Autor(es): Nishiura James T; Burgos Cynthia; Aya Samuel; Goryacheva Yekaterina; Lo Wingyin

Resumo: During holometabolous insect development the critical weight marks a physiological transition after which juvenile hormone (JH) concentration decreases to such a level that a subsequent increase in ecdysone titer will initiate metamorphosis. Starvation experiments indicate that the Aedes aegypti critical weight is achieved by 24 h after the last larval-larval molt. When grown at 24 degrees C with excess food, the time between the critical weight and maximum weight (interval to cessation of growth) is about 24 h and pupation occurs about 24 h after the maximum weight is achieved. Oil Red O staining of 3rd and early 4th instars indicates that the midgut is a neutral lipid storage organ during this period. Coincident with the attainment of the critical weight is the depletion of stored midgut neutral lipid. Application of methoprene to 24 h post-molt 4th instars results in renewed midgut storage of neutral lipid suggesting that midgut neutral lipid storage is a JH dependent process. Starvation of 4th instars during the 24 h post-molt period suspends development in a fraction of the larvae, and with the resumption of feeding, development resumes. A regimen of starvation and resumption of feeding of 4th instars suggests that JH concentration decreased over a 40 h period after the resumption of feeding and maximum weight is attained about 48 h after the resumption of feeding. We hypothesize that this results in a shortening of the interval to cessation of growth. Real-time PCR experiments indicate that shortening the interval to cessation of growth compresses the time period during which increases in AHR3, AaEcR-B and AaUSP-a expression occur.

Palavras-Chave: Critical weight; Juvenile hormone; Starvation; Metamorphosis; Mosquito; Neutral lipid; Transcription factors

Imprenta: Journal of Insect Physiology, v. 53, n. 1, p. 47-58, 2007

Identificador do objeto digital: 10.1016/j.jinsphys.2006.09.014

Descritores: Aedes aegypti - Proteins ; Aedes aegypti - Real Time PCR

Data de publicação: 2007