Repellent activity of the non-host semiochemical (E)-2-octenal against Amblyomma sculptum and Amblyomma dubitatum ticks under field conditions.

Amblyomma ticks pose a significant public health threat due to their potential to transmit pathogens associated with rickettsial diseases. (E)-2-octenal, a compound found in donkeys (Equus asinus), exhibits strong repellent properties against Amblyomma sculptum nymphs under laboratory conditions. This study assessed the effectiveness of the (E)-2-octenal in wearable slow-release devices for personal human protection against Amblyomma ticks under natural conditions. Slow-release devices treated with (E)-2-octenal and untreated controls were prepared and tested on two volunteers walking through a tick-infested area in Goiania, Brazil. The experiment was conducted twice daily for three series of 10 days, with each volunteer wearing two devices attached to each leg, one on the ankle and one just above the thigh. Volunteers with control and treated devices exchanged them between rounds. Also, the daily release rate of (E)-2-octenal from the slow-release devices was determined in the laboratory, increasing significantly from 0.77 ± 0.14 µg/day on the first day to 9.93 ± 1.92 µg/day on the 4th day and remaining constant until the 16th day. A total of 5409 ticks were collected from both volunteers. Treated devices resulted in recovering fewer ticks (n = 1,666; 31%) compared to untreated devices (control: n = 3,743; 69%). (E)-2-octenal effectively repelled Amblyomma spp. larvae, A. sculptum adults, and exhibited pronounced repellency against A. dubitatum nymphs and adults. These findings suggest the potential of (E)-2-octenal delivered by wearable slow-release devices as a green-based repellent. Further improvements, however, are necessary to provide better protection for humans against A. sculptum and A. dubitatum in field conditions.

The repellent activity evaluation of the ethanolic extract of the tipi herb against the Bothrops moojeni serpents / Avaliação da atividade repelente do extrato etanólico da erva tipi frente a serpentes Bothrops moojeni

The serpent study involves physiological, behavioral and interaction factors with an extremely dynamic and complex environment. The relation of these animals with biodiversity is still quite preliminary, little studied and sustained by popular practices related to traditional medicine, esoteric and mystical currents. Therefore, this study proposed to know about the effect of 80% crude alcoholic extract of Petiveria alliacea L., popularly known as Tipi Herb, and its effects associated with the repellency of the Bothrops moojeni serpent. A complex of boxes was built for the observation of the snake's displacement, carried out for a total period of six days, the first three for defining the exploratory pattern and the other two for testing the alcoholic extract of Tipi, and finally on the sixth day, one cycle with the presence of a live attractant as bait. It was observed that the animal had no inhibition behavior and moved through the complex in a way like what occurs in nature and showed behavior to avoid remaining in the presence of the extract both with the presence of a live attractant or without it, preferring to move in the other compartments. The results show that this proposed tool is valid for the study of displacement of Bothrops moojeni snakes, in the same way that it added values on the importance of cerrado biome biodiversity and on the popular medicine practices of Tipi Herb, since the repellent effect on the snake was significant in the two tests performed.

O estudo das serpentes envolve fatores fisiológicos, comportamentais e de interação com um ambiente extremamente dinâmico e complexo. A relação destes animais com a biodiversidade ainda é bastante preliminar, pouco estudada e muito alimentada por práticas populares ligadas a medicina tradicional, correntes esotéricas e místicas. Nessa linha que este estudo propôs conhecer sobre o efeito do extrato bruto alcoólico a 80% da Petiveria alliacea L, popularmente conhecida como Erva Tipi, e seus efeitos associados à repelência da serpente Bothrops moojeni. Foi construído um complexo de caixas para a observação do deslocamento da serpente, realizado por um período total de seis dias, sendo os três primeiros para definição do padrão exploratório e os outros dois para o teste ao extrato alcóolico de Tipi e finalmente no sexto dia um ciclo com presença de um atrativo vivo. Foi observado que o animal não teve comportamento de inibição e se deslocou pelo complexo de forma análoga ao que ocorre na natureza e demonstrou comportamento de evitar se manter na presença do extrato tanto com a presença de um atrativo vivo como sem ele, preferindo se deslocar nos outros compartimentos. Os resultados mostram que essa ferramenta proposta é valida para estudo de deslocamento das serpentes Bothrops moojeni, da mesma maneira que agregou valores na importância da biodiversidade do Cerrado e sobre as práticas populares da Erva Tipi, uma vez que o efeito repelente sobre a serpente foi significativo nos dois testes realizados.

