Phenothrin 0.5% liquid

In this investigation of effectiveness of an alternative pediculicide dosage form, we recruited 228 children and 50 adult participants from Bedfordshire, UK, to a randomised, controlled, assessor blind trial comparing two insecticide products with mechanical removal of lice as a control group.  Participants using insecticide were treated with either the investigative 0.5% phenothrin mousse, for 30 minutes, or 0.2% phenothrin lotion, for 2 hours as the reference product.  Both treatments were applied only once, followed by shampoo washing.  Those treated by wet-combing with conditioner were combed 4 times over 12 days.  Parents/carers carried out the treatments to mimic normal consumer use.  The outcome measure was the absence of lice, 14 days after treatment for the insecticides, and up to 14 days after completion of combing.  Intention to treat analysis of the outcomes for 275 participants showed success for phenothrin mousse in 21/105 (20.0%), in 23/107 (21.5%) for phenothrin lotion, and in 12/63 (19.1%) for wet-combing.  People receiving mousse were 1.07 (95% CI, 0.63 to 1.81) times more likely to still have lice after treatment compared with those treated with lotion. The group of participants who received the wet combing treatment were 1.13 (95% CI, 0.61 to 2.11) times more likely to still have lice after the treatment.  None of the treatments was significantly (p < 0.05) more effective than any other. This study was carried out in an area where moderate resistance to phenothrin was demonstrated after the study by using a bioassay.  Analysis of post treatment assessments found that failure of insecticides to kill louse eggs had influenced the outcome.

Abstract licence: CC BY 3.0

D-phenothrin is one of the most popular pyrethroid insecticides for its broad spectrum and high insecticidal activity. However, continuous use of D-phenothrin has resulted in serious environmental contamination and raised public concern about its impact on human health. Biodegradation of D-phenothrin has never been investigated and its metabolic behaviors remain unknown. Here, a novel bacterial strain P31 was isolated from active sludge, which completely degraded (100%) D-phenothrin at 50 mg⋅L-1 in 72 h. Based on the morphology, 16S rRNA gene and Biolog tests, the strain was identified as Pseudomonas fulva. Biodegradation conditions were optimized as 29.5°C and pH 7.3 by utilizing response surface methodology. Strain P31 depicted high tolerance and strong D-phenothrin degradation ability through hydrolysis pathway. Strain P31 degraded D-phenothrin at inhibition constant (Ki) of 482.1673 mg⋅L-1 and maximum specific degradation constant (qmax) of 0.0455 h-1 whereas critical inhibitor concentration remained as 41.1189 mg⋅L-1. The 3-Phenoxybenzaldehyde and 1,2-benzenedicarboxylic butyl dacyl ester were identified as the major intermediate metabolites of D-phenothrin degradation pathway through high-performance liquid chromatography and gas chromatography-mass spectrometry. Bioaugmentation of D-phenothrin-contaminated soils with strain P31 dramatically enhanced its degradation, and over 75% of D-phenothrin was removed from soils within 10 days. Moreover, the strain illustrated a remarkable capacity to degrade other synthetic pyrethroids, including permethrin, cyhalothrin, β-cypermethrin, deltamethrin, fenpropathrin, and bifenthrin, exhibiting great potential in bioremediation of pyrethroid-contaminated environment.

Abstract licence: CC BY 4.0

Honey bees encounter a diverse array of pesticides in their foraging areas and inside their colonies. Beekeepers have expressed tremendous concern about the impacts of pesticides on honey bee colony health and their beekeeping business. The fungicide chlorothalonil is frequently detected at concentrations above 5 ppm within colonies. Exposure to chlorothalonil in lab studies have shown impacts on larval development and morphology of emerging adults while field studies have shown that colony losses are associated with chlorothalonil at 5 ppm. This research was conducted to test if chlorothalonil has effects on honey bee toxicity, insecticide synergism, detoxification activity, and expression of esterase and cytochrome P450 genes in order to assess if chlorothalonil may contribute to colony losses via direct or enhanced toxicity. Exposure to 10 μg topically applied doses or 5 ppm orally applied concentrations of technical or formulated chlorothalonil did not result in significant direct mortality, demonstrated <2-fold levels of synergism or antagonism with phenothrin, chlorpyrifos, and clothianidin, and did not impact activity or expression of detoxification enzymes. Therefore, the impacts of chlorothalonil on honey bee colony health is likely not due to toxicity or synergism but rather other physiological mechanisms.

