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Mosquitoes, as insect vectors, play a crucial role in transmitting viruses and parasites, leading to millions of human deaths in tropical and subtropical regions worldwide. This study aimed to evaluate the effects of ethanolic extracts of three species within the genus Myrothecium (M. roridum, M. dimerum, and M. nivale) on Aedes aegypti mosquito larvae to assess the inhibitory effect on growth and development, as well as to determine mortality. We quantify the average lethal concentrations and provide a qualitative characterization of the chemical groups responsible for their potential. Phytochemical screening revealed the presence of alkaloids, flavonoids, and terpenoids in the ethanolic extracts of the three fungal species. Tannins were found only in the extracts of M. dimerum and M. roridum. We observed a clear dependence of the effects of the crude extracts on mosquito larvae on the concentrations used and the duration of exposure. The toxic effect was observed after 48 h at a concentration of 800 ppm for both M. dimerum and M. nivale, while M. roridum showed effectiveness after 72 h. All three species within the genus Myrothecium exhibited 100% biological activity after 72 h of exposure at 600 ppm. At lower concentrations, there was moderate growth and development inhibitory activity in the insect life cycle. The study highlights the effectiveness of crude Myrothecium extracts in combating mosquito larvae, with effects becoming apparent between 48 and 72 h of exposure. This initial approach underscores the potential of the fungus's secondary metabolites for further in-depth analysis of their individual effects or synergies between them.

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Aedes aegypti and Aedes albopictus are the main vectors of arboviruses such as Dengue, Chikungunya and Zika, causing a major impact on global economic and public health. The main way to prevent these diseases is vector control, which is carried out through physical and biological methods, in addition to environmental management. Although chemical insecticides are the most effective strategy, they present some problems such as vector resistance and ecotoxicity. Recent research highlights the potential of the imidazolium salt "1-methyl-3-octadecylimidazolium chloride" (C18MImCl) as an innovative and environmentally friendly solution against Ae. aegypti. Despite its promising larvicidal activity, the mode of action of C18MImCl in mosquito cells and tissues remains unknown. This study aimed to investigate its impacts on Ae. aegypti larvae and three cell lines of Ae. aegypti and Ae. albopictus, comparing the cellular effects with those on human cells. Cell viability assays and histopathological analyses of treated larvae were conducted. Results revealed the imidazolium salt's high selectivity (> 254) for mosquito cells over human cells. After salt ingestion, the mechanism of larval death involves toxic effects on midgut cells. This research marks the first description of an imidazolium salt's action on mosquito cells and midgut tissues, showcasing its potential for the development of a selective and sustainable strategy for vector control.

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Organic synthetic insecticides continue to be part of the arsenal for combating vector-borne diseases in Mexico. Larvicides are a fundamental part of the process in programs for mosquito control, temephos being one of the most widely used in Mexico. In the present study, we analyzed the frequency of temephos resistance in twenty-three Aedes aegypti populations using the discriminating concentration (DC) of 0.012 mg/L. We also tested 5× DC (0.6 mg/L) and 10× DC (0.12 mg/L) of temephos. The resistance distribution to temephos was interpolated to unsampled sites using the inverse distance weighting (IDW) method. The populations of Ae. aegypti showed a high frequency of resistance (1× DC) with mortality rates below 93% in 22 of the 23 populations analyzed. Moderate resistance intensity (5× DC) was found in 78% of the populations, and high intensity (10× DC) in 30%. Predicted mortality was below 60% in the populations of the Pacific Coast, along the Gulf of Mexico, and in the state of Coahuila in Northeastern Mexico in relation to 1× DC; the Pacific Coast and Northeast patterns hold for 5× and 10× DC. The results suggest the need for rotation of the larvicide to effectively control the larval populations of the vector in the country.

