Residual Insecticide Research Articles

Use of an Argentine Ant, Linepithema humile, Semiochemical to Deliver an Acute Toxicant

The Argentine ant, Linepithema humile, is an invasive nuisance, agricultural, and ecological pest from South America. In the United States, its primary distribution is in California and the Southeast. The structural pest control industry responds to property owner complaints when this ant’s populations become problematic and a persistent nuisance. Actions taken to control Argentine ants in the urban and suburban environment are typically complaint-driven, and often involve the application of insecticide sprays applied to the outdoor environment by professional pest managers. In California, and elsewhere, spray treatments of various residual insecticides by property owners and pest management professionals has resulted in significant runoff and in subsequent surface water contamination. As a result, an immediate need exists to develop alternative methods of ant control targeted at reducing environmental contamination. The purpose of this study was to investigate the potential for the development of an alternative method of toxicant delivery focused on the Argentine ant’s behavior modifying cuticular chemistry. In short, methanol and hexane washes of Argentine ant pupae applied to paper dummies were handled significantly more by worker ants than the paper dummies that did not contain the solvent extracts. Additionally, paper wicks soaked in a methylene chloride wash from Argentine ant cadavers, air dried, and then treated with fipronil, were removed by worker ants and placed on a midden pile at the same rate (≈86% to 99% removal at 1 h) as untreated and fipronil-treated ant cadavers. The paper wicks that did not contain the methylene chloride extract were ignored by the worker ants. After three days, the mortality of the ants exposed to the fipronil-treated wicks or the ant cadavers were dose-related. In conclusion, our study suggests that there is potential for the use of ant semiochemicals for the delivery of acute toxicants.

Baseline entomologic data on malaria transmission in prelude to an indoor residual spraying intervention in the regions of Alibori and Donga, Northern Benin, West Africa

BackgroundDespite the success of indoor residual insecticide spraying (IRS) in Africa, particularly in Benin, some gaps of information need to be filled to optimize the effectiveness of this intervention in the perspective of the country’s effort to eliminate malaria. In anticipation to the 2018 IRS campaign in two targeted regions of northern Benin, this study aimed, to collect baseline information on vector composition, spatio-temporal variation and peak malaria transmission in the Alibori and Donga, two targeted regions of northern Benin. Information collected will help to better plan the implementation and later on the impact assessment of this IRS campaign.MethodsThe study was carried out in four districts of the two IRS targeted regions of northern Benin. Human landing catches and pyrethrum spray catches protocols were used to assess the biting rate (HBR) and, biting/resting behaviour of malaria vector populations. After morphological identification of collected Anopheles, the heads and thoraxes of Anopheles gambiae sensu lato (s.l.) were analysed by the ELISA CSP tests to estimate the sporozoite index (SI). The entomological inoculation rate was calculated as the product of mosquito biting rate (HBR) and the SI.ResultsThe biting rates of An. gambiae s.l., the major vector in this study sites, varied significantly from region to region. It was higher: in rural than in urban areas, in rainy season than in dry season, indoors than outdoors. Overall, SI was comparable between sites. The highest EIRs were observed in the Donga region (16.84 infectious bites/man/month in Djougou district and 17.64 infectious bites/man/month in Copargo district) and the lowest in the Alibori region (10.74 infectious bites/man/month at Kandi district and 11.04 infectious bites/man/month at Gogounou district).ConclusionThis study showed the heterogeneous and various nature of malaria epidemiology in Northern Benin. Indeed, the epidemiological profile of malaria transmission in the Alibori and Donga regions is made of a single season of transmission interrupted by a dry season. This period of transmission is relatively longer in Donga region than in Alibori. This information can be used to guide the extension of IRS in the Alibori and in the Donga, by primarily targeting areas with short periods of transmission, and easy to cover.

Phytochemical-based nano emulsions for stored grain protection:

Stored grain losses caused by pest insects contribute significantly to the global food crisis. Currently, there are two main chemical control methods against stored product insect pests: fumigation with very toxic gases and grain protection by residual contact insecticides. Today, the global tendency is to prevent/reduce the wide use of insecticides, which have high toxicity to humans and harm the environment. Therefore, there is an urgent need to develop alternative eco-friendly approaches for stored insect pest control. Essential oils from Micromeria fruticosa and Mentha rotundifolia (Fam. Labiatae) and their main constituent pulegone which previously were shown by us as very active against stored product insect pests, were encapsulated into coarse and nano emulsions. The insecticidal activity of the developed formulations against primary internal insect rice weevil (Sitophilus oryzae L.) and secondary external pest red flour beetle (Tribolium castaneum Herbst) was evaluated in laboratory and pilot experiments. It was found that the phytochemical-based nano emulsions offered significant advantages and provided powerful and prolonged biological activity compare with the coarse formulations. The developed nano emulsions could serve as a natural, effective, low-toxify for human, and environmentally preferred method for protection stored grain and dry food products from pest insects.