The Response of Susceptible and Pyrethroid-Resistant Blattella germanica (Dyctioptera: Blattellidae) to Shelter-Associated Cues.

In this work, it was studied the role of faeces in the location and permanence in a shelter in susceptible and pyrethroid-resistant individuals of Blattella germanica (Linnaeus 1767). Additionally, the effect of different concentrations of palmitic acid on the modulation of these behaviours was tested. A shelter constituted by a square cardboard structure was offered to susceptible as well as to resistant specimens. The shelter bases were treated with faecal extracts obtained from susceptible or resistant cockroaches, or with solutions of palmitic acid. The behaviour of susceptible as well as resistant specimens was analysed using infrared videography software. Susceptible's faecal extract attracted both specimens since the time spent by cockroaches to locate the treated shelters was lower, whereas the faecal extract from resistant insects did not elicit any effect on both strains. Faecal extracts showed an arrestant effect on both strains, suggested by the time spent inside the shelter that was significantly higher in their presence. On the other hand, treatment with palmitic acid produced an attractant or a repellent effect depending on the concentration and strain. The tested lower concentration was attractant to susceptible insects, but did not produce any effect on resistant ones. In addition, the higher concentrations did not produce any effect on susceptible individuals, but resulted repellent for resistant ones. Palmitic acid did not produce an arrestant effect on the strains as there was not an increase in time spent inside the shelter in the presence of this substance. An increase in the number of visits to the shelter and to the periphery was also observed in shelters treated with the faecal extract and with the lower concentration of palmitic acid. These results show that compounds of the susceptible faeces were attractant to cockroaches of both strains, while faecal extracts from resistant insects were not. Moreover, a dual effect of palmitic acid was observed, being attractant at low concentrations and repellent as concentration increased. Additionally, a difference in the concentration threshold at which the effect of this substance changes was observed between strains.

Repellent Screening of Selected Plant Essential Oils Against Dengue Fever Mosquitoes Using Behavior Bioassays.

Among the efforts to reduce mosquito-transmitted diseases, such as malaria and dengue fever, essential oils (EOs) have become increasingly popular as natural replacements for the repellant DEET. In this study, seven commercially available plant EOs against Aedes species mosquitoes were evaluated for their complete protection time (CPT, min) in vivo using human-hand in cage tests (GB2009/China and WHO2009). Among the EOs with the highest efficacy in repelling mosquitoes, Aedes albopictus (Skuse) were clove bud oil and patchouli oil. Both were further assessed according to the in vivo method recommended by the WHO, to determine their minimum effective dose and CPT. A comparison of the ED50 values (dose yielding a 50% repellent response) of these two EOs against Aedes aegypti(L.) showed that the ED50 (2.496 µg/cm2) of patchouli oil was 1248 times higher than that of clove bud oil (0.002 µg/cm2), thus demonstrating them greater efficacy of the latter in repelling Ae. aegypti mosquitoes. For the 2 EOs, eugenol was the major component with higher than 80% in relative amount of the clove bud oil. The patchouli oil had more than 30% of character chemical patchouli alcohol along with α-bulnesene (10.962%), α-guaiene (9.227%), and seychellene (7.566%). Clove bud oil was found to confer longer complete protection than patchouli oil against a common species of mosquito. These results suggest use of EOs as safe, highly potent repellents for use in daily life and against mosquito-transmitted diseases, such as malaria and dengue fever.

Development of a Nanotechnology Matrix-Based Citronella Oil Insect Repellent to Obtain a Prolonged Effect and Evaluation of the Safety and Efficacy.

