In Senegal, scaling up vector control has significantly reduced malaria, but coastal transmission remains a challenge due to secondary vectors like Anopheles melas. This exophilic and zoophilic species evades conventional indoor interventions, yet its bionomics and insecticide resistance profiles remain poorly characterized due to difficulties in laboratory colonization. Anopheles melas larvae were collected from brackish breeding sites in Mbine Coly (Mbour District). A laboratory colony was established from 26 PCR-confirmed founder females and stabilized up to the F17 generation by optimizing water salinity (10 g/L) and transitioning to communal oviposition. Standardized WHO tube bioassays were conducted on generations F2 to F9 to evaluate susceptibility to pyrethroids, organophosphates, and carbamates, alongside synergist tests using 4% piperonyl butoxide (PBO). The colony showed confirmed resistance to alpha-cypermethrin (81.7% mortality) and suspected resistance to deltamethrin (91.3%) and permethrin (94.3%). Pre-exposure to PBO fully restored susceptibility to deltamethrin and permethrin (100%), and significantly increased alpha-cypermethrin mortality to 96.3% (p < 0.001). While metabolic resistance typically involves multiple enzyme families including cytochrome P450s, glutathione S-transferases (GSTs), and esterases, these synergist results demonstrate a predominant role of cytochrome P450-mediated detoxification pathways in this population. Moderate-intensity resistance was confirmed for alpha-cypermethrin at 5× diagnostic doses. Conversely, the population was 100% susceptible to pirimiphos-methyl and bendiocarb. This study reports the successful long-term colonization of a wild An. melas strain for the first time and provides the first comprehensive evidence of multi-insecticide resistance in this population. The presence of high-intensity, metabolic pyrethroid resistance strongly justifies the immediate deployment of next-generation PBO-LLINs and the integration of organophosphates or carbamates in indoor residual spraying rotations to manage resistance in coastal Senegal.

Background: The bean flower thrips, Megalurothrips usitatus, is a destructive agricultural pest with increasing resistance to pyrethroid insecticides. Most mechanistic studies emphasize mutations in the pore-forming voltage-gated sodium channels α-subunit, whereas the contribution of insect-specific sodium-channel auxiliary subunits remains unclear. Methods: We used dsRNA feeding, pyrethroid bioassays, RNA sequencing, and RT-qPCR validation to evaluate the role of temperature-induced paralytic E (TipE) in M. usitatus. Results: The optimized RNAi condition was 400 μg/mL of dsTipE for 48 h, which reduced TipE expression by 32.55%. TipE knockdown increased adult mortality after exposure to λ-cyhalothrin and permethrin, indicating increased pyrethroid-associated susceptibility under laboratory conditions. Transcriptome sequencing identified 205 differentially expressed genes, with enrichment in metabolism-related pathways. RT-qPCR confirmed reduced expression of CYP307a1, an ecdysteroid-biosynthesis-related P450 gene, and SCD, a lipid-metabolism gene, while Nav α-subunit transcript abundance did not change significantly. Conclusions: These results identify TipE as an auxiliary-subunit factor associated with pyrethroid susceptibility in M. usitatus and provide a transcriptome-based working model linking sodium-channel auxiliary regulation with endocrine- and lipid-metabolism-related responses. This study expands the candidate space for pyrethroid resistance research beyond Nav α-subunit mutations, although the causal roles of CYP307a1 and SCD require further validation.

Insecticide resistance reduces the effectiveness of current malaria-vector-control interventions. To understand the mechanisms underlying permethrin resistance in field-derived Anopheles gambiae vectors collected from Cameroon, we used ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) to comprehensively analyze metabolic changes in resistant and susceptible samples to gain insights into mechanisms driving permethrin resistance. Resistant mosquitoes exhibited upregulated levels of inosine, nicotinic acid, dipeptides, amino acids, fumarate, uracil, and aldopentoses. These data suggest that altered metabolic-based detoxification, as well as target site and metabolic shifts, and enhanced energy production contribute to permethrin resistance. Conversely, susceptible mosquitoes showed increased levels of N-acetyl-aspartic acid, xanthurenic acid, 2-hydroxyglutarate, 3-hydroxykynurenine, propanoylcarnitine, and l-pipecolic acid. These metabolites are associated with neurotoxicity, energy disruption, as well as tryptophan and lysine catabolism, leading to susceptible phenotypes. These findings provide deeper metabolic insight into An. gambiae permethrin resistance and compel further investigations into how these metabolic pathways contribute to the emergence of pyrethroid cross-resistance.

Preventive pesticide monitoring in tropical agricultural catchments is frequently constrained by limited analytical capacity, incomplete environmental datasets, and the large number of potentially relevant compounds requiring evaluation. To address these limitations, this study developed and applied a multicriteria screening framework for prioritizing agrochemical residues in support of preventive surface water monitoring in a tropical rice-growing catchment in Colombia. The framework integrated four criteria associated with environmental relevance: human health concern, aquatic toxicity, transport potential, and use-based occurrence proxies. An analytic hierarchy process approach was used to derive criterion weights and evaluate prioritization consistency. A total of 162 pesticides associated with rice production were evaluated. Cypermethrin, isopyrazam, 2,4-D, chlorpyrifos, oxadiazon, mancozeb, fentin hydroxide, triadimenol, permethrin, and malathion were identified as the highest priority compounds, reflecting different combinations of toxicological relevance, transport-related behavior, mobility potential, and expected occurrence. Sensitivity analysis demonstrated stable ranking behavior under moderate weight perturbations. The prioritization generated operationally relevant outputs for monitoring design, including environmental matrix selection according to mobility and partitioning behavior, rainfall- and application-related sampling windows, and analytical targeting guidance. Overall, the framework provides a transferable screening tool for supporting preventive pesticide-monitoring strategies in tropical agricultural catchments under data-limited conditions.