Residual Pesticide On Hesco® Blast Protection Wall In Temperate Florida Habitat Effective Against Mosquitoes, Stable Flies, and Sand Flies.

United States military troops in the field are exposed to the environment and are thus at high risk for transmission of arboviruses, and degradation of mission from continual harassment from insects. Passive vector control, such as application of residual insecticides to US military materials common in the field such as tents and camouflage netting, has been shown to be effective and can contribute to a successful integrated vector management (IVM) plan in the field to reduce this risk. However, other common US military field materials have not been evaluated with residual pesticides. In this study we conducted the first known investigation of the efficacy and longevity of a residual pesticide containing λ-cyhalothrin applied to HESCO® blast protection wall geotextile. We exposed treated material to a temperate Florida environment and found that this treatment can be effective against sand flies, filth-breeding flies, and mosquitoes for at least 6 wk. This study provides evidence that residual treatment of this US military material may be leveraged as an IVM component to enhance the US Department of Defense pest management system.

A cross-sectional study of asymptomatic Plasmodium falciparum infection burden and risk factors in general population children in 12 villages in northern Uganda

BackgroundPlasmodium falciparum malaria is an important cause of morbidity in northern Uganda. This study was undertaken to assess village-, household-, and individual-level risk factors of asymptomatic falciparum malaria in children in 12 villages in northern Uganda.MethodsBetween 10/2011 and 02/2014, 1006 apparently healthy children under 16 years old were enrolled in 12 villages using a stratified, multi-stage, cluster survey design and assessed for P. falciparum malaria infection using the rapid diagnostic test (RDT) and thick film microscopy (TFM), and structured interviewer-administered questionnaires. Associations between weighted P. falciparum malaria prevalence (pfPR), based on RDT, and covariates were estimated as odds ratios and 95% confidence intervals (ORs, 95% CIs) using logistic models accounting for the survey design.ResultsAmong 942 (93.5%) children successfully tested, pfPR was 52.4% by RDT and 32.7% by TFM. Overall pfPR was lower in villages where indoor residual insecticide spray (IRS) was, versus not, implemented (18.4% versus 75.2%, P < 0.0001). However, pfPR was heterogeneous both within IRS (10.6–34.8%) and non-IRS villages (63.6–86.2%). Elevated pfPR was associated with having a sibling who was RDT positive (OR 5.39, 95% CI 2.94–9.90, P = 0.0006) and reporting a fever at enrollment (aOR 4.80, 95% CI 1.94–11.9, P = 0.0094). Decreased pfPR was associated with living in an IRS village (adjusted OR 0.06, 95% CI 0.04–0.07, P < 0.0001), in a household with one (aOR 0.48, 95% CI 0.30–0.76) or more than one child below 5 years (aOR 0.23, 95% CI 0.12–0.44, Ptrend = 0.014), and reporting keeping a goat inside or near the house (aOR 0.42, 95% CI 0.29–0.62, P = 0.0021).ConclusionsThe results show high but heterogeneous pfPR in villages in northern Uganda, confirm significantly decreased pfPR associated with IRS implementation, and suggest significant associations with some household characteristics. Further research is needed to elucidate the factors influencing malaria heterogeneity in villages in Uganda.

