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1. Monitoring of pyrethroid resistance in Aedes aegypti: first report of double and triple kdr mutations in Buenos Aires Province

Author

Alberto N. Barrera-Illanes, Lorena Ledesma, Agustin Alvarez-Costa, Agustín Balsalobre, Corina Juliana Toloza, Agustín Hernandez-Maiztegui, Andrea Jait, Ivana Sierra, María Victoria Micieli, Mariana Manteca-Acosta, and Sheila Ons

Subjects
Dengue, Mosquito, High-resolution melting, Vector management, Insecticide, Infectious and parasitic diseases, RC109-216
Abstract

Abstract Background Dengue is an emerging disease in Argentina due to the colonization of Aedes aegypti, the mosquito vector. Buenos Aires Province is the biggest and most populated district in Argentina, suffering dengue outbreaks of growing magnitude. During epidemic periods, pyrethroid insecticides are used in this country to control adult mosquitoes. Pyrethroid resistance in dengue vectors has been reported worldwide, making it necessary to implement resistance management strategies. The voltage-gated sodium channel is the target site of pyrethroids. Mutations in the gene encoding this protein, called kdr mutations, are usually the molecular cause of pyrethroid resistance in insects. In Ae. aegypti from the Americas, three kdr substitutions were described: V410L, V1016I, and F1534C. The diagnostic of kdr mutations is recommended for the early detection of pyrethroid resistance as well as the consequent planning of evidence-based control policies. Methods We distributed ovitraps across 16 localities in Buenos Aires Province, collecting 22,123 eggs. A total of 522 mosquitoes were genotyped in positions 1016 and 1534 of voltage-gated channel using multiplex high-resolution melting and/or TaqMan probe methods. A subset of 449 samples was also genotyped by a singleplex high-resolution melting method developed ad hoc and/or Sanger sequencing. Results We have documented, for the first time to our knowledge in the central region of Argentina, the presence of the 1016Ikdr + 1534Ckdr allele. Additionally, our study reports the first identification of the V410L mutation in central Argentina. These results underscore a growing trend of pyrethroid resistance in Ae. aegypti, fueled by the widespread use of these insecticides. Conclusions We detected 1016Ikdr + 1534Ckdr and 410Lkdr mutations in central Argentina for the first time and improved the processivity and accuracy of kdr genotyping methods. The results are both a tool for resistance monitoring and a sign of alarm to direct efforts towards finding sustainable methods for vector control to complement or replace pyrethroids. Joint efforts between academia and authorities to develop and implement public policies for vector control are a productive way to transfer scientific results for their application in public health. Graphical Abstract

Published
2024
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2. Challenging Popular Belief, Mosquito Larvae Breathe Underwater

Author

Agustin Alvarez-Costa, Maria Soledad Leonardi, Silvère Giraud, Pablo E. Schilman, and Claudio R. Lazzari

Subjects
Aedes, metabolism, survival, respiration, temperature, Q10, Science
Abstract

Immature mosquitoes are thought to breathe only atmospheric air through their siphons despite reports of prolonged submerged survival. We studied the survival of last-instar larvae of Aedes aegypti fully submerged at different temperatures and measured the oxygen consumption from air and water-dissolved larvae and pupae of this species under different conditions. Larvae survived much longer than expected, reaching 50% mortality only after 58, 10, and 5 days at 15°, 25°, and 35 °C, respectively. Larval to pupa molt was only observed in larvae with access to air, whereas individuals kept submerged never molted. Although most of the oxygen was obtained from the air, larvae obtained 12.72% of their oxygen from the water, while pupae took only 5.32%. In both media, temperature affected the respiration rate of the larvae, with relatively close Q10 values (1.56 and 1.83 for water and air, respectively). A similar pattern of O2 consumption was observed in Ae. albopictus, whose larvae obtained 12.14% of their oxygen from the water. The detailed quantification of oxygen consumption by mosquito larvae showed that water-dissolved oxygen is not negligible and physiologically relevant, challenging the idea that mosquito larvae only breathe atmospheric oxygen.

