The research team, led by Tongjit Thanchomnang of Mahasarakham University together with colleagues at Burapha University and the University of Lincoln, screened 960 schoolchildren attending five public schools in urban and rural areas of Chonburi Province between May and July 2024. The overall prevalence of pediculosis, the medical term for head louse infestation, came out at 20.42 percent, with a 95 percent confidence interval of 17.91 to 23.11 percent. That figure masks a striking geographic pattern: infestation was markedly more common in rural schools than in urban ones. The study was approved by the Institutional Review Board of Burapha University, and written informed consent was obtained from parents or legal guardians before any child took part, with age-appropriate assent from the children themselves.

Beyond the headline prevalence number, the team used logistic regression to identify which characteristics of the children were statistically associated with carrying lice. Four factors stood out: sex, school level, hair length, and a reported history of pediculicide use, meaning the use of chemical lice treatments. The association with reported pediculicide use is perhaps the most intriguing of the four, because it hints at a self-reinforcing cycle in which children who have been treated remain infested, either because the treatment failed or because reinfection occurred quickly, prompting yet more rounds of chemical exposure. The authors are careful to frame these as epidemiological associations rather than proof of causation, but the pattern is consistent with what happens in populations where the parasites are no longer reliably killed by the standard drugs.

To understand what was happening at the molecular level, the researchers collected lice from infested children and first confirmed their identity. Every sample examined was morphologically identified as Pediculus humanus capitis, the head louse, and analysis of the mitochondrial cytochrome c oxidase subunit 1 gene, known as cox1, placed the insects in mitochondrial clades A or C. These clades describe the deep maternal lineages of head lice and are used by researchers worldwide to track louse populations. Clade A is the most widespread lineage globally, while clade C has a more patchy distribution, and finding both in the same school settings gives a snapshot of the genetic diversity circulating among Thai schoolchildren.

The heart of the study, however, lies in its exploratory search for knockdown resistance mutations, commonly abbreviated as kdr. These mutations occur in the gene encoding the voltage-sensitive sodium channel, or VSSC, a protein in the nerve cell membranes of insects that is the primary molecular target of pyrethroid insecticides. Pyrethroids, the synthetic compounds modeled on natural chrysanthemum-derived toxins, work by binding to this channel and holding it open, paralyzing and killing the insect. Permethrin, the pyrethroid most commonly formulated against head lice, depends entirely on this mechanism. When specific amino acid substitutions appear in the sodium channel protein, the insecticide binds less effectively, the insect survives exposure, and the mutation spreads through the population under the relentless selection pressure of repeated treatments.

Two such mutations are the classic markers of pyrethroid resistance in head lice: T917I, in which the amino acid threonine at position 917 of the channel protein is replaced by isoleucine, and L920F, in which leucine at position 920 is replaced by phenylalanine. Using polymerase chain reaction and sequencing on a stratified subsample of the collected lice, the researchers detected these resistance-associated mutations in the Thai lice populations. More significantly, they identified homozygous resistant genotypes, in which an individual louse carries two copies of the resistance-associated allele, one inherited from each parent. These homozygous resistant individuals, the genotype most strongly linked to survival after pyrethroid exposure, were found in lice collected from four of the sampled schools, indicating that the resistance-associated variants are not isolated curiosities but established features of the local louse populations.

Perhaps the most sobering detail is that resistance-associated genotypes were detected among lice collected from children both with and without reported histories of permethrin treatment. This suggests that the resistant insects are circulating through the school community regardless of whether an individual child has been directly exposed to the drug, carried from head to head by the close contact that defines childhood social life. A louse carrying resistance mutations does not need its host to have used permethrin; it simply needs to have descended from a lineage that survived such exposure somewhere in the local population. In this way, individual treatment decisions ripple outward, shaping the genetic composition of parasites that infest the entire community.

The authors are appropriately measured in their interpretation. Molecular detection of kdr mutations, they emphasize, cannot by itself confirm clinical resistance, because genotype is a proxy rather than a direct measurement of treatment failure. Confirming that permethrin genuinely fails in the clinic would require phenotypic validation studies, in which live lice are exposed to controlled doses of the insecticide and their survival is measured. Nevertheless, the molecular findings carry weight in context. Previous studies in the region have reported incomplete treatment outcomes following permethrin use, and the new genetic data provide a plausible mechanism for those observations. The convergence of epidemiological signals, molecular markers, and prior clinical reports paints a coherent picture of a treatment under strain.