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The Asian tiger mosquito, Aedes albopictus, is a highly invasive and aggressive species capable of transmitting a large number of etiological agents of medical and veterinary importance, posing a high risk for the transmission of emerging viruses between animals and humans. In this work, we evaluated the mosquitocidal activity of Neochloris aquatica against A. albopictus throughout its development and analyzed whether this effect was potentiated when the microalga was cultivated under stress conditions due to nutrient deprivation. Our results suggest that N. aquatica produces metabolites that have negative effects on these insects, including larval mortality, interruption of pupal development, and incomplete emergence of adults when fed on microalgae in the larval stages. When microalgae were cultured under stress conditions, an increase in molting defects was recorded, and the number of healthy adults emerged drastically decreased. Histological studies revealed severe signs of total disintegration of different tissues and organs in the thorax and abdomen regions. The muscles and fat bodies in the midgut and foregut were severely distorted. In particular, larval intestinal tissue damage included vacuolization of the cytoplasm, destruction of brush border microvilli, and dilation of the intercellular space, which are distinctive morphological characteristics of apoptotic cells. Evidence suggests that N. aquatica produces metabolites with mosquitocidal effects that affect development and, therefore, the ability to vector etiological agents of medical and veterinary importance.

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The Aedes aegypti mosquito is a vector of severe diseases with high morbidity and mortality rates. The most commonly used industrial larvicides have considerable toxicity for non-target organisms. This study aimed to develop and evaluate liquid and solid carrier systems to use pentyl cinnamate (PC), derived from natural sources, to control Ae. aegypti larvae. The liquid systems consisting of nanoemulsions with different lecithins systems were obtained and evaluated for stability over 30 days. Microparticles (MPs) were obtained by the spray drying of the nanoemulsions using maltodextrin as an adjuvant. Thermal, NMR and FTIR analysis indicated the presence of PC in microparticles. Indeed, the best nanoemulsion system was also the most stable and generated the highest MP yield. The PC larvicidal activity was increased in the PC nanoemulsion system. Therefore, it was possible to develop, characterize and obtain PC carrier systems active against Ae. aegypti larvae.

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The growing use of synthetic chemical compounds/substances in vector control of mosquitoes, associated with their adverse effects on the environment and non-target organisms, has demanded the development of eco-friendly alternatives. In this context, this study aimed to evaluate the larvicidal action of different cellulose microcrystalline (CMs) concentrations and investigate their toxicity mechanisms in Culex quinquefasciatus fourth instar larvae as a model species. Probit analysis revealed that the median lethal concentrations (LC50) for 24 h and 36 h exposure were 100 and 58.29 mg/L, respectively. We also showed that such concentrations induced a redox imbalance in the larvae, marked by an increase in the production of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), as well as a reduction in the activity of superoxide dismutase (SOD) and catalase (CAT). Furthermore, different alterations in the external morphology of the larvae were associated with the ingestion of CMs. On the other hand, exposure of adult zebrafish (Danio rerio) to LC5024h and LC5036h for seven days did not induce any behavioral changes or alterations mutagenic, genotoxic, biochemical, or in the production of cytokines IFN-γ and IL-10. Thus, taken together, our study demonstrates for the first time that the use of CMs can constitute a promising strategy in the control of C. quinquefasciatus larvae, combining insecticidal efficiency with an "eco-friendly" approach in the fight against an important mosquito vector of several human diseases.

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Using larvicides is an essential method in the strategy to control the Aedes aegypti (Diptera: Culicidae) mosquito in Brazil. However, over the years this practice can select resistant strains, decreasing the efficiency of the larvicide in vector control. We compared two Aedes aegypti populations to verify mosquito resistance to pyriproxyfen larvicide: a population from Araraquara and a susceptible Rockefeller strain. We tested four concentrations of pyriproxyfen (0.005, 0.01, 0.02, and 0.04 mg/L) and observed that the Araraquara strain showed a significant reduction in mortality when compared to the Rockefeller strain, except in the highest concentration tested. We also found a moderate resistance for the Araraquara larvae, which may be related to Araraquara temperatures due to be optimum for Ae. aegypti most part of the epidemic periods. Survivor mosquitoes of pyriproxyfen exposure showed reduced wing centroid sizes, which is related to the mosquitoes' vectorial capacity: frequency of blood meals, chances of hematophagy, and virus dissemination ability. Our results provide the current susceptibility status of an Araraquara Ae. aegypti population and can assist in promoting information to epidemiologic surveillance agencies.

