Study on Morphological Changes and Interference in the Development of Aedes aegypti Caused by Some Essential Oil Constituents.

Dengue, Chikungunya and Zika are arboviruses, transmitted by the mosquito Aedes aegypti, that cause high mortality and serious health consequences in human populations. Efforts to control Ae. aegypti are important for preventing outbreaks of these diseases. Essential oil constituents are known to exhibit many activities, such as their use as larvicides. Given their potential, the present study aimed to characterize the larvicidal effect of dihydrojasmone, p-cymene, carvacrol, thymol, farnesol and nerolidol on the larvae of Ae. aegypti and their interference over the morphology of the mosquitos. The essential oil constituents were dissolved in dimethylsulfoxide at concentrations of 1-100 µg/mL and were applied in the breeding environment of third-stage larvae. The larvae from bioassays were fixed, dehydrated and embedded. Ultrathin sections were contrasted using 5% uranyl acetate and 1% lead citrate for observation through transmission electron microscopy. The oil with the highest larvicidal efficiency was found to be nerolidol, followed by farnesol, p-cymene, carvacrol, thymol and dihydrojasmone, with an LC50 of 11, 21, 23, 40, 45 and 66 µg/mL, respectively. The treated Ae. aegypti larvae caused alteration to the tegument or internal portions of larvae. The present study demonstrated which of these oils-dihydrojasmone, farnesol, thymol, p-cymene, carvacrol and nerolidol-have effective larvicidal activity.

A Novel Model of Pathogenesis of Metarhizium anisopliae Propagules through the Midguts of Aedes aegypti Larvae.

We assessed the effect of the entomopathogenic fungus Metarhizium anisopliae against Aedes aegypti. Conidia of M. anisopliae strains CG 489, CG 153, and IBCB 481 were grown in Adamek medium under different conditions to improve blastospore production. Mosquito larvae were exposed to blastospores or conidia of the three fungal strains at 1 × 107 propagules mL-1. M. anisopliae IBCB 481 and CG 153 reduced larval survival by 100%, whereas CG 489 decreased survival by about 50%. Blastospores of M. anisopliae IBCB 481 had better results in lowering larval survival. M. anisopliae CG 489 and CG 153 reduced larval survival similarly. For histopathology (HP) and scanning electron microscopy (SEM), larvae were exposed to M. anisopliae CG 153 for 24 h or 48 h. SEM confirmed the presence of fungi in the digestive tract, while HP confirmed that propagules reached the hemocoel via the midgut, damaged the peritrophic matrix, caused rupture and atrophy of the intestinal mucosa, caused cytoplasmic disorganization of the enterocytes, and degraded the brush border. Furthermore, we report for the first time the potential of M. anisopliae IBCB 481 to kill Ae. aegypti larvae and methods to improve the production of blastospores.

Evaluation of the Diversity of Culicidae Vectors of the Sylvatic Yellow Fever Virus in Atlantic Forest Remnants with the Use of Ovitraps and Bamboo Traps.

Mosquitoes transmit several pathogens in tropical regions, especially in forest areas. The diseases caused by these pathogens include malaria and several arboviruses such as yellow fever. Brazil has the largest endemic area in the world for yellow fever. Many factors can affect the sylvatic cycle of the disease, shifting it into human-inhabited areas. This study aims to examine the oviposition behavior of mosquito species that are effective or potential vectors of the yellow fever virus and which colonize bamboo traps and ovitraps installed at different heights. The positions of the traps in the strata were changed every 15 days. The collection of immature stages (eggs, larvae, and pupae) was performed every 2 weeks for 12 months from August 2018 to July 2019 in the city of Nova Iguaçu, state of Rio de Janeiro, Brazil, in an area near the Tinguá Biological Reserve (REBIO) in the districts of Adrianópolis and Rio D'ouro. Statistical tests were used to compare oviposition at each stratum, and correlation tests showed the relationship between the presence of eggs and immature mosquitoes (larvae and pupae) and temperature, precipitation, and trap type. The diversity was calculated for each trap type and height, as well as the dry and rainy seasons. During the sampling period, 3929 eggs and 4953 larvae and pupae were collected. The traps installed in the high strata remained empty when traps on the ground were installed at the same time, although not when they were installed on their own. The results obtained with this new proposed methodology suggest that diversity is greatest in the rainy season and in bamboo traps for either stratum. Furthermore, this study suggests that mosquitoes begin searching for breeding sites at ground level. Higher levels may be occupied due to the absence or impermanence of other breeding sites.

