Susceptibility of Anopheles sinensis to insecticides in Puyang City, Henan Province / 中国血吸虫病防治杂志

Objective To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. Methods An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda-cyhalothrin was tested using the filter-paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. Results In 2018 and 2010, the half knock-down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock-down rates of 37.50% and 60.87% 60 min post-exposure to malathion and 24-hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock-down rates of 22.92% and 16.98% 60 min post-exposure to malathion and 24-hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda-cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock-down rates of 30.39% and 38.30% 60 min postexposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. Conclusion An. sinensis is relatively susceptible to malathion but has developed high-level resistance to deltamethrin and lambda-cyhalothrin in Puyang City, Henan Province..

Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use

BACKGROUND Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.

Experimental hut to study the indoor behaviour and effects of insecticide-treated bednets on phlebotomine sand flies (Diptera: Psychodidae)

BACKGROUND Behavioural effects of insecticides on endophagic phlebotomine sand fly vectors of Leishmania are poorly understood mainly because of the lack of an experimental hut (EH) in which to study them. OBJECTIVE To build an EH to evaluate the effects of long-lasting insecticide-treated nets (LLINs) on Lutzomyia longiflocosa. METHODS The study had two phases: (1) Laboratory experiments using tunnel tests to select the traps for the EH; and (2) EH construction and evaluation of the effects of deltamethrin and lambda-cyhalothrin LLINs on L. longiflocosa females inside the EH. FINDINGS Phase 1: The horizontal-slit trap was the best trap. This trap collected the highest percentage of sand flies, and prevented them from escaping. Therefore, this trap was used in the EH. Phase 2: The main effects of LLINs on L. longiflocosa in the EH were: landing inhibition, inhibition from entering the bednet, induced exophily, and high mortality (total and inside exit traps). CONCLUSIONS The EH was effective for evaluating the effects of LLINs on endophagic sand flies. Although both types of LLINs showed high efficacy, the lambda-cyhalothrin-treated LLIN performed better. This is the first report of induced exophily in sand flies.

Bio-efficacy, physical integrity, community usage and washing practices of mosquito nets treated with ICON MAXX long-lasting insecticidal treatment in India

BACKGROUND New brands of potential long lasting insecticide nets (LLINs) and LLIN treatment kits require field evaluation before they are used in a vector control programme. OBJECTIVES The aim of this study was to evaluate the bio-efficacy, usage, washing practice and physical integrity of nets treated with LLIN treatment kit, ICON MAXX in a phase III field trial in Odisha state, India. METHODS A total of 300 polyester nets treated with ICON MAXX and 140 polyester nets treated conventionally with lambda-cyhalothrin CS 2.5% ITNs were distributed. The bio-efficacy was evaluated with WHO cone bioassay. The chemical analysis of netting pieces was done at the beginning, after 12 and 36 months of the trial. FINDINGS After one year of distribution of nets, the bioassay showed 100% mortality on both ITNs and ICON MAXX treated nets. At 36 months, the overall pass rate was 58.8% and the mean lambda-cyhalothrin content of LLINs was 34.5 mg ai/m2, showing a loss of 44.4% of the original concentration. CONCLUSION ICON MAXX treated LLIN was found to retain bio-efficacy causing 97% knockdown of Anopheles stephensi up to 30 months and met the WHOPES criteria. However, the desired bio-efficacy was not sustained up to 36 months.

Synergistic potential of dillapiole-rich essential oil with synthetic pyrethroid insecticides against fall armyworm / Potencial sinérgico do óleo essencial rico em dilapiol para inseticidas piretroides sintéticos frente à lagarta-do-cartucho