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We analyzed the effects of pyriproxyfen (PPF) on oxidative stress and ovarian morphology in zebrafish. PPF (10-9  M) exposure increased reactive oxygen species generation in ovaries, in association with a decrease in glutathione content. The activities of glutathione S-transferase, superoxide dismutase, and catalase were increased, while γ-glutamyltransferase activity was not altered by pesticide treatment. The histology of ovarian tissue showed an increase in the number of previtellogenic oocytes I, and a decrease in the rate of vitellogenic oocyte (VIT) count, suggesting inhibition of follicular maturation. An increase in the thickness of the vitelline envelope was observed in VIT, as was a tendency toward an increase in atresia in the ovary of the PPF-treated group. These findings indicate that the deleterious effect of PPF on ovarian maturation is mediated by a redox imbalance and oxidative damage. So, PPF acts as an endocrine disruptor chemical and may compromise fish reproduction by reducing female fertility.

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Dengue fever is a reemerging disease of global concern among health authorities due to its high rate of proliferation. In 2019, Brazil registered its second-highest dengue mortality rate since 1998, with approximately 754 deaths and 1.5 million probable cases. Brazilian Ministry of Health prevention and control strategies for Aedes include insecticides, eradication of breeding sites, and awareness campaigns. However, as new mosquito variants resistant to conventional insecticides emerge, there is an increasing demand for effective environment-friendly plant extracts and natural substances against adult mosquitos and/or larvae of Aedes aegypti L. with no negative impacts on human health. This study aimed to investigate the larvicidal activity of Dizygostemon riparius extracts and analyze its chemical profile for the first time. Dizygostemon is a Plantaginaceae bytipic genus and D. riparius is an aromatic plant recently identified in Maranhão, Brazil. The essential oil from its lilac morphotype already exhibited larvicidal potential against Aedes albopictus, but the still limited data on this new plant species require further chemical and biological studies on other species, such as Aedes aegypti. Ethyl acetate and methanol crude leaf extracts yielded, respectively, 17.60 and 25.96%. High-performance liquid chromatography (HPLC) with UV detection coupled with electrospray ionization mass spectrometry (HPLC-UV-ESI-IT/MS) analyses confirmed the presence of polymethoxyflavones and coumarins, such as isorhamnetin 3-galactoside-7-rhamnoside, 5,7-dihydroxy-3-(3-hydroxy-4,5-dimethoxyphenyl)-6-methoxy-4-benzopyrone and 3',5-dihydroxy-4',6,7-trimethoxyflavone. Ethyl acetate extract presented the best performance in larvicide bioassays (LC50 = 542.2 ± 11.5 µg.mL-1). Our results highlight the chemical and biological potential of this new species found in the cerrado of eastern Maranhão and open perspectives for future studies focusing on isolating and identifying other active secondary metabolites of Dizygostemon riparius.