Spatial distribution of synanthropic triatomines in Piaui State, Northeastern Brazil.

This study aimed to describe the spatial distribution and assess entomological indicators of synanthropic triatomines in Piaui State, Northeastern Brazil. We used surveillance data on the detection, identification and assessment of natural infection with trypanosomatids from triatomines in the State from 2014 to 2017. The State was divided into four macroregions. In relation to the dispersion rates of triatomines, they were much lower in the North, when compared to Southwest, Southeast and Central North macroregions. Infestation rates were higher in the Southwest and Southeast and intradomicile infestation rates varied during the study period, reaching high values in all regions. Insects belonging to the species Triatoma brasiliensis complex, Triatoma pseudomaculata, Triatoma sordida, and to the genus Panstrongylus spp. and Rhodnius spp. were collected during this period. T. brasiliensis was collected from all four regions of the State, but more frequently in those located in the Southeast. A similar pattern was observed for T. pseudomaculata. T. sordida was detected in the municipalities in the Southeast and Southwest regions, and less frequently in the Central North municipalities. Rhodnius spp. was detected in the Central North and North regions, and Panstrongylus spp. in the Central North and Southeast regions. The highest trypanosomatid-positivity rate of T. brasiliensis and Panstrongylus spp. was in the Southeast region. A significant proportion of the municipalities of Piaui State presents entomological parameters that indicate a risk of Chagas disease by vector transmission.

Scanning Electron Microscopy of Sand Flies of the Chagasi Series, Psychodopygus (Diptera: Psychodidae) Genus, Focusing on the Genitalia.

Males of cryptic or closely related species present great morphological variation in their genitalia, whereas females, such as those of the Chagasi Series of the Psychodopygus Mangabeira, 1941 genus, are more similar. Therefore, our aim was to study the fine structure of the male genitalia of five species of the Chagasi Series to better understand the variation in their morphology and its influence on the copulatory process. The sand fly species were captured in the following Brazilian states: Psychodopygus chagasi (Costa Lima, 1941) (Rondônia), Psychodopygus complexus (Mangabeira, 1941) (Tocantins), Psychodopygus squamiventris maripaensis (Floch & Abonnenc, 1946) (Amapá), Psychodopygus squamiventris squamiventris (Lutz & Neiva, 1912) (Amazonas), and Psychodopygus wellcomei Fraiha, Shaw & Lainson, 1971 (Pará and Ceará). Insects were stored in ethanol 70% (then dehydrated) and dry after they were sputtered with gold. The samples were observed under a scanning electron microscope. Microtrichiae, two types of trichoid sensilla, coeloconic and chaetic sensillae, were observed on the antenna of all species, with no difference between them. Only on the anepimeron of P. squamiventris squamiventris a modified 'racket'-like scale was observed. As for the male genitalia, the setae and structures of each species were fully described, such as the small setae on the paramere apex of the P. squamiventris subspecies, and the grooves present in this region and on the paramere lobe of P. complexus and P. wellcomei, which are impossible to observe with optic microscopy. New information is thus provided on the male genitalia, which can contribute to future bionomic studies of these species.

