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Fig. 4. Food level affects survivorship to eclosion, development rate and food intake in rovers and sitters. (A) Larvae were reared from egg-hatch on media containing 100%, 75%, 50%, 25% or 15% of the yeast and sucrose content of standard medium (100%; see Materials and methods). Values are means ± s.e.m. Between-strain survivorship analysis revealed that differences were not significant at 100% (F_(2,21)=0.91, P=0.4), 75% (F_(2,20)=1.70, P=0.2), 50% (F_(2,21)=1.17, P=0.3) or 25% (F_(2,21)=0.73, P=0.5) food levels, but at 15% rovers differed significantly from for^s (F_(1,14)=6.00, P<0.03) and for^s2 (F_(1,14)=13.29, P<0.003). Between-strain comparisons of developmental delay revealed that rovers differed from both for^s and for^s2 at 15% (F_(2,21)=4.33, P<0.03) and rovers differed from for^s2 at 100% (F_(2,21)=4.42, P<0.03), 50% (F_(2,21)=7.06, P<0.005) and 25% (F_(2,21)=3.80, P<0.04) food levels but not at 75% (F_(2,20)=2.58, P=0.1). (B) Rovers (for^R) ingested less yeast paste after 15 min feeding than sitters (for^s and for^s2) when raised on high levels of food (100%, 75%, 50%), but not when reared on low levels of food (25%, 15%) [two-way ANOVA for strain (F_(2,435)=5.13, P<0.006) and strain-by-food level (F_(8,435)=2.28, P<0.02); one-way ANOVA on 100% (F_(2,87)=6.86, P<0.002), 75% (F_(2,87)=14.33, P<0.0001), 50% (F_(2,87)=6.34, P<0.003), 25% (F_(2,87)=0.14, P=0.9), 15% (F_(2,87)=0.11, P=0.9)]. (C) Rovers and sitters differ in food intake measured after 5 min feeding on yeast paste when reared at 100%, food quality but not when food-deprived (reared on 25% and 15% food) [ANOVA, at 100%, F_(2,87)=5.53, P<0.0006, 25% F_(2,87)=0.69, P=0.50), 15% F_(2,87)=0.33, P=0.7]. (D) All larvae reared under low food levels were staged to mid-third instar prior to measuring food intake. Rover and sitter larvae reared in dilute (15% and 25%) food were smaller in size at mid-third instar compared to larvae reared in normal (100%) food. However, no within-strain differences were found at any food level [two-way ANOVA, F_(8,260)=56.50, P<0.0001; strain, F_(2,260)=0.19, P=0.82; food quality, F_(2,260)=73.25, P<0.0001, with significantly smaller larvae at 25% (P<0.0001) and 15% (P<0.0001) compared to 100%; strainxfood quality F_(2,4)=0.23, P=0.92]. (E) At 15% food, rovers, sitters and sitter mutants ingested similar amounts of ¹⁴C-labeled media in15 min (F_(2,15)=0.67, P=0.3), but rovers absorbed more than sitter and sitter mutants (F_(2,17)=45.51, P<0.0001). for^R larvae had a twofold increase in absorption compared to for^s and for^s2 larvae at 15% food levels (F_(2,12)=41.96, P<0.0001; for^R vs for^s, P<0.0001; for^R vs for^s2, P<0.0001; for^s vs for^s2, P=0.12). (F) After 15 min of feeding on a yeast–water paste containing ¹⁴C-labeled L-U-leucine, rover larvae reared on 15% food did not differ significantly from sitters in amount of ¹⁴C ingested (F_(2,15)=0.37, P=0.70). When subsequently exposed to unlabeled medium for 3 h, rovers absorbed significantly more ¹⁴C label compared to sitter mutants (F_(2,15)=4.55, P=0.03; for^R vs for^s, P=0.15; for^R vs for^s2, P=0.009; for^s vs for^s2, P=0.53).

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