Principal Component Analysis (PCA) of larval behaviours in the M and S forms of An. gambiae in the absence of a predator. A) Principal Component 1 (PC1) shows the relationship between time spent browsing at the bottom of the container and thrashing in the middle vs. all other behaviours of 2nd (dark grey), 3rd (light grey) and 4th (white) instar larvae of An. gambiae M and S molecular forms. Mean (± SE) with similar letters are not significantly different from one another (Tukey-Kramer multiple comparisons test). B) Biplot along PC2 and PC3 (mean ± SE) showing the behaviour of 2nd (dark grey), 3rd (light grey) and 4th (white) instars larvae of An. gambiae M (squares) and S (circles) molecular forms.