Published
2024
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3. Challenging popular belief, mosquito larvae breathe underwater

Author

Agustin Alvarez-Costa, Maria Soledad Leonardi, Silvère Giraud, Pablo E. Schilman, and Claudio R. Lazzari

Abstract

It is taken for granted that immature mosquito only breathe atmospheric air through their siphons. However, there is no quantitative study that demonstrated it. We analysed the survival of the last instar larvae ofAedes aegyptifully submerged at different temperatures, and measured oxygen consumption from air and dissolved in water, of larvae and pupae of this species under different conditions. Results revealed that under water, larvae survived much longer than expected, reaching 50% mortality only after 58, 10, and 5 days at 15°, 25° and 35°C, respectively. Interestingly, whereas we registered moults to pupae in larvae with access to air, individuals kept submerged never moulted. When remaining at the water surface, larvae obtained 12.72% of O2from the water, while pupae only 5.32%. When completely submerged, larvae consumed less oxygen than in contact with the surface, but enough for surviving, while pupae did not. At both media, temperature affected larvae respiration rate, with relatively close Q10values. In the related species,Ae. albopictus, a similar pattern of O2consumption were observed. Larvae got 12.14% of their oxygen from the water. Interestingly, no significant differences in total O2consumption were found between water O2consumption, whenAe. albopictuslarvae were submerged, or when they also have access to air (dual O2consumption). Our findings not only challenge the classical idea that mosquito larvae only breathe atmospheric O2, but also force us to reconsider the potential effectiveness of control methods based on asphyxiating larvae by detaching from water surface.Summary statementWe present the first quantitative analysis of mosquito larvae respiration in air and water, unravelling the unknown capacity of larvae of the most cosmopolitan disease vector of breathing underwater.

Published
2023
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4. Machine-learning model led design to experimentally test species thermal limits: The case of kissing bugs (Triatominae)

Author

Jorge E. Rabinovich, Nicholas M. Fountain-Jones, Pablo E. Schilman, Agustin Alvarez Costa, and Ignacio J. Muñoz

Subjects
0106 biological sciences, Life Cycles, Chagas disease, Artificial intelligence, Physiology, Computer science, RC955-962, Microclimate, Disease Vectors, computer.software_genre, 01 natural sciences, Life stage, Body Temperature, Medical Conditions, 0302 clinical medicine, Arctic medicine. Tropical medicine, Medicine and Health Sciences, Triatoma, Triatominae, biology, Experimental Design, Eukaryota, Hemiptera, Insects, Infectious Diseases, Physiological Parameters, Process Engineering, Reduviidae, Research Design, Rhodnius, Engineering and Technology, Environmental niche modelling, Public aspects of medicine, RA1-1270, Research Article, Heat Treatment, Computer and Information Sciences, Arthropoda, Active learning (machine learning), Trypanosoma cruzi, 030231 tropical medicine, Industrial Processes, Research and Analysis Methods, Machine learning, Models, Biological, 010603 evolutionary biology, 03 medical and health sciences, Industrial Engineering, Triatoma infestans, medicine, Animals, Ciencias Naturales, business.industry, Organisms, Public Health, Environmental and Occupational Health, Biology and Life Sciences, Panstrongylus, medicine.disease, biology.organism_classification, Invertebrates, Insect Vectors, Nymphs, Species Interactions, Manufacturing Processes, business, Zoology, Entomology, computer, Developmental Biology
Abstract

Species Distribution Modelling (SDM) determines habitat suitability of a species across geographic areas using macro-climatic variables; however, micro-habitats can buffer or exacerbate the influence of macro-climatic variables, requiring links between physiology and species persistence. Experimental approaches linking species physiology to micro-climate are complex, time consuming and expensive. E.g., what combination of exposure time and temperature is important for a species thermal tolerance is difficult to judge a priori . We tackled this problem using an active learning approach that utilized machine learning methods to guide thermal tolerance experimental design for three kissing-bug species (Hemiptera: Reduviidae: Triatominae), vectors of the parasite causing Chagas disease. As with other pathogen vectors, triatomines are well known to utilize micro-habitats and the associated shift in microclimate to enhance survival. Using a limited literature-collected dataset, our approach showed that temperature followed by exposure time were the strongest predictors of mortality; species played a minor role, and life stage was the least important. Further, we identified complex but biologically plausible nonlinear interactions between temperature and exposure time in shaping mortality, together setting the potential thermal limits of triatomines. The results from this data led to the design of new experiments with laboratory results that produced novel insights of the effects of temperature and exposure for the triatomines. These results, in turn, can be used to better model micro-climatic envelope for the species. Here we demonstrate the power of an active learning approach to explore experimental space to design laboratory studies testing species thermal limits. Our analytical pipeline can be easily adapted to other systems and we provide code to allow practitioners to perform similar analyses. Not only does our approach have the potential to save time and money: it can also increase our understanding of the links between species physiology and climate, a topic of increasing ecological importance., Trabajo publicado en PLOS Neglected Tropical Diseases: doi:10.1371/journal.pntd.0008822 (hacer clic en "Documentos relacionados" para acceder a él)., Centro de Estudios Parasitológicos y de Vectores