Effects of semi-purified fractions from stems of Clusia hilariana on the development of Dysdercus peruvianus

ABSTRACT Plants represent a huge source of substances, with pharmacological potential. Brazil has a diversity of agricultural insect pests and an urgent need for safer methods of insect control. Dysdercus peruvianus (Guerin-Meneville, 1831), Pyrrhocoridae, is an economically important species of the Order Hemiptera and a pest of cotton (Gossypium hirsutum L., Malvaceae). Secondary metabolites in stems of Clusia hilariana Schltdl., Clusiaceae, such as terpenes and benzophenones, have been reported to be insecticidal. The present study investigated the effects of semi-purified fractions of hexane crude extracts from male C. hilariana stems on development of D. peruvianus. Biological parameters at different stages of development including body malformations, range of molting period and toxicity were evaluated. Most insects died and failed to develop due to attachment of their exuviae to the abdomen. Deformations of wings and defective tarsi also occurred. The secondary metabolites from semi-purified fractions of C. hilariana caused mortality, interference in molting and metamorphosis, and body deformations, probably by interacting with the neuroendocrine system. The results demonstrate the potential of C. hilariana extracts as an alternative for the control of the phytophagous insect D. peruvianus and for the development of environmentally safe and biodegradable bio insecticides.

Ultrastructure and morphometry of the egg of Coquillettidia albifera (Prado) with illustrations of male genitalia (Diptera: Culicidae).

The ultrastructure and morphometry of the egg of Coquillettidia albifera (Prado) (Diptera: Culicidae) studied under scanning electronic microscopy is presented for the first time. The identification of the species was confirmed by examination of the genitalia of males collected with females. The male genitalia are redescribed and digital photographs are provided. The eggs are elliptical with the anterior region elongate and tubuliform, length 661 ± 2.59 µm and width 183 ± 2.59 µm (ratio length/width 3.61 ± 0.08). The dorsal surface is covered by a hexagonal, pentagonal and rectangular chorionic network with randomly distributed tubercles. The micropylar disc has a diameter of 18.91 ± 0.65 µm, surrounded by a continuous protuberant collar with a thickness of 4.4 ± 0.3 µm. No structure or vestige of cement related to egg attachment was observed.

Triatomine dispersion rates and their association with socioeconomic and environmental conditions in Northeastern Brazil, from 2009 to 2013.

Triatomines are vectors of Trypanosoma cruzi , the etiological agent of Chagas disease, which affects between 6 and 12 million people in Latin America, with an incidence rate of 12 thousand cases per year. In the Ceara State, the predominance of the caatinga biome, coupled with a large rural area with precarious human habitations, provides several s shelters for these insects. In this study, we determined the spatiotemporal distribution of triatomine dispersion rates in the Cariri region, Southern Ceara and ascertained the possible association between these rates with socioeconomic and environmental factors. Dispersion rates (number of positive localities/number of searched localities × 100) were analyzed regarding 13 municipalities from the Ceara State, from 2009 to 2013. Socioeconomic and environmental variables collected from national research institutes were associated with the dispersion rates and their local empirical Bayesian estimates. All the municipalities recorded dispersion rates over 10% in all years, and 11 municipalities had average rates over 40% for the period of study. Significant differences were observed among the municipality means. The highest rates were observed in Antonina do Norte and Potengi. According to the correlation analysis, the proportion between the occupied population and the total population showed a significant negative correlation, as well as the percentage of the population who lives under adequate sanitary conditions. Both, the percentage of revenues from external sources and the percentage of urban households in reforested blocks had a significant positive correlation. Our results show that socioeconomic and environmental variables can be factors that contribute to both, the maintenance and the reduction of the elevated dispersion rates observed in the study area. Similar researches that encompass more municipalities from that region may reinforce Chagas disease surveillance and control in the Northeast of Brazil.

Triatoma costalimai Naturally Infected by Trypanosoma cruzi: A Public Health Concern.

