Seasonality of Mansonia titillans during dam construction, Biritiba-Mirim, São Paulo State, Brazil

Abstract

Ma. titillans (n = 2,401) was 27.3% of all culicideans and 58.8% of Mansoniini. Its abundance was equally important among the capture sites. Ma. titillans females (98,4%) were more frequently seen than males in the traps.Interspecific competition with Coquillettidia and other Mansonia species did not play a major role in this study, since relative abundance of all species of this genus was consistently lower then Ma. titillans during the two and a half years studied.The weather was typical for the region during the studied period. The dry season take place between late fall and early spring, during 4 months, with some period variation. Rainy season began in September-October, and the heaviest rainfall period was from December to February (Figure 1).Three population peaks were recorded (Figure 2), all of them occurred in September [2002] or October [2003/2004], coinciding with the end of the dry season and beginning of the wet one at this region.First of all, the normality of the samples distribution was tested through Shapiro-Wilk Test and, as expected, normality of the sample was rejected (p < 0.001 , W = 0,67)The Kruskal-Wallis Test was performed to search for preference among the seasons. The null hypothesis, that the samples from different seasons have the same median, was accepted (H = 7.6779, p = 0.05316, df = 3), indicating that the seasonality of Ma. titillans was not directly determined by rainfall.Spearman's rank correlation coefficient showed little correlation between rainfall and Ma. titillans abundance (ρ = 0.173), and also was little when compared Other Mansoninii with rainfall (ρ = 0.008) and Ma. titilans and other Mansoninii abundance (ρ = 0.017).On Pairwise Wilcoxon Rank Sum Test, a significant difference was found between the Fall and Spring samples (0.049), while all other comparisons were non-significant. DiscussionAlthough statistical insignificance, Kruskal-Wallis' p-value was placed at the boundary of H 0 acceptance. This data is complemented by Pairwise Wilcoxon, which had significant difference. The combination of both tests can be interpreted by Ma. titillans having a relative stable abundance along the year, with one peaks of great abundance. So is clear that there are cyclical peaks of abundance, somehow related to the seasons of the year.The statistical analysis of the data did not reveal a connection between abundance and rainfall; this result can be explained by its ecology. Ma. titillans immature stages live on permanent breeding sites, which abundance and quality are not directly dependent of rainfall allowing Ma. titillans to be abundant throughout the year. An explanation on abundance peaks can be its breathing technique; using aerenchymas allow Mansoniini, and Ma. titillans specifically, to find they optimum environment, while others, lwhen also living on eutrophized waters, find hard times during dry season. De Kruijf (1975) also registered an abundance peak at similar season.

Mosquitoes (Diptera: Culicidae) from crepuscular period in an Atlantic Forest area in Southern Brazil

“…strodei (Lopes, 1997) in artificial breeding were reported. Moreover, Mansoniini species found in the fragment, has its growing in perennial aquatic environments which have aquatic plants, and develop very well in anthropogenic environments (Wermelinger et al, 2012;D'Avila and Gomes, 2013).…”

Bioecological Aspects of Species of the Subgenus Mansonia (Mansonia) (Diptera: Culicidae) Prior to the Installation of Hydroelectric Dams on the Madeira River, Rondônia State, Brazil

“…Uncontrolled reproduction of species of Mansonia is generally associated with the imbalance of aquatic flora in areas influenced by hydroelectric projects [5,20]. Macrophytes serve as reproduction sites in these areas, as they provide oxygen for the respiration of larvae and pupae [22][23][24]. This sequence of phenomena occurred in the area influenced by the Tucuruí hydroelectric plant in the state of Pará, with a marked population growth of species of Mansonia during the post-construction phase, when each collector captured 600 mosquitoes per hour [11].…”

Ultrastructure of the egg ofCoquillettidia juxtamansonia(Chagas, ) (Diptera: Culicidae)

“…pseudotitillans (Theobald), collected with Cq. juxtamansonia (Suárez et al , Lopes and Lozovei, , Dantur Jury et al , D’Ávila and Gomes ), and possibly sharing the same breeding places, have quite different eggs (Mattingly ) or do not have their eggs described.…”