Search Results (82)

Background/Objectives: Despite the increasing emergence of resistance, insecticide-based tools remain the primary method for malaria vector control in Africa. To maintain the effectiveness of these interventions, continuous monitoring and identification of novel resistance mechanisms is essential. This study aimed to investigate potential new insecticide resistance genes in the Anopheles gambiae complex. Methods: We analyzed whole-genome sequencing data from the An. gambiae 1000 Genomes Project. A broad range of genomic analysis techniques and tools were used to identify and explore genetic variation in the candidate resistance genes. Results: High haplotype homozygosity values, indicative of positive selection, were detected in a 2L chromosomal region corresponding to an aldehyde oxidase gene cluster (AGAP006220, AGAP006221, AGAP006224, AGAP006225, AGAP006226). Single nucleotide polymorphisms (SNPs) have been identified in these genes with frequencies up to 100%, including 569, 691, 1433, 978, and 811 non-synonymous SNPs in AGAP006220, AGAP006221, AGAP006224, AGAP006225, and AGAP006226, respectively. Copy number variations (CNVs) such as deletions and amplifications were also identified at low frequencies (<12%). Population structure analyses revealed adaptive and geographic gene flow between An. gambiae and An. coluzzii. Conclusions: This study provides evidence that aldehyde oxidase genes may contribute to insecticide resistance in An. gambiae s.l. populations. These results highlight the importance of genomic surveillance for detecting novel resistance loci and guiding the development of improved vector control strategies under changing ecological and evolutionary conditions. Full article

Insect pests impose major economic, agricultural, and public health burdens, damaging crops and transmitting pathogens such as dengue, malaria, and Zika. Conventional chemical control is increasingly ineffective due to insecticide resistance and environmental concerns, prompting a search for innovative strategies. The insect microbiome—comprising both obligate symbionts and environmentally acquired microbes—emerges as a key driver of host physiology and behavior. Microbes influence nutrient acquisition, immunity, reproduction, and chemosensory processing, often to promote their own transmission. By modulating olfactory and gustatory pathways, microbiota can alter host-seeking, mate choice, foraging, and oviposition patterns, reshaping ecological interactions and vector dynamics. These effects are shaped by microbial acquisition routes, habitat conditions, and anthropogenic pressures such as pesticide use, pollution, and climate change. Understanding these multi-directional interactions offers opportunities to design highly specific, microbe-based insect control strategies, from deploying microbial metabolites that disrupt host sensory systems to restoring beneficial symbionts in threatened pollinators. Integrating microbiome ecology with insect physiology and behavior not only deepens our understanding of host–microbe coevolution but also enables the development of sustainable, targeted alternatives to chemical insecticides. This review synthesizes current evidence linking microbiomes to insect biology and explores their potential as tools for pest and vector management. Full article