Mosquito-borne diseases affect millions of people worldwide each year, and the use of a topically applied insect repellent is an economically viable preventative health practice. The general objective of this work was to encapsulate citronella oil (CO) in a nanostructured lipid carrier (NLC) to formulate a topical repellent with a long duration of efficacy on the skin and a good safety profile based on minimizing skin penetration. In the studied CO, the main chemical constituents of geraniol, citronellal, and citronellol were identified and subsequently used as markers for the in vitro skin permeation testing (IVPT). An optimal NLC encapsulating CO formulation was developed and had an average particle size of 350 nm. The NLC was then formulated in combination with CO at ratios of 2:1, 1:1, and 1:2 CO:NLC-CO as oil-in-water (O/W) emulsions and compared to CO in the same O/W emulsion base (all at 10% CO in the final O/W topical formulation). The markers geraniol, citronellol, and citronellal were detected in all samples tested F1 (10% CO in O/W emulsion) and F3 (10% CO/NLC-CO 1:1 in O/W emulsion). Even the percentages of F3 markers were higher than F1. The recovery of the percentage balance (based on the total remaining on the skin surface, on the skin, and penetrated through the skin to the receptor) of geraniol, citronellol, and citronellal markers for F1 and F3 was 7.70% and 11.96%; 25.51% and 31.89%; and 5.09% and 4.40%, respectively. The nanoparticle lipid solid forms a repellent reservoir on the skin surface, releasing the active ingredients slowly through volatilization, extending the repellent action, and reducing permeation through the skin. It is possible to assume that the remaining 92.30% and 88.03%; 74.49% and 68.11%; and 94.10% and 95.60% of geraniol, citronellol, and citronellal markers of F1 and F3, respectively, were lost to evaporation. In the in vivo efficacy test carried out with the Aedes aegypti mosquito, F3 was the optimal formulation, providing the greatest repellent action compared to free oil in O/W emulsion. Thermal analysis showed that the NLC-CO raised the boiling point of the encapsulated CO compared to the free oil, suggesting that the controlled release of the CO was a possible mechanism for its prolonged effect. We concluded that the nanocarriers developed with CO were stable and provided improved mosquito-repellent efficacy with minimal skin penetration of the CO actives over 24 h. Indeed, regardless of whether the CO was applied as free oil, a 1:1 mixture of CO (pure/free oil) or NLC-CO applied in an O/W emulsion can be considered safe for topical application due to minimal skin penetration.

Topical Mosquito Repellent Formulations for Enhanced Repellency Time and Reduced Toxicity.

Mosquito-borne diseases such as dengue, malaria, yellow fever, chikungunya and Zika virus affect millions of people worldwide each year. Vector control and personal protection are very important to minimize the spread of diseases, and the use of repellent is an economic practice to prevent them. The application of repellent, which acts on the skin to form a vapor layer with a repellent odor to mosquitos, is recommended as an economic prevention and practice. The natural botanical product Citronella is an effective mosquito repellent due to the high concentrations of active chemical constituents present, notably terpenic alcohols. However, citronella tends to evaporate quickly from the skin surface, resulting in a rapid loss of activity. Strategies to increase repellency time, while at the same time minimizing toxicity, are major focuses of research and development in natural repellent products. Here we highlight the role of extended-release systems (ERS) of citronella oil in this approach.

Comparative study of the oil repellent activity of Copaifera officinalis Linnaeus and Copaifera reticulata Ducke front nymphs of Periplaneta americana Linnaeus

To control urban pests, especially cockroaches of the Periplaneta americana species, various pesticides have been developed that are increasingly potent and effective. However, the unrestrained application of pesticides has had negative consequences, such as the disappearance of some useful insect species and, consequently, the appearance of new pests, both in the countryside and cities. Due to the current scenario, it was necessary to search for new alternatives for the control of these insects. Among the species studied, Copaíba stood out. The oils were analyzed using GC-MS, b-caryophyllene and a-bergamotene being the predominant compounds. Repellency tests were performed with three different concentrations of C. officinalis and C. reticulata, 500 µg/mL, 250 µg/mL and 125 µg/mL, in triplicate. It can be observed that the oil of C. officinalis was more repellent to the nymphs at concentrations of 500 µg/mL and 250 µg/mL, however, when the behavior in nymphs exposed to the concentration of 125 µg/mL was compared, it was noted that C. reticulata oil was more repellent at this concentration. Copaifera has shown promising activity as a repellent against arthropods owing to the complex chemical composition of its oils

Avaliação dos repelentes: efeitos na saúde humana / Evaluation of repellents: effects on human health / Evaluación de repelentes: efectos sobre la salud humana