Demodex mites are commonly found on human skin, but excessive proliferation can contribute to inflammatory eruptions. Pityriasis folliculorum is a Demodex‑associated condition characterized by follicular roughness and fine scale. Although it most often affects the cheeks, its presentation can vary and may resemble other papulopustular disorders. We describe a patient who developed a perioral papulopustular eruption with prominent follicular roughness. The condition persisted despite treatment with topical metronidazole, topical tretinoin, and topical antifungal therapy. Given the lack of response to topical therapies, a potassium hydroxide (KOH) skin scraping was performed and demonstrated numerous Demodex mites, with rapid resolution following the initiation of topical ivermectin. This case highlights the importance of considering Demodex‑related disease in the evaluation of perioral papulopustular eruptions when standard therapies are ineffective. Early recognition can help guide appropriate management and prevent prolonged symptoms.

Insecticide resistance is threatening malaria control. While the evolution and spread of resistance has been linked to scale-up in the distribution of public health insecticides, the role of environmental pollutants such as the polyaromatic hydrocarbons (PAHs) from industrial and agricultural use remains largely uncharacterized. The PAHs are potent ligands of the aryl hydrocarbon receptor (Ahr) transcription factors involved in the regulation of xenobiotic metabolizing enzymes, and potentially involved in insecticide resistance. Here, using field insecticide-resistant (Auyo) An. coluzzii and a laboratory-susceptible colony (Ngousso), we conducted a multi-generational selection experiment using naphthalene, fluorene and a mixture of both PAHs. After ten generations, the changes in susceptibility to insecticides were monitored using WHO bioassays and whole-transcriptome analysis (RNASeq) was conducted. Compared with the non-selected colony lines, PAH exposures significantly reduced pyrethroid and DDT resistance in the field population, suggesting a fitness cost associated with established resistance. In contrast, Ngousso showed a significant increase in DDT resistance (p = 0.01) at the tenth generation. A significant increase in permethrin resistance was also observed at the seventh generation (p = 0.03). Several candidate genes from the major detoxification classes were overexpressed in the selected lines (including GSTe2, CYP6Z1, and CYP6P4); the most consistent were CYP6M4 and CYP4C27, as well as those from the Ahr pathway. Heterologous expression of CYP6M4 revealed its ability to metabolise pyrethroids, including permethrin, deltamethrin, and α-cypermethrin, as well as PAHs (naphthalene and fluorene). These findings establish the role of environmental pollutants as additional drivers of metabolic insecticide resistance in An, coluzzii.

Widespread insecticide resistance and the potential for sublethal exposures to alter mosquito fitness have increased interest in alternative approaches such as attractive toxic sugar baits (ATSBs), yet their lethal and sublethal effects in insecticide-resistant versus susceptible populations remain poorly understood. We evaluated the lethal and sublethal effects (LC25) of a novel boric acid and dinotefuran ATSB on ingestion, mortality, blood feeding, and reproductive traits in permethrin-resistant and permethrin-susceptible Aedes aegypti. Aedes aegypti is the primary global vector of dengue, Zika, chikungunya, and yellow fever viruses, placing billions at risk and underscoring the need for sustainable vector control strategies. ATSB affected ingestion, mortality, and reproductive traits in a resistance-dependent manner. Susceptible mosquitoes exhibited reduced ATSB ingestion, whereas resistant mosquitoes showed increased ingestion, suggesting that resistance status modifies feeding responses to the bait formulation. ATSB ingestion increased acute mortality in both strains, with a stronger effect in susceptible mosquitoes, and similarly shortened survival time across strains, indicating consistent sublethal toxicity regardless of resistance status. ATSB reduced blood feeding in both strains, suggesting potential downstream effects on pathogen transmission. Fertility exhibited a significant resistance × treatment interaction, with ATSB increasing fertility in resistant mosquitoes but reducing it in the susceptible strain. These findings indicate that the effects of this ATSB on mosquito fitness and arbovirus transmission-related traits are strongly influenced by permethrin resistance, highlighting the importance of incorporating resistance status into ATSB evaluations and integrated vector control strategies.

Crusted scabies is a severe and uncommon variant of Sarcoptes scabiei var. hominis infestation and typically arises in older adults with impaired cellular immunity. Secondary erythroderma and bacteremia are feared complications that may lead to increased morbidity. Herein, we report a case of crusted scabies with subungual involvement in a 65-year-old man with vascular dementia, schizophrenia, and chronic obstructive pulmonary disease presenting from an assisted living facility. At presentation, the patient was erythrodermic, alongside diffuse scaling with scattered excoriations and marked palmar/subungual hyperkeratosis. Laboratory investigations revealed methicillin-resistant Staphylococcus aureus bacteremia, coronavirus disease 2019 infection (COVID-19) and markedly elevated serum immunoglobulin E levels. The patient was started on vancomycin, topical permethrin 5%, and oral ivermectin, with subsequent resolution of the rash and pruritus prior to discharge from the hospital. This case highlights subungual hyperkeratosis as a practical diagnostic clue and potential mite reservoir in crusted scabies presenting as erythroderma. Recognition of this morphology can prompt immediate bedside microscopy, combined topical and systemic scabicidal therapy, and contact precautions to reduce nosocomial transmission.