What makes this study particularly valuable is its integrated design. Rather than measuring prevalence, risk factors, and molecular resistance in separate investigations, the team combined all three within the same school settings, allowing a direct link to be drawn between the children experiencing infestations and the genetic character of the lice infesting them. This kind of joined-up surveillance is exactly what public health authorities need when deciding how to respond. If resistance mutations are present, simply recommending more frequent permethrin applications may be futile or even counterproductive, intensifying the selection pressure that drives resistance further. Alternative non-pyrethroid therapies exist, and the study’s ethical protocol already reflected this reality: when treatment failure was suspected, alternative non-pyrethroid treatments were recommended in consultation with local healthcare professionals.

The broader implications extend well beyond Chonburi Province. Pyrethroid resistance in head lice has now been documented across multiple continents, and each new geographic confirmation reinforces the case for coordinated management approaches rather than ad hoc, drug-by-drug responses. The researchers call for continued molecular surveillance, phenotypic validation studies, and future evaluation of coordinated management strategies in endemic settings. For the millions of families worldwide who reach for a permethrin shampoo at the first sign of lice, the message is that the era of assuming the first bottle will work is drawing to a close. Head lice remain a common and treatable condition, but treating them effectively in the twenty-first century increasingly requires knowing what the local lice look like, genetically speaking, before choosing the weapon. Studies like this one provide exactly that knowledge, and they suggest that in eastern Thailand, the lice have already adapted to the old playbook.

Subject of Research: Head louse infestation prevalence and knockdown resistance mutations in schoolchildren in eastern Thailand

Article Title: High prevalence of pediculosis, associated factors, and exploratory detection of the knockdown resistance mutations in head lice from school settings in Chonburi Province, eastern Thailand

Article References: Thanchomnang, T., Gordon, C. N., Krittanan, P., Yangthaworn, K., Thetkathuek, A., Clegg, S. R., Mano, C., & Yingklang, M. (2026). High prevalence of pediculosis, associated factors, and exploratory detection of the knockdown resistance mutations in head lice from school settings in Chonburi Province, eastern Thailand. Parasites & Vectors, 19(1), Article 391. https://doi.org/10.1186/s13071-026-07672-y

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07672-y

Keywords: head lice, pediculosis, kdr mutations, pyrethroid resistance, permethrin, schoolchildren, Thailand, molecular surveillance, voltage-sensitive sodium channel, cox1, public health, Parasites & Vectors

The team, led by Mst. Samia Sultana of Hokkaido University’s Graduate School of Agriculture, ran their trial during the late spring season from April 15 to August 20, 2024, at the university’s Field Science Center for the Northern Biosphere in Hokkaido. They grew the popular Japanese cabbage variety ‘Kinkei-201’ in a randomized complete block design, with each of three treatments replicated three times across plots of 24 plants. One group of plants was sprayed with the bottle gourd leaf extract dissolved in dilute dimethyl sulfoxide, a second received the chemical insecticide permethrin 3.2 EC as a positive control, and a third received only the aqueous DMSO carrier as a negative control. Spraying began ten days after transplanting and continued at seven-day intervals until the end of the growing season, for a total of eight applications at ten milliliters per plant.

The results were striking. Compared with the untreated control, the bottle gourd extract reduced looper larval infestation by 41.18 percent in the fifth week, 39.71 percent in the sixth, 52.08 percent in the seventh, and 37.96 percent in the eighth week of monitoring. Permethrin still delivered the strongest protection overall, but the botanical extract was not far behind where it mattered most: at the harvest. The extract-treated plots produced 48.26 metric tons of cabbage per hectare, essentially identical to the 48.23 metric tons per hectare achieved with permethrin, while the control plots yielded only 41.61 metric tons per hectare. That difference translates to a 15.98 percent yield increase over the control, driven almost entirely by the extract’s ability to keep hungry caterpillars at bay.

