Figure 3.

Temporal analysis of mosquito data from the Des Moines, Iowa trap site (1976–2009). Trap index averages (standardized counts) for each year at the Des Moines site for the five most collected mosquito species (A): Anopheles punctipennis (Ap), Culex pipiens group (CPG), Aedes vexans (Av), Culex tarsalis (Ct), and Aedes triseriatus (At). The relative abundance of the two most common species, Ae. vexans and CPG, are displayed over the study period (B). No significant differences (R² = 0.07793, p = 0.1099, F = 2.704, df: 1, 32) were detected in Culex pipiens group (CPG) populations over time using simple linear regression (C) or when trap index averages were compared for the first half (1976–1992) and the second half (1993–2009) of the study using Mann-Whitney analysis (p = 0.1598, two-tailed, exact) (D).