Published
2021

5. A Video-Tracking Analysis-Based Behavioral Assay for Larvae of Anopheles pseudopunctipennis and Aedes aegypti (Diptera: Culicidae)

Author

Agustin Alvarez Costa, Hector Mario Masuh, and Paula Valeria Gonzalez

Subjects
ANOPHELES PSEUDOPUNCTIPENNIS, 0301 basic medicine, animal structures, LARVA, Movement, Otras Ciencias Biológicas, 030231 tropical medicine, Video Recording, Zoology, Aedes aegypti, Dengue fever, Ciencias Biológicas, 03 medical and health sciences, 0302 clinical medicine, Aedes, Anopheles, parasitic diseases, medicine, Animals, Swimming, Larva, Thigmotaxis, General Veterinary, biology, fungi, Yellow fever, biology.organism_classification, medicine.disease, MOSQUITO, 030104 developmental biology, Infectious Diseases, Insect Science, Vector (epidemiology), Parasitology, Software, AEDES AEGYPTI, BEHAVIOR, CIENCIAS NATURALES Y EXACTAS
Abstract

Aedes aegypti (L.) is the primary vector of dengue, yellow fever, Zika, and chikungunya viruses, whereas Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin America. The larval stage of these mosquitoes occurs in very different development habitats, and the study of their respective behaviors could give us valuable information to improve larval control. The aim of this study was to set up a bioassay to study basic larval behaviors using a video-tracking software. Larvae of An. pseudopunctipennis came from two localities in Salta Province, Argentina, while Ae. aegypti larvae were of the Rockefeller laboratory strain. Behaviors of individual fourth-instar larvae were documented in an experimental petri dish arena using EthoVision XT10.1 video-tracking software. The overall level of movement of larval An. pseudopunctipennis was lower than that for Ae. aegypti, and, while moving, larval An. pseudopunctipennis spent significantly more time swimming near the wall of the arena (thigmotaxis). This is the first study that analyzes the behavior of An. pseudopunctipennis larvae. The experimental system described here may be useful for future studies on the effect of physiological, toxicological, and chemosensory stimuli on larval behaviors. Fil: Gonzalez, Paula Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina Fil: Alvarez Costa, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Masuh, Hector Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina

Published
2017
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6. Quantitative Evaluation of the Behavioral Response to Attractant and Repellent Compounds in Anopheles pseudopunctipennis and Aedes aegypti (Diptera: Culicidae) Larvae

Author

Laura Vanesa Harburguer, Paula Valeria Gonzalez, Hector Mario Masuh, and Agustin Alvarez Costa

Subjects
0106 biological sciences, Entomology, animal structures, Zoology, DEET, Aedes aegypti, Mosquito Vectors, Biology, medicine.disease_cause, 010603 evolutionary biology, 01 natural sciences, Dengue fever, Ciencias Biológicas, chemistry.chemical_compound, Aedes, parasitic diseases, Anopheles, medicine, Animals, YEAST, Chikungunya, Ecosystem, Larva, Ecology, Zika Virus Infection, fungi, Yellow fever, IR3535, General Medicine, Zika Virus, biology.organism_classification, medicine.disease, MOSQUITO, 010602 entomology, chemistry, Insect Science, Insect Repellents, PROLINE, Otros Tópicos Biológicos, CIENCIAS NATURALES Y EXACTAS
Abstract