The rupestrian Triatoma costalimai species has been found infected by Trypanosoma cruzi in wild, peridomicile, and intradomicile environments in the municipality of Aurora do Tocantins, Tocantins, Brazil. Proximity between rock outcrops increases the risk of vector transmission of Chagas disease via this species. This work describes a focus of colonization by T. costalimai specimens infected by T. cruzi in rock outcrops located in an urban area in this municipality. Parasitological examination of feces from the collected specimens, axenic cultivation of T. cruzi-positive samples, and genetic characterization of the isolates were performed. Nymph and adult specimens were collected with a high infection prevalence (64.5%) for T. cruzi discrete type unit (DTU I). Participation of the T. costalimai species in the wild cycle of T. cruzi in rock outcrops located in an urban area demonstrates the need for entomological surveillance and control of vector transmission of Chagas disease in the municipality of Aurora do Tocantins, Tocantins.

Chagasic infection among blood donors in Brazil: an integrative review.

Based on the literature, this work aimed to discuss infection by Chagas disease among blood donors in Brazil. Studies on the prevalence of Trypanosoma cruzi infection in donors or candidates for blood donation in Brazil are important. The prevalence of infection appears to be a sensitive indicator and can be a true marker of the risk of the transmission of Chagas disease by blood transfusion. Moreover, it serves as a marker of the level of transmission of the disease in a region, as well as a tool to characterize the epidemiological profile of individuals affected by the disease. The present study is an integrative review of the literature on chagasic infection among blood donors. An evaluation of the literature identified the epidemiological profile of blood donors infected by T. cruzi, which is characterized in general as men, over 30 years old, with a low level of schooling, low income and mainly coming from rural areas.

Entomological survey in the state of Piauí, Northeastern Brazil, reveals intradomiciliary colonization of Triatoma brasiliensis macromelasoma.

This survey aimed to assess the presence of triatomine vectors of Chagas disease within the rural communities of São João do Piauí, Northeast Brazil. Intradomiciliary and peridomiciliary collection strategies were implemented wherein 279 specimens of Triatoma brasiliensis macromelasoma, both nymph and adult were found in 15 (50%) of the studied homes. Of the intradomiciliary insects, 73 (67.6%) were identified as nymph instars (1st instar [N1]= 6, N2= 14, N3= 28, N4= 7 and N5= 18). In the studied communities, a continuous interaction between triatomine bugs and humans could be shown. It is therefore urgent that suitable strategies for the control of the triatomine vector are implemented in this area.

Entomological survey in the state of Piauí, Northeastern Brazil, reveals intradomiciliary colonization of Triatoma brasiliensis macromelasoma

ABSTRACT This survey aimed to assess the presence of triatomine vectors of Chagas disease within the rural communities of São João do Piauí, Northeast Brazil. Intradomiciliary and peridomiciliary collection strategies were implemented wherein 279 specimens of Triatoma brasiliensis macromelasoma, both nymph and adult were found in 15 (50%) of the studied homes. Of the intradomiciliary insects, 73 (67.6%) were identified as nymph instars (1st instar [N1]= 6, N2= 14, N3= 28, N4= 7 and N5= 18). In the studied communities, a continuous interaction between triatomine bugs and humans could be shown. It is therefore urgent that suitable strategies for the control of the triatomine vector are implemented in this area.

Biology of Triatoma carcavalloi Jurberg, Rocha & Lent, 1998 under laboratory conditions.

INTRODUCTION: Triatoma carcavalloi is a wild species that is found in sympatry with Triatoma rubrovaria and Triatoma circummaculata, which are vectors of Trypanosoma cruzi currently found in rural areas of Rio Grande do Sul, Brazil. METHODS: Fertility was assessed and to determine the incubation period, the eggs were observed until hatching. The first meal was offered to 1st stage nymphs. The intermolt period was also determined. The number of blood meals was quantified at each nymphal stage and the resistance to fasting as the period between ecdysis and death. Mortality was assessed and longevity was determined by recording the time that elapsed from molting to the adult stage and until death. The developmental cycle was assessed by recording the length in days of each stage from molting to adult hood. RESULTS: The average incubation period was 22.7 days. The average first meal occurred 3.1 days after hatching. The 5th stage nymph to adult intermolting period was the longest at 193.4 days. The average number of feedings during nymphal development was 13.4. The resistance to fasting assay indicated that the 3rd, 4th and 5th stage nymphs presented higher resistance than did adults. The highest mortality rate was observed in the 3rd stage nymphs (22.2%). The average length of adult survival was 25.6 weeks, and the average total life cycle lasted 503.4 days. CONCLUSIONS: This study is the first report on the biology of T. carcavalloi that fed on mice. The presented findings expand the bionomic knowledge of these species.

