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First published online February 12, 2007
Journal of Experimental Biology 210, 854-864 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02715
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Larval feeding duration affects ecdysteroid levels and nutritional reserves regulating pupal commitment in the yellow fever mosquito Aedes aegypti (Diptera: Culicidae)

Aparna Telang*, Laura Frame and Mark R. Brown

Department of Entomology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA


Figure 1
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  		Fig. 1. Mean wet mass (white bars) and dry mass (gray bars) of A. aegypti at different times during their fourth larval stadium and in 12 h old pupae (P). Values represent least square means ± s.e.m.; N=18. Within both dry and wet mass values, columns with different letters are significantly different from each other (Tukey–Kramer HSD, P≥0.05). The relationship between wet and dry mass was analyzed by regression analysis: (dry mass larva–1)=–0.23+0.257(wet mass larva–1), r2=0.96, P<0.0001. NM, newly molted fourth instars.

 

Figure 2
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  		Fig. 2. Hemolymph ecdysteroid titers in a single larva (filled circles) and ecdysteroid secretion by a single set of thorax and abdomen (bars) at different times during A. aegypti fourth larval stadium and in 12 h old pupae (P). Each point or bar represents least square means ± s.e.m.; N=27. For ecdysteroid secretion values, columns with different letters are significantly different from each other (Tukey–Kramer HSD, P≥0.05). NM, newly molted fourth instars never given access to food.

 

Figure 3
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  		Fig. 3. (A) Effect of duration of food access on metamorphosis of A. aegypti fourth instars. Shown are percentages of individuals that remained as fourth instars (black bars) or that underwent metamorphosis and subsequently emerged as males (striped bars) or females (gray bars) in response to a period of access to food. Control (C) group of larvae were given food in excess and never underwent a period of time in which food was withheld. N=335. (B) Effect of supplementing food to fourth instars initially fed for 12 h followed by a 7 day fast. Shown are percentages of individuals that remained as fourth instars (black bars) or underwent metamorphosis and subsequently emerged as males (striped bars) or females (gray bars) in response to supplementary feeding. N=80.

 

Figure 4
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  		Fig. 4. Effect of food access period on wing length of newly emerged A. aegypti females. Values represent least square means ± s.e.m.; N=116. Columns with different letters are significantly different from each other (Tukey–Kramer HSD, P≥0.05).

 

Figure 5
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  		Fig. 5. Hemolymph ecdysteroid titers in a single larva (striped bars) and ecdysteroid secretion by a single set of thorax and abdomen (gray bars) in groups of 36 h old fourth instar A. aegypti given different periods of time to feed or not. Newly molted fourth instars were either deprived of food for 36 h, or fed for 12 h or 36 h prior to tissue collection at 36 h for the ecdysteroid bioassay. Values represent least square means ± s.e.m.; N=12. For both ecdysteroid secretion and hemolymph values, columns with different letters are significantly different from each other (Tukey–Kramer HSD, P≥0.05). NM, newly molted fourth instars never given access to food. No bar indicates that the s.e.m. is smaller than column scale.

 

Figure 6
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  		Fig. 6. Dry mass and nutrient reserves in groups of 36 h old fourth instar A. aegypti given different periods of time to feed or not. Newly molted fourth instars were either deprived of food for 36 h, or fed for 12 h only, or fed for 36 h prior to weighing and analyses. (A) Dry mass of fourth instars, (B) lipid amounts in fourth instars, (C) glycogen amounts in fourth instars, and (D) protein levels in fourth instars. All values represent least square means ± s.e.m.; N=12. All nutrient values were obtained from an ANCOVA model and are corrected for larval dry mass (covariate). Error bars represent s.e.m.; no bar indicates that the s.e.m. is smaller than column scale.

 




© The Company of Biologists Ltd 2007