Оцінка ризику перорального надходження залишкових кількостей інсектицидів після дезінсекції запасів продовольчого зерна

Introduction. Treatment of grain reserves (GR) with insecticides at the beginning of storage is a common technology for combating insect pests. In Ukraine, deltamethrin (synthetic pyrethroid), pirimiphos-methyl and chlorpyrifos-methyl (organophosphorus compounds) are used for GR disinsection. The use of GR with residual insecticides can be a significant risk to human health. Objective of the study. To evaluate the risk of toxic effects after oral administration of residual amounts (RA) of insecticides after disinsection of food grain reserves. Materials and methods. To identify the risk and evaluate the exposure, physical and chemical properties, LD50 per os, consumption rate of active substances (AS) of insecticides, ratio of consumption rate and LD50 per os, results of AS RA measurement in GR (gas-liquid chromatography), half-life of insecticides in grain (T50), ratio of possible daily intake (DI) of AS RA to allowable daily intake (ADI), processing factors (PF), daily consumption of grain products were analysed. An integral exposure vector (combining DDI, DI, T50) was calculated, which was evaluated according to the proposed scale. Results. The coefficients of selectivity of insecticide action are obtained, physical and chemical properties contributing to AS stability in the processed grain, the relationship between the consumption rate and RA are determined. AS with the largest values of the integral exposure vector is established. Based on the relationship between theoretical DI and DDI both without and taking into account PF and daily consumption of grain products, AS with the highest and lowest exposure levels are determined. Conclusions. AS have a sufficient selectivity of action: their effective consumption rates when protecting GR 180–640 times below LD50 per os. Low solubility in water, hydrolytic stability and high lipophilicity contribute to AS stability and their concentration in bran and germ seeds after processing GR. Due to high AS resistance per RA in grain at the end of the study (up to 90 days), the initial consumption rates, which increase in the range of deltamethrin — chlorpyrifos-methyl-pirimiphos-methyl, play an important role. With conservative evaluation, 80–90 days after the treatment, theoretical DI of deltamethrin did not exceed DDI, whereas DI of pirimiphos-methyl exceeded DDI by 5 times and chlorpyrifos-methyl — by 11 times. When exposed at the level of residues, the greatest risk is represented by insecticides with the highest values of the integral exposure vector — pirimiphos-methyl and chlorpyrifos-methyl. Upon a more realistic assessment, the largest exposure to pirimiphos-methyl is associated with the consumption of whole wheat bread (at DDI level), to chlorpyrifos-methyl — with the consumption of whole wheat bread with bran (2,4 and 2,3 times higher than DI, respectively); the smallest exposure level of pirimiphos-methyl and chlorpyrifos-methyl is possible when consuming white flour and white bread. Upon exceeding the allowable value of DI theoretical level of insecticides with treated grain reserves in the period of its use as food raw materials, it is expedient to carry out studies on the content of insecticide RA in grain products in order to assess the exposure when consuming these products at the level of scientifically substantiated and accepted norms. Key words: insecticides, grain stocks, risk assessment, exposure, oral intake.

HUBUNGAN WAKTU PENYEMPROTAN PESTISIDA SEBELUM PANEN TERHADAP RESIDU PROFENOFOS DAN KARAKTERISTIK MUTU SAWI PAKCOY (Brassica rapa L)

This research aims to 1) to know the correlation of different pesticide spraying time before harvest to the residual level of profenofos on the mustard pakcoy, 2) knowing the tendency of the relationship of different pesticide spraying time before harvest to the decrease of residual insecticidal content of profenofos and the quality characteristic of the mustard pakcoy. This research uses regression and correlation analysis, the factors used are the last spraying time 0 days, 2 days, 4 days, 6 days, 8 days, 10 days, before harvest. Each treatment was group in to 3 to obtain 18 experimental units. The parameters observed were the residual insecticide content of profenofos, pakcoy mustard characteristics and the relationship between the use of pesticide with the time interval of spraying on the residual content and the characteristics of the pakcoy. The results showed that the time of spraying before harvest was related to the residue of profenofos on the mustard pakcoy with treatment 0, 2, 4, 6, 8, 10 days before harvest 0.001860 mg / kg, 0.000615 mg / kg, 0.000511 mg / kg, 0.000394 mg / kg, 0.000279 mg / kg, and 0.000270 mg / kg. quality evaluation results with yellowish green to green color criteria, freshness of light and slightly damaged 1.6 to 3.75 (very damaged-undamaged). The result of correlation between the use of pesticide with the time of spraying on the residual insecticide content of profenofos and the characteristics of the quality of pakcoy mustard with the correlation coefficient value of 0.80 to the residual content, 0.96 to the color, 0.88 to freshness, and 0.97 to the damage value. &#x0D; Keywords: Brassica rapa L, time of pesticide spraying, profenofos and residue

Insulin receptor knockdown blocks filarial parasite development and alters egg production in the southern house mosquito, Culex quinquefasciatus.

