Modeling the Impact of Batrachochytrium Dendrobatidis in the Life History Dynamics of Eleutherodactylus Coqui Under Seasonality Glorimar Melendez-Rosario 1 and Karen Rios-Soto 1 1 University of Puerto Rico, Mayaguez Campus August 3, 2010 Abstract Eleutherodactylus Coqui a native amphibian in Puerto Rico and invasive specie in Hawaii, can be infected by an endemic disease called Batrachochytrium dendrobatidis. Puerto Rico and Hawaii have two main seasons, a wet/warm season and a dry/cool season, although not at the same period of time. E. coqui reproduces the entire year but tend to breed higher during the wet/warm season. In contrast, it has been found that the disease tend to affect them more in the dry/cool season. The Hawaiian government wants to eradicate E. coqui populations, based on the fact that E. coqui affects native species and have negative impact in their tourism population. The use of chemical and biological agents, such as B. dendrobatidis has been introduced without successful results. We use two stage-structured models to represent the effects of the disease, the juvenile stage and adult stage. Since E. Coqui in Puerto Rico gets infected and dies because of the disease or predator-induced mortality, the Puerto Rican model is a susceptible-infected (SI) model. The Hawaiian model is a susceptible-infected-carrier (SIC) model due to the absence of predators in the population and consequently, longer life-span. We look at how the seasonality of the disease impacts these two stages in Puerto Rico and in Hawaii We perform sensitivity analysis on the system equations to study the effect the seasonality function on the transmission of the disease by the environment. Numerical results show that the infected population are higher in Puerto Rico and in Hawaii. The environmental function infer a seasonality atmosphere in Hawaii and that in Hawaii the carriers will higher than the infected population. 1 Introduction The Eleutherodactylus coqui is a frog native in Puerto Rico that belongs to the Phylum Chordata, class Amphibia, order Anura, family Leptodactylidae. There reproduction is different from other frogs since they do not need water to reproduce and they do not have a tadpole phase [1]. These amphibians are native of the tropical island of Puerto Rico. This island have a mildly seasonal weather [2]. 1