ABSTRACT: The objective of this study was to evaluate the synergy and response homogeneity of the Spodoptera frugiperda larvae population to the Piper aduncum essential oil in combination with pyrethroid insecticides (alpha-cypermethrin, beta-cypermethrin, fenpropathrin, and gamma-cyhalothrin) compared to piperonylbutoxide (PBO) as positive control. Synergism (SF) comparisons were obtained using lethal concentration (LC50) and lethal dose (LD50) ratios of insecticides individually and in their respective synergistic combinations with essential oil and PBO. Dose/concentration-mortality slope curves were used to establish relative toxicity increase promoted by synergism. They also determined homogeneity response. Residual contact revealed significant potentiation for commercial insecticides formulated with beta-cypermethrin (SF=9.05-0.5) and fenpropathrin (SF=34.05-49.77) when combined with the P. aduncum essential oil. For topical contact, significant potentiation occurred only for alpha-cypermethrin (SF=7.55-3.68), fenpropathrin (SF=3.37-1.21), and gamma-cyhalothrin (SF=5.79-10.48) insecticides when combined with essential oil. With the exception of fenpropathrin and gamma-cyhalothrin, insecticides synergistic combinations presented homogeneous response by topical as well as residual contact at least with essential oil. The SF significance values ​​of the P. aduncum essential oil combined with alpha-cypermethrin, beta-cypermethrin, fenpropathrin, and gamma-cyhalothrin insecticides indicated potential for this oil to be used as an alternative to PBO.

RESUMO: O objetivo deste trabalho foi avaliar a sinergia e homogeneidade de resposta de lagartas de Spodoptera frugiperda ao óleo essencial de Piper aduncum, em combinações com inseticidas do grupo dos piretroides: alfa-Cipermetrina, beta-Cipermetrina, Fenpropatrina e gama-Cialotrina, em comparação ao butóxido de piperonila (PBO controle positivo). Por meio da relação das CL50 e DL50 dos inseticidas tomados isoladamente e de suas respectivas combinações sinérgicas com o óleo essencial e o PBO, foram obtidos os fatores de sinergismo (FS) para comparação entre si. O coeficiente angular das curvas de dose/concentração-mortalidade foi utilizado no estabelecimento do aumento de toxicidade relativa, promovida pelos sinérgicos e determinação da homogeneidade de resposta. Por contato residual, evidenciou-se significativa potencialização dos inseticidas comerciais formulados com beta-Cipermetrina (FS=9,05-0,5) e Fenpropatrina (FS=34,05-49,77), quando combinados com o óleo essencial de P. aduncum. Já por contato tópico, ocorreu significativa potencialização somente dos inseticidas alfa-Cipermetrina (FS=7,55-3,68), Fenpropatrina (FS=3,37-1,21) e gama-Cialotrina (FS=5,79-10,48) quando em combinação com o óleo essencial. Com exceção da Fenpropatrina e gama-Cialotrina, as demais combinações sinérgicas apresentaram homogeneidade de resposta tanto por contato tópico como residual, para pelo menos uma combinação sinérgica com o óleo essencial de P. aduncum. A significância dos valores do FS das combinações do óleo essencial de P. aduncum com os inseticidas a base de alfa-Cipermetrina, beta-Cipermetrina, Fenpropatrina e gama-Cialotrina pode indicar que esse óleo essencial é uma alternativa ao PBO.

Protective effect of curcumin on oxidative stress and DNA fragmentation against lambda cyhalothrin-induced liver damage in rats.

LCT is a synthetic pyrethroid, developed as an insecticide for agricultural and public health applications. The purpose of this study was to investigate the adverse effects of LCT on rat liver and to elucidate hepatoprotective ability of CMN against LCT. Liver injury in male rats was induced by oral administration of LCT at a dose of 0.6 mg/kg/day for 4 weeks. CMN (200 mg/kg/day by oral administration) was used as a protective agent for the same period as LCT. Serum and liver samples were collected from all groups at the end of the experimental period. LCT-intoxication elicited significant elevations in hepatic markers enzymes (ALT and AST) and MDA concomitant with significant declines in the antioxidant enzymes (GPx, GST and GR), GSH and TP levels. In addition, it was noted that LCT-intoxicated group exhibited a degree of liver DNA fragmentation. Oral intake of CMN to LCT-intoxicated rats exhibited significant decrease in liver enzymes activities and lipid peroxidation, significant increase in antioxidant enzymes activities and partial inhibition in DNA fragmentation. Therefore, it was concluded that CMN has the ability to scavenge free radicals, protect against oxidative stress and prevent DNA fragmentation induced by LCT intoxication.