Biology of Triatoma carcavalloi Jurberg, Rocha & Lent, 1998 under laboratory conditions

Introduction Triatoma carcavalloi is a wild species that is found in sympatry with Triatoma rubrovaria and Triatoma circummaculata, which are vectors of Trypanosoma cruzi currently found in rural areas of Rio Grande do Sul, Brazil. Methods Fertility was assessed and to determine the incubation period, the eggs were observed until hatching. The first meal was offered to 1st stage nymphs. The intermolt period was also determined. The number of blood meals was quantified at each nymphal stage and the resistance to fasting as the period between ecdysis and death. Mortality was assessed and longevity was determined by recording the time that elapsed from molting to the adult stage and until death. The developmental cycle was assessed by recording the length in days of each stage from molting to adult hood. Results The average incubation period was 22.7 days. The average first meal occurred 3.1 days after hatching. The 5th stage nymph to adult intermolting period was the longest at 193.4 days. The average number of feedings during nymphal development was 13.4. The resistance to fasting assay indicated that the 3rd, 4th and 5th stage nymphs presented higher resistance than did adults. The highest mortality rate was observed in the 3rd stage nymphs (22.2%). The average length of adult survival was 25.6 weeks, and the average total life cycle lasted 503.4 days. Conclusions This study is the first report on the biology of T. carcavalloi that fed on mice. The presented findings expand the bionomic knowledge of these species. .

Ultrastructure of immature stages of Peckia (Euboetcheria) collusor (Diptera: Sarcophagidae).

Peckia (Euboettcheria) collusor (Diptera: Sarcophagidae) is a necrophagous insect and represents an important role in forensic entomology, as it is always collected at animal/human corpses. Immature sarcophagids are extremely similar in morphological aspects and can be found colonizing both fresh and mummified bodies. Flesh fly larvae are reported to cause accidental myiasis. In the Neotropical regions little is known about the ultrastructure of immature stages of Sarcophagidae. Scanning electron microscopy gives detailed information on the morphological characters, which can help identify the immature forms of the flies. The aim of this study is to identify larvae and puparia of P. (E.) collusor using this methodology. The integument with net-like patches and the shape and disposition of intersegmental spines of the larval instars can be used to distinguish this flesh fly larva. The number of spiracular ramifications is variable at larval instars. The puparia are very similar to third instar larvae, except for the cephalic structures that are retracted. In conclusion, scanning electron microscopy could help entomologists to identify the immature forms of P. (E.) collusor in forensic investigations and consequently serves as a tool in crime scene investigations.

Triatoma jatai sp. nov. in the state of Tocantins, Brazil (Hemiptera: Reduviidae: Triatominae).

Triatoma jatai sp. nov. is the first new species of triatomine to be described in the state of Tocantins, in the northern region of Brazil. It was caught on rock outcrops in the wild environment and, more recently, invading homes. While T. jatai sp. nov. is morphologically similar to Triatoma costalimai, it is distinguished by its general colouring, differences in the blotches on the connexivum, wing size in females and external structures of the male genitalia. The type series has been deposited in the Entomological Collection and Herman Lent Collection, Oswaldo Cruz Institute-Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.

Triatoma jatai sp. nov. in the state of Tocantins, Brazil (Hemiptera: Reduviidae: Triatominae)

Triatoma jatai sp. nov. is the first new species of triatomine to be described in the state of Tocantins, in the northern region of Brazil. It was caught on rock outcrops in the wild environment and, more recently, invading homes. While T. jatai sp. nov. is morphologically similar to Triatoma costalimai, it is distinguished by its general colouring, differences in the blotches on the connexivum, wing size in females and external structures of the male genitalia. The type series has been deposited in the Entomological Collection and Herman Lent Collection, Oswaldo Cruz Institute-Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.