Este artigo teve como objetivo avaliar os efeitos do uso de repelentes na população brasileira. Para alcançar o objetivo proposto, foram utilizadas as metodologias da revisão de literatura e a pesquisa documental junto à ANVISA referentes aos repelentes registrados e comercializados no Brasil. De acordo com a RDC nº 7 de 2015 da ANVISA, os repelentes são classificados como produtos de Grau 2, compostos por Produtos de Higiene Pessoal, Cosméticos e Perfumes. Nessa categoria, constatou-se a existência de 113 produtos registrados para comercialização no Brasil. Verificou-se que, apesar do aumento do consumo devido às doenças causadas por picada dos mosquitos Aedes aegypti, a maioria dos repelentes comercializados possuem como princípio ativo as substâncias DEET, Icaridina ou IR3535, não resultando em reações tóxicas relevantes para a população, visto que, essas substâncias são de baixa toxicidade ou atóxicas, como é o caso do IR3535. Faz-se necessário considerar que o uso desses produtos deve seguir rigorosamente as orientações dos fabricantes disponíveis nos rótulos das embalagens no que tange à aplicação, reaplicação, frequência e uso específico para crianças, gestantes e lactantes. No que se refere à eficácia, a Icaridina apresenta-se como mais eficaz que o IR3535 quando considerados os fatores tempo de proteção versus concentração do princípio ativo. Entretanto, a Icaridina, em alguns casos, pode apresentar moderada toxicidade, enquanto que, o IR3535 é atóxico. Observa-se ainda, que mesmo diante desse cenário, o DEET é o mais comercializado e amplamente estudado no país.

This article aimed to evaluate the effects of the use of repellents in the Brazilian population. To achieve the proposed objective, the methodologies of literature review and documentary research with ANVISA regarding repellents registered and marketed in Brazil were used. According to ANVISA's RDC No. 7 of 2015, repellents are classified as Grade 2 products, composed of Personal Hygiene Products, Cosmetics and Perfumes. In this category, it was found the existence of 113 products registered for commercialization in Brazil. It was found that, despite the increased consumption due to diseases caused by bites from Aedes aegypti mosquitoes, most repellents marketed have as active ingredients the substances DEET, Icaridin or IR3535, not resulting in toxic reactions relevant to the population, since these substances are of low toxicity or non- toxic, as is the case of IR3535. It is necessary to consider that the use of these products should strictly follow the manufacturers' guidelines available on the packaging labels regarding application, reapplication, frequency and specific use for children, pregnant and lactating women. With regard to efficacy, Icaridin is more effective than IR3535 when considering the factors protection time versus concentration of the active ingredient. However, Icaridin, in some cases, may present moderate toxicity, while IR3535 is non- toxic. It is also observed that, even in this scenario, DEET is the most marketed and widely studied in the country.

artículo tuvo como objetivo evaluar los efectos del uso de repelentes en la población brasileña. Para alcanzar el objetivo propuesto, se utilizaron las metodologías de revisión bibliográfica e investigación documental con ANVISA sobre repelentes registrados y comercializados en Brasil. De acuerdo con el CDR nº 7 de 2015 de ANVISA, los repelentes se clasifican como productos de Grado 2, compuesto por Productos de Higiene Personal, Cosméticos y Perfumes. En esta categoría, se constató la existencia de 113 productos registrados para comercialización en Brasil. Se constató que, a pesar del aumento del consumo debido a las enfermedades causadas por picaduras de mosquitos Aedes aegypti, la mayoría de los repelentes comercializados tienen como principios activos las sustancias DEET, Icaridina o IR3535, no resultando en reacciones tóxicas relevantes para la población, ya que estas sustancias son de baja toxicidad o no tóxicas, como es el caso del IR3535. Es necesario considerar que el uso de estos productos debe seguir estrictamente las directrices de los fabricantes disponibles en las etiquetas de los envases en cuanto a aplicación, reaplicación, frecuencia y uso específico para niños, mujeres embarazadas y lactantes. En cuanto a la eficacia, la Icaridina es más eficaz que el IR3535 si se consideran los factores tiempo de protección frente a concentración del principio activo. Sin embargo, la Icaridina, en algunos casos, puede presentar una toxicidad moderada, mientras que el IR3535 no es tóxico. También se observa que, incluso en este escenario, el DEET es el más comercializado y ampliamente estudiado en el país.

Repellent active ingredients encapsulated in polymeric nanoparticles: potential alternative formulations to control arboviruses.