The cabbage looper earns its ominous name from the looping gait of its caterpillars, which arch their bodies as they crawl across leaf surfaces. It is among the most troublesome pests of cruciferous crops worldwide, and it is most damaging once cabbage enters the heading stage, when larvae chew through the undersides of leaves and burrow into the developing head. A single female moth can lay between 300 and 600 eggs over roughly ten to twelve days, and in warm conditions the insect can complete its entire life cycle from egg to adult in as little as 18 to 25 days. Mature larvae are voracious, eventually consuming up to three times their body weight in plant tissue each day. During the Hokkaido trial, the looper was the only pest present in meaningful numbers, making it an ideal target for a controlled comparison of treatments.

Preparing the extract was a straightforward affair that farmers in many regions could plausibly replicate. The researchers collected bottle gourd leaves on the Hokkaido University campus, discarded any damaged or discolored samples, and dried the rest at room temperature before grinding them into a powder. Roughly 100 grams of powder was soaked in 400 milliliters of ethanol and shaken for 74 hours in a constant-temperature incubator, after which the mixture was centrifuged, filtered, and evaporated at 50 degrees Celsius to yield a crude extract. One gram of this extract was dissolved in one milliliter of DMSO and diluted into a liter of distilled water for spraying. The choice of DMSO was deliberate: the solvent is powerful enough to carry a complex mixture of plant compounds into solution, and at concentrations below 0.1 percent it is considered safe for plants and animals.

To understand why the extract works, the team turned the crude preparation over to liquid chromatography coupled with high-resolution mass spectrometry. The analysis tentatively identified 21 chemical compounds in the ethanolic extract, five of which stand out as plausible biopesticide agents: apigenin-7-O-glucoside, indole-3-butyric acid, strychnine, phytol, and hexadecanoic acid. Apigenin-7-O-glucoside, a flavonoid, has documented insecticidal effects, killing insects, reducing their egg-laying, deterring feeding and growth, and interfering with their ability to digest plant tissue. Indole-3-butyric acid, better known as a plant growth regulator, has been used alongside other chemicals to boost plant resistance to insect attack. Phytol, a diterpene alcohol, has shown considerable promise as an eco-friendly botanical insecticide, while hexadecanoic acid, a common fatty acid, carries known nematicidal and pesticidal activity.

The presence of strychnine among the identified compounds is notable and, on its face, alarming, since the alkaloid is infamous as a rodenticide and avicide. The authors note that strychnine is also classified as an insecticide, and its detection here was tentative, based on mass-spectrometric matching rather than isolation and quantification. That caveat matters: identifying a compound in a complex plant extract does not establish how much of it is present, whether it is bioavailable to insects, or whether it contributes to the observed pest suppression. It also raises questions that any regulatory pathway would need to answer, since a biopesticide is only as acceptable as its most toxic constituent. The researchers themselves frame the compound list as a set of targets for future work rather than a finished safety profile.

Complementary Fourier transform infrared spectroscopy added a second layer of chemical characterization. The spectra revealed absorption bands consistent with primary aliphatic amines, carboxylic acids, alkanes, alcohols, sulfones, phenols, anhydrides, alkenes, and even a halo compound, painting a picture of an extract rich in the kinds of secondary metabolites that plants deploy as chemical defenses. Such compounds can disrupt insect cell membranes, inactivate enzymes, and derail metabolic processes, leading to growth inhibition or death. Notably, the extract did not appear to harm the crop itself: chlorophyll content measured by SPAD meter, photosynthesis rates, plant spread, and head diameter showed no significant differences among treatments, and extract-treated plants actually grew tallest, though not significantly so.

The broader context gives the work its urgency. Synthetic pesticides remain the backbone of pest control in intensive vegetable production, but chronic exposure has been linked in assessments to cancers, neurological and cardiovascular disease, reproductive harm, and impaired respiratory health, while agricultural chemicals contribute to documented declines in insects, birds, bats, earthworms, fish, and amphibians. Botanical biopesticides, by contrast, tend to be target-specific, sparing natural enemies of pests, and they decompose quickly in the environment, leaving minimal residues on fresh produce. Bottle gourd itself is an apt source: among the first plants ever domesticated and the only crop with a global distribution before Columbus, it is already cultivated worldwide for food and medicine, and earlier studies have shown its leaf extracts effective against cabbage aphids and mosquito larvae.