Contact unmodified antisense DNA biotechnology (CUADb), developed in 2008, employs short antisense DNA oligonucleotides (oligos) as a novel approach to insect pest control. These oligonucleotide-based insecticides target pest mature rRNAs and/or pre-rRNAs and have demonstrated high insecticidal efficacy, particularly against sap-feeding insect pests, which are key vectors of plant DNA viruses and among the most economically damaging herbivorous insects. To further explore the potential of CUADb, this study evaluated the insecticidal efficacy of short 11-mer antisense DNA oligos against Coccus hesperidum, in comparison with long 56-mer single-stranded and double-stranded DNA sequences. The short oligos exhibited higher insecticidal activity. By day 9, the highest mortality rate (97.66 ± 4.04%) was recorded in the Coccus-11 group, while the most effective long sequence was the double-stranded DNA in the dsCoccus-56 group (77.09 ± 6.24%). This study also describes the architecture of the DNA containment (DNAc) mechanism, highlighting the intricate interactions between rRNAs and various types of DNA oligos. During DNAc, the Coccus-11 treatment induced enhanced ribosome biogenesis and ATP production through a metabolic shift from carbohydrates to lipid-based energy synthesis. However, this ultimately led to a ‘kinase disaster’ due to widespread kinase downregulation resulting from insufficient ATP levels. All DNA oligos with high or moderate complementarity to target rRNA initiated hypercompensation, but subsequent substantial rRNA degradation and insect mortality occurred only when the oligo sequence perfectly matched the rRNA. Both short and long oligonucleotide insecticide treatments led to a 3.75–4.25-fold decrease in rRNA levels following hypercompensation, which was likely mediated by a DNA-guided rRNase, such as RNase H1, while crucial enzymes of RNAi (DICER1, Argonaute 2, and DROSHA) were downregulated, indicating fundamental difference in molecular mechanisms of DNAc and RNAi. Consistently, significant upregulation of RNase H1 was detected in the Coccus-11 treatment group. In contrast, treatment with random DNA oligos resulted in only a 2–3-fold rRNA decrease, consistent with the normal rRNA half-life maintained by general ribonucleases. These findings reveal a fundamental new mechanism of rRNA regulation via complementary binding between exogenous unmodified antisense DNA and cellular rRNA. From a practical perspective, this minimalist approach, applying short antisense DNA dissolved in water, offers an effective, eco-friendly and innovative solution for managing sternorrhynchans and other insect pests. The results introduce a promising new concept in crop protection: DNA-programmable insect pest control. Full article

Malaria, typhoid fever, respiratory tract infections, and urinary tract infections significantly impact women, especially in remote, resource-constrained settings, due to limited access to quality healthcare and certain risk factors. Most studies have focused on vector control measures, such as insecticide-treated nets and time series analysis, often neglecting emerging yet critical risk factors vital for effectively preventing febrile diseases. We address this gap by investigating the use of machine learning (ML) models, specifically extreme gradient boost and random forest, in predicting adult females’ susceptibility to these diseases based on biological, environmental, and socioeconomic factors. An explainable AI (XAI) technique, local interpretable model-agnostic explanations (LIME), was applied to enhance the transparency and interpretability of the predictive models. This approach provided insights into the models’ decision-making process and identified key risk factors, enabling healthcare professionals to personalize treatment services. Factors such as high cholesterol levels, poor personal hygiene, and exposure to air pollution emerged as significant contributors to disease susceptibility, revealing critical areas for public health intervention in remote and resource-constrained settings. This study demonstrates the effectiveness of integrating XAI with ML in directing health interventions, providing a clearer understanding of risk factors, and efficiently allocating resources for disease prevention and treatment. Full article

Background: Indoor residual spraying (IRS) is a core insecticide-based vector control tool employed in most malaria-affected settings globally. However, mosquito vectors have developed resistance to nearly all of the insecticides currently used in IRS. This has necessitated a transition to new classes of insecticides, from mostly using dichlorodiphenyltrichloroethane (DDT) and pyrethroids from 1997 to 2010 to carbamates in 2011 and organophosphates in 2013. In addition, other vector control measures, like the use of long-lasting insecticide-treated bed nets (LLINs), have also been employed for malaria control. Despite the implementation of these mosquito vector control interventions, malaria remains a disease of public health concern, especially in sub-Saharan Africa, which bears over 90% of the disease burden. This review will thus collate evidence on the effectiveness of IRS for malaria control in sub-Saharan Africa. Methods and analysis: The systematic review will be conducted following a priori criteria developed using the PRISMA guidelines. Articles will be obtained through a search of the Web of Science, Google Scholar, Medline via PubMed, Scopus and Embase databases. Mesh terms and Boolean operators (“AND”, “OR”) will be used in the article search. Additionally, websites of malaria research institutions will be searched. The article search will be conducted by two independent librarians (AAK and RS). All identified articles will be transferred to EPPI-reviewer v6.15.1.0 software. Article screening and data abstraction will be performed in duplicate by four reviewers (KOO, LN, GK and MO), and any further disagreements will be resolved through discussion and consensus. We shall extract data on the country, region, study design, insecticide combination, season, susceptibility procedure used, vector control interventions, population, mosquito species, malaria incidence or prevalence, insecticide efficacy, susceptibility, genotypic resistance, vector mortality and knockdown effect. Data analysis will be performed using STATA v17.0. Effect sizes will be statistically pooled using inverse-variance-weighted random-effects meta-analysis. Heterogeneity and publication bias in the articles will be assessed using the I² statistic and a funnel plot, respectively. For the studies that will not be included in the meta-analysis, a narrative synthesis will be written following the Cochrane Consumer and Communication Review Group format. Results: The findings of this review will help generate evidence on the effectiveness of indoor residual spraying using WHO pre-qualified insecticides in malaria control in sub-Saharan Africa. This protocol was registered in PROSPERO, registration number CRD42024517119. Full article