Lymphatic filariasis, commonly known as elephantiasis, is a painful and profoundly disfiguring disease. Wuchreria bancrofti (Wb) is responsible for >90% of infections and the remainder are caused by Brugia spp. Mosquitoes of the genera Culex (in urban and semi-urban areas), Anopheles (in rural areas of Africa and elsewhere), and Aedes (in Pacific islands) are the major vectors of W. bancrofti. A preventive chemotherapy called mass drug administration (MDA), including albendazole with ivermectin or diethylcarbamazine citrate (DEC) is used in endemic areas. Vector control strategies such as residual insecticide spraying and long-lasting insecticidal nets are supplemental to the core strategy of MDA to enhance elimination efforts. However, increasing insecticide resistance in mosquitoes and drug resistance in parasite limit the effectiveness of existing interventions, and new measures are needed for mosquito population control and disruption of mosquito-parasite interactions to reduce transmission. Mosquito insulin signaling regulates nutrient metabolism and has been implicated in reduced prevalence and intensity of malaria parasite, Plasmodium falciparum, infection in mosquitoes. Currently no data are available to assess how insulin signaling in mosquitoes affects the development of multi-cellular parasites, such as filarial nematodes. Here, we show that insulin receptor knockdown in blood fed C. quinquefasciatus, the major vector of Wb in India, completely blocks the development of filarial nematode parasite to the infective L3 stage, and results in decreased ecdysteroid production and trypsin activity leading to fewer mosquito eggs. These data indicate that a functional mosquito insulin receptor (IR) is necessary for filarial parasite development and mosquito reproduction. Therefore, insulin signaling may represent a new target for the development of vector control or parasite blocking strategies.

Effectiveness of control strategies against visceral leishmaniasis in Brazil: there is no silver bullet

Control of zoonotic visceral leishmaniasis has been a deceiving effort for Brazilian public health officers and researchers. Since the implementation of the Brazilian program for visceral leishmaniasis control (PVLC) in the beginning of the 1960s, the disease has undergone a notable process of urbanization and geographical dissemination and the epidemiological situation is far from showing any substantial progress. The main strategies to reduce transmission proposed by the current PVCL still are vector control with residual insecticides and culling of seropositive dogs. However, few well- designed epidemiological studies give support for their wide-scale use, most showing limited effectiveness and only in specific settings. Novel promising approaches have been advocated such as dog vaccines, insecticide-impregnated dog collars, treatment of infected dogs, and topical insecticides, but there are still many doubts about their effectiveness. The few available effectiveness estimates are not high, suggesting that no intervention would alone solve the problem. There is no simple solution but considering the heterogeneous spatial pattern of disease distribution and the lack of high levels of effectiveness for individual interventions, there is probably no means to reduce transmission without using a combination of interventions delivered according to the different transmission scenarios, preferably targeting areas at highest risk.

PELAPISAN UREA DENGAN ARANG AKTIF YANG DIPERKAYA MIKROBA DAPAT MEMPERCEPAT PENURUNAN KONSENTRASI RESIDU INSEKTISIDA HEPTAKLOR DI LAHAN SAWAH

Heptachlor insecticide is a toxic organochlorine insecticide, persistent and bio-cummulative in the environment. Remediation using actived carbon and microbial is a solution to pollution due to pesticide in the environment.The objective of this study was to obtain fertilizer technology using urea with activated carbon and enriched with microbes degrading heptachlor insecticide in order to reduce the insecticide residue in paddy fields. The research was conducted at the Jakenan Experimental Station between February to September 2012. The soil used as the planting medium was brought from the village Sukamenak, District Rawagempol Wetan, Karawang. The experiment was conducted in the field at micro-plot scale with lysimeter, and using a randomized block design (RBD) with 3 replications and 6 fertilizer treatments ( control , prill urea , urea with activated carbon maize cobs ( UAATJ ) , urea with activated carbon coconut shell ( UAATK ) , urea with activated carbon cob corn + microbes ( UAATJM ) , urea with activated carbon coconut shell + microbes ( UAATKM ). The plants used were from Inpari 13 variety. The insecticide residue analysis was performed in the Residu Bahan Agrikimia (RBA) laboratory of Balingtan. The results showed significant orthogonal countrast tests of different treatments. The highest reduction of residual insecticide was observed in urea coated with activated carbon cob corn and enriched with microbial consortia degrading POPs, which was 36.30 %. It is suspected that activated carbon coated cob corn with microbial enrichment was favored as its home and the microbes utilized carbon sources of heptachlor as the food.