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This study evaluated the effects of acute exposure of Aedes aegypti third instar (L3 ) larvae to the saline extract of Opuntia ficus-indica cladodes on the biological cycle and fertility of the emerging adults. For this, larvae were treated for 24 h with the extract at » LC50 (lethal concentration to kill 50% of larvae), ½ LC50 or LC50 ; the development and reproduction of the emerged adults were evaluated after a recovery period of 9 days. The resistance of proteins in the extract to hydrolysis by L3 digestive enzymes and histomorphological alterations in the larval midgut were also investigated. The extract contained lectin, flavonoids, cinnamic derivatives, terpenes, steroids, and reducing sugars. It showed a LC50 of 3.71% for 48 h. The data indicated mean survival times similar in control and extract treatments. It was observed development delay in extract-treated groups, with a lower number of adults than in control. However, the females that emerged laid similar number of eggs in control and treatments. Histological evaluation revealed absence of bacterial and fungal microorganisms in the food content in midguts from larvae treated with cladode extract. Electrophoresis revealed that three polypeptides in the extract resisted to hydrolysis by L3 digestive proteases for 90 min. The lectin activity was not altered even after 24-h incubation with the enzymes. In conclusion, the extract from O. ficus-indica can delay the development of Ae. aegypti larvae, which may be linked to induction of an axenic environment at larval midgut and permanence of lectin activity even after proteolysis.

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The continuous use of synthetic insecticides for controlling the arboviral vector Aedes aegypti has led to the natural selection of mosquito populations resistant to different chemical groups. Thus, plant-derived compounds have emerged as a viable alternative for vectorcontrol. This study determined whether the crude methanolic extract (CME) from leaves of Clibadium surinamense has larvicidal activity against Ae. aegypti. Third- and fourth-instar Ae. Aegyptilarvae were kept in recipients containing 99 mL of water and 1mL of ethanol-diluted CMEat concentrations of 250, 500, 750, and 1000 ppm. The control group contained 99 mL of water and 1 mL of ethanol. Three trials were performed in triplicate for each group.After 24 hours of treatment, the LC50 and LC90 values were determined to be 283 and 430 ppm, respectively, according to one-way analysis of variance. In conclusion, we have demonstrated for the first time that the CME from leaves of C. surinamense show larvicidal activity against Ae. aegypti under laboratory conditions.

O uso contínuo de inseticidas sintéticos para o controle do mosquito vetor de arbovírus, Aedes aegypti, tem levado à seleção natural de populações resistentes a diferentes grupos químicos. Assim, compostos derivados de plantas surgiram como uma alternativa viável para o controle desses vetores. Desse modo, este estudo foi realizado para determinar se o extrato metanólico bruto (CME) das folhas de Clibadium surinamense possui atividade larvicida contra Ae. aegypti. Para isso, Larvas de terceiro e quarto instar de Ae. aegypti foram mantidas em recipientes contendo 99 mL de água e 1 mL de CME diluído em etanol nas concentrações de 250, 500, 750 e 1000 ppm. O grupo controle continha 99 mL de água e 1 mL de etanol. Três ensaios foram realizados em triplicata para cada grupo. Após 24 horas de observação, de acordo com a análise de variância de uma via,os valores de CL50 e CL90 foram de 283 e 430 ppm, respectivamente. Em conclusão, demonstramos pela primeira vez que o CME das folhas de C. surinamense apresenta atividade larvicida contra Ae. aegypti em condições de laboratório.

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Around the world, the main problems of livestock are caused by ectoparasites, however, commercial acaracide are toxic to the environment and detrimental to One Health. Therefore, research has increasingly focused on development of natural products as alternatives for tick control. The purpose of this study was to evaluate the larvicidal effect on Rhipicephalus (Boophilus) microplus, through use of essential oils (EOs) extracted from the leaves, flower buds and stems of Tetradenia riparia. The chemical composition of these EOs was determined through gas chromatography coupled to mass spectrometry (GC-MS). They were tested on larvae at concentrations of 100.000 to 40 µg/mL, using the larval packet test and under semi-natural conditions. The main class of compounds in the chemical composition was sesquiterpenes (both oxygenates and hydrocarbons), whereas the predominant compounds in the leaves, flower buds and stems were 14-hydroxy-9-epi-caryophyllene, T-cadinol and 6-7-dehydroroyleanone, respectively. The leaves proved to be the most effective, with highest larvicidal activity (LC99.9 = 83.53 µg/mL). When tested under semi-natural conditions, the oils obtained efficiency above 98% in all compound tests. The results indicated that these EOs were effective against R. (B.) microplus larvae in vitro and ex-situ, proving that this plant has bioactive molecules with significant larvicidal activity.(AU)