Background: Genetic control tools, such as the sterile insect technique (SIT) and genetically modified mosquitoes (GMMs), require releasing males comparable to their wild counterparts. Ensuring that released males do not exhibit higher insecticide resistance is critical. This study assessed the phenotypic characteristics and insecticide susceptibility of key dengue and malaria vector species. Methods: Phenotypic resistance to deltamethrin (0.05%) was tested in two-to-five-day-old male and female Aedes aegypti (Linnaeus, 1762) (Borabora and Bobo strains) and Anopheles coluzzii (Coetzee & Wilkerson, 2013) (Vallee du Kou strain) using WHO susceptibility guidelines. Wing measurements of live and dead mosquitoes were used to assess body size. Results: Mortality rates were similar between male and female Ae. aegypti (Bobo strain) and An. coluzzii, while Ae. aegypti Borabora was fully susceptible in both sexes. Females were consistently larger than males, with significantly larger live females than dead ones in the Ae. aegypti Bobo strain. Conclusion: This study highlights sex-specific differences in body size and insecticide susceptibility. Integrating these analyses into vector management programs is essential for the success and sustainability of SIT- and GMM-based interventions targeting malaria and dengue vectors. Implications for integrating genetic control strategies are discussed. Full article

Background: Attractive Toxic Sugar Baits (ATSBs) are an innovative vector control strategy based on the “attract-and-kill” principle. The core of ATSBs lies in the preparation of attractive and toxic baits through the mixing and proportioning of luring and active ingredients. Although previous studies have investigated the effects of ATSBs on mosquitoes, significant challenges remain for broader field application. Methods: This study evaluated five fruit juices as ATSBs for mosquitoes, focusing on feeding preferences. Preservative concentrations were assessed by measuring antimicrobial activity over time. Two commercial traps were tested for mosquito entry rates. The optimal insecticide species and concentration were determined based on mortality rates. An optimized ATSBs system was developed and tested under a semi-field cage. Statistical analysis was performed using GraphPad Prism. Results: Within 24 h, apple juice-based ATSBs had the highest attractant index for Culex quinquefasciatus and Anopheles sinensis, while a pear juice-based ATSB was most effective for Aedes albopictus. A 0.1% preservative concentration best maintained juice stability. The LC50 values of dinotefuran-based ATSBs for Cx. quinquefasciatus, Ae. albopictus, and An. sinensis were 1.18 × 10⁻³, 4.06 × 10⁻⁴, and 5.20 × 10⁻⁵ g/L, respectively. The Spodoptera frugiperda trap outperformed the Drosophilidae trap. Simulated semi-field cage tests showed 48 h mortality rates of 86.00% for Cx. quinquefasciatus and 95.67% for Ae. albopictus. Conclusion: This study optimized an ATSB system by screening various fruit juices, preservative concentrations, insecticides, and trap devices. The system’s efficacy in mosquito control was evaluated under a semi-field cage. These findings provide a strong foundation for the future application and refinement of ATSB-based mosquito control strategies. Full article