The Hokkaido team is careful to note the limits of the study. It was a small-scale field trial in a single season at a single site, and the extract’s formulation, concentration, and spray schedule were not optimized. Whether the same results hold across different climates, soil types, and pest pressures remains to be seen, as does the extract’s compatibility with integrated pest management programs and its effects on beneficial insects under real-world conditions. Still, the headline numbers are hard to ignore: a leaf extract from a plant most gardeners grow for its fruit cut looper damage nearly in half in peak weeks and matched a commercial pyrethroid on yield. If follow-up research can pin down the active compounds, standardize the formulation, and clear the safety questions, the ancient bottle gourd may find a new role as a factory for sustainable crop protection.

Subject of Research: Botanical biopesticide control of cabbage looper in cabbage using bottle gourd leaf extract

Article Title: Efficacy of bottle gourd (Lagenaria siceraria) leaf extract in protecting against cabbage looper (Trichoplusia ni) (Lepidoptera: Noctuidae) infestation

Article References: Sultana, M. S., Shimizu, N., Itoh, T., & Iwabuchi, K. (2025). Efficacy of bottle gourd (Lagenaria siceraria) leaf extract in protecting against cabbage looper (Trichoplusia ni) (Lepidoptera: Noctuidae) infestation. Crop Health, 3(1), Article 11. https://doi.org/10.1007/s44297-025-00050-7

Image Credits: AI Generated

DOI: 10.1007/s44297-025-00050-7

Keywords: bottle gourd, cabbage looper, biopesticide, botanical insecticide, Lagenaria siceraria, Trichoplusia ni, cabbage, LC-MS, phytochemicals, sustainable agriculture, permethrin, pest management

The research, led by Kylee R. Noel and colleagues at the University of Illinois Urbana-Champaign and the Illinois Natural History Survey, set out to answer a question that has received surprisingly little rigorous experimental attention. Insecticides applied to agricultural fields, suburban lawns, and mosquito control zones inevitably find their way into surface waters, where concentrations rarely reach levels that kill mosquito larvae outright. Yet these sublethal concentrations can still perturb larval physiology, development, and behavior. Because many of the traits that determine how efficiently a mosquito transmits a virus — adult survival, fecundity, and vector competence — are shaped during the aquatic juvenile stages, the researchers hypothesized that early-life insecticide exposure could leave a lasting imprint on transmission potential.

To test this, the team reared Culex pipiens larvae under standard insectary conditions, with temperatures maintained at approximately 27.6 degrees Celsius, relative humidity around 70 percent, and a photoperiod of 16 hours of light and 8 hours of darkness. One group of larvae was exposed to a sublethal concentration of permethrin, a widely used synthetic pyrethroid insecticide, at 0.01 milligrams per liter — a dose low enough not to cause mortality but high enough to exert physiological stress. Upon eclosion, adult mosquitoes from both the exposed and unexposed control groups were transferred into environmental chambers held at either 25 or 29 degrees Celsius, two temperatures within the range that Culex pipiens routinely experiences during the summer transmission season in the American Midwest.

The experimental design is notable because it separates the larval and adult environments, allowing the investigators to disentangle effects that occur during development from those imposed on the adult stage. Mosquitoes infected with West Nile virus were then monitored across the key parameters that together constitute vectorial capacity, the epidemiological framework used to estimate how effectively a vector population can transmit a pathogen. These parameters include adult survival, which determines how long a female lives and therefore how many blood meals she can take; fecundity, which influences population growth; and vector competence, a composite measure encompassing infection rate, dissemination rate from the midgut to other tissues, and the ability to transmit virus in saliva during a subsequent bite.

The life-history results revealed that permethrin exposure during the larval stage slowed development: exposed larvae took longer to mature into adults than untreated controls. More strikingly, the adult females that emerged from treated larvae survived longer than their control counterparts. Extended adult longevity is a critical variable in vectorial capacity, because the extrinsic incubation period of West Nile virus — the time it takes for an infected mosquito to become infectious — must be shorter than the mosquito’s lifespan for transmission to occur. Females that live longer have a greater probability of surviving that incubation window and biting another host while infectious, effectively multiplying their contribution to the transmission cycle.