Os principais problemas para a pecuária estão relacionados às ectoparasitoses, e ao fato dos carrapaticidas apresentarem elevada toxicidade ao meio ambiente e à saúde única. Surgem, então, demandas na busca por inovações e desenvolvimento de produtos naturais, como alternativas para o controle dos carrapatos. O objetivo deste trabalho foi avaliar o potencial da atividade larvicida sobre Rhipicephalus (Boophilus) microplus a partir dos óleos essenciais de Tetradenia riparia (TrOEs) extraídos das folhas, botões florais e caules. A composição química foi determinada por cromatografia gasosa acoplada à espectrometria de massa (GC/MS). Os TrOEs foram testados sobre larvas nas concentrações de 100.000 a 40 µg/mL pelo teste de pacote de larvas e em condições seminaturais. Na composição química, a classe majoritária foi os sesquiterpenos (oxigenados e hidrocarbonetos); já os compostos em destaques foram 14-hidroxy-9-epi-caryophyllene, T-cadinol e 6-7-dehidroroyleanone para folhas, botões florais e caules, respectivamente. As folhas demonstraram ser mais eficientes e com maior poder larvicida (CL99.9 = 83.53 µg/mL). Quando testado em condições seminaturais os óleos obtiveram eficiência acima de 98% em todos os compostos testados. Os resultados indicaram que os TrOEs, foram eficazes sobre as larvas de R. (B.) microplus in vitro e ex-situ, evidenciando que esta planta possui moléculas bioativas com ação larvicidas significativas.(AU)

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ABSTRACT: The continuous use of synthetic insecticides for controlling the arboviral vector Aedes aegypti has led to the natural selection of mosquito populations resistant to different chemical groups. Thus, plant-derived compounds have emerged as a viable alternative for vectorcontrol. This study determined whether the crude methanolic extract (CME) from leaves of Clibadium surinamense has larvicidal activity against Ae. aegypti. Third- and fourth-instar Ae. Aegyptilarvae were kept in recipients containing 99 mL of water and 1mL of ethanol-diluted CMEat concentrations of 250, 500, 750, and 1000 ppm. The control group contained 99 mL of water and 1 mL of ethanol. Three trials were performed in triplicate for each group.After 24 hours of treatment, the LC50 and LC90 values were determined to be 283 and 430 ppm, respectively, according to one-way analysis of variance. In conclusion, we have demonstrated for the first time that the CME from leaves of C. surinamense show larvicidal activity against Ae. aegypti under laboratory conditions.

RESUMO: O uso contínuo de inseticidas sintéticos para o controle do mosquito vetor de arbovírus, Aedes aegypti, tem levado à seleção natural de populações resistentes a diferentes grupos químicos. Assim, compostos derivados de plantas surgiram como uma alternativa viável para o controle desses vetores. Desse modo, este estudo foi realizado para determinar se o extrato metanólico bruto (CME) das folhas de Clibadium surinamense possui atividade larvicida contra Ae. aegypti. Para isso, Larvas de terceiro e quarto instar de Ae. aegypti foram mantidas em recipientes contendo 99 mL de água e 1 mL de CME diluído em etanol nas concentrações de 250, 500, 750 e 1000 ppm. O grupo controle continha 99 mL de água e 1 mL de etanol. Três ensaios foram realizados em triplicata para cada grupo. Após 24 horas de observação, de acordo com a análise de variância de uma via,os valores de CL50 e CL90 foram de 283 e 430 ppm, respectivamente. Em conclusão, demonstramos pela primeira vez que o CME das folhas de C. surinamense apresenta atividade larvicida contra Ae. aegypti em condições de laboratório.