Dengue, yellow fever, Chinkungunya, Zika virus, and West Nile fever have infected millions and killed a considerable number of humans since their emergence. These arboviruses are transmitted by mosquito bites and topical chemical repellents are the most commonly used method to protect against vector arthropod species. This study aimed to develop a new generation of repellent formulations to promote improved arboviruses transmission control. A repellent system based on polycaprolactone (PCL)-polymeric nanoparticles was developed for the dual encapsulation of IR3535 and geraniol and further incorporation into a thermosensitive hydrogel. The physicochemical and morphological parameters of the prepared formulations were evaluated by dynamic light scattering (DLS), nano tracking analysis (NTA), atomic force microscopy (AFM). In vitro release mechanisms and permeation performance were evaluated before and after nanoparticles incorporation into the hydrogels. FTIR analysis was performed to evaluate the effect of formulation epidermal contact. Potential cytotoxicity was evaluated using the MTT reduction test and disc diffusion methods. The nanoparticle formulations were stable over 120 days with encapsulation efficiency (EE) of 60% and 99% for IR3535 and geraniol, respectively. AFM analysis revealed a spherical nanoparticle morphology. After 24 h, 7 ± 0.1% and 83 ± 2% of the GRL and IR3535, respectively, were released while the same formulation incorporated in poloxamer 407 hydrogel released 11 ± 0.9% and 29 ± 3% of the loaded GRL and IR3535, respectively. GRL permeation from PCL nanoparticles and PCL nanoparticles in the hydrogel showed similar profiles, while IR3535 permeation was modulated by formulation compositions. Differences in IR3535 permeated amounts were higher for PCL nanoparticles in the hydrogels (36.9 ± 1.1 mg/cm2) compared to the IR3535-PCL nanoparticles (29.2 ± 1.5 mg/cm2). However, both active permeation concentrations were low at 24 h, indicating that the formulations (PCL nanoparticles and PCL in hydrogel) controlled the bioactive percutaneous absorption. Minor changes in the stratum corneum (SC) caused by interaction with the formulations may not represent a consumer safety risk. The cytotoxicity results presented herein indicate the carrier systems based on poly-epsilon caprolactone (PCL) exhibited a reduced toxic effect when compared to emulsions, opening perspectives for these systems to be used as a tool to prolong protection times with lower active repellent concentrations.

Field Evaluation of Novel Spatial Repellent Controlled Release Devices (CRDs) against Mosquitoes in an Outdoor Setting in the Northern Peruvian Amazon.

U.S. military troops are exposed to mosquito-borne pathogens when deployed to endemic regions. Personal protective measures such as permethrin-treated uniforms and dermal repellents are the cornerstones of mosquito-borne disease prevention for the U.S. military. These measures have limitations and additional personal protection tools, such as spatial repellent devices to decrease the risk of vector-borne pathogen transmission, are required. Novel spatial repellent controlled-release devices formulated with metofluthrin were evaluated in an outdoor setting in the northern Amazon of Peru to evaluate performance under field conditions. The metofluthrin emitting devices lowered the number of mosquitoes captured in protected human landing collections (HLC) compared to blank devices, although there were effect differences between Anopheles spp. and species in other mosquito genera. A computational-experimental model was developed to correlate HLC and active ingredient (AI) concentrations as a function of time and space. Results show a strong correlation between the released AI and the decrease in HLC. This model represents the first effort to obtain a predictive analytical tool on device performance using HLC as the entomological endpoint.

Use of mobile data collection systems within large-scale epidemiological field trials: findings and lessons-learned from a vector control trial in Iquitos, Peru.

Vector-borne diseases are among the most burdensome infectious diseases worldwide with high burden to health systems in developing regions in the tropics. For many of these diseases, vector control to reduce human biting rates or arthropod populations remains the primary strategy for prevention. New vector control interventions intended to be marketed through public health channels must be assessed by the World Health Organization for public health value using data generated from large-scale trials integrating epidemiological endpoints of human health impact. Such phase III trials typically follow large numbers of study subjects to meet necessary power requirements for detecting significant differences between treatment arms, thereby generating substantive and complex datasets. Data is often gathered directly in the field, in resource-poor settings, leading to challenges in efficient data reporting and/or quality assurance. With advancing technology, mobile data collection (MDC) systems have been implemented in many studies to overcome these challenges. Here we describe the development and implementation of a MDC system during a randomized-cluster, placebo-controlled clinical trial evaluating the protective efficacy of a spatial repellent intervention in reducing human infection with Aedes-borne viruses (ABV) in the urban setting of Iquitos, Peru, as well as the data management system that supported it. We discuss the benefits, remaining capacity gaps and the key lessons learned from using a MDC system in this context in detail.