Insecticide resistance surveillance systems for vector-borne diseases are crucial for early detection of resistance and the implementation of evidence-based resistance management strategies. While insecticide susceptibility bioassays are typically conducted under controlled laboratory conditions, mosquitoes in the field experience varying environmental conditions, with temperature being a key determinant. Understanding the relationship between temperature and insecticide toxicity is essential for interpreting and extrapolating assay results across different climate zones or more locally across days with different weather conditions. In this study, we examined Aedes aegypti mosquitoes with different genetic backgrounds of insecticide resistance. Mosquitoes were homozygous for the knockdown resistance (kdr) F1534C mutation, plus either (1) homozygous for the kdr 1016V wildtype allele, (2) homozygous for the kdr V1016I mutant allele, or (3) heterozygous genetic crosses. These three genotypes were exposed to deltamethrin using WHO tube tests at three temperatures (22 °C, 27 °C, and 32 °C) and varying dosages. LC50 values were determined for each genotype and temperature combination. A negative temperature coefficient was observed exclusively in female mosquitoes homozygous for the 1016V wildtype allele, indicating reduced pyrethroid toxicity at higher temperatures. No temperature–toxicity relationship was found in males of this genotype or in other genotypes of either sex. These findings suggest that temperature may interact with kdr mutations and possibly even sex, highlighting the complex interactions between genetic mutations and environmental factors, such as temperature, in determining the insecticide resistance phenotype. Given the wide distribution of Ae. aegypti, understanding how local climate conditions influence insecticide performance will help improve control strategies and slow resistance evolution, protecting public health efforts against mosquito-borne diseases Full article

A deterministic model for controlling the neglected tropical filariasis disease known as elephantiasis, caused by a filarial worm, is developed. The model incorporates drug resistance in human and insecticide-resistant vector populations. An investigation into whether the model is of biological importance reveals that it is positively invariant, mathematically well posed, and tractable for epidemiological studies. The filariasis-free and filariasis-present equilibrium points were obtained. The next-generation matrix technique is used to derive the basic reproduction number $R_0$, which is then used to determine the local stability analysis of the model. It is established that the system is locally asymptotically stable when $R_0<1$. The technique by Castillo-Chavez and a Lyapunov function were employed to prove the global stability of the model’s fixed points. The results of this analysis of filariasis-free equilibrium show that the system is globally asymptotically stable when $R_0<1$ and unstable when $R_0>1$. Similarly, the filariasis-present equilibrium point is proved to be globally asymptotically stable when $R_0>1$ and unstable otherwise. This indicates that the fight against the spread of the disease is achievable. It is observed that increasing human-infected mosquito contacts or mosquito-infected human contacts raises the value of $R_0$, whereas decreasing the progression of micro-filaria into infective larva and killing more mosquitoes will decrease the $R_0$ value according to the sensitivity analysis of the model. The variable precision arithmetic technique executed in MATLAB R2014a was used to determine the elasticity indices of the parameters of $R_0$, which showed that the value of $R_0=0.94639$. Further investigations revealed that ${\omega }_2$ has a significant influence on the reproduction number, suggesting that treatment of acute infections is crucial in the control of the disease. Pontryagin’s Maximum Principle (PMP) is used for optimal control analysis. The numerical result revealed that strategy D is the most effective based on the infection averted ratio (IAR) value. Full article

