise concerns for potential non-target effects of P. californica and P. hermaphrodita on terrestrial gastropod communities and emphasize the need for testing biocontrol agents against multiple life stages.

The ichneumonid subfamily Eucerotinae has been thought to be almost absent from the tropics, with the only known Afrotropical species found in Madagascar. We report the subfamily to be present in the mainland Afrotropics, and describe a new species, Euceros species 1 from Uganda and Cameroon (name not yet shown in preprint). The subfamily had likely not been observed in the mainland Afrotropics before due to low abundances and insufficient sampling. More Eucerotinae likely remain to be discovered in tropical Africa and Asia, although tropical America may genuinely have few eucerotine species. Much more extensive sampling will be needed before it is possible to make confident estimates of how eucerotine diversity is distributed globally.

ObjectivesTo estimate the pooled prevalence of Wolbachia infection in biting midges (Ceratopogonidae) across Southwest Asia and to evaluate ecological and biological factors associated with infection patterns. Study DesignSystematic review and meta-analysis. MethodsA comprehensive search of international and regional databases (PubMed, Scopus, Web of Science, Embase, SID, MagIran) was conducted without date restriction. Eligible studies included those using molecular techniques to detect Wolbachia in Ceratopogonidae collected from Southwest Asia. Pooled prevalence was calculated using a random-effects model. Subgroup and meta-regression analyses were performed to assess variations by country, species, altitude, habitat type, and sex. Heterogeneity and publication bias were evaluated using I{superscript 2}, Cochrans Q, and Eggers tests in accordance with PRISMA guidelines. ResultsTwenty-four studies comprising 14,832 midges from six countries were included. The pooled prevalence of Wolbachia infection was 32.6% (95% CI: 28.4-36.9%; I{superscript 2}=78.3%). Iran showed the highest prevalence (38.2%), and Culicoides imicola was the most frequently infected species (36.8%). Higher prevalence was associated with lower altitudes (<500 m; P=0.012), rural habitats (P=0.034), and female midges (P=0.008). Limited evidence suggested the presence of cytoplasmic incompatibility and reduced bluetongue virus competence in infected midges. ConclusionsWolbachia infection is common among Ceratopogonidae in Southwest Asia and is influenced by ecological and biological factors. These findings highlight the potential of Wolbachia as a biocontrol tool in regional vector management, underscoring the need for further experimental and strain-level studies.

Insects are increasingly recognised as behaviourally complex animals, yet whether they experience pain as an affective state beyond nociception remains unresolved. Voluntary ingestion of analgesics by injured individuals has been proposed as a key but largely untested criterion for evaluating insect pain. This study tested whether Blaptica dubia cockroaches injured by wing clipping preferentially consumed an ibuprofen-sucrose solution over sucrose alone, and whether injury altered rates of abnormal behaviour when individuals were not feeding. Adult males were assigned to injured or sham-handled groups and completed 30-minute two-choice assays, with behaviour scored at 30-second intervals across analgesic, sucrose-only, and neutral zones. We also repeated the experiment with vanilla scent added as a masking agent to both analgesic and sucrose-only solutions. Injured cockroaches did not show greater preference for the analgesic solution either in the presence or absence of the vanilla masking agent. Instead, strong differences emerged between experimental conditions, with individuals in the vanilla-flavoured condition showing reduced feeding engagement overall. We therefore have no evidence that injured cockroaches actively seek out analgesics. We suggest methodological refinements are required before we can absolutely reject the possibility of analgesia preference and so the sensation of pain. In contrast, injury increased persistent abnormal behaviours, including abdominal pulsations, wing-fluttering, wound-directed grooming and body flexion. Therefore, injury produced clear behavioural disruption consistent with an internally driven aversive or discomfort-related state, highlighting both the challenges of adapting voluntary analgesic assays to insects and the welfare relevance of injury in B. dubia.