Select β- and γ-branched 1-alkylpyrazol-4-yl methylcarbamates exhibit high selectivity for inhibition of Anopheles gambiae versus human acetylcholinesterase

The widespread emergence of pyrethroid-resistant Anopheles gambiae has intensified the need to find new contact mosquitocides for indoor residual spraying and insecticide treated nets. With the goal of developing new species-selective and resistance-breaking acetylcholinesterase (AChE)-inhibiting mosquitocides, in this report we revisit the effects of carbamate substitution on aryl carbamates, and variation of the 1-alkyl group on pyrazol-4-yl methylcarbamates. Compared to aryl methylcarbamates, aryl dimethylcarbamates were found to have lower selectivity for An. gambiae AChE (AgAChE) over human AChE (hAChE), but improved tarsal contact toxicity to G3 strain An. gambiae. Molecular modeling studies suggest the lower species-selectivity of the aryl dimethylcarbamates can be attributed to a less flexible acyl pocket in AgAChE relative to hAChE. The improved tarsal contact toxicity of the aryl dimethylcarbamates relative to the corresponding methylcarbamates is attributed to a range of complementary phenomena. With respect to the pyrazol-4-yl methylcarbamates, the previously observed low An. gambiae-selectivity of compounds bearing α-branched 1-alkyl groups was improved by employing β- and γ-branched 1-alkyl groups. Compounds 22a (cyclopentylmethyl), 21a (cyclobutylmethyl), and 26a (3-methylbutyl) offer 250-fold, 120-fold, and 96-fold selectivity, respectively, for inhibition of AgAChE vs. hAChE. Molecular modeling studies suggests the high species-selectivity of these compounds can be attributed to the greater mobility of the W84 sidechain in the choline-binding site of AgAChE, compared to that of W86 in hAChE. Compound 26a has reasonable contact toxicity to G3 strain An. gambiae (LC50 = 269 μg/mL) and low cross-resistance to Akron strain (LC50 = 948 μg/mL), which bears the G119S resistance mutation.

A Microsatellite-Based Analysis of House Infestation With Triatoma Infestans (Hemiptera: Reduviidae) After Insecticide Spraying in the Argentine Chaco.

Prevention of vector-borne transmission of Chagas disease mainly relies on residual insecticide spraying. Despite significant success at a regional scale, house infestation with Triatoma infestans (Klug) (Hemiptera: Reduviidae) still persists in the Gran Chaco ecoregion. One key aspect is the identification of the sources of reinfestant triatomines. After detecting fine-scale genetic structure in two rural villages of Pampa del Indio, Argentine Chaco, we tested hypotheses on the putative origins of the triatomines collected at 4, 8, and 12 mo after insecticide house spraying. We genotyped 10 microsatellite loci in 262 baseline and 83 postspraying triatomines from different houses. Genetic variability was similar between baseline and postspraying populations, but 13 low-frequency alleles were not detected at postspraying. FSTs were not significant between insects collected before and after insecticide spraying at the same house in all but one case, and they clustered together in a neighbor-joining tree. A clustering algorithm detected seven genetic groups, four of them mainly composed of baseline and postspraying insects from the same house. Assignment tests suggested multiple putative sources (including the house of collection) for most postspraying insects but excluded a house located more than 9 km from the study area. The origin of three triatomines was attributed to immigration from other unaccounted sources. Our study is compatible with the hypothesis that house reinfestations in the Argentine Chaco are mostly related to residual foci (i.e., survival of insects within the same community), in agreement with field observations, spatial analysis, and morphometric studies previously published.

Insecticide treated curtains and residual insecticide treatment to control Aedes aegypti: An acceptability study in Santiago de Cuba.

