A expressão "doenças tropicais negligenciadas" (NTDs) representa uma série de doenças que afetam a população de países de baixa renda, sendo insetos vetores os responsáveis pela transmissão de grande parte dessas doenças. Ferramentas de controle são necessárias para impedir o contato entre humanos e insetos vetores destas doenças. Este controle é comumente realizado pelo uso intensivo de inseticidas, porém, resistência a estes xenobióticos ocorre nos casos mais relevantes de espécies de vetores de doenças. Portanto, metodologias alternativas para o controle de vetores são urgentemente necessárias para evitar a transmissão da maioria das NTDs. Nesta revisão, uma série de compostos químicos que podem auxiliar no desenvolvimento de ferramentas de controle desses vetores, as quais se baseiam na manipulação do comportamento dos insetos associado à estas moléculas, são descritas. Tais relações incluem os odores de hospedeiros usados por artrópodes na busca de fontes de sangue, assim como feromônios utilizados por estes em diversos contextos como, por exemplo, na reprodução. Adicionalmente, são apresentados caminhos recentemente explorados na busca de compostos capazes de modificar comportamentos através de metodologias de alto rendimento. Especificamente, são mostrados exemplos de como estas metodologias mediam a busca por novos repelentes e atrativos.

The expression "neglected tropical diseases" (NTDs) represents a series of illnesses that affect the population of low-income countries, being vector insects responsible for the transmission of a large part of these diseases. Control tools are needed to impede contacts between humans and insects vectoring some of them. This control is currently attained by intensive insecticide use but resistance to such xenobiotics exists in the most relevant disease vector species. Therefore, alternative vector control methodologies are urgently needed to avoid most NTD transmission. The present review describes a series of molecules that could assist on developing vector control tools, which could be based on manipulating insect behaviors associated with them. Such relations include host odors used by arthropods to search for blood sources, as well as pheromones used by them to communicate in diverse contexts, e.g., reproduction. Additionally, avenues recently explored in the search of behavior modifying compounds by means of high throughput methodologies are discussed. Specifically, examples of how such methodologies mediate the search for new repellents and attractants are described.

Many arthropod species have adopted vertebrate blood as their main food source. Blood is rich in nutrients and, except for the presence of parasites, sterile. However, this food source is not freely available, nor is obtaining it devoid of risk. It circulates inside vessels hidden underneath the skin of mobile hosts that are able to defend themselves and even predate the insects that try to feed on them. Thus, the haematophagous lifestyle is associated with major morphological, physiological and behavioural adaptations that have accumulated throughout the evolutionary history of the various lineages of blood-sucking arthropods. These adaptations have significant consequences for the evolution of parasites as well as for the epidemiology of vector-transmitted diseases. In this review article, we analyse various aspects of the behaviour of triatomine bugs to illustrate how each behavioural trait represents a particular adaptation to their close association with their hosts, which may easily turn into predators. Our aim is to offer to the reader an up-to-date integrative perspective on the behaviour of Chagas disease vectors and to propose new research avenues to encourage both young and experienced colleagues to explore this aspect of triatomine biology.

Triatomines have been important model organisms for behavioural research. Diverse reports about triatomine host search, pheromone communication in the sexual, shelter and alarm contexts, daily cycles of activity, refuge choice and behavioural plasticity have been published in the last two decades. In recent times, a variety of molecular genetics techniques has allowed researchers to investigate elaborate and complex questions about the genetic bases of the physiology of insects. This, together with the current characterisation of the genome sequence of Rhodnius prolixus allows the resurgence of this excellent insect physiology model in the omics era. In the present revision, we suggest that studying the molecular basis of behaviour and sensory ecology in triatomines will promote a deeper understanding of fundamental aspects of insect and, particularly, vector biology. This will allow uncovering unknown features of essential insect physiology questions for a hemimetabolous model organism, promoting more robust comparative studies of insect sensory function and cognition.

Despite the relevant achievements in the control of the main Chagas disease vectors Triatoma infestans and Rhodnius prolixus, several factors still promote the risk of infection. The disease is a real threat to the poor rural regions of several countries in Latin America. The current situation in Brazil requires renewed attention due to its high diversity of triatomine species and to the rapid and drastic environmental changes that are occurring. Using the biology, behaviour and diversity of triatomines as a basis for new strategies for monitoring and controlling the vectorial transmission are discussed here. The importance of ongoing long-term monitoring activities for house infestations by T. infestans, Triatoma brasiliensis, Panstrongylus megistus, Triatoma rubrovaria and R. prolixus is also stressed, as well as understanding the invasion by sylvatic species. Moreover, the insecticide resistance is analysed. Strong efforts to sustain and improve surveillance procedures are crucial, especially when the vectorial transmission is considered interrupted in many endemic areas.

Living in close association with a vertebrate host and feeding on its blood requires different types of adaptations, including behavioural adjustements. 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.

We tested the attraction of Triatoma dimidiata and T. pallidipennis to traps baited with yeast volatiles. Two traps were simultaneously presented in opposite sides of an experimental arena. One trap presented a yeast culture in sucrose solution, while the other contained sucrose solution as control. A first experimental series was done without offering a central refuge for bugs. In a second series, one shelter where the insects could hide was offered and the traps were presented afterwards. In the first series, yeast baited traps attracted significantly more insects than control ones for both species. In the second series, T. pallidipennis was significantly attracted to yeast, whereas T. dimidiata was not attracted. The potential use of yeast baited traps for capturing these vectors of Chagas disease is discussed.