Abstract licence: CC BY

Populations are exposed to pesticides through diet on a daily basis. However, there is no research guiding how to evaluate dietary pesticide exposure, and researchers used 1-day, 3-days, 7-days or even longer dietary survey to evaluate without any consensus. It is important for dietary pesticide evaluation to identify the minimum survey days. To increase knowledge of this, a data combination was applied between a two-wave consecutive repeated-measures study in Baoding City and the Fifth China Total Diet Study. Further policy consistency on pesticides were evaluated to explain its credibility. We computed the sensitivity and specificity to evaluate how well different days of dietary survey classify participants with high exposure, and calculated the minimum days required to estimate the participant-specific mean at different acceptable error range. With 1 day of dietary survey, the classification sensitivity was low (<0.6) for total HCH, endosulfan, chlordane, cyhalothrin, allethrin, and prallethrin; that for the other pesticides was high sensitivity (≥0.6). Sensitivity increased as the number of days increased, and the maximum marginal sensitivity increase (≥0.039) occurred from 1 to 2 days for all pesticides except phenothrin, whose maximum marginal sensitivity increase (0.042) occurred from 2 to 3 days. The specificity increased gradually from 0.8 to 0.9 from 1 to 7 days. Under the acceptable error range of 0.5%, 3-28 days were required for participant-specific mean estimation and 1-7 days were required when acceptable error range was shrunk in 1%. Only 1 day was enough if 5% error range was acceptable. In conclusion, 3 days in the study period was cost-effective to distinguish high exposure group, and it rose to 7 when estimating participant-specific mean from a conservative perspective. This study can serve as a reference to determine the minimum survey days for epidemiological studies employing dietary surveys.

Abstract licence: CC BY-NC-ND

Tungiasis, caused by the sand flea Tunga penetrans, results in itching and pain. Effective treatments, such as dimeticones, are often unaffordable. A 3% phenothrin lotion has shown safety and efficacy in Kenyan trials. This study compared the cure rate and safety of 3% phenothrin lotion (as the intervention) and 0.05% potassium permanganate (KMnO4; as the standard-care comparator) over 14 days. This parallel-group, three-arm, non-blinded, randomised comparative trial was conducted in Vihiga County, Kenya. Participants aged ≥2 years with ≥1 viable flea on each foot were allocated (2:1:1) to KMnO4, single-dose 3% phenothrin, or two-dose 3% phenothrin groups. Overall, 415 fleas from 79 participants were followed up to day 14 (KMnO4, 213; single-dose, 129; two-dose, 73). On days 4 and 7, the single-dose phenothrin showed significantly higher cure rates (11.6% and 21.7%) than KMnO4 (0.9% and 11.7%) (p p = 0.013). The differences diminished by days 10 and 14 because of spontaneous flea death. The cure rate of the two-dose group on day-7 (8.2%) was lower than that of the single-dose group. Single-dose 3% phenothrin improved early cure rates compared to KMnO4, but not by days 10–14; two-dose phenothrin showed no benefit compared with single dose from day 7 onwards.

Abstract licence: CC BY 4.0

BackgroundKnockdown effect, especially in pyrethroid-based household and public insecticides, is often considered a practical indicator of insecticidal efficacy. However, whether faster knockdown implies lethality remains uncertain because the relationship between the two effects has not been systematically explored. This study examined whether knockdown speed is associated with mortality across type-I pyrethroids, type-II pyrethroids, and organophosphate insecticides in the house fly.ResultsFor type-I pyrethroids, faster knockdown did not predict higher mortality. Early knockdown did not necessarily lead to lethality, and no significant differences were observed among LD20, LD50, and LD80 treatments. In contrast, type-II pyrethroid and organophosphate insecticides showed a positive knockdown-mortality relationship, with most lethal individuals being knocked-down early. In the mixture study, d-phenothrin showed an additive interaction with prallethrin but a synergistic interaction with tetramethrin, although all three compounds are type-I pyrethroids. Computer vision-based analyses using a convolutional neural network (CNN) of symptomology revealed a synergistic shift in intoxication phenotype from type-I-like to type-II-like symptoms in the synergistic d-phenothrin and tetramethrin mixture.ConclusionKnockdown speed should not be used as a proxy for lethality for type-I pyrethroids, highlighting class- and mixture-dependent dynamics between knockdown and mortality. These findings support regulatory and operational decisions that consider knockdown and mortality as distinct performance endpoints, particularly when substantiating claims such as 'quick kill' or 'kills on contact' for pesticide registration. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Abstract licence: CC BY-NC-ND