The influence of larval density on triacylglycerol content in Aedes aegypti (Linnaeus) (Diptera: Culicidae).

Given the importance of Aedes aegypti as an arbovirus vector, understanding the impact of population density during larval development is fundamental to improve control methods. The aims of this study were to analyze the effects of larval density on the triacylglycerol (TAG) reserves, fecundity, and the size of mosquitos. To evaluate the influence of density on the amount of TAG in the different stages of development of A. aegypti, the larvae were reared in densities of 0.04, 0.32, and 0.8 larvae/ml, represented by D1, D2, and D3, respectively. Larval rearing density affected the amount of TAG in the different developmental stages of this insect. The group reared with the highest population density (D3) presented greater storage of TAG, except when analyzing the amount of TAG µg/protein in the fat body of blood-fed females. In addition, it was possible to observe higher resistance to fasting and a greater number of eggs laid. Insects reared in D2 and D3 were larger than those in the D1 group. This study provides interesting data for future investigations on how the density of larval rearing affects the lipid metabolism for synthesis and mobilization of TAG stored in A. aegypti and how it influences size and reproduction.

Drivers of molecular and morphometric variation in Triatoma brasiliensis (Hemiptera: Triatominae): the resolution of geometric morphometrics for populational structuring on a microgeographical scale.

BACKGROUND: The protozoan Trypanosoma cruzi circulates in semiarid areas of northeastern Brazil in distinct ecotopes (sylvatic, peridomestic and domestic) where Triatoma brasiliensis Neiva, 1911 is the most important Chagas disease vector. In this study, we analyzed microevolutionary and demographic aspects of T. brasiliensis populations at the ecotypic, micro and macro-geographic scales by combining morphometrics and molecular results. Additionally, we aimed to address the resolution of both markers for delimiting populations in distinct scales. METHODS: We sampled populations of T. brasiliensis from distinct ecotypic and geographic sites in the states Rio Grande do Norte (RN) and Paraíba (PB). The geometric morphometry was carried out with 13 landmarks on the right wings (n = 698) and the genetic structure was assessed by sequencing a region of cytochrome b mitochondrial gene (n = 221). Mahalanobis distance (MD) and coefficient of molecular differentiation (ΦST) were calculated among all pairs of populations. The results of comparisons generated MD and ΦST dendrograms, and graphics of canonical variate analysis (CVA). RESULTS: Little structure was observed for both markers for macro-geographic scales. Mantel tests comparing geographic, morphometric and genetic matrices showed low correlation (all R2 < 0.35). The factorial graphics built with the CVA evidenced population delimitation for the morphometric data at micro-geographic scales. CONCLUSIONS: We believe that T. brasiliensis carries in its genotype a source of information to allow the phenotypical plasticity across its whole distribution for shaping populations, which may have caused a lack of population delimitation for CVAs in morphometric analysis for macro-geographic scale analysis. On the other hand, the pattern of morphometric results in micro-geographic scales showed well-defined groups, highlighting the potential of this tool to inferences on the source for infestation.

Inferences about antennal phenotype: the "Triatoma maculata complex" (Hemiptera: Triatominae) is valid?

The "Triatoma maculata complex" is presently formed by two epidemiologically important species of Triatominae, Triatoma maculata and Triatoma pseudomaculata, which share morphologic and chromatic characteristics. In order to clarify the systematic status and infer the evolutionary relationships of these vectors of Chagas disease, we performed a comparative analysis of their antennal phenotype, taking also into account Triatoma wygodzinskyi, a possible sister species. The comparison was based on sensilla arrays on the three distal segments of the antenna. Our results show a close similarity between T. pseudomaculata and T. wygodzinskyi antennal phenotypes, and significant differences with T. maculata. The inter-population study reinforces the idea that T. pseudomaculata (arboricolous species) and T. wygodzinskyi (rupicolous species) would originate from a common ancestor.

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.

Some considerations about the ecology of Triatominae.

Observations on the ecology of silvatic Triatominae are still fragmentary, principally because target species in control process are almost exclusively domestic. Report of silvatic species invading human dwellings must lead research to be focused on their original ecology, in order to assist in understanding their process of domestication and devising strategies for surveillance.

Some considerations about the ecology of Triatominae

As informações sobre a ecologia de Triatominae silvestres são ainda incompletas, sobretudo porque as espécies mais importantes, alvos dos programas de controle, são exclusivamente domésticas. Registros de espécies silvestres invadindo as habitações humanas devem ser investigados para ampliação do conhecimento de sua ecologia no ambiente natural, de modo que se possa compreender melhor o processo de domiciliação e se criar novas estratégias para vigilância.