BackgroundWithin the context of a field trial conducted by the Cuban vector control program (AaCP), we assessed acceptability of insecticide-treated curtains (ITCs) and residual insecticide treatment (RIT) with deltamethrin by the community. We also assessed the potential influence of interviewees’ risk perceptions for getting dengue and disease severity.Methodology/principal findingsWe embedded a qualitative study using in-depth interviews in a cluster randomized trial (CRT) testing the effectiveness of ITCs and RIT in Santiago de Cuba. In-depth interviews (N = 38) were conducted four and twelve months after deployment of the tools with people who accepted the tools, who stopped using them and who did not accept the tools. Data analysis was deductive. Main reasons for accepting ITCs at the start of the trial were perceived efficacy and not being harmful to health. Constraints linked to manufacturer instructions were the main reason for not using ITCs. People stopped using the ITCs due to perceived allergy, toxicity and low efficacy. Few heads of households refused RIT despite the noting reasons for rejection, such as allergy, health hazard and toxicity. Positive opinions of the vector control program influenced acceptability of both tools. However, frequent insecticide fogging as part of routine AaCP vector control actions diminished perceived efficacy of both tools and, therefore, acceptability. Fifty percent of interviewees did feel at risk for getting dengue and considered dengue a severe disease. However, this did not appear to influence acceptability of ITCs or RIT.Conclusion/significanceAcceptability of ITCs and RIT was linked to acceptability of AaCP routine vector control activities. However, uptake and use were not always an indication of acceptability. Factors leading to acceptability may be best identified using qualitative methods, but more research is needed on the concept of acceptability and its measurement.

Zoonotic leishmaniasis and control in Ethiopia

Visceral leishmaniasis and cutaneous leishmaniasis are important public health problems in Ethiopian lowland and highland areas respectively. Failure of antimonial drugs to respond in some diffused cutaneous leishmaniasis and HIV/AIDS-leishmaniasis co-infected patients, side effects of these drugs, highly mutilating diagnostic procedures and high health care expense are among the problems associated with leishmaniasis. Control of leishmaniasis requires proper understanding of human parasites transmissions (anthroponotic or zoonotic or both). The aim of this review was to elaborate different ecologies of leishmaniasis based on evidences from previous researches and information from literatures obtained from different sources including PubMed to describe zoonotic leishmaniasis in Ethiopia with possible control methods. Although vectors of leishmaniasis in Ethiopia are not endophelic, night indoor visits of Phlebotomus vectors for possible blood meal on human have been indicated. Thus, application of indoor and domestic residual insecticides spraying, use of insecticide impregnated fine mashed bed net for visceral leishmaniasis, community based manipulation (destruction) and residual insecticide fogging of hyrax-sand fly habitats for cutaneous leishmaniasis are the visible vector and reservoir control methods that can be used for control of these diseases in Ethiopia. Use of repellants during night outdoor activities of people in the endemic areas requires further investigations.

Urban malaria transmission in a non-endemic area in the Andean region of Colombia.

BACKGROUNDRapid urbanisation in difficult socio-economic conditions such as inadequate housing infrastructure, lack of public services, improper sanitation, and poor water drainage systems in vegetation-rich areas lead to ecological conditions that are conducive to the breeding of mosquitoes and transmission of malaria, in semi-urban and urban settings.OBJECTIVESThis study aimed to describe the cases of malaria that were reported in the peri-urban areas of Pereira (Colombia), between 2008 and 2015.METHODSA retrospective study was conducted using data from the Malaria Surveillance System 2009-2015 and an outbreak study (between December 2008 and March 2009). Frequency distributions and summary measures, as well as univariate analysis were performed for all the variables in consideration. The annual parasite index (API) was calculated.FINDINGSData on 214 cases were obtained from the surveillance system. A majority of the cases were reported in men (63.1%), followed by in children < 15 years (23.8%), and were caused predominantly by Plasmodium vivax (86.0%), with most of the infection occurring in the urban areas (52.8%) of Pereira. The API, by sex and age group, was higher among men ≥ 80 years. The outbreak study reported 14 cases of malaria in rural/peri-urban neighborhoods, and it was observed that the anopheline breeding sites were in close proximity to the houses in these areas. This population did not use protective measures against mosquitoes and chemical control was conducted through residual and spatial insecticide spraying.MAIN CONCLUSIONSThis study suggested the presence of autochthonous malaria transmission, in Pereira, between 2008 and 2015, most of which were cases of P. vivax. A greater intensity was observed between 2008 and 2009 when malaria was possibly reintroduced to the region. During the years of the study, a gradual decrease in the number of reported cases of malaria was observed in Pereira, except for the time period between 2008 and 2009 when a spike was noted (estimated using the API); this was most likely caused by an outbreak. Interventions that are more aggressive in nature are required to prevent further malarial transmission and dissemination.