Indoor residual spraying (IRS) and the use of insecticide-treated bednets for malaria vector control have contributed substantially to a reduction in malaria disease burden. However, these control tools have important shortcomings including being donor-dependent, expensive, and often failing because of insufficient uptake. We assessed the safety and efficacy of a user-friendly, locally tailored malaria vector control approach dubbed “Hut Decoration for Malaria Control” (HD4MC) based on the incorporation of a WHO-approved insecticide, Actellic^® 300 CS, into a customary hut decoration practice in rural Uganda where millions of the most vulnerable and malaria-prone populations live in mud-walled huts. Three hundred sixty households were randomly assigned to either the HD4MC (120 households), IRS (120 households) or control group without any wall treatment (120 households). Entomological indices were assessed using pyrethrum spray catching, CDC light traps and human landing catches. The Actellic^® 300 CS toxicity on acetylcholinesterase activity among applicators of HD4MC was evaluated using the Test-mate (Model 400) erythrocyte acetylcholinesterase (AChE) test V.2, whereas toxicity in household occupants was monitored clinically. The Actellic^® 300 CS level in house dust was analyzed using reversed-phase high-performance liquid chromatography (RP-HPLC). Entomological indices were compared between the three study arms at 1.5, 3 and 6 months post-intervention. HD4MC- and IRS-treated huts had a significantly reduced malaria vector density and feeding rate compared to control huts. There was no significant reduction in acetylcholinesterase activity at 1.5 and 24 h post exposure. Actellic^® 300 CS exposure did not result in any serious adverse events among the household occupants. In conclusion, HD4MC was safe and had comparable efficacy to canonical IRS. Full article

Background: The swift expansion of the invasive malaria vector Anopheles stephensi throughout Africa presents a major challenge to malaria control initiatives. Unlike the native African vectors, An. stephensi thrives in urban settings and has developed resistance to multiple classes of insecticides, including pyrethroids, organophosphates, and carbamates. Methods: Insecticide susceptibility tests were performed on field-collected An. stephensi mosquitoes from Awash Sebac Kilo, Ethiopia, to assess insecticide resistance levels. Illumina RNA-seq analysis was then employed to compare the transcriptomes of field-resistant populations and susceptible laboratory strains (STE2). Results: An. stephensi populations exhibited high levels of resistance to both deltamethrin (mortality, 39.4 ± 6.0%) and permethrin (mortality, 59.3 ± 26.3%) in WHO tube bioassays. RNA-seq analysis revealed that both field-resistant and field-unexposed populations exhibited increased expressions of genes associated with pyrethroid resistance, including esterases, P450s, and GSTs, compared to the susceptible STE2 strain. Notably, esterase E4 and venom carboxylesterase-6 were significantly overexpressed, up to 70-fold, compared to the laboratory strain. Functional enrichment analysis revealed a significant overrepresentation of genes associated with catalytic activity under molecular functions and metabolic process under biological process. Using weighted gene co-expression network analysis (WGCNA), we identified two co-expression modules (green and blue) that included 48 genes strongly linked to pyrethroid insecticide resistance. A co-expression network was subsequently built based on the weight values within these modules. Conclusions: This study highlights the role of esterases in the pyrethroid resistance of an An. stephensi population. The identification of candidate genes associated with insecticide resistance will facilitate the development of rapid diagnostic tools to monitor resistance trends. Full article

Human arboviral diseases such as dengue, chikungunya, and Zika can be transmitted by the mosquito Aedes aegypti. The insecticide-based vector control strategy is critical in reducing transmission of these Aedes-borne diseases but is threatened mainly by the emergence of insecticide resistance. Adult Ae. aegypti from the National Capital Region (NCR), Philippines, were subjected to bioassays to determine their susceptibility to diagnostic doses of pyrethroid, organochlorine, and organophosphate insecticides following the standard World Health Organization insecticide susceptibility test. This study reports the detection of insecticide resistance to pyrethroids and organochlorine in Ae. aegypti from the Philippines for the first time. Most of the Ae. aegypti populations from NCR exhibited phenotypic resistance to permethrin, etofenprox, and DDT. Varying resistance levels to deltamethrin, cyfluthrin, and lambda-cyhalothrin were observed in the different mosquito populations, while all populations tested to malathion were susceptible to this organophosphate. This finding should alert public health authorities to consider modifying the existing vector management package for greater control efficacy. Best practices proven to prevent or delay the development of insecticide resistance, such as insecticide rotation, should also be implemented, while alternative chemicals with a different mode of action should be explored to ensure the continuing efficacy of program interventions. Full article

