The Rpfor gene modulates the locomotory activity and host-seeking behaviour of Rhodnius prolixus.

The molecular bases of animal behaviour are intricate due to the pleiotropic nature of behaviour-modulating genes, which are often expressed across multiple tissues. The foraging gene (for) encodes a cGMP-dependent protein kinase (PKG), pivotal in regulating downstream target proteins through phosphorylation. In insects, for has been implicated in various behavioural contexts and physiological processes regarding searching for food. Rhodnius prolixus, a hematophagous bug that transmits Trypanosoma cruzi, the causative agent of Chagas disease, exhibits specific activity patterns associated with its hematophagous behaviour. Our previous work demonstrated a correlation between locomotor activity profiles and the expression of Rpfor, suggesting its involvement in modulating triatomine locomotion. In this study, we investigated the impact of Rpfor knockdown on locomotory activity, host-seeking behaviour, feeding performance and lipid metabolism in R. prolixus nymphs. Using RNA interference, we achieved a significant reduction of Rpfor expression in both the brain and fat body of R. prolixus nymphs. Knocked-down nymphs exhibited diminished non-oriented locomotory activity compared with controls, without altering the characteristic bimodal pattern of activity. Additionally, they displayed an increased tendency to approach a host, suggesting a role for Rpfor in modulating host-seeking behaviour. Feeding performance and lipid metabolism remained unaffected by Rpfor knockdown. Our findings underscore the multifaceted role of Rpfor in modulating locomotor activity and host-seeking behaviour in R. prolixus nymphs, shedding light on the molecular mechanisms underlying their hematophagous behaviour and potential implications for disease transmission. Further research is necessary to elucidate the intricate interplay between Rpfor expression, behaviour and physiological processes in triatomine bugs.

As bases moleculares do comportamento animal são complexas devido à natureza pleiotrópica dos genes envolvidos na sua modulação, normalmente expressos em múltiplos tecidos. O gene foraging (for) codifica para uma proteína quinase dependente de cGMP, fundamental para a regulação de proteínas alvo via fosforilação. Em insetos, o gene for tem sido associado a vários contextos comportamentais e processos fisiológicos relacionados com forrageamento. Rhodnius prolixus, um inseto hematófago que transmite Trypanosoma cruzi, o agente causativo da doença de Chagas, exibe padrões de atividade específicos associados com o seu comportamento hematófago. Em um estudo anterior, demonstramos uma correlação entre os perfis de atividade locomotora e a expressão de Rpfor, sugerindo o seu envolvimento na modulação da locomoção de triatomíneos. No presente estudo, investigamos o impacto do silenciamento de Rpfor na atividade locomotora, no comportamento de busca por hospedeiro, na performance alimentar, e no metabolismo de lipídeos em ninfas de R. prolixus. Através da técnica de RNA de interferência, obtivemos uma redução significativa da expressão do gene Rpfor no cérebro e no corpo gorduroso de R. prolixus. Insetos silenciados exibiram uma redução da atividade locomotora não orientada em comparação com controles, sem alterações no padrão bimodal da atividade. Adicionalmente, os insetos apresentaram um aumento no comportamento de busca por hospedeiro, sugerindo um papel para o Rpfor na sua modulação. A performance alimentar e o metabolismo de lipídeos não foram alterados pelo silenciamento do gene. Nossas descobertas ressaltam o papel multifuncional do gene Rpfor na modulação da atividade locomotora e no comportamento de busca por hospedeiro em R. prolixus, ampliando o conhecimento sobre os mecanismos moleculares relacionados ao seu comportamento hematófago e potenciais implicações para a transmissão de doenças. Estudos adicionais são necessários para elucidar a intrincada interação entre expressão, comportamento e processos fisiológicos de Rpfor em insetos triatomíneos.

Egg-laying by female Aedes aegypti shapes the bacterial communities of breeding sites.