Methyl anthranilate as pig repellent: effects on the feeding behavior and production performance

Preventing pigs such as wild pigs (Sus scrofa) from accessing the farm can be blocked by installing fences or repellent to make them feel reluctant to access the farm. Most wild pigs were captured to prevent crop damage and incidence of African swine fever (ASF). Still, there is a limit to capturing them due to the rapid population growth. A study was conducted using "To Nature" repellent with an active ingredient of Methyl anthranilate (MA) to assess the effectiveness of MA as a pig repellent and determine its effect on feeding behavior and production performance. A total of eight female pigs [(Landrace x Yorkshire) x Duroc] were randomly arranged and used in the experiment for five weeks. Each treatment was replicated four times, having one pig in every replication. The feeders' position with MA repellent was shifted weekly with a ratio of 0.25% and mixed with 10kg of feed. The number of approaches of pigs to the feeder was monitored daily using a full HD CCTV 5-megapixel camera. A significantly lower number of approaches, feed intake, and total time spent feeding in the feeding trough was recorded from the feeder with MA repellent mixed in the diet. Regression analysis revealed a positive relationship in the feeding behavior of pigs in the feeder mixed with MA repellent in the diet. Therefore, 0.25% MA repellent can be used as pig repellent without adverse effects on the production performance of growing pigs.

Efficacy of a spatial repellent for control of Aedes-borne virus transmission: A cluster-randomized trial in Iquitos, Peru.

Over half the world's population is at risk for viruses transmitted by Aedes mosquitoes, such as dengue and Zika. The primary vector, Aedes aegypti, thrives in urban environments. Despite decades of effort, cases and geographic range of Aedes-borne viruses (ABVs) continue to expand. Rigorously proven vector control interventions that measure protective efficacy against ABV diseases are limited to Wolbachia in a single trial in Indonesia and do not include any chemical intervention. Spatial repellents, a new option for efficient deployment, are designed to decrease human exposure to ABVs by releasing active ingredients into the air that disrupt mosquito-human contact. A parallel, cluster-randomized controlled trial was conducted in Iquitos, Peru, to quantify the impact of a transfluthrin-based spatial repellent on human ABV infection. From 2,907 households across 26 clusters (13 per arm), 1,578 participants were assessed for seroconversion (primary endpoint) by survival analysis. Incidence of acute disease was calculated among 16,683 participants (secondary endpoint). Adult mosquito collections were conducted to compare Ae. aegypti abundance, blood-fed rate, and parity status through mixed-effect difference-in-difference analyses. The spatial repellent significantly reduced ABV infection by 34.1% (one-sided 95% CI lower limit, 6.9%; one-sided P value = 0.0236, z = 1.98). Aedes aegypti abundance and blood-fed rates were significantly reduced by 28.6 (95% CI 24.1%, ∞); z = -9.11) and 12.4% (95% CI 4.2%, ∞); z = -2.43), respectively. Our trial provides conclusive statistical evidence from an appropriately powered, preplanned cluster-randomized controlled clinical trial of the impact of a chemical intervention, in this case a spatial repellent, to reduce the risk of ABV transmission compared to a placebo.

Essential oils loaded on polymeric nanoparticles: bioefficacy against economic and medical insect pests and risk evaluation on terrestrial and aquatic non-target organisms.

This paper introduces the lethal, sublethal, and ecotoxic effects of peppermint and palmarosa essential oils (EOs) and their polymeric nanoparticles (PNs). The physicochemical analyses indicated that peppermint PNs were polydisperse (PDI > 0.4) with sizes of 381 nm and loading efficiency (LE) of 70.3%, whereas palmarosa PNs were monodisperse (PDI < 0.25) with sizes of 191 nm and LE of 89.7%. EOs and their PNs were evaluated on the adults of rice weevil (Sitophilus oryzae L.) and cigarette beetle (Lasioderma serricorne F.) and the larvae of Culex pipiens pipiens Say. On S. oryzae and L. serricorne, PNs increased EOs' lethal activity, extended repellent effects for 84 h, and also modified behavioral variables during 24 h. Moreover, EOs and PNs generated toxic effects against C. pipiens pipiens. On the other hand, peppermint and palmarosa EOs and their PNs were not toxic to terrestrial non-target organisms, larvae of mealworm (Tenebrio molitor L.), and nymphs of orange-spotted cockroach (Blaptica dubia S.). In addition, PNs were slightly toxic to aquatic non-target organisms, such as brine shrimp (Artemia salina L.). Therefore, these results show that PNs are a novel and eco-friendly formulation to control insect pests.

