Biological control strategy with Poecilia reticulata for the reduction of Aedes spp. and Culex sp. in urban stormwater drains: Experience at Universidad del Valle, Cali, Colombia

Abstract

Abstract Introduction. Dengue is one of the most significant arboviral diseases in Latin America and the Caribbean, with Aedes aegypti as its primary vector. The elimination of breeding sites is the most effective control strategy; however, the presence of stormwater drains in urban environments poses a challenge. Objective. To evaluate the effectiveness of biological control using Poecilia reticulata in reducing Aedes (Aedes aegypti and Aedes albopictus) and Culex sp. larvae in urban stormwater drains at Universidad del Valle, Cali, Colombia. Materials and methods. A quasi-experimental study was conducted with a nine-month follow-up (October 2022 - June 2023). All stormwater drains catch basins at the University were inspected, and 12 catch basins were selected that contained Aedes (A. aegypti and A. albopictus) and Culex sp. mosquito larvae. The number of mosquito larvae by genus, water temperature, and pH were recorded weekly. The intervention involved the introduction and monitoring of P. reticulata, with reintroductions as needed. A Bayesian multilevel logistic regression model was used to estimate the intervention effect, adjusting for environmental factors and variability among stormwater drains. Results. The intervention group showed a trend toward lower larval presence, although it did not reach statistical significance (ß = -0.90, 95% CI: -2.01 to 0.21). Water temperature was positively associated with larval presence (ß = 0.25, 95% CI: 0.07 to 0.45), while pH showed a negative association (ß = -1.50, 95% CI: -3.06 to -0.06), indicating reduced larval development in more alkaline water. Conclusions. Biological control with P. reticulata showed potential for reducing larval presence. Temperature and pH were key determinants of larval presence, emphasizing the need to consider environmental factors in vector control strategies.