BACKGROUND: Aedes aegypti, the main arboviral mosquito vector, is attracted to human dwellings and makes use of human-generated breeding sites. Past research has shown that bacterial communities associated with such sites undergo compositional shifts as larvae develop and that exposure to different bacteria during larval stages can have an impact on mosquito development and life-history traits. Based on these facts, we hypothesized that female Ae. aegypti shape the bacteria communities of breeding sites during oviposition as a form of niche construction to favor offspring fitness. RESULTS: To test this hypothesis, we first verified that gravid females can act as mechanical vectors of bacteria. We then elaborated an experimental scheme to test the impact of oviposition on breeding site microbiota. Five different groups of experimental breeding sites were set up with a sterile aqueous solution of larval food, and subsequently exposed to (1) the environment alone, (2) surface-sterilized eggs, (3) unsterilized eggs, (4) a non-egg laying female, or (5) oviposition by a gravid female. The microbiota of these differently treated sites was assessed by amplicon-oriented DNA sequencing once the larvae from the sites with eggs had completed development and formed pupae. Microbial ecology analyses revealed significant differences between the five treatments in terms of diversity. In particular, between-treatment shifts in abundance profiles were detected, showing that females induce a significant decrease in microbial alpha diversity through oviposition. In addition, indicator species analysis pinpointed bacterial taxa with significant predicting values and fidelity coefficients for the samples in which single females laid eggs. Furthermore, we provide evidence regarding how one of these indicator taxa, Elizabethkingia, exerts a positive effect on the development and fitness of mosquito larvae. CONCLUSIONS: Ovipositing females impact the composition of the microbial community associated with a breeding site, promoting certain bacterial taxa over those prevailing in the environment. Among these bacteria, we found known mosquito symbionts and showed that they can improve offspring fitness if present in the water where eggs are laid. We deem this oviposition-mediated bacterial community shaping as a form of niche construction initiated by the gravid female.

Triatomines of the Genus Rhodnius Do Not Mark Shelters with Feces.

Aggregation to volatile compounds emitted by feces has been demonstrated for several triatomine species. This signal guides the insects to suitable places that offer physical protection while providing contact with conspecifics. Though the use of aggregation marks has also been reported for Rhodnius spp., it is still unclear whether feces really cause these insects to aggregate inside shelters. In two-choice assays using artificial shelters, we found that refuges associated with a blend of synthetic compounds based on volatiles released by the feces of some triatomine species and reported to be attractive to several species, did not induce shelter choice in Rhodnius prolixus Stål, 1859. In addition, we show that refuges associated with feces of conspecifics did not induce shelter choice in R. prolixus, R. robustus Larrousse, 1927, R. neglectus Lent, 1954, and R. ecuadoriensis Lent and León, 1958. In contrast, as expected, control experiments with Triatoma infestans (Klug, 1834), another triatomine known to aggregate in shelters marked with feces, definitely showed preference for shelters containing feces of conspecifics. Our results clearly show that volatile signals associated with feces do not mediate shelter choice in Rhodnius spp. As a consequence, a paradigm shift will be necessary and, consequently, ab ovo investigations on the clues inducing aggregation behavior in these species.

Temperature and parasite life-history are important modulators of the outcome of Trypanosoma rangeli-Rhodnius prolixus interactions.

Trypanosoma rangeli is a protozoan parasite, which does not cause disease in humans, although it can produce different levels of pathogenicity to triatomines, their invertebrate hosts. We tested whether infection imposed a temperature-dependent cost on triatomine fitness using T. rangeli with different life histories. Parasites cultured only in liver infusion tryptose medium (cultured) and parasites exposed to cyclical passages through mice and triatomines (passaged) were used. We held infected insects at four temperatures between 21 and 30 °C and measured T. rangeli growth in vitro at the same temperatures in parallel. Overall, T. rangeli infection induced negative effects on insect fitness. In the case of cultured infection, parasite effects were temperature-dependent. Intermoult period, mortality rates and ecdysis success were affected in those insects exposed to lower temperatures (21 and 24 °C). For passaged-infected insects, the effects were independent of temperature, intermoult period being prolonged in all infected groups. Trypanosoma rangeli seem to be less tolerant to higher temperatures since cultured-infected insects showed a reduction in the infection rates and passaged-infected insects decreased the salivary gland infection rates in those insects submitted to 30 °C. In vitro growth of T. rangeli was consistent with these results.

Odor-mediated response of gravid Aedes aegypti to mosquito-associated symbiotic bacteria.

