Convergent evolution of intraguild predation in phytotelm-inhabiting mosquitoes

Urbanization and Water Containers Influence the Mosquito Community with Consequences for Aedes aegypti

We aimed to determine how the degree of urbanization in a Neotropical city influences Aedes aegypti (L.), a pantropical vector of urban yellow fever, dengue, Zika and Chikungunia, via other mosquito species, whether they are competitors or predators, native to the area or invasive. We conducted experiments twice a month during one year in the city of Kourou, French Guiana, on three sites characterized by increasing percentages of imperviousness (i.e., 0.65%, 33.80% and 86.60%). These sites were located in a ≈5 ha forest fragment, a residential area with gardens, and in the older part of the city, respectively, and correspond to slightly, moderately and highly urbanized sites. There, we monitored twice a month during one year a total of 108 mosquito communities inhabiting four types of containers (i.e., a tank bromeliad, dry stumps of bamboo, ovitraps and car tires) installed in a random block design. In the tanks of the bromeliad, likely due to the acidity of the water, the immatures of native mosquito species prevailed, particularly Wyeomyia pertinans (Williston) in the slightly urbanized site. The general pattern was very similar in the three other types of containers where Limatus durhamii Théobald dominated in the slightly urbanized site, so that the abundance of Ae. aegypti immatures was low compared to those of native species. Yet, Ae. aegypti strongly dominated in the two more urbanized sites. These findings open up perspectives for vector management, including the conservation and/or the augmentation of natural enemies through modifications to landscape features.

Mosquitoes (Diptera: Culicidae) of the Amazonian savannas of French Guiana with a description of two new species

Amazonian savannas are among the most noteworthy landscape components of the coastal plain of French Guiana. Although they cover only 0.22% of the territory, they bring together a large part of the animal and plant diversity of this overseas region of France. This article outlines the results of the first study dedicated to mosquitoes (Diptera: Culicidae) of Amazonian savannas. Samplings were conducted in eight independent savannas evenly distributed along a transect of 170 km on the coastal plain of French Guiana. A total of 50 mosquito species were recorded, which is about 20% of the culicid fauna currently known in French Guiana. Among them, Culex (Melanoconion) organaboensis sp. nov. and Cx. (Mel.) zabanicus sp. nov. are newly described based on both morphological features of the male genitalia and a DNA barcode obtained from type specimens. Diagnostic characters to assist their identification are provided and their placement within the infrasubgeneric classification of the subgenus Melanoconion is discussed.

Mosquitoes Eating Mosquitoes: How Toxorhynchites amboinensis, Psorophora ciliata, and Sabethes cyaneus (Diptera: Culicidae) Capture Prey

High-speed microcinematography was used to elucidate the details of prey capture by the larvae of three predatory mosquito species. The obligate predators Toxorhynchites amboinensis and Psorophora ciliata exhibited a high degree of convergence as both utilize three essential elements: 1) abdominally-generated hemostatic pressure to propel the head towards the prey; 2) lateral palatal brushes (LPB) opening and fanning into anterior-directed basket-like arrangements; 3) simultaneously with the LPB-basket formation, the wide opening of sharp-toothed mandibles. Thus, LPBs and mandibles are used for prey capture by both species. The facultative predator Sabethes cyaneus utilizes a vastly different prey-capture mechanism that involves ventro-lateral body arching and scooping of prey with axially pointed siphons into the grasp of open maxillae bearing elongate apical teeth. Prey consumption, which is typically incomplete in this species, then involves the action of teeth on the mandibles which cut into the held prey. Although prey consumption is incomplete, simple experiments show that Sa. cyaneus do gain nutritionally from consuming mosquito larvae and that they do discriminate heterospecific from conspecific larvae and actively approach heterospecific mosquito prey. These findings indicate that independent evolutionary pathways have produced diverse predatory behaviors and morphologies in aquatic environments where the immature stages of mosquitoes co-occur.

A new species of Wyeomyia (Diptera: Culicidae) from Heliconia flower bracts in northern South America

A new species of the genus Wyeomyia, Wyeomyia (Decamyia) anthica sp. n., is described based on morphological and molecular analyses and is illustrated in larval, pupal and adult life stages. Among the four valid species of the subgenus Decamyia, the new species is closest to Wy. ulocoma (Theobald, 1903), from which it can be distinguished by morphological characters of the male genitalia, larval and pupal stages, and mitochondrial cytochrome c oxidase 1 gene sequence. Wyeomyia ulocoma is recorded from Brazil for the first time.