Effects of anti-Leishmania compounds in the behavior of the sand fly vector Lutzomyia longipalpis.

BACKGROUND: Leishmaniasis is an infectious parasitic disease caused by pathogens of the genus Leishmania transmitted through the bite of adult female sand flies. To reduce case numbers, it is necessary to combine different control approaches, especially those aimed at the sand fly vectors. Innovative forms of control with the use of attractive sugar baits explored the fact that adult sand flies need to feed on sugars of plant origin. Leishmania parasites develop in the gut of sand flies, interacting with the sugars in the diet of adults. Recent studies have shown that sugar baits containing plant-derived compounds can reduce sand fly survival, the number of parasites per gut, and the percentage of infected sand flies. Several synthetic compounds produced from naphthoquinones and pterocarpans have anti-parasitic activity on Leishmania amazonensis and/or Leishmania infantum in cell culture. This work aimed to assess the inclusion of these compounds in sugar baits for blocking transmission, targeting the development of the Leishmania parasite inside the sand fly vector. RESULTS: We evaluated the attractant or repellent properties of these compounds, as well as of the reference compound N,N'-diethyl-m-toluamide (DEET), in sugar baits. We also observed changes in feeding preference caused by these compounds, looking for anti-feeding or stimulation of ingestion. Pterocarpanquinone L4 and pentamidine showed attractant and repellent properties, respectively. CONCLUSION: Based on the effects in feeding preference and intake volume, pterocarpanquinone L6, and the pyrazole-derived compound P8 were chosen as the most promising compounds for the future development of anti-Leishmania sugar baits. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Smoke of Capsicum baccatum L. var. baccatum (Solanaceae) repels nymphs of triatoma infestans (Klug) (Hemiptera: Reduviidae) / Humo de capsicum baccatum L. var. baccatum (Solanaceae) repele las ninfas de Triatoma infestans (Klug) (Hemiptera: Reduviidae)

Control of the Chagas disease vector, Triatoma infestans (Klug) (Hemiptera: Reduviidae) with synthetic pesticides in Bolivia has become increasingly inefficient due to the development of resistance in the insects. In the Chaco region of Bolivia, guaraní populations have approached the problem by fumigating their houses with the smoke of native plants. Through interviews and field work with local guides, the main plant used by the guaraníes was collected and later identified as Capsicum baccatumL. var. baccatum (Solanaceae). In choice bioassays, filter papers exposed to the smoke of the plant repelled nymphs of T. infestans. Activity remained significant after storing the exposed filter papers for 9 days. Chemical analysis of smoke and literature data suggested that capsaicinoids present in the smoke were responsible for the repellent effect. The data presented provide a rationale for the use of C. baccatumvar. baccatumto control the Chagas vector bythe guaraní populations.

El control del vector de la enfermedad de Chagas, Triatoma infestans (Klug) (Hemiptera: Reduviidae) con plaguicidas sintéticos en Bolivia se ha vuelto cada vez más ineficiente debido al desarrollo de resistencias en los insectos. En la región del Chaco de Bolivia, las poblaciones guaraníes han abordado el problema fumigando sus casas con el humo de las plantas nativas. A través de entrevistas y trabajo de campo con guías locales, se recogió la principal planta utilizada por los guaraníes y posteriormente se identificó como Capsicum baccatumL. var. baccatum (Solanaceae). En bioensayos selectos, los papeles de filtro expuestos al humo de la planta repelieron a las ninfas de T. infestans. La actividad siguió siendo significativa después de almacenar los papeles de filtro expuestos durante 9 días. El análisis químico del humo y los datos de la literatura sugieren que los capsaicinoides presentes en el humo eran responsables del efecto repelente. Los datos presentados proporcionan una justificación para el uso de C. baccatum var. baccatum para el control del vector Chagas por las poblaciones guaraníes.

Cellulose Hydrogels Containing Geraniol and Icaridin Encapsulated in Zein Nanoparticles for Arbovirus Control.

