Essential Oil of Piper Purusanum C.DC (Piperaceae) and Its Main Sesquiterpenes: Biodefensives Against Malaria and Dengue Vectors, Without Lethal Effect on Non-target Aquatic Fauna

The mosquitoes vectors of the genus Aedes and Anopheles present resistance to several commercial insecticides, which are also toxic to non-predators targets. On the other hand, essential oils are a promising source of insecticides. Thus, in this work, the essential oil from the leaves of Piper purusanum was characterized by gas chromatography based approaches and evaluated as biodefensive against malaria and dengue vectors. The main compounds of P. purusanum essential oil were β-caryophyllene (57.05%), α-humulene (14.50%) and germacrene D (8.20%). The essential oil inhibited egg hatching (7.6 ± 1.5 to 95.6 ± 4.5%) caused larval death (LC50 from 49.84 to 51.60 ppm) and inhibited the action of acetylcholinesterase (IC50 of 2.29 µg/mL), which can be related to the mechanisms of action. On the other hand, the biological activity of β-caryophyllene, α-humulene and germacrene D were higher than the essential oil. In addition, these sesquiterpenes and essential oil did not show a lethal effect on Toxorhynchites splendens, Anisops bouvieri, Gambusia affinis and Diplonychus indicus (LC50 from 2098.80 to 7707.13 ppm), although D. indicus is more sensible (SI/PSF from 48.56 to 252.02 ppm) to essential oil, representing a natural alternative against these relevant vectors.

Correlation of dengue cases and pluviometric precipitation, in Pará state, Brazil (2014 to 2019)

The climate can lead to the emergence of environments conducive to the proliferation of dengue vectors, in addition to diseases and illnesses related to climatic phenomena. In this context, it is necessary to relate the exposure devices, that is, as associated variables associated with dengue cases. The objective of this research was to carry out a retrospective epidemiological study, with an emphasis on sex, age group and municipalities reporting dengue cases, as well as to correlate the cases of the disease with rainfall levels, in the state of Pará, Brazil. The correlation between rainy periods, transition from rainy to less rainy (C-MC) and less rainy to rainy (MC-C) showed a statistical correlation (p <0.05) with dengue cases in the period studied. Thus, it was found that dengue cases had an increase in the year subsequent to 2018, in which the majority were women with complete high school, in the age group of 20 to 39 years old. Given this scenario, the analysis of epidemiological data is important so that preventive measures and control of the agent are adopted by the government.Keywords: clinical-laboratory; epidemiological; gender; age group. Correlação de casos de dengue e precipitação pluviométrica, no estado do Pará, Brasil (2014 a 2019) RESUMOO clima pode levar ao surgimento de ambientes propícios à proliferação de vetores da dengue, além de doenças e enfermidades relacionadas aos fenômenos climáticos. Nesse contexto, é necessário relatar os mecanismos de exposição, ou seja, as variáveis climáticas associada aos casos de dengue. O objetivo desta pesquisa foi realizar um estudo epidemiológico retrospectivo, com ênfase no sexo, faixa etária e municípios que notificaram casos de dengue, bem como correlacionar os casos da doença com os níveis de precipitação, no estado do Pará, Brasil. A correlação entre os períodos chuvoso, transição de chuvoso para menos chuvoso (C-MC) e menos chuvoso para chuvoso (MC-C) apresentou correlação estatística (p <0,05) com os casos de dengue no período estudado. Assim, constatou-se que os casos de dengue aumentaram no ano subsequente a 2018, em que a maioria eram mulheres com ensino médio completo, na faixa etária de 20 a 39 anos. Diante desse cenário, a análise dos dados epidemiológicos é importante para que medidas preventivas e de controle do agente sejam adotadas pelo poder público.Palavras-chave: clínico-laboratorial; epidemiológico; Gênero sexual; grupo de idade.

Spatial Mapping of Aedes Sp. Densities and Endemicity Level of Dengue in Three Villages in South Sulawesi, Indonesia

The study aim to analyze the spatial map of the density of Aedes sp., several measurement methods, and the relationship between environmental factors with mosquito density in Makassar City, Maros and Gowa Cities. The research method used an ecological study design. In this study, surveys of larvae, ovitrap and Lighttrap were be used to measure the density of Aedes sp. Data processing using SPSS version 22 and Arview GIS 10.5. The results that spatial analysis showed a random pattern or spread of density of larvae, ovitrap and adult mosquitoes. the Larva and Ovitrap survey methods were specific measured the density of Dengue vectors (larvae, eggs and adult mosquitoes Aedes aegypti) while the Light Trap method was not specific. There was a significant relationship between temperature, humidity and egg density and Aedes aegypti mosquitoes in three DHF endemic sub-districts; except humidity and mosquito density was not significant in Bontoa Village of Maros Regency (p> 0.05). There was no significant relationship between the wire netted ventilation factor and the density of Aedes aegypti mosquitoes in the three DHF endemic sub-districts except for the mosquito density there was a significant relationship in Bontoa Village, Maros Regency.