Complex oviposition decisions allow gravid Aedes aegypti mosquitoes to select suitable sites for egg-laying to increase the probability that their progeny will thrive. The bacterial communities present in larval niches influence mosquito oviposition behavior, and gravid mosquitoes transmit key microbial associates to breeding sites during oviposition. Our study evaluated whether symbiotic Klebsiella sp., which are strongly associated with mosquitoes, emit volatiles that affect mosquito oviposition decisions. Dual-choice behavioral assays demonstrated that volatile organic compounds emitted by Klebsiella sp. induce a preference in oviposition decisions by Ae. aegypti. Bacterial headspace volatiles were sampled by solid-phase microextraction, and subsequent combined gas chromatography and electroantennogram detection analysis, revealed that the antennae of gravid females detect two compounds present in the Klebsiella sp. headspace. These compounds were identified by gas chromatography and mass spectrometry as 2-ethyl hexanol and 2,4-di­tert-butylphenol. The binary blend of these compounds elicited a dose-dependent egg-laying preference by gravid mosquitoes. We propose that bacterial symbionts, which are associated with gravid mosquitoes and may be transferred to aquatic habitats during egg-laying, together with their volatiles act as oviposition cues indicating the suitability of active breeding sites to conspecific females.

Effects of mating on female reproductive physiology in the insect model, Rhodnius prolixus, a vector of the causative parasite of Chagas disease.

The blood-sucking hemipteran Rhodnius prolixus is one of the main vectors of Chagas disease, a neglected tropical disease that affects several million people worldwide. Consuming a blood meal and mating are events with a high epidemiological impact since after each meal, mated females can lay fertile eggs that result in hundreds of offspring. Thus, a better knowledge of the control of R. prolixus reproductive capacity may provide targets for developing novel strategies to control vector populations, thereby reducing vector-host contacts and disease transmission. Here, we have used a combination of gene transcript expression analysis, biochemical assays, hormone measurements and studies of locomotory activity to investigate how mating influences egg development and egg laying rates in R. prolixus females. The results demonstrate that a blood meal increases egg production capacity and leads to earlier egg laying in mated females compared to virgins. Virgin females, however, have increased survival rate over mated females. Circulating juvenile hormone (JH) and ecdysteroid titers are increased in mated females, a process mainly driven through an upregulation of the transcripts for their biosynthetic enzymes in the corpus allatum and ovaries, respectively. Mated females display weaker locomotory activity compared to virgin females, mainly during the photophase. In essence, this study shows how reproductive output and behaviour are profoundly influenced by mating, highlighting molecular, biochemical, endocrine and behavioral features differentially expressed in mated and virgin R. prolixus females.

Molecular and functional basis of high-salt avoidance in a blood-sucking insect.

Salts are essential nutrients required for many physiological processes, and accordingly, their composition and concentration are tightly regulated. Taste is the ultimate sensory modality involved in resource quality assessment, resulting in acceptance or rejection. Here we found that high salt concentrations elicit feeding avoidance in the blood-sucking bug Rhodnius prolixus and elucidate the molecular and neurophysiological mechanisms involved. We found that high-salt avoidance is mediated by a salt-sensitive antennal gustatory receptor neuron (GRN). Using RNAi, we demonstrate that this process requires two amiloride-sensitive pickpocket channels (PPKs; Rpro PPK014276 and Rpro PPK28) expressed within these cells. We found that antennal GRNs project to the insect primary olfactory center, the antennal lobes, revealing these centers as potential sites for the integration of taste and olfactory host-derived cues. Moreover, the identification of the gustatory basis of high-salt detection in a hematophagous insect suggests novel targets for the prevention of biting and feeding.

Triggering the proboscis extension reflex (PER) in Rhodnius prolixus.

The heat emitted by the host body constitutes a short distance orientation cue for most blood-sucking insects, as is the case of the kissing-bug Rhodnius prolixus. We evaluated here how kissing bugs assess the distance to a warm target, in order to reach it by displaying the Proboscis Extension Reflex (PER). We confronted blind-folded insects to a thermal source either at 35° or at 40 °C under both, open- and closed-loop conditions. The results showed that nymphs were able to estimate the distance to a thermal source just using thermal information. Free walking insects displayed PER with a maximum frequency at 5 mm from the object, even without touching it. Yet, our experiments showed that the insects need to walk freely to estimate the distance to the source accurately, i.e. performing the PER at a distance allowing them to reach the target with the tip of the proboscis. The distance at which PER was triggered was independent of the temperature of the thermal source (35° or 40 °C). Moreover, our results also unravelled that mechanical stimuli can be integrated with thermal cues, being capable of affecting the triggering of PER in kissing bugs. This is the first study providing evidence that blood-sucking vector insects use mechanoreception for eliciting their bites. We discuss our findings in the light of present models explaining the ability of kissing bugs to estimate the distance and the temperature of a potential food sources.

Multi-Omic Analysis of Symbiotic Bacteria Associated With Aedes aegypti Breeding Sites.

