Figure 1.
Central Gambia, showing study villages (red squares), other villages (green circles), main channel of The River Gambia and tributaries (blue lines), alluvial sediment (solid yellow). The Gambia nation is shaded grey, surrounded by Senegal in white. Inset: location of the study area in The Gambia.
Figure 2.
Mosquito dispersal in The Gambia.
A) Geometric mean (GM) female Anopheles gambiae s.l./night in villages in the rainy season (Jul–Dec) 1996 at different distances from the landward edge of alluvial sediments; B) Two-parameter negative exponential non-linear regression model (solid line) with 95% CIs of curve (dashed lines) with points from A in grey for reference; C) Two-parameter half-Cauchy non-linear regression model (solid line) with 95% CIs of the curve (dashed lines) with points from A) in grey for reference.
Figure 3.
Cumulative probability of female Anopheles gambiae s.l. dispersal into villages in The Gambia versus distance from village to nearest alluvial sediments (solid line) estimated from non-linear regression. Grey shaded areas indicate 95% CI of the curve and red marker lines indicate distances over which 95% of the population has dispersed; A) two parameter negative exponential model; B) two-parameter half-Cauchy model.
Figure 4.
Two parameter negative exponential (blue line) and half-Cauchy (black line) regression models of female Anopheles gambiae s.l. dispersal into villages and simulated dispersal distances (red, 1000 simulations) from a random walk (daily survival = 0.8; daily movement = 0.35 km) of 10,000 mosquitoes emerging from a point source and dispersing until population extinction or day 30, whichever came first.
Table 1.
Predicted dispersal of adult female Anopheles gambiae s.l. mosquitoes away from breeding sites in The Gambia, using a 2-parameter negative exponential regression model and a 2-parameter half-Cauchy regression model.