The factors affecting the sexual behaviour of Panstrongylus megistus were studied under laboratory conditions. A general description of mating behaviour is presented for this species. The effect of the time elapsed after the first imaginal feeding on the mating frequency, the motivation of males to mate and the rejection behaviour by females, were analyzed. We also determined the number of copulas accepted by females of this species. Finally, the possible existence of a sexual chemical signal promoting male aggregation around mating couples was evaluated. Results showed that mating frequency increased with the time elapsed since the first adult meal. Despite the number of male copulatory attempts did not change as a function of time, the rejection behaviour of females became gradually less frequent. Females rejected mating by means of body flattening on the substrate, abdominal movements, evasion or stridulation. After a single copula, females did not usually accept to mate again. Neither male nor female aggregation around mating couples was observed, suggesting the absence of a sexual assembling pheromone in P. megistus.

The behavioural response of Triatoma pseudomaculata to chemical substances present in their faeces or cuticle (footprints) was analyzed. Groups of larvae were simultaneously exposed to a clean filter paper and to another paper impregnated with a chemical stimulus in a circular arena. In these choice experiments, the insects aggregated significantly around papers impregnated with dry faeces. In addition, the bugs also showed a significant aggregation response to papers impregnated with compounds derived from their cuticle that were deposited by contact on the substrate. These results indicate that chemical compounds that affect the behaviour of T. pseudomaculata are present in the faeces and in the cuticle of this species. Results are discussed in relation to chemical communication in the Triatominae, as well as to the potential use of these substances in traps or sensors for the detection of this species.

Vector-borne transmission of Chagas disease in Northeast Brazil is basically by Triatoma brasiliensis. It is thus crucial to determine this species' microclimatic preferences as limiting factors for its distribution and ability to infest domestic environments. We analyze the microclimatic properties of the shelters in which these insects are found in wild, domestic, and peridomiciliary environments in the State of Ceará, at Brazil. We measure temperature and relative humidity (RH) every 15 minutes for 3 days. Thermal variation was greatly dampened inside both domiciliary refuges and the more protected internal places in wild stony sites. For RH, we observed a similar dampening pattern, but mean RH was lower in both domiciliary refuges and wild ones inside stony sites as compared to reference levels in the surrounding environment. The results are discussed with regard to this species' microclimatic preferences in the laboratory and its potential as determinants of its geographical distribution.

Triatoma brasiliensis es el principal vector de la enfermedad de Chagas en la región nordeste de Brasil. En este sentido, resulta fundamental conocer las preferencias microclimáticas de esta especie como condicionantes de su distribución y capacidad de infestación de domicilios. En el presente trabajo se analisan las características microclimáticas de los refugios en que este insecto es hallado, tanto en sitios silvestres como domiciliarios y peridomiciliarios del Estado de Ceará, Brasil. Se realizaron medidas de temperatura y humedad relativa (HR) cada 15 minutos, durante un periodo de 3 días. La variación de temperatura se halla fuertemente amortiguada en el interior de los refugios domiciliarios, así como en los sitios más protegidos dentro de los pedregales silvestres. En relación con la HR, se pudo observar un patrón de amortiguación semejante, sin embargo, la HR media fue inferior tanto en el interior de refugios intradomiciliarios como en aquellos silvestres entre montículos de piedras, en comparación con los valores registrados como referencia en el ambiente. Los resultados son discutidos en relación con las preferencias microclimáticas de esta especie observadas en el laboratorio y con la posible importancia de éstas como determinantes de su distribución geográfica.

Vector-borne transmission of Chagas disease in Northeast Brazil is basically by Triatoma brasiliensis. It is thus crucial to determine this species' microclimatic preferences as limiting factors for its distribution and ability to infest domestic environments. We analyze the microclimatic properties of the shelters in which these insects are found in wild, domestic, and peridomiciliary environments in the State of Ceará, at Brazil. We measure temperature and relative humidity (RH) every 15 minutes for 3 days. Thermal variation was greatly dampened inside both domiciliary refuges and the more protected internal places in wild stony sites. For RH, we observed a similar dampening pattern, but mean RH was lower in both domiciliary refuges and wild ones inside stony sites as compared to reference levels in the surrounding environment. The results are discussed with regard to this species' microclimatic preferences in the laboratory and its potential as determinants of its geographical distribution.

Triatoma brasiliensis es el principal vector de la enfermedad de Chagas en la región nordeste de Brasil. En este sentido, resulta fundamental conocer las preferencias microclimáticas de esta especie como condicionantes de su distribución y capacidad de infestación de domicilios. En el presente trabajo se analisan las características microclimáticas de los refugios en que este insecto es hallado, tanto en sitios silvestres como domiciliarios y peridomiciliarios del Estado de Ceará, Brasil. Se realizaron medidas de temperatura y humedad relativa (HR) cada 15 minutos, durante un periodo de 3 días. La variación de temperatura se halla fuertemente amortiguada en el interior de los refugios domiciliarios, así como en los sitios más protegidos dentro de los pedregales silvestres. En relación con la HR, se pudo observar un patrón de amortiguación semejante, sin embargo, la HR media fue inferior tanto en el interior de refugios intradomiciliarios como en aquellos silvestres entre montículos de piedras, en comparación con los valores registrados como referencia en el ambiente. Los resultados son discutidos en relación con las preferencias microclimáticas de esta especie observadas en el laboratorio y con la posible importancia de éstas como determinantes de su distribución geográfica.