Field evaluation of lambda-cyhalothrin (ICON 10 CS) indoor residual spraying against Anopheles culicifacies in India.

Background & objectives: Field trials of lambda-cyhalothrin 10 CS (ICON 10 CS) in indoor residual spraying (IRS) with 25 mg a.i./m2 against Anopheles culicifacies was undertaken vs malathion IRS (25% WP–2 g a.i./ m2) in Tumkur district, Karnataka; vs deltamethrin IRS (2.5% WP–20 mg a.i./m2) in Dharmapuri district; and vs lambda-cyhalothrin (10 WP–25 mg a.i./m2) in Ramanathapuram district, Tamil Nadu, India. Methods: Spray operations in the experimental villages were done by the National Institute of Malaria Research (NIMR) and in the control villages by the respective State Health Department staff. Persistence of efficacy of insecticide sprayed in villages was assessed by contact bioassays against vector mosquitoes. Entomological indicators such as per structure density, parity rates of vector mosquitoes and sporozoite rates were measured in all the three study areas using standard procedures. Mass blood surveys and active fever case detections were carried out in experimental and control villages to study the impact of IRS on malaria transmission. Results: Persistence of effectiveness of ICON 10 CS was observed up to 2–3 months in all the three study areas. ICON 10 CS was found effective at par with or better than the insecticides used in the national programme in reducing the mosquito densities and in interrupting malaria transmission in the study villages. Vector density, parity rates and malaria cases considerably reduced in the ICON 10 CS-sprayed villages. Conclusion: Field trials at three sites have established that ICON 10 CS formulation was relatively more effective than malathion 25% WP, deltamethrin 2.5% WP and lambda-cyhalothrin 10% WP in some evaluation parameters like indoor resting mosquitoes, parity rates in vector mosquitoes and persistence of effectiveness. It can be used for IRS for malaria vector control with two rounds of spray at an interval of 3 months for curtailing the malaria transmission and an additional round is recommended in perennial malaria transmission areas.

Effect of lambda cyhalothrin on rats: An acute toxicity study.

The objective of the study was to evaluate the acute toxicity of lambda cyhalothrin in rat. Male albino rats were exposed to 80 mg/kg body weight of lambda cyhalothrin by means of gavage. The toxicological manifestations include myocardial hyalinisation, lysis of reticular framework in spleen, and spermatogonial cell degeneration in testes.

Residual effect of Demand CS-impregnated bednets to Anopheles sinensis / 中国血吸虫病防治杂志

Objective To observe the residual effect of Demand CS - impregnated bednets to Anopheles sinensis.Methods The numbers of adult mosquitoes which were knocked down at every minute after treatment were observed by using the enforced contact method recommended by WHO,and the mortality of mosquitoes tested after 24 h was calculated.Results The Kt_(50) of Demand CS - impregnated bednets with impregnations concentrations of 10,15,20 mg/m~2 to Anopheles sineasis were 21.40,16.20,15.70 min,respectively,and the 24 h mortality was 100%.The Kt_(50) of Responsar SC (12.5 % Beta - cyfluthrin) impregnated bednets with a impregnation concentration of 15 mg/m~2 to Anopheles sinensis was 16.06 min,and the 24 h mortality was 100%,too.Conclusions Both the Demand CS - impregnated bednets and the Responsar SC impregnated bednets can kill Anopheles sinensis.