The additional benefit of residual spraying and insecticide-treated curtains for dengue control over current best practice in Cuba: Evaluation of disease incidence in a cluster randomized trial in a low burden setting with intensive routine control.

BackgroundAedes control interventions are considered the cornerstone of dengue control programmes, but there is scarce evidence on their effect on disease. We set-up a cluster randomized controlled trial in Santiago de Cuba to evaluate the entomological and epidemiological effectiveness of periodical intra- and peri-domiciliary residual insecticide (deltamethrin) treatment (RIT) and long lasting insecticide treated curtains (ITC).Methodology/Principal findingsSixty three clusters (around 250 households each) were randomly allocated to two intervention (RIT and ITC) and one control arm. Routine Aedes control activities (entomological surveillance, source reduction, selective adulticiding, health education) were applied in the whole study area. The outcome measures were clinical dengue case incidence and immature Aedes infestation. Effectiveness of tools was evaluated using a generalized linear regression model with a negative binomial link function.Despite significant reduction in Aedes indices (Rate Ratio (RR) 0.54 (95%CI 0.32–0.89) in the first month after RIT, the effect faded out over time and dengue incidence was not reduced. Overall, in this setting there was no protective effect of RIT or ITC over routine in the 17months intervention period, with for house index RR of 1.16 (95%CI 0.96–1.40) and 1.25 (95%CI 1.03–1.50) and for dengue incidence RR of 1.43 (95%CI 1.08–1.90) and 0.96 (95%CI 0.72–1.28) respectively. The monthly dengue incidence rate (IR) at cluster level was best explained by epidemic periods (Incidence Rate Ratio (IRR) 5.50 (95%CI 4.14–7.31)), the IR in bordering houseblocks (IRR 1.03 (95%CI 1.02–1.04)) and the IR pre-intervention (IRR 1.02 (95%CI 1.00–1.04)).ConclusionsAdding RIT to an intensive routine Aedes control programme has a transient effect on the already moderate low entomological infestation levels, while ITC did not have any effect. For both interventions, we didn’t evidence impact on disease incidence. Further studies are needed to evaluate impact in settings with high Aedes infestation and arbovirus case load.

Assessment of the effect of larval source management and house improvement on malaria transmission when added to standard malaria control strategies in southern Malawi: study protocol for a cluster-randomised controlled trial

BackgroundDue to outdoor and residual transmission and insecticide resistance, long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) will be insufficient as stand-alone malaria vector control interventions in many settings as programmes shift toward malaria elimination. Combining additional vector control interventions as part of an integrated strategy would potentially overcome these challenges. Larval source management (LSM) and structural house improvements (HI) are appealing as additional components of an integrated vector management plan because of their long histories of use, evidence on effectiveness in appropriate settings, and unique modes of action compared to LLINs and IRS. Implementation of LSM and HI through a community-based approach could provide a path for rolling-out these interventions sustainably and on a large scale.Methods/designWe will implement community-based LSM and HI, as additional interventions to the current national malaria control strategies, using a randomised block, 2 × 2 factorial, cluster-randomised design in rural, southern Malawi. These interventions will be continued for two years. The trial catchment area covers about 25,000 people living in 65 villages. Community participation is encouraged by training community volunteers as health animators, and supporting the organisation of village-level committees in collaboration with The Hunger Project, a non-governmental organisation. Household-level cross-sectional surveys, including parasitological and entomological sampling, will be conducted on a rolling, 2-monthly schedule to measure outcomes over two years (2016 to 2018). Coverage of LSM and HI will also be assessed throughout the trial area.DiscussionCombining LSM and/or HI together with the interventions currently implemented by the Malawi National Malaria Control Programme is anticipated to reduce malaria transmission below the level reached by current interventions alone. Implementation of LSM and HI through a community-based approach provides an opportunity for optimum adaptation to the local ecological and social setting, and enhances the potential for sustainability.Trial RegistrationRegistered with The Pan African Clinical Trials Registry on 3 March 2016, trial number PACTR201604001501493.

