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First published online January 31, 2006
Journal of Experimental Biology 209, 645-655 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02026

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Effects of larval nutrition on the endocrinology of mosquito egg development

Aparna Telang^1,*, Yiping Li², Fernando G. Noriega² and Mark R. Brown³

¹ University of Arizona, Department of Biochemistry and Molecular Biophysics, Tucson, AZ 85721, USA
² Florida International University, Department of Biological Sciences, Miami, FL 33199, USA
³ University of Georgia, Department of Entomology, Athens, GA 30602, Greece

View larger version (23K): [in a new window]   Fig. 1. Effects of larval food quantity on female dry mass and teneral metabolic reserves in both A. aegypti and Oc. atropalpus. (A) Dry mass (adjusted means ± s.e.m.; N=30) of newly emerged adults, (B) lipid amounts in newly emerged adults, (C) glycogen amounts in newly emerged adults, (D) protein amounts in newly emerged adults reared on a high larval food (striped columns) and a low larval food (grey columns) regimen. All nutrient values represent adjusted means ± s.e.m.; N=12 for Oc. atropalpus and N=8 for A. aegypti. Within each figure, columns with different letters are significantly different (from a linear contrast P<0.01). Error bars represent s.e.m. Lack of bar indicates that the s.e.m. is smaller than column scale.

View larger version (16K): [in a new window]   Fig. 2. Egg production as a relation of female wing length in A. aegypti given a blood meal (square) and Oc. atropalpus given no blood or sugar meal (circle). Females emerged from either a high larval food (open symbols) or a low larval food (filled symbols) regimen. For A. aegypti, N=28. For Oc. atropalpus, N=36.

View larger version (37K): [in a new window]   Fig. 3. In vitro synthesis of juvenile hormone by female corpora allata (CA) complexes as measured by incorporation of [3H]methionine at different times post-emergence (NE, newly emerged). CA-JH amounts (adjusted means ± s.e.m.; N=200) are presented for both A. aegypti and Oc. atropalpus as a function of high (top graphs) or low (bottom graphs) metabolic reserves and whether adults were given water (striped columns) or 3% sucrose (grey columns) upon eclosion.

View larger version (17K): [in a new window]   Fig. 4. For female A. aegypti, length of primary follicles (adjusted means ± s.e.m.; N=240) was measured 72 h post-emergence in response to high (striped columns) or low (grey columns) larval food amount and whether females were given water or 3% sucrose over this same time period. Lack of standard error bar indicates that the s.e.m. is smaller than column scale.

View larger version (21K): [in a new window]   Fig. 5. (A) In vitro ecdysteroid secretion by ovary pairs dissected from Oc. atropalpus females at different times during autogenous oogenesis and with large teneral reserves fed water as adults (striped columns), low teneral reserves fed water as adults (black columns) or low teneral reserves fed 3% sucrose as adults (grey columns). Values represent adjusted means ± s.e.m.; N=126. Within each time point, columns with different letters are significantly different (Tukey-Kramer HSD, P0.05). (B) Ecdysteroid titre measured in haemolymph collected from Oc. atropalpus females at different times during autogenous oogenesis with large teneral reserves fed water as adults (striped columns) or low teneral reserves fed water as adults (black columns). Values represent adjusted means ± s.e.m.; N=90. NE, newly emerged.

View larger version (21K): [in a new window]   Fig. 6. A model for the interaction among metabolic reserves, hormones and oocyte maturation in autogenous and anautogenous mosquitoes. A summary, from Fig. 1, of teneral reserves of lipid (L), glycogen (G) and protein (P) measured in Oc. atropalpus and A. aegypti females derived from high-food larvae (termed high reserve) or low-food larvae (termed low reserve) and resulting body size is shown in the table. To the right of the summary table, hormonal responses, presumably as a result of teneral reserves or adult nutrition, are depicted. This model for the first egg development cycle depicts hypotheses generated from the results of experiments presented in this paper, with the assumption that females are mated. In autogenous high-reserve Oc. atropalpus females, teneral glycogen and protein levels are sufficiently high to exceed the threshold for stimulation of ovarian ecdysteroid production (high ov. ecd.) and subsequent vitellogenesis (Vg) and egg maturation (eggs). In addition, the biosynthesis of JH by the corpora allata (CA) is low (low JH). In anautogenous high-reserve A. aegypti, glycogen and protein levels fall below a threshold needed for ovarian ecdysteroid production and vitellogenesis. Consequently, JH biosynthesis is high (high JH), ovarian ecdysteroid production is low (low ov. ecd.), and oocytes are arrested (pre-VG follicle arrest) until the females take a blood meal (Blood). Hormonal profiles and stage of egg development observed in both autogenous and anautogenous females emerging with low nutrient reserves are depicted similarly. Notes: 1results from Caroci et al. (2004); 2results from Sieglaff et al. (2005).