ABSTRACT
Objective@#To determine the adverse effect of pre- and postnatal exposure to carbamate (propoxur) and pyrethroid pesticides on children's cognitive functions at 4 and 6 years of age. @*Method@#As part of a prospective cohort study among children with known pre- and postnatal exposure to propoxur and pyrethroids, children were examined at time points, 4 and 6 years, to determine the adverse effect of pesticide exposure on neurocognitive function, i.e., intelligence (IQ) using the WPPSI-III test. Pre- and postnatal pesticide exposures were measured by meconium and hair analysis, respectively, using gas chromatography-mass spectrometry (GCMS).@*Results@#Seven hundred twenty-four (724) maternal/children dyads were seen at four years and 717 at six years of age. Their mean (SD) full-scale IQ was low on average: 83.9 (10.2) at four years and 83.6 (8.6) at six years. Prenatal but not postnatal exposure to propoxur (-0.139, p=0.01) and pyrethroids (-0.097, p=0.05) were significantly correlated (negative) with full-scale IQ at four years but not at six years. The confounders that were significantly correlated to full-scale IQ at four and/or six years of age were maternal IQ, child’s weight, height, head circumference, socio-economic status, child environment, and stimulation at home (HOME) violence or abuse at home. Regression analysis of pesticides and confounders showed similar results, except for weight and head circumference.@*Conclusion@#We conclude that prenatal exposure to propoxur and pyrethroids had a negative effect on the children’s IQ at four years but no longer at six years. Thus, the ability of the child’s IQ to recover from the adverse effect of intrauterine pesticide insult may be attributable to the neuronal plasticity of its brain. Similarly, confounders to these outcome measures are multiple and are essential to address when evaluating the effect of pesticides on neuro-cognitive development in children.
Subject(s)
CarbamatesABSTRACT
Objective To investigate the resistance dynamics of Blattella germanica to commonly used insecticides in Yangpu District of Shanghai during 2014‒2020， and to provide the basis for the rational use of insecticides against cockroaches. Methods Blattella germanica was captured in two farmer’s markets in 2014， 2017 and 2020. The residual film method recommended by WHO was used to test resistance of Blattella germanica to the insecticides. Results In 2014， 2017 and 2020， the resistance ratio of Blattella germanica in Yangpu District was 6.96， 4.39， 7.26 to beta-cypermethrin， 10.41， 6.71， 5.24 to permethrin， and 2.28， 3.16， 1.01 to propoxur. Conclusion The resistance of Blattella germanica to permethrin and propoxur decreases， and the resistance to beta-cypermethrin keeps at low level. Comprehensive management and rotation of insecticides should be implemented to delay the increase of resistance.
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Objective To explore the sensitivity of Culex pipiens pallens to common chemical insecticides in the southwestern region of Shandong Province, so as to provide a theoretical basis for the development of reasonable and effective mosquito control measures. Methods The resistance of Cx. pipiens pallens larvae to 5 chemical insecticides, such as cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate were tested by using the WHO biological test method in 2018, and the co-toxicity coefficients after compounding the above-mentioned insecticides were tested by using a drug compounding method. Results The resistance indexes of Cx. pipiens pallens to cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate in 3 cities were 144.43–557.54, 118.17–445.33, 6.44–19.00, 2.37–8.10, and 0.88–2.98, respectively, and expect the difference between the DDVP resistances of Cx. pipiens pallens in Jining City and Heze City was not statistically significant (P > 0.05), all the other differences were statistically significant (all P < 0.05). The synergistic coefficients of cypermethrin + DDVP, cypermethrin + propoxur, DDVP + acetofenate, and propoxur + acetofenate were 199.58 – 456.95, 190.56 – 292.37, 123.32 – 319.24, and 192.31 – 367.32, respectively. The lower synergism was observed by using the mixture of DDVP + propoxur (synergistic coefficient: 99.87–108.36) . Conclusions After decades of chemical control, Cx. pipiens pallens in the southwestern region of Shandong Province has produced different degrees of resistance to common chemical insecticides. Therefore, comprehensive control measures should be taken to control mosquito breeding and prevent the development of insecticide resistance.