In eastern Canada, the seedcorn maggot complex (SMC) includes three agriculturally important taxa: Delia platura biotypes H and N, and D. florilega. Because their larvae are morphologically indistinguishable, field-collected individuals are often grouped together despite differences in phenology and life history. Using larval collections from broccoli, green onion, and dry onion fields in Southern Quebec (2017-2022), we identified specimens via HRM analysis and characterized taxon-specific phenology and abundance using Bayesian hierarchical generalized additive models. In Allium crops, D. platura biotype N dominated early-season infestations (May), followed by a shift in early June towards increased abundance of biotype H and D. florilega. In broccoli, all SMC members appeared later, with overlapping abundance peaks in June. These results reveal strong crop-dependent phenological differences and underscore the need to treat SMC members as distinct biological entities in pest management. The implications for optimizing an emerging sterile insect technique (SIT) program for D. platura in Quebec are significant: field releases of sterile males should target early-season biotype N in Allium crops, followed by releases of both biotypes later in the season in broccoli to maximize control efficacy.

Aedes albopictus is a major arboviral vector whose global expansion, driven by human activities and climate change, poses a growing public health concern for a number of neglected tropical diseases in both tropical and temperate regions. As a poikilotherm, its biology and population dynamics are strongly influenced by temperature, thereby shaping disease transmission. To thwart and control its geographic expansion, effective vector control strategies are increasingly critical. Densoviruses (DVs), such as AalDV2, are being explored as mosquito viral biocontrol agents due to their restricted host range and ability to disseminate through oviposition sites. However, the influence of environmental parameters on the interactions between Ae. albopictus and AalDV2 remains poorly understood. This makes their performance under realistic, fluctuating thermal regimes difficult to estimate. In this study, we investigated the combined effects of temperature and AalDV2 exposure on Ae. albopictus survival and development across its full life cycle. Mosquitoes were reared under fluctuating temperature regimes (26-28 {degrees}C and 32-34 {degrees}C, 12:12 day[ndash]night cycles) and exposed to AalDV2 or a control treatment. Chronic exposure to 32-34 {degrees}C significantly reduced overall survival, decreasing median lifespan by approximately 10 days (HR=2.21, p=0.0018), with a deleterious effect increasing over time. It extended aquatic lifespan and increased pupal mortality. It also reduced adult lifespan in both sexes with a stronger effect in females. AalDV2 exposure had no significant effect on overall survival, stage-specific mortality, or adult lifespan. However, a significant interaction between viral exposure and thermal stress was detected on aquatic lifespan: AalDV2-exposed females showed further extended larval and pupal development specifically under the 32-34 {degrees}C regime, without any effect on survival. These results indicate that the biocontrol potential of AalDV2 cannot be assessed independently of thermal context: while lethal effects were absent under both fluctuating regimes, the prolongation of aquatic development by the virus under thermal stress may have indirect consequences for mosquito population dynamics that warrant further investigation.

Long-distance movement in insects has crucial impacts on agriculture, human health, and biodiversity. Although it was long assumed that only large, specialist insects had the navigation capacity to support long-distance dispersal, recent studies have demonstrated that smaller insects, such as the tiny fruit fly Drosophila melanogaster, can maintain extended, straight paths while flying or walking. This raises the question of whether other Drosophila species possess the navigation capacity to support extended dispersal. Resolving this question is particularly important for Drosophila suzukii(spotted-wing drosophila), a potent pest species that causes enormous damage worldwide to ripe fruit and berries. Spotted-wing drosophila has been thought to lack a capacity for long-distance dispersal, as prior studies have estimated maximal daily dispersal distances of less than 90 m. We developed a system to continuously track the flight trajectories of magnetically tethered D. suzukii relative to a discrete, overhead LED that mimicked the sun. We found that flies maintained remarkably straight flight headings that varied unpredictably across individuals. Male and female D. suzukii exhibited a similar navigation capacity; both sexes responded to rotation of a discrete sun stimulus with compensatory turns to maintain a stable relative heading. Our results suggest that D. suzukiihas an underappreciated capacity for rapid, radial dispersal, which could exceed 250 m in 15 min. This capacity may contribute to the pest species' invasiveness and its reliable, annual re-establishment in seasonally intolerable climates. Our findings highlight the importance of developing area-wide, regional strategies to manage the impacts of D. suzukii.

