Influence of physical chemical water parameters on abundance and presence of the arbovirus vector Aedes Albopictus (Dipteria: Culicidae) in Larval habitats of forest fragments

Introduction The species Aedes albopictus (Diptera: Culicidae) is a mosquito of great epidemiological importance because it carries several arboviruses that cause diseases in humans, including the dengue virus. In Brazil, this species was introduced in mid-1986 and nowadays is found in almost the whole country cities, developing in natural or artificial breeding sites in peri-urban and urban areas. For aquatic insects living in lentic environments, such as immature forms of mosquitoes, the physicochemical environment factors represent important constraints that can influence the development, survival and adaptation of the organism. Despite this, few studies have sought to investigate the influence of physicochemical factors on the incidence and abundance of vector mosquitoes. In this study we investigated the influence of pH, practical salinity unit (PSU), water temperature in degrees Celsius (°C) and oxygen dissolved in parts per million (DO ppm) on the incidence and abundance of Aedes albopictus collected in larval habitats found in four urban green spaces in the city of Sao Paulo. Methods Natural breeding sites (bromeliads, bamboos, trees holes, and puddles) and artificial ones were explored (water boxes, plant pots, tires, etc.) during 12 months of collection. The physicochemical parameters were measured using a multiparameter device Hanna-HI-9828. The predictive relationship between the measured physicochemical factors and the incidence and abundance of A. albopictus was evaluated by generalized additive models (GAM). Akaike Information Criterion corrected for small samples was used to select the model with the best fit and explanatory power. For a better understanding of the non-linearity of relationship between the variables, a tree regression analysis was made from the selected model. Results A total of 4212 specimens of A. albopictus were collected in 142 positive samples from both natural and artificial breeding sites. In relation to the positive samples the variation in the physicochemical parameters was: pH 2.3 to 9.8, PSU   4.8 and PSU > 0.175. The abundance was better explained by pH, salinity and temperature, with higher average abundance (151 individuals/mean) in PSU > 0.335, pH  Conclusions The mosquito A. albopictus showed to be adapted to wide variations in physicochemical conditions of larval habitats, which in part explains its wide ecological valence and worldwide dispersion. The predictive models proposed in this study may be useful to help understand the relationship of A. albopictus and other vector mosquitoes with abiotic environment constraints.