The most important arboviruses are those that cause dengue, yellow fever, chikungunya, and Zika, for which the main vector is the Aedes aegypti mosquito. The use of repellents is an important way to combat mosquito-borne pathogens. In this work, a safe method of protection employing a repellent was developed based on a slow release system composed of zein nanoparticles containing the active agents icaridin and geraniol incorporated in a cellulose gel matrix. Analyses were performed to characterize the nanoparticles and the gel formulation. The nanoparticles containing the repellents presented a hydrodynamic diameter of 229 ± 9 nm, polydispersity index of 0.38 ± 0.10, and zeta potential of +29.4 ± 0.8 mV. The efficiencies of encapsulation in the zein nanoparticles exceeded 85% for icaridin and 98% for geraniol. Rheological characterization of the gels containing nanoparticles and repellents showed that the viscoelastic characteristic of hydroxypropylmethylcellulose gel was preserved. Release tests demonstrated that the use of nanoparticles in combination with the gel matrix led to improved performance of the formulations. Atomic force microscopy analyses enabled visualization of the gel network containing the nanoparticles. Cytotoxicity assays using 3T3 and HaCaT cell cultures showed low toxicity profiles for the active agents and the nanoparticles. The results demonstrated the potential of these repellent systems to provide prolonged protection while decreasing toxicity.

Chemical Composition, Repellent Action, and Toxicity of Essential Oils from Lippia origanoide, Lippia. alba Chemotypes, and Pogostemon cablin on Adults of Ulomoides dermestoides (Coleoptera: Tenebrionidae).

The essential oils (EOs) from bioactive species can provide an alternative tool for the management of stored grain insects that is less environmentally damaging than synthetic chemicals. The aim of this study was to assess the repellent action and toxicity of EOs obtained from phellandrene-rich Lippia origanoides, carvone-rich Lippia alba, citral-rich L. alba, and Pogostemon cablin aerial parts on adults of Ulomoides dermestoides. These EOs were isolated by hydrodistillation and characterized by gas chromatography coupled to mass spectrometry (GC-MS). The repellency assay was carried out using the area preference method, and the toxicity evaluated utilizing a filter paper contact test. The major components (>10%) of the studied EOs were sabinene (16.9%), trans-ß-caryophyllene (18.6%) and α-humulene (10.1%) for phellandrene-rich L. origanoides EO; limonene (40.1%) and carvone (37.7%) for carvone-rich L. alba EO; geranial (24.5%), geraniol (19.0%), and neral (11.9%) for citral-rich L. alba EO; and α-guaiene (13.3%), α-bulnesene (15.7%), and patchoulol (35.3%) for P. cablin EO. All EOs displayed 100% repellency at a concentration of 16 µL/mL, with lower toxicity than that elicited by the commercial repellent DEET. EO concentrations up to 8 µL/mL did not induce any mortality on the beetle. These findings show that the EOs provide active and safe molecules for natural repellent formulations to prevent and control insect infestations of stored products.

Biosynthesized Gold Nanoparticles Integrated Ointment Base for Repellent Activity Against Aedes aegypti L.

The present study focused on preparing a nano-ointment base integrated with biogenic gold nanoparticles from Artemisia vulgaris L. leaf extract. As prepared, nano-ointment was characterized by using Fourier-transform infrared spectroscopy, and the morphology of the nano-ointment was confirmed through a scanning electron microscope. Initially, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide results showed nano-ointment cytocompatibility at different concentrations (20-200 µg/mL) against L929 cells. The in vitro hemolysis assay also revealed that the nano-ointment is biocompatible. Further studies confirmed that nano-ointment has repellent activity with various concentrations (12.5, 25, 50, 75, and 100 ppm). At 100 ppm concentration, the highest repellent activity was observed at 60-min protection time against the Aedes aegypti L. female mosquitoes. The results indicated that the increasing concentration of nano-ointment prolongs the protection time. Moreover, the outcome of this study provides an alternative nano-ointment to synthetic repellent and insecticides after successful clinical trials. It could be an eco-friendly, safer nano-bio repellent, which can protect from dengue fever mosquitoes.

Responses of green lacewings to semiochemicals: species- and sex-specificity (Neuroptera: Chrysopidae)

ABSTRACT Green lacewings (Chrysopidae) are important predators in agroecosystems. Frequently there are studies which treat these beneficial insects at family level as a whole. This approach, despite its practical advantages, may, however, include many species with markedly different life history traits. As green lacewings are also rather diverse in their chemical ecology, treating several different species within one unit may lead to confusion and confounding effects of natural phenomena in research. Besides interspecific differences, sex-specificity is another important factor to consider in respect of insect chemical ecology. This is especially important for green lacewings, in particular the attraction of females, since oviposition is crucial in their application as biological control agents. The aim of our paper is to provide a brief insight into the diversity of the chemical ecology of green lacewings with a special emphasis on the species- and sex-specific differences in their responses to semiochemicals.