Mosquito (Diptera: Culicidae) assemblages associated with Nidularium and Vriesea bromeliads in Serra do Mar, Atlantic Forest, Brazil

Abstract

Background: The most substantial and best preserved area of Atlantic Forest is within the biogeographical sub-region of Serra do Mar. The topographic complexity of the region creates a diverse array of microclimates, which can affect species distribution and diversity inside the forest. Given that Atlantic Forest includes highly heterogeneous environments, a diverse and medically important Culicidae assemblage, and possible species co-occurrence, we evaluated mosquito assemblages from bromeliad phytotelmata in Serra do Mar (southeastern Brazil).

Methods: Larvae and pupae were collected monthly from Nidularium and Vriesea bromeliads between July 2008 and June 2009. Collection sites were divided into landscape categories (lowland, hillslope and hilltop) based on elevation and slope. Correlations between bromeliad mosquito assemblage and environmental variables were assessed using multivariate redundancy analysis. Differences in species diversity between bromeliads within each category of elevation were explored using the Renyi diversity index. Univariate binary logistic regression analyses were used to assess species co-occurrence.

Results: A total of 2,024 mosquitoes belonging to 22 species were collected. Landscape categories (pseudo-F value = 1.89, p = 0.04), bromeliad water volume (pseudo-F = 2.99, p = 0.03) and bromeliad fullness (Pseudo-F = 4.47, p < 0.01) influenced mosquito assemblage structure. Renyi diversity index show that lowland possesses the highest diversity indices. The presence of An. homunculus was associated with Cx. ocellatus and the presence of An. cruzii was associated with Cx. neglectus, Cx. inimitabilis fuscatus and Cx. worontzowi. Anopheles cruzii and An. homunculus were taken from the same bromeliad, however, the co-occurrence between those two species was not statistically significant.

Conclusions: One of the main findings of our study was that differences in species among mosquito assemblages were influenced by landscape characteristics. The bromeliad factor that influenced mosquito abundance and assemblage structure was fullness. The findings of the current study raise important questions about the role of An. homunculus in the transmission of Plasmodium in Serra do Mar, southeastern Atlantic Forest.

Figure 1

Study area and collection sites. A: Location of study area in South America. B: The remnants of Atlantic Forest in Serra do Mar, São Paulo and Rio de Janeiro states. C: The study area showing the collection sites according to landscape categories: lowland, hillslope and hilltop. The range of elevation (0 to 1,514 m) is relative to Serra do Mar (B).

Figure 2

Renyi index curves showing differences in species diversity between each bromeliad within each landscape category (lowland, hillslope, and hilltop). The Renyi index estimates total richness for α = 0, Shannon-Weiner index for α = 1, the inverse Simpson-Yule index for ?α= 2 and 1/Berger-Parker index for α = Inf.