Temperature exerted its own powerful influence on the virological side of the equation. At 29 degrees Celsius, mosquitoes showed higher infection and dissemination rates, and viral RNA was detected at greater levels within mosquito tissues, compared with the cooler 25 degree environment. This pattern is consistent with a broader literature showing that warmer temperatures accelerate viral replication within mosquito vectors, shortening the extrinsic incubation period and pushing mosquitoes to infectious status sooner after an infective blood meal. However, the study’s most consequential finding emerged when the two stressors were analyzed together rather than in isolation.

At 29 degrees Celsius, the control mosquitoes — those with no larval insecticide exposure — exhibited the lowest transmission potential of any group in the experiment. By contrast, mosquitoes that had been exposed to permethrin as larvae displayed markedly higher transmission potential under the same warm conditions. This interaction indicates that sublethal pesticide exposure and elevated temperature do not simply add their effects; they combine in a non-additive manner that reshapes the overall transmission equation. A warmer world, in other words, may not uniformly increase West Nile virus risk — the outcome depends on what the vector population experienced during its aquatic development, and urban or agricultural waters contaminated with pyrethroid residues could tip the balance toward greater transmission.

Why would larval chemical stress enhance transmission potential at high temperatures while control mosquitoes fared worse? The authors’ data suggest that the combination of extended adult survival in permethrin-exposed females and temperature-driven gains in infection and dissemination rates produced a population of longer-lived, more competent vectors precisely under the conditions where unexposed mosquitoes performed least well. The physiological mechanisms linking larval permethrin exposure to adult longevity and vector competence were not fully resolved in this experiment, but stress-induced changes in larval metabolism, immune priming, or resource allocation could plausibly alter adult physiology in ways that interact with viral kinetics at elevated temperatures. Further mechanistic work will be needed to pin down these pathways, and the authors note that their experiment used a single permethrin concentration and two adult temperatures, leaving open questions about dose-response relationships and the full thermal range experienced in the field.

The public health and environmental implications are substantial. Mosquito abatement districts routinely apply pyrethroids as larvicides and adulticides, and agricultural runoff delivers additional residues into stormwater ponds, drainage ditches, and other habitats where Culex pipiens breeds. If those residues leave surviving larvae physiologically primed for greater transmission as adults — particularly during heat waves, when West Nile virus epidemics historically peak — then conventional insecticide use could carry an unrecognized trade-off: suppressing mosquito abundance in the short term while inadvertently enhancing the transmission efficiency of the mosquitoes that survive. The study therefore argues for integrated surveillance that monitors not just mosquito numbers but the chemical and thermal conditions of larval habitats, especially in environments exposed to rising temperatures driven by climate change.

As with all laboratory studies, translating these results to real-world epidemics will require field validation, since wild mosquito populations encounter fluctuating temperatures, heterogeneous insecticide mixtures, and competing larval stresses that a controlled chamber experiment cannot fully replicate. Nevertheless, the work provides a clear experimental demonstration that the developmental environment of a disease vector can rewrite the rules of transmission established by adult conditions alone. For a virus like West Nile, whose seasonal dynamics depend on a delicate interplay between vectors, hosts, and climate, understanding these cross-generational and cross-stressor interactions may prove essential for predicting and preventing the outbreaks of the future. The research was supported by the State of Illinois Used Tire Management and Emergency Public Health funds and by a grant from the University of Illinois Center for Advanced Climate Solutions.

Subject of Research: Interaction of sublethal insecticide exposure and temperature on West Nile virus transmission by Culex pipiens mosquitoes

Article Title: Sublethal insecticide exposure and temperature interact to shape West Nile virus transmission potential of Culex pipiens

Article References: Sublethal insecticide exposure and temperature interact to shape West Nile virus transmission potential of Culex pipiens. (n.d.). https://doi.org/10.1186/s13071-026-07700-x

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07700-x

Keywords: West Nile virus, Culex pipiens, permethrin, sublethal exposure, vector competence, vectorial capacity, temperature, insecticide pollution, mosquito-borne disease, Parasites & Vectors, life history traits, climate change