Parasites can manipulate host behavior to increase their fitness while decreasing host fitness, a phenomenon known as an extended phenotype. Nucleopolyhedroviruses (NPVs), baculoviruses that infect Lepidopteran larvae, have been found to induce vertical climbing behavior and hyperactivity in exposed larvae. We quantified variation in the horizontal wandering behavior induced by different naturally-occurring pathogen isolates in the NPV that infects Dione (Agraulis) vanillae Linnaeus (Lepidoptera: Nymphalidae). Lab-raised larvae were infected with a constant dose of one of five different field-collected NPV isolates or a water control (n=98 larvae total), and placed in mazes to measure the horizontal distance wandered away from a food source. Virus-exposed larvae exhibited increased maximum distance of horizontal movement compared to the control, but did not significantly differ in the probability of wandering versus no movement. We also found variation in the distance wandered among the five virus isolates. However, grouping the five isolates into two previously-described viral strains or genogroups did not improve predicted differences in movement, perhaps due to the presence of within-strain genetic variation among isolates in the viral genes involved in controlling host behavior. Further work is needed to determine whether the observed between-isolate variation is the result of adaptive evolution. These results suggest that the NPV infecting D. vanillae manipulates larval behavior to increase horizontal wandering, which could lead to higher pathogen fitness by increasing long-distance dispersal of the virus across the landscape.

The tick Ixodes ricinus is the main vector of human and animal pathogens in Europe. Despite its importance in epidemiology and medicine, our understanding of physiological mechanisms controlling blood feeding, osmoregulation, or development are still limited. Here, we identify novel neuropeptide invertebrate parathyroid hormone-like peptide (iPTH) and its two receptors - PTHR1 and PTHR2 in I. ricinus. Functional aequorin-based assay confirmed specific activation of both receptors by iPTH. Using RT-qPCR we detected the PTHR1 transcript in the synganglion, while increased expression levels of PTHR2 were found in the salivary glands, hindgut and female gonads. RNA-mediated knockdown of iPTH receptors in nymphs resulted in delayed blood feeding, and a high incidence of defects in adult ecdysis. Consistent with observed phenotypes, iPTH is expressed in multiple neurons of the synganglion which project arborizing axons to the salivary glands, rectal sack and skeletal muscles. iPTH was colocalized with orcokinin-immunoreactivity (OK-IR) in all neurons that innervate these peripheral tissues. iPTH is further colocalized with tachykinin (TK) in Pd1DL1 neurons, suggesting coordinated action with other neuropeptides. Our findings indicate that iPTH signaling is required for normal feeding, development and successful ecdysis.