Insecticide resistance of Dengue vectors in South East Asia: a systematic review

Background: The insecticides used widely has led to resistance in the vector and impose a challenge to vector control op- eration. Objectives: This review aims to analyse the distribution of insecticide resistance of dengue vectors in South East Asia and to describe the mechanism of insecticide resistance. Methods: Literature search for articles published on 2015 to 2019 from PubMed, Scopus and ProQuest was performed. Total of 37 studies included in the final review from the initial 420 studies. Results: Pyrethroid resistance was concentrated on the west coast of Peninsular Malaysia and Northern Thailand and scat- tered at Java Island, Indonesia while organophosphate resistance was seen across the Java Island (Indonesia), West Sumatera and North Peninsular Malaysia. Organochlorine resistance was seen in Sabah, Malaysia and scattered distribution in Nusa Tenggara, Indonesia. V1016G, S989P, F1269C gene mutation in Aedes Aegypti were associated with Pyrethroid resistance in Singapore and Indonesia. In Malaysia, over-expressed with monooxygenase P450 genes (CYP9J27, CYP6CB1, CYP9J26 and CYP9M4) Glutathione S-transferases, carboxylesterases commonly associated with pyrethroids resistance in Aedes Aegypti and CYP612 overexpressed in Aedes Albopictus. The genetic mutation in A302S in Aedes Albopictus was associated with organochlorine resistance in Malaysia. Conclusions: Rotation of insecticide, integration with synergist and routine assessment of resistance profile are recom- mended strategies in insecticide resistance management. Keywords: Insecticide resistance; vector management; Aedes; pyrethroid; mortality.

Homogeneity and Possible Replacement of Populations of the Dengue Vectors Aedes aegypti and Aedes albopictus in Indonesia

Currently, Aedes aegypti, the principal vector of dengue virus in Indonesia, has spread throughout the archipelago. Aedes albopictus is also present. Invasion and high adaptability of the Aedes mosquitoes to all of these areas are closely related to their ecology and biology. Between June 2016 and July 2017, larval and adult mosquito collections were conducted in 43 locations in 25 provinces of Indonesia using standardized sampling methods for dengue vector surveillance. The samples collected were analyzed for polymorphism and phylogenetic relationship using the mitochondrial cox1 gene and the nuclear ribosomal internal transcribed spacer 2 (ITS2). Almost all Ae. aegypti samples collected in this study (89%) belonged to the same haplotype. A similar situation is observed with the nuclear ITS2 marker. Populations of Ae. aegypti characterized few years ago were genetically different. A closely related observation was made with Aedes albopictus for which the current populations are different from those described earlier. Ae. aegypti populations were found to be highly homogenous all over Indonesia with all samples belonging to the same maternal lineage. Although difficult to demonstrate formally, there is a possibility of population replacement. Although to a lower extent, a similar conclusion was reached with Ae. albopictus.

Chemical Composition, Larvicidal Activity, and Enzyme Inhibition of the Essential Oil of Lippia grata Schauer from the Caatinga Biome against Dengue Vectors

Insect resistance and environmental pollution are among the drawbacks of continuous use of synthetic insecticides against the vectors of dengue, Aedesaegypti and Aedes albopictus. The objective of this study was to analyze the composition of the essential oil of Lippia grata Schauer collected from plants, in three periods of the year, to compare the larvicidal activity and enzymatic inhibition of the dengue vectors. The oilsanalyzed by gas chromatography coupled to mass spectrometry (GC-MS), presented thymol and 1,8-cineole, as the main constituents, in all three periods. This composition was different from that found in previous studies of the species from different places, thus, suggesting a new chemotype of Lippia grata. Larvicidal tests were performed at concentrations of 100, 75, 50, 25, and 12.5 μg.mL−1 and the essential oil from the rainy season showed the best results, with LC50 of 22.79 μg.mL−1 and 35.36 μg.mL−1 against Ae. aegypti and Ae. albopictus, respectively; this result was better than other reports. In the rainy period, however, there was a greater variety of components, which led to a better larvicidal effect, possibly due to synergistic action with minor constituents. Total proteins, amylases, and acetylcholinesterase of both species were inhibited by the oils.

Insecticide resistance and underlying targets-site and metabolic mechanisms in Aedes aegypti and Aedes albopictus from Lahore, Pakistan

Insecticide resistant Aedes populations have recently been reported in Pakistan, imposing a threat to their control. We aimed to evaluate the susceptibility of Aedes aegypti and Aedes albopictus populations from Lahore to WHO-recommended insecticides and to investigate metabolic and target-site resistance mechanisms. For this purpose, we first carried out bioassays with the larvicides temephos and pyriproxyfen, and the adulticides malathion, permethrin, deltamethrin, alpha-cypermethrin, and etofenprox. We looked for Knockdown resistance mutations (kdr) by qPCR, High-Resolution Melt (HRM), and sequencing. In order to explore the role of detoxifying enzymes in resistance, we carried out synergist bioassay with both species and then checked the expression of CYP9M6, CYP9J10, CYP9J28, CYP6BB2, CCAe3a, and SAP2 genes in Ae. aegypti. Both species were susceptible to organophosphates and the insect growth regulator, however resistant to all pyrethroids. We are reporting the kdr haplotypes 1520Ile + 1534Cys and T1520 + 1534Cys in high frequencies in Ae. aegypti while Ae. albopictus only exhibited the alteration L882M. PBO increased the sensitivity to permethrin in Ae. aegypti, suggesting the participation of P450 genes in conferring resistance, and indeed, CYP928 was highly expressed. We presume that dengue vectors in Lahore city are resistant to pyrethroids, probably due to multiple mechanisms, such as kdr mutations and P450 overexpression.