ABSTRACT
Blattella germanica (L., 1757) (Dictyoptera: Blattellidae) vive há muito tempo em associação com o homem, próximo às suas fontes de alimentos e criou resistência a diversos inseticidas. Tornou-se, por isso a espécie de barata mais difícil de ser controlada, causando grande transtorno, afetando a economia e apresentando ainda importância médica. O objetivo deste trabalho foi avaliar a resistência de B. germanica aos inseticidas Diazinon® (organofosforado), Cipermetrina® (piretróide), Propoxur® (carbamato) e o período residual de ação até 15 dias após a aplicação. Para avaliar a resistência adquirida por B. germanica aos inseticidas, e melhor caracterização com o dia a dia das empresas controladoras de pragas, a diluição seguiu as instruções dos fabricantes e a técnica para este estudo foi a de contato tarsal. As baratas foram coletadas em diversos estabelecimentos comerciais no município de Juiz de Fora (Minas Gerais) e mantidas em condições controladas de laboratório (temperatura 28ºC ± 1ºC, umidade relativa do ar 60% ± 5%), tendo como alimento ração canina, leite em pó e água, oferecida de forma ininterrupta. Os espécimes obtidos a partir da 3º geração foram utilizados nos ensaios, eliminando qualquer contato anterior com produtos químicos. Para avaliação de cada inseticida foram utilizados 1800 espécimes. Os resultados mostraram maior resistência à Cipermetrina e Propoxur, sendo Diazinon o produto que apresentou maior eficácia, demonstrando ser o mais recomendável para o controle desse inseto. O efeito residual deixado pelos três inseticidas apresentou resultados bem parecidos, sendo o período mais favorável para o controle de B. germanica os primeiros 10 dias após a aplicação.
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Propoxur (2-isopropoxyphenyl N-methylcarbamate) is widely used as an acaricide in agriculture and public health programs. Studies have shown that sub-chronic exposure to propoxur can cause oxidative stress and immuno-suppression in rats. Carbamates are also known to exhibit inhibitory effect on cholinesterase activity, which is directly related to their cholinergic effects. In the present study, the effect of Withania somnifera (Ashwagandha), a widely used herbal drug possessing anti-stress and immuno-modulatory properties was studied on propoxur-induced acetylcholine esterase inhibition and impairment of cognitive function in rats. Male Wistar rats were divided into four groups. Group I was treated with olive oil and served as control. Group II was administered orally with propoxur (10 mg/kg b.wt.) in olive oil, group III received a combination of propoxur (10 mg/kg b.wt.) and W. somnifera (100 mg/kg b.wt.) suspension and group IV W. somnifera (100 mg/kg b.wt.) only. All animals were treated for 30 days. Cognitive behaviour was assessed by transfer latency using elevated plus maze. Blood and brain acetylcholine esterase (AChE) activity was also assessed. Oral administration of propoxur (10 mg/kg b.wt.) resulted in a significant reduction of brain and blood AChE activity. A significant prolongation of the acquisition as well as retention transfer latency was observed in propoxur-treated rats. Oral treatment of W. somnifera exerts protective effect and attenuates AChE inhibition and cognitive impairment caused by sub-chronic exposure to propoxur.
Subject(s)
Acetylcholinesterase/blood , Acetylcholinesterase/metabolism , Animals , Cholinesterase Inhibitors/toxicity , Cognition Disorders/blood , Cognition Disorders/chemically induced , Cognition Disorders/enzymology , Cognition Disorders/prevention & control , Dose-Response Relationship, Drug , Male , Medicine, Traditional , Plant Extracts/pharmacology , Propoxur/toxicity , Rats , Rats, Wistar , Withania/chemistryABSTRACT
Background & objectives: Resistance amongst cockroaches has been reported to most of the spray insecticides apart from the problem of food contamination and inconvenience. Gel baits which can be selectively applied have been found effective in control of cockroaches in laboratory studies but very few field studies are available. This trial was planned to evaluate the efficacy of fipronil (0.01%) and imidacloprid (2.15%) gels over synthetic pyrethroid (0.02% deltamethrin + 0.13% allethrin) and propoxur (2%) aerosols in control of cockroaches in the field. Methods: Survey was done to find out pre-treatment density in catering establishments and houses by visual count and sticky trap methods. A total of 10 catering establishments and 10 houses having high cockroach infestation were selected by sampling (two catering establishments and houses for each insecticidal treatment and two for control). Propoxur and synthetic pyrethroid aerosols were used for spraying the infested sites once only. Single application of fipronil and imidacloprid gels was used as crack and crevice treatment. Visual count method gave better indications of cockroach infestation as compared to sticky trap method, hence, the same was followed for post-treatment evaluation every week up to 12 weeks. Results: Synthetic pyrethroid could not bring about the desired reduction in cockroach infestation in the present study. Single application of fipronil gel was able to reduce cockroach infestation up to 96.8% at the end of 12 weeks whereas imidacloprid application resulted in 90.9% reduction and propoxur resulted in 77.5%. However, propoxur was more effective in reducing the cockroach density by first week in comparison to imidacloprid and fipronil gels but its efficacy started declining after 8th week. Difference was found statistically significant by Kruskal-Wallis H-test. Conclusion: The study reports the efficacy of propoxur aerosol, imidacloprid gel and fipronil gel baits for control of cockroaches.