Characterizing larval breeding sites: microbial density
We examined the microbial profile in a subset of larval breeding sites, as previous studies have shown that the microbiome, particularly bacteria, affect Ae. aegypti oviposition choices (Arbaoui & Chua, 2014; Ponnusamy et al., 2015) as well as larval development (Correa et al., 2018; Dickson et al., 2017; Souza et al., 2019). In brief, we collected 15 mL (in La Lopé) or 50 mL (in Rabai) water samples from each larval breeding site. To first examine the total microbial density, we fixed an aliquot of each water sample with formaldehyde and stained it with DAPI (4′,6-diamidino-2-phenylindole). The number of microbial cells was counted using hemocytometers under a fluorescence microscope and back-calculated to its original density.
Densities were log-transformed before statistical analysis. We compared the microbial density among larval breeding site groups in La Lopé with the Kruskal–Wallis test and post hoc pairwise Wilcoxon rank-sum tests. The distribution of data in Rabai samples did not violate parametric test assumptions, so we performed the comparisons using analysis of variance (ANOVA) and post hoc Tukey tests.