Anthropogenic influences on Rhodnius ecuadoriensis populations and nesting behaviors in sylvatic areas of southern ecuador.

Abstract

Background: Chagas disease, caused by the parasite Trypanosoma cruzi, remains a major public health concern. While Rhodnius ecuadoriensis, a key vector, is traditionally sylvatic, environmental disturbances have driven its adaptation to human-influenced habitats. This study explores a novel factor: how anthropogenic waste affects vector ecology by altering nest compositions. Unlike prior research, this study examines whether human-derived materials in nests influence triatomine colonization. Given rising pollution, particularly post-COVID-19, understanding its role in disease transmission is essential for developing innovative vector control strategies.

Methods: Nest records were collected and analyzed in 2018, 2022, and 2023, across eight communities in Loja province, Ecuador. Nests were categorized as peridomestic if found < 30 m from a house and sylvatic if > 30 m away. The number of insects found in these nests was quantified using entomological indices. Pearson correlation analysis was applied to assess relationships between nest location and the presence of anthropogenic materials.

Results: A total of 389 nests were examined, yielding 1,089 individuals of Rhodnius ecuadoriensis (including both nymphs and adults). The infestation index in peridomestic areas dramatically decreased from 33.3% in 2018 to 0% in 2022, highlighting an intriguing temporal shift that warrants further investigation. In contrast, sylvatic areas showed fluctuating infestation rates (27.5% in 2018, 16.5% in 2022, and 22.2% in 2023). The study uniquely identified a significant association between triatomine infestation and mammal nests, with 50.1% of infested nests located within mammal habitats. Notably, 35.2% of these nests contained anthropogenic materials, particularly near human-altered landscapes such as roads and paths. The weak to moderate negative correlation between the presence of anthropogenic materials and proximity to roads or rivers (r = -0.361, p = 0.039) highlights an innovative exploration of the influence of human environmental changes on vector ecology.

Conclusions: This study offers a novel perspective on the dual impact of increasing pollution levels on wildlife. It highlights how anthropogenic waste not only reduces vector populations but also increases mortality rates through entanglement in waste materials. These findings underscore the urgent need for environmental education programs focused on waste management within local communities. Furthermore, the study paves the way for further research to assess the rate of T. cruzi infection in relation to environmental and anthropogenic factors, offering a critical foundation for understanding and potentially mitigating Chagas disease transmission.