Influence of shading and pedestrian traffic on the preference of Aedes (Stegomyia) aegypti (Diptera: Culicidae) for oviposition microenvironments.

Aedes aegypti mosquitoes are highly adaptable to abiotic stimuli. To evaluate the influence of shading and pedestrian traffic on the preference of Ae. aegypti for oviposition microenvironments, 20 sites were sampled weekly using ovitraps within the perimeter of Universidade Federal do Espírito Santo, located in São Mateus, Espírito Santo, Brazil. A spatial and statistical analysis was performed in order to assess the relationship between shading time, pedestrian traffic, and the presence of biological forms of Ae. aegypti. A temporal analysis of temperature and precipitation influence on oviposition was also made. Between June, 2013 and June, 2014, 7,362 Ae. aegypti eggs were collected. Over a 12-month period, we made weekly collections of Ae. aegypti eggs from ovitraps. Pedestrian traffic and shading time influenced the number of positive ovitraps; precipitation and temperature were correlated with the number of positive ovitraps (p <0.05). We conclude that the influence of temperature and precipitation was not significant for the oviposition index, and the frequency of oviposition was directly proportional to the number of individuals moving close to the traps during periods of greater shading.

Does native bromeliads represent important breeding sites for Aedes aegypti (L.) (Diptera: Culicidae) in urbanized areas?

This study evaluates the importance of native bromeliads growing on rocky outcrops interspersed with urbanized areas as breeding sites for the Aedes aegypti (L.) in Vitória, state of Espírito Santo, Brazil. Oviposition traps were installed in backyards of houses in two separate zones. In the first zone houses were up to 50 m away from the rocky outcrops, while in the second zone they were at least at 200 m from the rocky outcrops. Aedes aegypti was significantly more abundant in the latter zone. The finding was that rocky outcrops with native bromeliads, even with the greater availability of potential breeding sites, do not play an important role as breeding sites for A. aegypti. This conclusion supports the hypothesis that the macrobiota of native bromeliads plays an important role in the natural control of A. aegypti. Besides, the interspecific competition between species of mosquitoes and the attractiveness of bromeliads could also be important factors.

Performance of two macrophyte species in experimental wetlands receiving variable loads of anaerobically treated municipal wastewater.

Two highly productive emergent macrophytes, Zizaniopsis bonariensis and Typha subulata were established in experimental subsurface flow, sand-based wetlands receiving anaerobically treated municipal wastewater. The hydraulic loading rate was tested in two levels, sequentially, 6.8 cm x d(-1) and 13.6 cm x d(-1), for 70 days each. In the 13.6 cm x d(-1)-loading treatment, among all monitored variables only COD, PO4-Total-P, and Turbidity were removed more efficiently by the planted beds in comparison to unplanted sand beds (P<0.001). When the 6.7 cm x d(-1)-loading rate was applied no significant improvement in removal was found comparing macrophyte beds to unplanted sand beds, except for PO4-P. T. subulata beds were significantly more efficient than Zbonariensis beds for most of the variables. The highest significant differences (P< 0.001) were related to the main effect of the factor hydraulic loading rate, with decreased removal for increased load when considering the variables Total Coliforms (99.4% to 87.7%), Fecal Coliforms (100% to 89.7%). NH3-N (95.8% to 55.2%), NO3(-)-N (-54% to -396%), Total-N (90.4% to 59.6%), and TSS (86.1% to 46.1%). The performance similarity of planted and unplanted wetland beds in the lower loading condition, except for PO4-P, indicates that plants may not be needed under low loading. However aquatic macrophytes improved wetland efficiency under high loading.