Mosquito breeding sites are complex aquatic environments with wide microbial diversity and physicochemical parameters that can change over time during the development of immature insect stages. Changes in biotic and abiotic conditions in water can alter life-history traits of adult mosquitos but this area remains understudied. Here, using microbial genomic and metabolomics analyses, we explored the metabolites associated with Aedes aegypti breeding sites as well as the potential contribution of Klebsiella sp., symbiotic bacteria highly associated with mosquitoes. We sought to address whether breeding sites have a signature metabolic profile and understand the metabolite contribution of the bacteria in the aquatic niches where Ae. aegypti larvae develop. An analysis of 32 mosquito-associated bacterial genomes, including Klebsiella, allowed us to identify gene clusters involved in primary metabolic pathways. From them, we inferred metabolites that could impact larval development (e.g., spermidine), as well as influence the quality assessment of a breeding site by a gravid female (e.g., putrescine), if produced by bacteria in the water. We also detected significant variance in metabolite presence profiles between water samples representing a decoupled oviposition event (oviposition by single females and manually deposited eggs) versus a control where no mosquito interactions occurred (PERMANOVA: p < 0.05; R 2 = 24.64% and R 2 = 30.07%). Five Klebsiella metabolites were exclusively linked to water samples where oviposition and development occurred. These data suggest metabolomics can be applied to identify compounds potentially used by female Ae. aegypti to evaluate the quality of a breeding site. Elucidating the physiological mechanisms by which the females could integrate these sensory cues while ovipositing constitutes a growing field of interest, which could benefit from a more depurated list of candidate molecules.

Flight initiation by male Rhodnius prolixus is promoted by female odors.

Several triatomine bug species utilize chemical cues for sexual communication. We tested whether female or male Rhodnius prolixus, a vector of Chagas disease, produce volatile chemicals that elicit flight responses from conspecifics, and then isolated the source of the chemical. Males confronted with an airstream containing female odors showed a significantly greater take-off frequency compared to a blank airstream or an airstream with male odors. In contrast, females exhibited similar take-off frequencies to male or female odor as to a clean airstream. Occlusion of female metasternal glands with paraffin wax resulted in a significant decrease in male take-off frequency compared to that of intact females. Additionally, excised female metasternal glands elicited a similar take-off frequency from males as did intact females, both significantly greater than the take-off frequency to clean air. These results show that R. prolixus females release a pheromone from their metasternal glands that causes upwind flight in conspecific males.

A standardizable protocol for infection of Rhodnius prolixus with Trypanosoma rangeli, which mimics natural infections and reveals physiological effects of infection upon the insect.

Trypanosoma rangeli is a protozoan parasite that shares hosts - mammals and triatomines - with Trypanosoma cruzi, the etiological agent of Chagas disease. Although T. rangeli is customarily considered to be non-pathogenic to human hosts, it is able to produce pathologies in its invertebrate hosts. However, advances are hindered by a lack of standardization of infection procedures and these pathologies need documentation. To establish a suitable, and standardizable, infection protocol, the duration of the fourth instar was evaluated in nymphs infected by injection into the thorax with different concentrations of parasites, and compared with nymphs infected naturally (i.e. orally). We demonstrate that delays in moult were attributable to the presence of the parasite in the haemolymph (vs. the gut) and propose that the protocol presented here simulates closely natural infections. This methodology was then used for the evaluation of physiological parameters and several hitherto unreported effects of T. rangeli infection on Rhodnius prolixus were revealed. Haemolymph volume was greater in infected than uninfected nymphs but this alteration could not be attributed to water retention, since infected insects lost the same amount of water as controls. However, we found that lipid content and fat body weight were both increased in insects infected by T. rangeli. We propose that this is due to the parasite's sequestration of host blood lipids and carrier proteins. With these findings, we have taken a few first steps to unravelling physiological details of the host-parasite interaction. We suggest future directions towards a fuller understanding of mechanistic and adaptive aspects of triatomine-trypanosomatid interactions.

Species-specific patterns of shelter exploitation in Chagas disease vectors of the genus Rhodnius.

