Fig. 3. for affects glucose absorption third-instar larvae. (A) No differences in path length between rover (for^R), sitter (for^s) and sitter mutant (for^s2) larvae were found during a 15 min test on a non-nutritive substrate (agar; F_(2,56)=0.34, P=0.71). However, as expected, rovers showed significantly longer foraging trails than sitter and sitter mutants during a 15 min test on a yeast substrate (F_(2,53)=35.77, P<0.0001). (B) After 15 min of feeding on a yeast–water paste containing ¹⁴C-labeled glucose, rover larvae ingested significantly less ¹⁴C than sitters (F_(2,17)=52.66, P<0.001). When subsequently exposed to unlabeled medium for 3 h, rovers retained significantly more ¹⁴C label, indicating a higher level of glucose absorption compared to sitters (F_(2,17)=7.36, P<0.006). (C) After 15 min of feeding on a yeast–water paste containing ¹⁴C-labeled L-U-leucine, well-fed rover larvae ingested significantly less ¹⁴C than sitters (F_(2,15)=11.03, P=0.001; for^R vs for^s, P=0.0003; for^R vs for^s2, P=0.03; for^s vs for^s2, P=0.04). When subsequently exposed to unlabeled medium for 3 h, rovers did not differ significantly from sitters in amount of ¹⁴C label (F_(2,15)=1.92, P=0.18). (D) Rovers (for^R) and sitters (for^s and for^s2) do not differ significantly in the number of contractions of the anterior midgut (F_(2,27)=0.17, P=0.85), acidic region (F_(2,27)=1.83, P=0.18) or posterior midgut (F_(2,27)=1.37, P=0.27). (E) No significant differences were found in the amount excreted by for^R, for^s or for^s2 larvae (F_(2,57)=0.049, P=0.95). In addition, no significant interaction between the number of fecal spots and strain was found with a logistic regression analysis on excreted food concentration (F_(2,5)=2.40, P=0.100).