Larval interference competition between the native Neotropical mosquito Limatus durhamii and the invasive Aedes aegypti improves the fitness of both species

Interspecific competition with native species during biological invasions can sometimes limit alien expansion. We aimed to determine the potential ecological effects of Limatus durhamii Theobald 1901, a native Neotropical mosquito (Diptera: Culicidae) species, on the invasive species Aedes (Stegomyia) aegypti (Linnaeus 1762) that breeds in the same artificial water containers. Development time and adult dry mass were measured in 3 rearing conditions: control (a single larva), intraspecific competition (2 conspecific larvae), and interspecific competition (2 heterospecific larvae). Food was provided ad libitum to eliminate exploitative competition. For Ae. aegypti, development time was not affected by interspecific interference competition (nonsignificant differences with the control) and the adult dry mass was significantly higher, meaning that individual fitness likely increased. Yet, because previous studies showed longer development time and lighter adults during competition with other invasive mosquitoes, it is likely that Ae. aegypti can express a different phenotype depending on the competing species. The similar pattern found for Li. durhamii females and the nonsignificant difference with the control for males explain in part why this species can compete with Ae. aegypti.

Ants impact the composition of the aquatic macroinvertebrate communities of a myrmecophytic tank bromeliad

In an inundated Mexican forest, 89 out of 92 myrmecophytic tank bromeliads (Aechmea bracteata) housed an associated ant colony: 13 sheltered Azteca serica, 43 Dolichoderus bispinosus, and 33 Neoponera villosa. Ant presence has a positive impact on the diversity of the aquatic macroinvertebrate communities (n=30 bromeliads studied). A Principal Component Analysis (PCA) showed that the presence and the species of ant are not correlated to bromeliad size, quantity of water, number of wells, filtered organic matter or incident radiation. The PCA and a generalized linear model showed that the presence of Azteca serica differed from the presence of the other two ant species or no ants in its effects on the aquatic invertebrate community (more predators). Therefore, both ant presence and species of ant affect the composition of the aquatic macroinvertebrate communities in the tanks of A. bracteata, likely due to ant deposition of feces and other waste in these tanks.

Aquatic life in Neotropical rainforest canopies: Techniques using artificial phytotelmata to study the invertebrate communities inhabiting therein

In Neotropical rainforest canopies, phytotelmata ("plant-held waters") shelter diverse aquatic macroinvertebrate communities, including vectors of animal diseases. Studying these communities is difficult because phytotelmata are widely dispersed, hard to find from the ground and often inaccessible. We propose here a method for placing in tree crowns "artificial phytotelmata" whose size and shape can be tailored to different research targets. The efficacy of this method was shown while comparing the patterns of community diversity of three forest formations. We noted a difference between a riparian forest and a rainforest, whereas trees alongside a dirt road cutting through that rainforest corresponded to a subset of the latter. Because rarefied species richness was significantly lower when the phytotelmata were left for three weeks rather than for six or nine weeks, we recommend leaving the phytotelmata for twelve weeks to permit predators and phoretic species to fully establish themselves.

DNA reference libraries of French Guianese mosquitoes for barcoding and metabarcoding

The mosquito family (Diptera: Culicidae) constitutes the most medically important group of arthropods because certain species are vectors of human pathogens. In some parts of the world, the diversity is so high that the accurate delimitation and/or identification of species is challenging. A DNA-based identification system for all animals has been proposed, the so-called DNA barcoding approach. In this study, our objectives were (i) to establish DNA barcode libraries for the mosquitoes of French Guiana based on the COI and the 16S markers, (ii) to compare distance-based and tree-based methods of species delimitation to traditional taxonomy, and (iii) to evaluate the accuracy of each marker in identifying specimens. A total of 266 specimens belonging to 75 morphologically identified species or morphospecies were analyzed allowing us to delimit 86 DNA clusters with only 21 of them already present in the BOLD database. We thus provide a substantial contribution to the global mosquito barcoding initiative. Our results confirm that DNA barcodes can be successfully used to delimit and identify mosquito species with only a few cases where the marker could not distinguish closely related species. Our results also validate the presence of new species identified based on morphology, plus potential cases of cryptic species. We found that both COI and 16S markers performed very well, with successful identifications at the species level of up to 98% for COI and 97% for 16S when compared to traditional taxonomy. This shows great potential for the use of metabarcoding for vector monitoring and eco-epidemiological studies.