GIS Derived Spatial Constraints for Agent-based Modeling of Aedes Aegypti Population Dynamics

The Aedes aegypti mosquito is responsible for the spread of several arboviruses including Dengue, Chikungunya, Yellow Fever and more recently the Zika virus. Accurate modeling of the population dynamics of this disease vector within its habitat allows us to understand conditions necessary for Aedes aegypti populations to thrive. Using agent-based modeling, model developers can provide public health administrators with tools to experiment with environmental conditions, intervention strategies and scenarios, and observe the potential effects on local mosquito populations. Innovative vector control strategies have emerged in recent years, besides the traditional techniques such insecticide sprays and breeding site removal. Some of these methods make use of weaknesses in the reproductive process of Aedes aegypti. Two such methods are the Release of Insects with Dominant Lethal gene (RIDL) and Wolbachia infection (an endosymbiotic bacteria). In the RIDL technique, male mosquitoes carrying a self-limiting gene are released and the resulting offspring of these released males die during emergence into adulthood [1, 2]. Cytoplasmic incompatibility resulting from Wolbachia infected males with uninfected wild females also causes all resulting offspring to die [3]. However, if infected females are released, all resulting offspring will survive into adults carrying the Wolbachia infection, allowing for the possibility of sustaining Wolbachia infection within the population and keeping mosquito numbers lowered [4]. In this study we present an agent-based model coupled with spatial resource constraints for both male and female mosquitoes and effects of monthly temperature fluctuation. This model is used to estimate the population of mosquitoes in a neighborhood in the Key West, Florida. Then, as a demonstration of the use of this model, simulations are performed to compare the sustainability of the two vector control strategies. The success of RIDL requires released males to successfully compete with wild males for mates [5]. Wolbachia infection also requires the successful mating of infected males and can additionally benefit from the release of infected females if sustained infection is desired [4]. Therefore, both techniques require a prior understanding of the mass and frequency of male and female mosquitoes to be released in order to cause a significant reduction in population. However, existing models of Aedes aegypti population dynamics focus on factors effecting the distribution of adult females, with little or no attention towards the dynamics of adult male mosquitoes. Originally, models were based off of derivative equations and dynamic life-tables, where mosquitoes populations were considered in aggregates or cohorts, such as CIMSim [6] or its spatially explicit version Skeeter Buster [7]. However, significant advances in computing power have allowed modelers to create individual-based or agent-based models (ABMs), where mosquitoes are modeled on a individual scale. In these models each agent acts and reacts to conditions in the environment according to a set of rules and parameters. These rules and parameters are derived from field studies of the Aedes aegypti and the balance between accuracy and computation time of the model can be controlled through assumptions of the rules and parameters. Additionally, by simply changing the parameters of the model, the modeler can adapt the model to simulate varying environmental conditions or even the behavior of various species of mosquito, making agent-based modeling a highly versatile technique.