The mosquito Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin-America. Aedes aegypti (L.) (Diptera: Culicidae) is the key vector of four important arboviral diseases: dengue, yellow fever, Zika, and chikungunya. Controlling larval stages to reduce the production of new adult mosquitoes is part of the integrated vector management strategies. However, there are few studies about the olfactory behavior on immature stages of mosquitoes, especially in An. pseudopunctipennis. In this work, we have evaluated the behavior of An. pseudopunctipennis and Ae. aegypti larvae in response to attractant or repellent stimuli through a video-tracking analysis. We used the software EthoVision to obtain behavioral variables related to the swimming activity, such as distance, speed, and mobility status. The response to the repellents stimulus results in an increase of the swimming activity and the absolute angular velocity in both species. Otherwise, the responses to the possible attractants stimulus results in a decrease of the activity of the larvae only for Ae. aegypti. The effects of these compounds were weaker in Anopheles; probably as a consequence of their adaptations to different aquatic ecosystems. The study of the larval olfactory response could contribute to the development of new control tools based on ‘push–pull’ strategies by ‘pushing’ mosquitoes away from certain places using repellents, and ‘pulling’ them towards other places like traps baited with attractive cues. Fil: Gonzalez, Paula Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina Fil: Alvarez Costa, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina Fil: Harburguer, Laura Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina Fil: Masuh, Hector Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentina

Published
2019
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7. Effects of Temephos, Permethrin, and Eucalyptus nitens Essential Oil on Survival and Swimming Behavior of Aedes aegypti and Anopheles pseudopunctipennis (Diptera: Culicidae) Larvae

Author

Laura Vanesa Harburguer, Agustin Alvarez Costa, Paula Valeria Gonzalez, and Hector Mario Masuh

Subjects
0106 biological sciences, Insecticides, animal structures, Medical entomology, 030231 tropical medicine, Zoology, Aedes aegypti, 01 natural sciences, SUBLETHAL EFFECTS, LARVAL BEHAVIOR, Ciencias Biológicas, 03 medical and health sciences, Temefos, chemistry.chemical_compound, 0302 clinical medicine, Aedes, parasitic diseases, Anopheles, medicine, Animals, Permethrin, Swimming, LARVICIDES, Larva, General Veterinary, biology, fungi, Zoología, Ornitología, Entomología, Etología, biology.organism_classification, 010602 entomology, Infectious Diseases, chemistry, Eucalyptus Oil, Insect Science, Vector (epidemiology), Parasitology, CIENCIAS NATURALES Y EXACTAS, medicine.drug
Abstract

An essential strategy to deal with mosquito-borne diseases is the control of larvae in their development sites. The mosquitoes Anopheles pseudopunctipennis (Theobald) (Diptera: Culicidae), a malaria vector, and Aedes aegypti (L.) (Diptera: Culicidae), vector of dengue, Zika, yellow fever, and chikungunya viruses, breed in very different habitats. Insecticide treatments of mosquito larvae focus mainly on their lethal effects. However, insecticide degradation or the poor dosage of larvicides will invariably lead to the sublethal exposure of a target (and nontarget) species, the nonlethal effects of these compounds may have important effects on vital insect activities, and therefore their evaluation is necessary. In this study, we assessed the survival and swimming behavior of larvae of Ae. aegypti and An. pseudopunctipennis exposed to increasing concentrations of three larvicides. We found that Ae. aegypti, was more sensitive to the larvicides than An. pseudopunctipennis, we also observed an overall decrease in the movement of those larvae of both species, which survive the treatments. This decrease might have ecological relevance in their natural habitats, increasing the chance to be predated and decreasing their ability to obtain food. Finally, this information will be valuable to assist authorities to make decisions in the implementation of further control programs. Fil: Alvarez Costa, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Gonzalez, Paula Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Harburguer, Laura Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Masuh, Hector Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina

Published
2018

8. Enantiomeric Ratio Changes of Terpenes in Essential Oils from Hybrid Eucalyptus grandis × E. tereticornis and its Pure Species

Author

Paola Gonzalez Audino, Cecilia Naspi, Agustin Alvarez Costa, Alejandro Lucia, and Hector Mario Masuh

Subjects
010405 organic chemistry, Chemistry, ENANTIOMERS, Otras Ciencias Químicas, Ciencias Químicas, General Chemistry, 010402 general chemistry, 01 natural sciences, Eucalyptus, 0104 chemical sciences, purl.org/becyt/ford/1 [https], Terpene, ESSENTIAL OILS, Botany, purl.org/becyt/ford/1.4 [https], EUCALYPTUS HYBRID, Enantiomer, CIENCIAS NATURALES Y EXACTAS
Abstract