BackgroundAnopheles stephensi, an invasive malaria vector originally endemic to South Asia, has rapidly expanded across East Africa. Its emerging malaria threats in urban Ethiopia threaten the elimination efforts, especially in areas once deemed low risk. A systematic review was conducted to synthesize the evidence regarding its bionomics and epidemiological impact, highlighting implications for urban malaria control strategies. This systematic review provides the first Ethiopia-specific quantitative evidence synthesis, addressing a vital knowledge gap necessary for guiding national malaria elimination programmes. MethodsWe conducted a PRISMA 2020-compliant systematic review and meta-analysis registered with PROSPERO (CRD420251176953). Searches of PubMed, Scopus, Web of Science, and regional repositories (2016-February 2026) identified studies reporting An. stephensi bionomics and epidemiological role in Ethiopia. Eligible studies required [&ge;]50% quality score on JBI appraisal tools. Random-effects meta-analysis estimated pooled proportions of An. stephensi among total Anopheles, with subgroup analyses by geography, habitat, and behavioural traits. Publication bias was assessed using Eggers and Beggs tests. ResultsEighteen studies (9 epidemiological, 11 bionomical) met inclusion criteria. The pooled proportion of An. stephensi was 0.51 (95% CI: 0.28-0.75) in epidemiological studies and 0.46 (95% CI: 0.26-0.66) in bionomics studies, with extreme heterogeneity (I{superscript 2} > 99%). Geographic analysis indicated significant variation: south-eastern Ethiopia showed a dominance of 0.73 (95% CI: 0.28-1.18) and eastern Ethiopia 0.57 (95% CI: 0.32-0.82), while central Ethiopia remained lower at 0.13 (95% CI: 0.12-0.14). These findings demonstrate genuine ecological differences rather than methodological objects, with substantial implications for region-specific vector management strategies. Extreme heterogeneity reflected genuine ecological variation across Ethiopia. No evidence of publication bias was detected. ConclusionAn. stephensi has very rapidly emerged as a major malaria vector in Ethiopia, with pooled proportions increasing from <10% at first detection (2016) to 51-73% in recent surveys (2024-2025), suggesting ongoing vector displacement parallel to invasion patterns documented in Djibouti. Geographic stratification indicates an urgent need for region-specific urban vector management integrating larval source management, resistance monitoring, and community engagement, particularly in south-eastern Ethiopia, where near-complete vector replacement has occurred. Author SummaryMalaria is usually thought of as a rural disease, but a new mosquito species called An. stephensi is changing that picture in Ethiopia. Originally found in South Asia, this mosquito has spread quickly across East Africa and is now common in Ethiopian towns and cities. We reviewed and combined results from published studies to understand how this species behaves and how much it contributes to malaria transmission. Our analysis shows that An. stephensi has become one of the dominant malaria vectors in several regions of Ethiopia, especially in the east and south-east, where it has almost replaced other mosquito species. This rapid change means that malaria risk is increasing in urban areas that were previously considered low risk. These findings highlight the urgent need for new control strategies that focus on city environments, such as managing breeding sites, monitoring insecticide resistance, and involving communities in prevention efforts. By understanding how An. stephensi is spreading and adapting, we can better protect urban populations and support Ethiopias malaria elimination goals.

Understanding how vector ecology intersects with host behaviour is essential for predicting zoonotic disease risk in tropical ecosystems. We conducted a two-year field study (November 2016-October 2018) in a riverine forest in Sabah, Malaysian Borneo, to characterize mosquito communities and the spatial distribution of potential simian-malaria vectors. Mosquitoes were sampled on 44 nights using CO{square}-baited light traps repeatedly deployed along a 500 m transect at three distances from the river (0, 250, 500 m) and two vertical strata (ground and canopy), yielding 244 trap collections across repeated sampling nights. In total, 9,928 mosquitoes were collected, dominated by Culex spp. (9,079; 91.4%), whereas Anopheles spp. were rare (153; 1.5%); most remaining specimens were unidentified to genus, and species-level identification was limited primarily to Anopheles. Nevertheless, female Anopheles (n=57) were more frequently detected near the river and less commonly at intermediate distance, and tended to be captured more often in ground traps. Zero-inflated negative binomial GLMMs based on the full mosquito dataset indicated significant effects of river distance and height on mosquito abundance, while night-time temperature and humidity showed no detectable effects. The zero-inflated structure of the data further suggested that many zero captures reflected true absence rather than sampling variability. The Anopheles assemblage was dominated by An. balabacensis, and molecular screening of 57 females detected simian Plasmodium DNA in two individuals. Overall, these findings suggest that river-edge habitats may represent localized areas where vectors persist and where primates and human activities overlap, creating repeated opportunities for host-vector contact even when vector densities are low.