Triatomines are insect vectors of Trypanosoma cruzi¸ the etiological agent of Chagas disease. Several species belonging to the genus Rhodnius (Hemiptera: Reduviidae) have been reported inhabiting domestic and peridomestic environments in different regions of Latin America. However, behavioral and sensory ecology aspects related to their use of shelters have been poorly studied. The objective of the present study was to characterize how bug density, illumination and thigmotactic information affect the use of shelters by three species belonging to the Rhodnius prolixus species complex. We evaluated whether exposure to different insect densities affects the proportion of R. prolixus, Rhodnius robustus and Rhodnius neglectus that choose to stay inside a refuge. Besides, we evaluated whether absence of an illumination regime affects their tendency to hide in shelters. Our results showed that the proportion of individuals that remained outside the shelter increased with rising insect densities. Nevertheless, while R. prolixus only reacted by augmenting this proportion with the highest density tested, the other species showed significant increases already at lower densities. On the other hand, a significantly higher number of R. robustus stayed outside the shelter in the absence of a light cycle, while no change was induced for the other species. Thus, this study determined species-specific profiles of refuge exploitation defined by factors such as thigmotaxis and negative phototaxis. The differences observed among these Rhodnius species may impact their house colonization abilities, which seem to be critically affected by bug hiding performance during health service detection processes.

Mechanism and plasticity of vectors' host-seeking behavior.

The host-seeking behavior of disease vector insects is central to the transmission of pathogens. In this context, an improved understanding of the mechanisms that allow vectors to detect, identify and locate a potential host will be crucial to refine existing control strategies and invent new ones. Host-seeking is mediated by the integration of cues that are processed by multiple sensory modalities, and provide robust information about host location and quality. Responses to these cues are plastic and vary as a function of the vector's internal state, age, and previous experience. Vectors also integrate other factors such as time of day, or even the level of defensiveness of the host. Here, we review the most recent advances on the molecular basis of host-seeking behavior, with a particular emphasis on disease vector mosquitoes.

Dengue infection modulates locomotion and host seeking in Aedes aegypti.

Pathogens may manipulate their human and mosquito hosts to enhance disease transmission. Dengue, caused by four viral serotypes, is the fastest-growing transmissible disease globally resulting in 50-100 million infections annually. Transmission of the disease relies on the interaction between humans and the vector Aedes aegypti and is largely dependent on the odor-mediated host seeking of female mosquitoes. In this study, we use activity monitors to demonstrate that dengue virus-1 affects the locomotion and odor-mediated behavior of Ae. aegypti, reflecting the progression of infection within the mosquito. Mosquitoes 4-6 days post-infection increase locomotion, but do not alter their odor-driven host-seeking response. In contrast, females 14-16 days post-infection are less active, yet more sensitive to human odors as assessed by behavioral and electrophysiological assays. Such an increase in physiological and behavioral sensitivity is reflected by the antennal-specific increase in abundance of neural signaling transcripts in 14 days post-infection females, as determined by transcriptome analysis. This suggests that the sensitivity of the mosquito peripheral olfactory system is altered by the dengue virus by enhancing the overall neural responsiveness of the antenna, rather than the selective regulation of chemosensory-related genes. Our study reveals that dengue virus-1 enhances vector-related behaviors in the early stages post-infection that aid in avoiding predation and increasing spatial exploration. On the other hand, at the later stages of infection, the virus enhances the host-seeking capacity of the vector, thereby increasing the risk of virus transmission. A potential mechanism is discussed.

Behavioral and electrophysiological responses of Triatoma brasiliensis males to volatiles produced in the metasternal glands of females.

In many insects, mate finding is mediated by volatile sex pheromones, but evidence for this phenomenon in triatomines (Heteroptera: Reduviidae) is still fragmentary. Recently, it was shown that metasternal glands (MGs) are involved in producing signals related to the sexual communication of Triatoma infestans and Rhodnius prolixus. Based on this, we tested whether MG volatiles could be involved in the sexual communication of Triatoma brasiliensis. Odor-mediated orientation responses were studied by using a T-tube olfactometer. These tests showed that males exhibit positive anemotaxis when confronted with adult odor-laden air currents. Moreover, females that had their metasternal glands occluded did not elicit significant orientation by males. Compounds produced by the MGs of T. brasiliensis females were identified by means of SPME, GC-FID, and GC-MS, with achiral and chiral columns. All substances identified were ketones and alcohols, and similar compound profiles were found in the secretions produced by both sexes. The most abundant compounds identified were 3-pentanone, followed by (4R)-methyl-1-heptanol, 3-pentanol, and (2S)-methyl-1-butanol. In addition, GC-EAD recordings showed that the antennae of males responded to several of the main components of female MG secretions. Our results showed that compounds produced by the MGs of T. brasiliensis females are involved in the sexual communication of this species.

Copulation and mate guarding behavior in Triatoma brasiliensis (Hemiptera: Reduviidae).