Susceptibility of Tribolium castaneum and Trogoderma variabile larvae and adults exposed to methoprene-treated woven packaging material

Methoprene is an insect growth regulator (IGR) registered in the United States for direct application to stored raw grains, as an aerosol or residual contact insecticide, and for use as a coating for protection of packaged products. A series of tests was conducted to determine the adverse effects of short term exposure, sub-lethal exposure, and continual exposure of the red flour beetle, Tribolium castaneum (Herbst) and warehouse beetle, Trogoderma variabile Ballion, on methoprene-treated woven packaging material at 27 and 32 °C and 60% r.h. In the first test, larvae of both species were added to individual arenas and exposed for different time intervals, removed and resulting adult emergence was assessed. In the second test, eggs of both species were exposed on the packaging surfaces to determine percent egg hatchability. In the third test, adults of T. castaneum and T. variabile were added to arenas and held for 7 and 3 d, respectively, to determine number of eggs laid per female and subsequent egg hatchability. The eggs were held in arenas to determine the effect of continual exposure on egg-to-adult emergence. Results showed normal adult emergence decreased with increasing exposure time and temperature. Exposure to methoprene-treated packaging did not adversely affect fecundity of T. variabile adults, but did affect fecundity of T. castaneum. Continual exposure gave 100% suppression of T. castaneum adult emergence and a reduction of T. variabile emergence. This study indicated that methoprene-treated packaging could be a valuable addition to an existing integrated pest management program to increase protection of packaged products.

Mosquito-Borne Diseases Related Knowledge and Perception among Residents of Semi Urban Region of Eastern Nepal

Background : Mosquito borne diseases are endemic in most part of the country. While public health efforts are placed towards the elimination of major vector borne diseases like malaria and filariasis, climatic and manmade environmental changes has led to threats of reemergence of mosquito borne diseases like dengue and chikungunya in new regions. There are needs of studies among community people regarding knowledge and perception of vector borne diseases to change the attitudes of people towards vector control and avoid risky behavior by application of behavior change communication tools.Material &amp; Methods: A cross sectional study was done among households from 2 wards of Tankisinwari VDC in semi-urban region near Biratnagar sub-metropolitan city. The study duration was of 3 months from November 27 2014 to February 27 2015. Study population was 566 and 654 households from 2 wards. Among them, 57 from one ward and 65 from other ward, a total of 122 households were taken proportionately from both wards. Data was entered into excel sheet and analysis was done using SPSS 16.Results: People who heard of filariasis as disease transmitted by mosquito bite were 23.8% and malaria (89.3%), Dengue (19.6%). Among the participants, 85% responded that mosquito borne disease can be prevented in their area while 4.9% and 6.6% only heard of indoor residual spraying and insecticide treated bed nets respectively. Among those who did not know about breeding places of mosquito, 29.2% were illiterates, who were significantly more than literates 5.1% (p&lt;0.05). Among those who were aware of environmental vector control measure, closed drainage was preferred by 52.5% and disposal of waste by burial or burning was practiced by 64.4%.Conclusion: There is need of public health intervention with interactive tools of behavior change communication in the community to enhance perception about mosquito and mosquito borne diseases.Journal of Nobel Medical CollegeVolume 6, Number 1, Issue 10 (January-June, 2017), Page: 36-43

Behavioral Responses of the Common Bed Bug, Cimex lectularius, to Insecticide Dusts.

Bed bugs have reemerged recently as a serious and growing problem not only in North America but in many parts of the world. These insects have become the most challenging pest to control in urban environments. Residual insecticides are the most common methods used for bed bug control; however, insecticide resistance limits the efficacy of treatments. Desiccant dusts have emerged as a good option to provide a better residual effect for bed bug control. Several studies have focused on determining the efficacy of dust-based insecticides against bed bugs. However, behavioral responses of bed bugs to insecticide dusts could influence their efficacy. The behavioral responses of bed bugs to six insecticide dusts commonly used in the United States were evaluated with an advanced video tracking technique (Ethovision). Bed bugs took longer to make first contact with areas treated with the diatomaceous earth (DE)-based products MotherEarth D and Alpine than pyrethroid, pyrethrins or silica gel based products, DeltaDust, Tempo 1% Dust and CimeXa, respectively. Lower visitation rates of bed bugs were recorded for areas treated with MotherEarth D, Alpine and CimeXa than that of DeltaDust, Tempo 1% Dust, and Tri-Die Silica + Pyrethrum Dust. Bed bugs spent less time in areas treated with Tri-Die Dust, CimeXa, Alpine, and MotherEarth D than DeltaDust and Tempo 1% Dust, and they exhibited a reduction in locomotor parameters when crawling on areas treated with CimeXa and Alpine. The implications of these responses to bed bug control are discussed.