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Schistosomiasis has been controlled for more than 40 years with a single drug, praziquantel, and only one molluscicide, niclosamide, raising concern of the possibility of the emergence of resistant strains. However, the molecular targets for both agents are thus far unknown. Consequently, the search for lead compounds from natural sources has been encouraged due to their diverse structure and function. Our search for natural compounds with potential use in schistosomiasis control led to the identification of an algal species, Laurencia dendroidea, whose extracts demonstrated significant activity toward both Schistosoma mansoni parasites and their intermediate host snails Biomphalaria glabrata. In the present study, three seaweed-derived halogenated sesquiterpenes, (-)-elatol, rogiolol, and obtusol are proposed as potential lead compounds for the development of anthelminthic drugs for the treatment of and pesticides for the environmental control of schistosomiasis. The three compounds were screened for their antischistosomal and molluscicidal activities. The screening revealed that rogiolol exhibits significant activity toward the survival of adult worms, and that all three compounds showed activity against S. mansoni cercariae and B. glabrata embryos. Biomonitored fractioning of L. dendroidea extracts indicated elatol as the most active compound toward cercariae larvae and snail embryos.

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Abstract Tetradenia riparia (Hochst.) Codd (Lamiaceae) is a species native to the African continent and used as an insect repellent. The objective of the study was to evaluate the larvicidal potential of essential oils (EOs) from the leaves, flower buds, and stem of T. riparia, collected in winter against Aedes aegypti larvae. The EOs were extracted by hydrodistillation (3 h) and identified by GC/MS. The EOs were tested against larvae of A. aegypti at concentrations ranging from 12500 to 1.5 µg/mL for 24 h. The insecticide activity was evaluated by probit analysis, and the anticholinesterase activity was determined by bioautographic method. The results of the class projection indicated sesquiterpenes as the majority class, corresponding to 60.66% (leaves), 64.70% (flower buds) and 83.99% (stem), and the bioassays on A. aegypti larvae indicated LC50 of 1590, 675 and 665 µg/mL, respectively. The anticholinesterase activity indicated that the EO of the leaves inhibited the enzyme at a concentration of 780 µg/mL, and those from the flower buds and stem inhibited up to 1560 µg/mL. The results indicated weak activity of essential oils against A. aegypti larvae.

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Schistosomiasis has been controlled for more than 40 years with a single drug, praziquantel, and only one molluscicide, niclosamide, raising concern of the possibility of the emergence of resistant strains. However, the molecular targets for both agents are thus far unknown. Consequently, the search for lead compounds from natural sources has been encouraged due to their diverse structure and function. Our search for natural compounds with potential use in schistosomiasis control led to the identification of an algal species, Laurencia dendroidea, whose extracts demonstrated significant activity toward both Schistosoma mansoni parasites and their intermediate host snails Biomphalaria glabrata. In the present study, three seaweed-derived halogenated sesquiterpenes, (−)-elatol, rogiolol, and obtusol are proposed as potential lead compounds for the development of anthelminthic drugs for the treatment of and pesticides for the environmental control of schistosomiasis. The three compounds were screened for their antischistosomal and molluscicidal activities. The screening revealed that rogiolol exhibits significant activity toward the survival of adult worms, and that all three compounds showed activity against S. mansoni cercariae and B. glabrata embryos. Biomonitored fractioning of L. dendroidea extracts indicated elatol as the most active compound toward cercariae larvae and snail embryos.

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The chemical composition and biological properties of citronella essential oil were modified by enzymatic esterification reaction of the major monoterpenic alcohols with cinnamic acid. The almost complete conversion of geraniol and citronellol present in the citronella (Cymbopogon winterianus) essential oil, into geranyl (99%) and citronellyl (98%) cinnamates was obtained after 48 hours of reaction using a molar ratio of 3:1 (cinnamic acid/alcohol), lipase concentration (Novozym 435) of 15% (w/w) and 70 °C. The esterified oil showed higher antimicrobial activity against Staphylococcus aureus bacteria resistant to oxacillin and penicillin and also greater larvicidal activity against Aedes aegypti larvae compared to unesterified oil. The results concerning the evaluation of toxicity against Artemia salina and cytotoxicity against monkey kidney epithelial cells also showed the superiority of the esterified oil.

