Infectious diseases can impact human welfare and impede wildlife management. Much recent research explores whether biodiversity increases or decreases infectious disease risk. Here we theoretically study the relationship between vector species richness and the risk of vector-borne diseases by an epidemiological model of a single host and multiple vectors. The model considers that vectors are involved in interspecific feeding interference that causes transmission interference and in interspecific recruitment competition that mediates susceptible vector regulation. The model reveals three possible shapes of the vector richness-disease risk relationship: monotonic amplification, hump-shaped, and monotonic dilution patterns. Monotonic amplification pattern occurs across a wide parameter region. Hump-shaped or monotonic dilution patterns are found when transmission interference is strong and recruitment competition is weak. Unexpectedly, susceptible vector regulation does not only promote dilution but can strengthen amplification if coupled with strong transmission interference. Our results suggest that vector richness might be more likely to cause amplification rather than dilution, and shifts in the community mean trait values of vectors could also affect disease risk along the vector richness gradient.

Contents
- vector.richness-disease.risk_R2_fig02.nb
- vector.richness-disease.risk_R2_fig03.nb
- vector.richness-disease.risk_R2_fig04.nb
- vector.richness-disease.risk_R2_data.generation.for.figS01.nb
- vector.richness-disease.risk_R2_figS01.nb
- R0bias2.wl
- R0bias10.wl
- R0bias100.wl

Description
- vector.richness-disease.risk_R2_fig02.nb
-- Mathematica file to draw figure 2.
-- Run the whole script.

- vector.richness-disease.risk_R2_fig03.nb
-- Mathematica file to draw figure 3.
-- Run the whole script.

- vector.richness-disease.risk_R2_fig04.nb
-- Mathematica file to draw figure 4.
-- Run the whole script.

- vector.richness-disease.risk_R2_data.generation.for.figS01.nb
-- Mathematica file to generate data for figure S1.
-- Run all cells from the top to bottom.
-- Data files of simulation outputs are created in the same local directory as of this code file.
-- The data files are named as R0bias2.wl, R0bias10.wl, R0bias100.wl.

- vector.richness-disease.risk_R2_figS01.nb
-- Mathematica file to generate data for figure S1.
-- Have the data files generated by the code file "vector.richness-disease.risk_R2_data.generation.for.figS01.nb."
-- Have The data files in the same local directory as of this file.
-- Run all cells from the top to bottom.

- R0bias2.wl
-- Data file generated by "vector.richness-disease.risk_R2_data.generation.for.figS01.nb."
-- Contains the data with vector richness = 2.

- R0bias10.wl
-- Data file generated by "vector.richness-disease.risk_R2_data.generation.for.figS01.nb."
-- Contains the data with vector richness = 10.

- R0bias100.wl
-- Data file generated by "vector.richness-disease.risk_R2_data.generation.for.figS01.nb."
-- Contains the data with vector richness = 100.