Abstract:
Background: A fundamental understanding of the spatial distribution and ecology of mosquito larvae is essential
for effective vector control intervention strategies. In this study, data-driven decision tree models, generalized linear
models and ordination analysis were used to identify the most important biotic and abiotic factors that affect the
occurrence and abundance of mosquito larvae in Southwest Ethiopia.
Methods: In total, 220 samples were taken at 180 sampling locations during the years 2010 and 2012. Sampling
sites were characterized based on physical, chemical and biological attributes. The predictive performance of
decision tree models was evaluated based on correctly classified instances (CCI), Cohen’s kappa statistic (κ) and the
determination coefficient (R2). A conditional analysis was performed on the regression tree models to test the
relation between key environmental and biological parameters and the abundance of mosquito larvae.
Results: The decision tree model developed for anopheline larvae showed a good model performance (CCI = 84 ± 2%,
and κ = 0.66 ± 0.04), indicating that the genus has clear habitat requirements. Anopheline mosquito larvae showed a
widespread distribution and especially occurred in small human-made aquatic habitats. Water temperature, canopy
cover, emergent vegetation cover, and presence of predators and competitors were found to be the main variables
determining the abundance and distribution of anopheline larvae. In contrast, anopheline mosquito larvae were
found to be less prominently present in permanent larval habitats. This could be attributed to the high abundance
and diversity of natural predators and competitors suppressing the mosquito population densities.
Conclusions: The findings of this study suggest that targeting smaller human-made aquatic habitats could result in
effective larval control of anopheline mosquitoes in the study area. Controlling the occurrence of mosquito larvae via
drainage of permanent wetlands may not be a good management strategy as it negatively affects the occurrence and
abundance of mosquito predators and competitors and promotes an increase in anopheline population densities.
