Cockroach juvenile

Abstract Pheromones are utilized by many insects in a complex chemical communication system. This review will look at the biosynthesis of sex and aggregation pheromones in the model insects, moths, flies, cockroaches, and beetles. The biosynthetic pathways involve altered pathways of normal metabolism of fatty acids and isoprenoids. Endocrine regulation of the biosynthetic pathways will also be reviewed for the model insects. A neuropeptide named pheromone biosynthesis activating neuropeptide regulates sex pheromone biosynthesis in moths. Juvenile hormone regulates pheromone production in the beetles and cockroaches, while 20-hydroxyecdysone regulates pheromone production in the flies. 

Another aspect of the sex pheromone communication system concerns the endogenous signals that control pheromone production and release from the emitting insect. A number of hormones have been found to be involved in the control of pheromone production in various insect species (18). Juvenile hormone was found to induce vitellogenesis and sex pheromone production in some cockroach and beetle species. However, ecdysteroids were found to be involved in regulating reproductive processes, including vitellogenin synthesis, in dipteran species. 

Schafer, R. and Sanchez, T. V. (1976). The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. II. Juvenile hormone regulates sexual dimorphism in the distribution of antennal olfactory receptors. Journal of Experimental Zoology 198 323-336. 

Schal, C., Holbrook, G. L., Bachmann, J. A. S. and Sevala, V. L. (1997). Reproductive biology of the German cockroach, Blattella germanica juvenile hormone as a pleiotropic master regulator. Archives of Insect Biochemistry and Physiology 35 405 126. 

Sreng L., Leoncini I. and Clement J. L. (1999) Regulation of sex pheromone production in the male Nauphoeta cinerea cockroach role of brain extracts, corpora allata (CA), and juvenile hormone (JH). Arch. Insect Biochem. Physiol. 40, 165-172. 

Chiang A.-S., Gadot M., Burns E. L. and Schal C. (1991) Developmental regulation of juvenile hormone synthesis ovarian synchronization of volumetric changes in corpus allatum cells in cockroaches. Molec. Cell. Endocrinol. 75, 141-147. 

Schal C., Chiang A-S., Burns E. L., Gadot M. and Cooper R. A. (1993). Role of the brain in juvenile hormone synthesis and oocyte development effects of dietary protein in the cockroach Blattella germanica (L.). J. Insect Physiol. 39, 303-313. 

Smith A. F., Yagi K., Tobe S. S. and Schal C. (1989) In vitro juvenile hormone biosynthesis in adult virgin and mated female brown-banded cockroaches, Supella longipalpa. J. Insect Physiol. 35, 781-785. 

The endocrine regulation of sex pheromone production in a laboratory strain of the housefly has been summarized (Blomquist, 2003). Because housefly sex pheromone production was correlated with ovarian development, it was possible that both oogenesis and (Z)-9-tricosene synthesis were regulated by a common hormone. Such a common factor was found in cockroaches and beetles, where juvenile hormone (JH) induces both vitellogenesis and sex pheromone production. 

Insects utilize propionate and methylmalonate in the biosynthesis of ethyl branched juvenile hormones and methyl branched cuticular hydrocarbons. The sources of propionate and methylmalonate in some insects appear to differ from those in mammals. Succinate is the precursor of propionate and methylmalonate in a termite, whereas valine and probably other amino acids are the sources of propionate and methylmalonate in several other species. An unusual pathway for propionate metabolism has been shown to occur in insects and it may be related to the absence or low levels of vitamin B found in many species. Propionate is converted directly to acetate with carbon 1 of propionate lost as C02> carbon 2 of propionate becoming the methyl carbon of acetate and carbon 3 of propionate becoming the carboxyl carbon of acetate. This pathway suggested the possibility that 2-fluoropropionate might be selectively metabolized in insects to the toxic 2-fluoro-acetate. However, preliminary data indicate that 2-fluoropropionate is not toxic to the housefly or the American cockroach. 

Two of the better known "anti-juvenile "Hormone" agents, preco-cenes (9) and fluoromevalonate (10) are inhibitors of JH biosynthesis. The mode of action of fluoromevalonate at the molecular level is unknown. Elucidation of the mode of action of precocenes indicates that these plant chromene derivatives reach the site of JH biosynthesis, the corpora allata (CA), where they undergo a lethal epoxidation leading to extensive macromolecular alkylation and ultimately cause cell death (11, 12). Bioactivation of precocenes to the highly reactive precocene epoxide (13) in the corpora allata is almost certainly catalyzed by methyl farnesoate (MF) epoxidase (14), a cytochrome P-450 sonooxygenase (15) tdtich is the last enzyme of the JH biosynthetic pathway (at least in locusts and cockroaches). 

Hydroprene, a juvenile hormone analog, is registered for use against cockroaches. It has an oral LD50 in rats of >34,000 mg/kg. 

Epoxide rings of alkene and arene compounds are hydrated to form trans-diols. The enzymes that catalyze the addition of a molecule of water to an epoxide ring to yield diols are called epoxide hydrolases (also known as epoxide hydrases). Epoxide hydrolase activity has been detected in numerous species of insects. Enzymatic epoxide hydration of certain cyclodiene insecticides and their analogs has been demonstrated in the housefly, blowfly (Calliphora erythrocephala), yellow mealworm (Tenebrio molitor), Madagascar cockroach (Gromphadorhina portentosa), southern army worm (Spodoptera eridania), and red flour beetle (Tribolium castaneum). Epoxide hydrolase is also important in the metabolism of juvenile... 

Neuropeptide Inhibitors of Juvenile Hormone Synthesis in Brain and Corpora Allata of the Cockroach Diploptera punctata... 

The allatostatins are a family of brain peptides which rapidly and reversibly inhibit juvenile hormone biosynthesis in isolated insect corpora allata. Five allatostatic peptides from brains of the cockroach Diploptera punctata have now been structurally identified (i 2 our unpublished results), their size ranging from octapeptide to octadecapeptide. The currently identified allatostatins all possess the consensus C-terminal sequence (L/V)YXFGL-amide, which has no significant homology with other known peptides. It is likely that they are released locally from nerve terminals within the glands (3). 

The potential for using endocrine imbalance as a means of insect pest control was suggested by Williams (9,10) He proposed that exposing immature insects to juvenile hormone (JH) at the time of metamorphosis, when JH is normally absent, would cause abnormal development and individuals incapable of survival. Since insect metamorphosis is unique, JH disruption would affect only insects. This would result in an environmentally safe approach to insect control as compared to current chemical pesticides which are less insect specific and more biocidal. The JH approach to pest insect control is most effective when adults are the destructive stage, and commercial preparations of JH mimics are available for use in the control of adult flies, mosquitoes, and fleas and, recently, for cockroach reproduction. However, many pest insects are destructive as larvae. 

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