Studying nanotoxic effects of CdTe quantum dots in Trypanosoma cruzi

Semiconductor nanoparticles, such as quantum dots (QDs), were used to carry out experiments in vivo and ex vivo with Trypanosoma cruzi. However, questions have been raised regarding the nanotoxicity of QDs in living cells, microorganisms, tissues and whole animals. The objective of this paper was to conduct a QD nanotoxicity study on living T. cruzi protozoa using analytical methods. This was accomplished using in vitro experiments to test the interference of the QDs on parasite development, morphology and viability. Our results show that after 72 h, a 200 μM cadmium telluride (CdTe) QD solution induced important morphological alterations in T. cruzi, such as DNA damage, plasma membrane blebbing and mitochondrial swelling. Flow cytometry assays showed no damage to the plasma membrane when incubated with 200 μM CdTe QDs for up to 72 h (propidium iodide cells), giving no evidence of classical necrosis. Parasites incubated with 2 μM CdTe QDs still proliferated after seven days. In summary, a low concentration of CdTe QDs (2 μM) is optimal for bioimaging, whereas a high concentration (200 μM CdTe) could be toxic to cells. Taken together, our data indicate that 2 μM QD can be used for the successful long-term study of the parasite-vector interaction in real time.

Scanning electron microscopy of the egg of Ochlerotatus albifasciatus (Diptera: Culicidae).

Ochlerotatus albifasciatus (Macquart) (Diptera: Culicidae) is a mosquito species of medical and veterinary importance, usually associated with temporary groundwater habitats. Eggs obtained from females collected in Córdoba city, in the center of Argentina, were studied using scanning electron microscopy. The eggs are elliptical in outline, measuring approximately 615.7 +/- 37.24 microm in length (1) and 180.7 +/- 22.87 microm in width (w), with an egg index (l/w ratio) of 2.9-3.7. The outer chorionic sculpture has racquet-shaped and wristwatch-shaped cells consisting of a small central tubercle surrounded by larger tubercles and followed by a row of smaller tubercles on one or both sides, respectively, although variations between regions of the egg were observed. The micropylar apparatus has a collar with evident molding and edges of determined length, albeit irregular, with defined margins for the transition area and a thickness of approximately 10.7 microm. The margins of the micropylar disc are raised and the disc measures approximately 21.1 microm in diameter. The micropyle is distinct.

Ultrastructure of the salivary glands in Cimex hemipterus (Hemiptera: Cimicidae).

Cimex hemipterus (Fabricius) is a hematophagous insect that can be an experimental host of Trypanosoma cruzi and may play a role as vector of Chagas' disease. This work analyzed the structure of the salivary glands of C. hemipterus. The secretory portion of main salivary glands has a single oval lobe that is translucent and is formed from a simple columnar epithelium lined by muscle cells. The gland cells are high, with one or two spherical nuclei, nucleolus, and some condensed chromatin. The cell cytoplasm has a well-developed rough endoplasmic reticulum, electron lucent vesicles, lysosomes, and glycogen deposits. The apical plasma membrane has microvilli, zonula adherens, and desmosomes, whereas the basal plasma membrane has some infoldings associated with mitochondria. The duct of the main salivary glands has flattened cells. The secretory portion of the accessory salivary glands is a single vesicular lobe that is translucent and is formed from a single layer of cells that varies from flattened to cubical onto muscle cells. The cytoplasm contains a well-developed smooth endoplasmic reticulum, vacuoles of different sizes containing secretions, electron lucent, and abundant mitochondria. The baso-lateral plasma membrane of adjacent cells shows septate junctions. The duct is formed from a flattened epithelium like the duct of the principal salivary gland. The secretory cells of the main salivary glands are related to protein synthesis and transport of ions. However, the secretory cells of the accessory salivary glands are related mainly to transport of ions and water from the hemolymph to glandular lumen.