Insects, hormones molting

Tebufenozide acts by mimicking the effects of the insect hormone ecdysone, which along with juvenile hormone, controls the initiation of a molt. Exposure to tebufenozide induces a premature molt that traps the insect in its old cuticle. This compound is especially effective against caterpillars. 

Polarimeters for measuring optical rotation are so sensitive that they can measure rotations to 0.001°, an important fact when only small amounts of sample are available. Ecdysone, for example, is an insect hormone that controls molting in the silk- j worm moth. When 7.00 mg ecdysone was dissolved in 1.00 mL chloroform and the solution was placed in a cel with a 2.00 cm pathlength, an observed rotation dT -I-0.087° was found. Calculate [a]n for ecdysone. 

Molting hormones secreted by endocrine glands (corpora allata) of insects for the purpose of triggering larval molting for details on the specific action, see under insect hormones. JH I [C]g-JH, methyl (2 ,6 , 10 , 11S)-10,11 -epoxy-7-ethyl-3,11 -dime-thyl-2,6-tridecatrienoate, CigHjoOa, Mr 294.43, [a] +14.9° (CHCI3)] was isolated from the silkworm the J. 

Sloughing or molting hormone see ecdysteroids and insect hormones. 

Juvenile hormone, larval hormone, stalus-quo hormone insect hormone responsible for the control of molting. The first J.h. to be isolated and structurally elucidated was obtained from the abdomens of the male silk worm moth (Hyalophora cecropia) in 200 ig quantities. Homologs of this compound were discovered later, and other J.h. were postulated. Juva-bione (see) and famesol derivatives are among the... 

Eedysone was the first insect hormone to be obtained in pure crystalline form. It has the action of the molting and metamorphosis hormone and has also been called, by Scharrer, the growth and differentiation hormone . 

Fig. 56. Action of insect hormones. In the upper part, the hormone-producing glands are represented. Below that, the molting stages initiated by the hormones are shown.

Figure 8.8 is an example of the use of solvent extraction to Isolate and concentrate the insect molting hormone eedysterone... 

While the above observation is interesting and could possibly have some implications for the control of the pink bollworm, the complexity of the steroid nucleus of ponasterone A and other molting hormone analogs and their weak insecticidal effect when applied topically or administered orally to most species of economically important insects may preclude their commercialization. The only commercial use of the molting hormone analogs thus far has been in the sericultural industry for the synchronization of cocoon spinning of silkworm colonies (17). 

Figure 6. Stereostructures of the Insect Molting Hormone, Ecdysterone, and a Plant Analog, Ponasterone A...

Ecdysone, a highly hydroxylated steroid (Fig. 22-12), is a molting hormone for insects.331,332 Several molecules with ecdysone activity are known, and some of these are produced by certain plants. Although ecdysones are needed by insects for larval molting, they are toxic in excess. Perhaps plants protect themselves from insects by synthesizing these substances. 

Ecdysteroids. Ecdysteroids can be isolated from many species of the annual kingdom that belong to the phyla Protomia, e.g., insects, worms, and arthropods, as well as a variety of different plant species. Ecdysteroids include the molting hormones, however, nnl all the over 60 ecdysteroids that have been isolated are active hormones. Ecdysteroids from animals... 

Structure of /3-ecdysone and juvenile hormone. These hormones play major roles in the growth and maturation of insects by controlling the timing for molting of the insect exoskeleton. 

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