Figure 2
From: Predicting outbreaks: a spatial risk assessment of West Nile virus in British Columbia
Flowchart illustrating the mosquito abundance model developed in the study. * Condition to clear the stages: ddx ≥ DDi (i specifying stages; 1 egg, 2 lava, 3 pupa, 4 adult) where, ddx is the accumulated degree-days till day x; DDi is the degree-days required to clear the stage i. ddx is calculated as follows:
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where tx is the daily mean temperature of the day x; t0 is the lower threshold temperature for dd accumulation (DDi and ti for each stage and species are presented in Table 1). ** Dependent upon accumulation of sufficient DD plus adult drying and host seeking period. †Dependent upon accumulation of sufficient DD for ovary development (presented in Table 1). ††Calculated as: (no. of female mosquitoes) × (no. of avg. gonotrophic cycles) × (avg. no. of eggs per gonotrophic cycle)