Some Eucalyptus species produce oils with biological activities and the effect of their interspecifc hybridization on the enantiomeric composition of terpenes has not been reported. The enantiomeric excesses of monoterpenes in the essential oil of Eucalyptus grandis × E. tereticornis and its parental taxa were determined by gas chromatography-mass spectrometry (GC-MS), and to resolve coelutions problems by preparative high performance liquid chromatography (HPLC)and GC-MS with two columns in series. The essential oil composition of the hybrid presented qualitative and quantitative differences with the composition of its parental taxa. Great differences were found for the enantiomeric ratio in monoterpene alcohols among the three essential oils. Our results suggest that the enantiomeric analysis can be a reliable method for the study of how theinterspecifc hybridization can module the enantiomeric chemical profle in Eucalyptus essential oils. These results suggest the use of interspecifc hybridization to improve or expand the source of bioactive compounds. Fil: Naspi, Cecilia Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Alvarez Costa, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Lucia, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Gonzalez Audino, Paola Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina Fil: Masuh, Hector Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina

Published
2017
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9. High effectiveness of an adulticide-larvicide formulation for field control of sandflies (Diptera: Psychodidae) in the city of Clorinda, Argentina

Author

Andrea Gómez-Bravo, Agustín Alvarez-Costa, Georgina Fronza, Marcelo Abril, Eduardo N. Zerba, and Laura W. Juan

Subjects
Infectious and parasitic diseases, RC109-216
Abstract

In Argentina, Leishmania infantum (syn. L. chagasi) is the etiologic agent of human visceral leishmaniosis (HVL), and Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) is the main vector. The objective of this study was to evaluate the effectiveness and residual effect of two commercial insecticide formulations, one with permethrin and pyriproxyfen as active ingredients (Dragon Max®) and the other with only permethrin (Flop®) for the control of sandflies. Both formulations were applied in chicken coops and other surroundings structures of the peridomicile of urban houses in Clorinda, Formosa (Argentina). Entomological monitoring was carried out weekly for 44 weeks after the intervention. The results showed great effectiveness and residual effect up to 21 weeks post-intervention for Dragon Max®. This result could be explained by the excellent larvicidal activity of the Insect Growth Regulator (IGR) pyriproxyfen against the immature forms of phlebotomines and by the delay on the restoration of the natural threshold of the vector population in treated sites. Keywords: Sandflies, Permethrin, Pyriproxyfen, Vector control, Long-term effect

Published
2019
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10. Surfactantless Emulsions Containing Eugenol for Imidacloprid Solubilization: Physicochemical Characterization and Toxicity against Insecticide-Resistant Cimex lectularius

Author

Mariano Cáceres, Eduardo Guzmán, Agustín Alvarez-Costa, Francisco Ortega, Ramón G. Rubio, Carlos Coviella, Pablo L. Santo Orihuela, Claudia V. Vassena, and Alejandro Lucia

Subjects
eugenol, surfactantless emulsions, ternary mixtures, imidacloprid, bed bugs, Organic chemistry, QD241-441
Abstract

Synthetic insecticides have been used for a long time as one of the most effective tools for insect pest control. However, the re-emergence of insect pests and their fast development of resistance, as has occurred for pyrethroid-resistant bed bugs Cimex lectularius L., make it necessary to develop new and safe strategies for effective pest control. This has fostered the research on new eco-sustainable formulations based on essential oils, which allows reducing the impact associated with the intensive use of synthetic insecticides on the environment and their effects on human health. This research explores the stability of water/eugenol/ethanol surfactantless emulsions loaded with imidacloprid (0.003 wt%), and their toxicity against a resistant bed bug strain. The results have shown that these emulsions enable the solubilization of a poorly water-soluble drug, such as the imidacloprid, without any significant modification of their stability. Furthermore, the application of the obtained formulations against the pyrethroid-resistant bed bug results in mortality in the 50–85% range upon topical and spray applications, with the increase of the eugenol content enhancing the effectiveness of the formulations. It may be expected that the ternary water/eugenol/ethanol mixtures could be further developed in the preparation of ready to use formulations, enabling the dispersion of insecticides for pest control.

Published
2020
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