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Pyriproxyfen is used in Brazil to combat epidemics of Dengue Fever, Chikungunya Fever, and Zika virus. This study assessed the effects of pyriproxyfen on reproductive performance, embryo-fetal development, head measurements, and DNA integrity in a preclinical model. Thirty pregnant mice were divided into three groups (n = 10): control (drinking water-0.1 ml/10 g (body weight-b.w., gavage) and treated with pyriproxyfen 0.0002 mg/kg and 0.0021 mg/kg (b.w., gavage) during the gestational period. Analysis of biometric, reproductive performance and embryo-fetal development parameters related to control presented no significant differences, suggesting no maternal or embryo-fetal toxicity. Head measurements showed no differences except an increase in anterior/posterior measurement and glabella/external occipital protuberance. Analysis of DNA integrity showed an increase in micronucleus only at 72 h for the lowest dose group. Thus, we infer that pyriproxyfen is not related to the occurrence of microcephaly, nor does it alter reproductive performance, embryo-fetal development or DNA integrity.

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The mosquito Aedes aegypti is a primary vector for major arboviruses, and its control is mainly based on the use of insecticides. Caffeine and spent coffee grounds (CG) are potential agents in controlling Ae. aegypti by reducing survival and blocking larval development. In this study, we analyzed the effects of treatment with common CG (CCG: with caffeine), decaffeinated CG (DCG: with low caffeine), and pure caffeine on the survival, behavior, and morphology of the midgut of Ae. aegypti under laboratory conditions. Third instar larvae (L3) were exposed to different concentrations of CCG, DCG, and caffeine. All compounds significantly affected larval survival, and sublethal concentrations reduced larval locomotor activity, delayed development, and reduced adult life span. Damage to the midgut of treated larvae included changes in epithelial morphology, increased number of peroxidase-positive cells (more abundant in DCG-treated larvae), and caspase 3-positive cells (more abundant in CCG-treated larvae), suggesting that the treatments triggered cell damage, leading to activation of cell death. In addition, the treatments reduced the FMRFamide-positive enteroendocrine cells and dividing cells compared to the control. CG and caffeine have larvicidal effects on Ae. aegypti that warrant field testing for their potential to control mosquitoes.

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The measures currently used to minimize the spread of arboviruses, comprising dengue, Chikungunya, and Zika virus, involve controlling the size of population of the mosquito Aedes aegypti. However, the search for formulations containing new insecticides is gaining pace due to reports of mosquito populations showing resistance to commonly used compounds. In this study, tablets containing a protein fraction of Moringa oleifera seeds enriched in the WSMoL lectin, known to show larvicidal and ovicidal activities against A. aegypti, were developed. The compatibility between the fraction and the excipients used in obtaining the tablets was evaluated by thermogravimetry (TG), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) absorption spectroscopy. The larvicidal and ovicidal activities of the resulting tablets [5%, 10%, and 15% (w/w) of the fraction] were evaluated, as well as their effect on mosquito oviposition. Assays were also performed using a placebo tablet. According to the TG, DSC, and FTIR results, the protein composition of the fraction did not change when mixed with the components of the formulation. Tablets containing 10% and 15% WSMoL-rich fraction caused mortality of 42.5% and 95% of the larvae after 48 h, respectively, with larvae incubated with these tablets showing reduced acetylcholinesterase activity. All tablets inhibited egg hatching after 72 h (36-74%), and tablets containing 15% fraction were found to exert a repellent effect on oviposition. Our results show that the formulation developed in this study interfered with the life cycle of A. aegypti, and thus show potential for use in the control of this mosquito.

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