Bemisia tabaci (Gennadius) is as a major pest of vegetable crops in Cameroon. These sap-sucking insects are the main vector of many viruses infecting plants, and several cryptic species have developed resistance against insecticides. Nevertheless, there is very little information about whitefly species on vegetable crops and the endosymbionts that infect them in Cameroon. Here, we investigated the genetic diversity of whiteflies and their frequency of infection by endosymbionts in Cameroon. Ninety-two whitefly samples were collected and characterized using mitochondrial cytochrome oxidase I (mtCOI) markers and Kompetitive Allele Specific PCR (KASP). The analysis of mtCOI sequences of whiteflies indicated the presence of six cryptic species (mitotypes) of Bemisia tabaci, and two distinct clades of Bemisia afer and Trialeurodes vaporariorum. Bemisia tabaci mitotypes identified included: MED on tomato, pepper, okra, and melon; and SSA1-SG1, SSA1-SG2, SSA1-SG5, SSA3, and SSA4 on cassava. The MED mitotype predominated in all regions on the solanaceous crops, suggesting that MED is probably the main phytovirus vector in Cameroonian vegetable cropping systems. The more diverse cassava-colonizing B. tabaci were split into three haplogroups (SNP-based grouping) including SSA-WA, SSA4, and SSA-ECA using KASP genotyping. This is the first time that SSA-ECA has been reported in Cameroon. This haplogroup is predominant in regions currently affected by the severe cassava mosaic virus disease (CMD) and cassava brown streak virus disease (CBSD) pandemics. Three endosymbionts including Arsenophonus, Rickettsia, and Wolbachia were present in female whiteflies tested in this study with varying frequency. Arsenophonus, which has been shown to influence the adaptability of whiteflies, was more frequent in the MED mitotype (75%). Cardinium and Hamiltonella were absent in all whitefly samples. These findings add to the knowledge on the diversity of whiteflies and their associated endosymbionts, which, when combined, influence virus epidemics and responses to whitefly control measures, especially insecticides. Full article

Among the main arboviruses affecting public health in tropical regions are dengue, zika, and chikungunya, transmitted mainly by mosquitoes of the Aedes genus, especially Aedes aegypti. In recent years, outbreaks have posed major challenges to global health, highlighting the need for integrated and innovative strategies for their control and prevention. Prevention strategies include the elimination of vectors and avoiding mosquito bites; this can be achieved through the use of bioinsecticides and repellents based on plant phytochemicals, as they offer sustainable, ecological, and low-cost alternatives. Mexico has a variety of plants from which both extracts and essential oils have been obtained which have demonstrated significant efficacy in repelling and/or killing insect vectors. This review examines the current knowledge on plant species found in Mexico which are promising options concerning synthetic compounds in terms of their repellent and insecticidal properties against mosquitoes of the genus Aedes and that are friendly to the environment and health. Full article

Malaria poses a serious threat to human health. Existing vector-based interventions have shortcomings, such as environmental pollution, strong resistance to chemical insecticides, and the slow effects of biological insecticides. Therefore, the need to develop novel strategies for controlling malaria, such as reducing mosquito vector competence, is escalating. Human defensin 5 (HD5) has broad-spectrum antimicrobial activity. To determine its effect on Plasmodium development in mosquitoes, HD5 was injected into Anopheles stephensi at various time points. The infection density of Plasmodium yoelii in An. stephensi was substantially reduced by HD5 treatment administered 24 h prior to infection or 6, 12, or 24 h post-infection (hpi). We found that HD5 treatment upregulated the expression of the innate immune effectors TEP1, MyD88, and Rel1 at 24 and 72 hpi. Furthermore, the RNA interference of MyD88, a key upstream molecule in the Toll signaling pathway, decreased the HD5-induced resistance of mosquitoes against Plasmodium infection. These results suggest that HD5 microinjection inhibits the development of malaria parasites in An. stephensi by activating the Toll signaling pathway. Full article