Effect of cyhalothrin on Ehrlich tumor growth and macrophage activity in mice

Cyhalothrin, a pyrethroid insecticide, induces stress-like symptoms, increases c-fos immunoreactivity in the paraventricular nucleus of the hypothalamus, and decreases innate immune responses in laboratory animals. Macrophages are key elements in cellular immune responses and operate at the tumor-host interface. This study investigated the relationship among cyhalothrin effects on Ehrlich tumor growth, serum corticosterone levels and peritoneal macrophage activity in mice. Three experiments were done with 10 experimental (single gavage administration of 3.0 mg/kg cyhalothrin daily for 7 days) and 10 control (single gavage administration of 1.0 mL/kg vehicle of cyhalothrin preparation daily for 7 days) isogenic BALB/c mice in each experiment. Cyhalothrin i) increased Ehrlich ascitic tumor growth after ip administration of 5.0 x 106 tumor cells, i.e., ascitic fluid volume (control = 1.97 ± 0.39 mL and experimental = 2.71 ± 0.92 mL; P < 0.05), concentration of tumor cells/mL in the ascitic fluid (control = 111.95 ± 16.73 x 106 and experimental = 144.60 ± 33.18 x 106; P < 0.05), and total number of tumor cells in the ascitic fluid (control = 226.91 ± 43.22 x 106 and experimental = 349.40 ± 106.38 x 106; P < 0.05); ii) increased serum corticosterone levels (control = 200.0 ± 48.3 ng/mL and experimental = 420.0 ± 75.5 ng/mL; P < 0.05), and iii) decreased the intensity of macrophage phagocytosis (control = 132.3 ± 19.7 and experimental = 116.2 ± 4.6; P < 0.05) and oxidative burst (control = 173.7 ± 40.8 and experimental= 99.58 ± 41.7; P < 0.05) in vitro in the presence of Staphylococcus aureus. These data provide evidence that cyhalothrin simultaneously alters host resistance to Ehrlich tumor growth, hypothalamic-pituitary-adrenocortical (HPA) axis function, and peritoneal macrophage activity. The results are discussed in terms of data suggesting a link between stress, HPA axis activation and resistance to tumor growth.

Volume de calda e inseticidas no controle de Piezodorus guildinii (Westwood) na cultura da soja / Diferent spray volumes and insecticides in the control of Piezodorus guildinii (Westwood) in soybean crop

Em pulverizações com bicos hidráulicos, o volume de calda é um dos aspectos mais importantes para o sucesso do controle químico de pragas. O objetivo deste trabalho foi avaliar o efeito do volume de calda e inseticidas no controle de Piezodorus guildinii (Westwood), na cultura da soja. Testaram-se os volumes de calda de 50, 100 e 150l ha-1 e os inseticidas endossulfam (437,5g i.a. ha-1) e tiametoxam + lambda-cialotrina (21,15 + 15,90g i.a. ha-1). Tiametoxam + lambda-cialotrina apresentou maior efeito residual e controle de P. guildinii em relação à endossulfam. Esses inseticidas respondem da mesma forma, aumentando a eficiência de controle da praga com o aumento do volume de calda.

The spray volume is one of the most important aspects interfering on the success of pest control. The objective of this study was to evaluate the effects of spray volume on the efficiency of the insecticides in the control of Piezodorus guildinii (Westwood) in soybean crop. Were evaluated the volumes of 50, 100 and 150l ha-1 and the insecticides endosulfan (437.5g a.i. ha-1) and tiametoxan + lambda-cyhalothrin (21.15 + 15.90g a.i. ha-1). Tiametoxan + lambda-cyhalothrin had better residual and control of P. guildinii than endosulfan. Both insecticides showed the same behavior, increasing P. guildinii control with spray volume increasing.

Lambda cyhalothrin induced alterations in Clarias batrachus.

The present study was undertaken to find out the toxic effect of synthetic pyrethroid lambda cyhalothrin on the functioning of endocrine glands in freshwater catfish, Clarias batrachus.The fish were exposed to the pesticide for a period of 45 days at a sublethal concentration of 5.768 ppm. Analysis of hormone profile was carried out on the 15, 30 and 45 days of exposure to find out the alteration in hormone secretion and the response of the fish to the compound. The results obtained showed a significant decline(p<0.05) in levels of thyroid hormones and testosterone while a significant increase (p<0.05) was observed in cortisol levels during the different days of exposure of the fish to lambda cyhalothrin