The hematophagous bug Triatoma brasiliensis (Neiva) is an important vector of Chagas disease in Brazil. We describe the mating behavior of this species in a comparative manner and analyze the effect of time elapsed since the first imaginal bloodmeal on motivation of males to mate, on female mate-rejections, and on overall mating frequency. We also evaluate whether females of this species copulate with several males in short time intervals, and we examine whether the duration of copulation may vary in the presence of other males compared with what is observed with isolated pairs. Age affected the motivation of males to perform mating attempts, whereas nutritional status affected the receptivity of females. Results showed that 70% of the females tested accepted copulating with three males over a period of 90 min, whereas the remaining 30% mated with at least two males. Mating duration in T. brasiliensis was prolonged in the presence of other males compared with observations of isolated pairs, and males of this species performed long postcopulatory associations only in the presence of other males, apparently as a mate guarding response to the presence of potential competitors.

Exploiting triatomine behaviour: alternative perspectives for their control.

Living in close association with a vertebrate host and feeding on its blood requires different types of adaptations, including behavioural adjustments. Triatomines exhibit particular traits associated with the exploitation of their habitat and food sources and these traits have been the subject of intense analysis. Many aspects of triatomine behaviour have been relatively well characterised and some attempts to exploit the behaviours have been undertaken. Baited traps based on host-associated cues, artificial refuges and light-traps are some of the tools used. Here we discuss how our knowledge of the biology of Chagas disease vectors may help us sample and detect these insects and even increase the efficiency of control measures.

Molecular bases of sensory processes in kissing bugs, vectors of Chagas disease.

Sensory processes represent an information gathering interface between animals and their surrounding world. Therefore, they serve to scan the environment for resources and threats. The behavior of kissing bugs has been studied to aid their control because they transmit Chagas disease to humans. Besides, a few triatomines represent important insect models since Wigglesworth times. These hematophagous insects rely on different sensory systems to scan their environment for blood-sources, mating partners, and hiding places. The study of the molecular bases of sensory processes has undergone a dramatic progress due the advent of new technologies allowing mass-sequencing of genes. Here, we focus on reviewing the fundamental knowledge gathered to date about the molecular bases of kissing bug sensory processes.

Attraction of Rhodnius prolixus males to a synthetic female-pheromone blend.

BACKGROUND: The triatomine bug Rhodnius prolixus Stål, 1859 (Heteroptera: Reduviidae) is the primary vector of Chagas disease in Colombia and Venezuela. An important step in controlling Chagas disease is monitoring the growth and spread of bug populations to inform effective management. Such monitoring could be carried out using pheromone traps. To develop effective pheromone traps, it is vital to understand the pheromone chemistry of R. prolixus. Previous studies have found that female R. prolixus metasternal gland secretions induce males to: leave shelters, take off, orientate during walking, aggregate around mating pairs, and mate. This study aims to identify a synthetic blend of female metasternal gland compounds that could be used to attract R. prolixus. RESULTS: We investigated the electrophysiological activity of the ten most abundant compounds in female R. prolixus metasternal glands using single sensillum recordings. In total we obtained 60 recordings from basiconic sensilla in male R. prolixus. In 31 of these recordings, responses to individual compounds were observed. Each of the ten tested compounds elicited neuron responses in a minimum of eight recordings. Having confirmed their electrophysiological activity, we tested these ten compounds by presenting them to male Rhodnius prolixus in a "T" olfactometer. Male bugs showed a significant preference for the blend of metasternal gland compounds compared to the clean air control. CONCLUSIONS: A simple blend of ten compounds found in female R. prolixus metasternal glands is attractive to conspecific males. All compounds in the blend are either commercially available at low cost, or easily synthetically prepared from simple precursors. We hope that this blend will be evaluated as a lure for pheromone traps in field bioassays.

Flight dispersal of the Chagas disease vectors Triatoma brasiliensis and Triatoma pseudomaculata in northeastern Brazil.

The present paper reports for the first time the capture of wild Triatoma brasiliensis and Triatoma pseudomaculata by means of light traps in Brazil. We tested commercially available lighting devices powered by batteries to attract the bugs to a white piece of cloth in the field. Two main findings showed to be significant: first, the results presented here show that light traps can be used for sampling these species in wild environments; second, they reveal that house colonization by triatomines may also happen as a consequence of the arrival of flying sylvatic bugs guided by artificial light sources. In addition, we discuss the effect of some environmental and biological factors on triatomine flight activity modulation.