Ying An

Significance of specific factors produced throughout diapause in pharate first instar larvae and adults

Publisher Summary In most insects of the temperate zone, diapause and hibernation are strategies for reproductive synchronization and survival during difficult seasons in their life cycle. In general, the role of insect diapause has been understood to be an arrest of development that frequently overcomes unsatisfactory seasons. Individuals in diapause accumulate cryoprotectants, such as polyols and antifreeze proteins. This chapter presents an article that describes specific factors produced during diapause. It examines specific factors and molecules involved in diapause by focusing on the diapause syndrome in two species. Experimental results from a Japanese wild silkmoth Antheraea yamamai , a producer of wild silk and a huge experimental insect; and results from the leaf beetle, Gastrophysa atrocyanea , a species being used for biological control of the dock weed, are described in the chapter. It discusses specific factors and molecules associated with diapause in pharate first instar larvae of the wild silkmoth and adults of the leaf beetle, in the context of the regulatory basis for insect diapause and as a source of molecules of potential interest for biotechnology.

A palmitoyl conjugate of insect pentapeptide Yamamarin arrests cell proliferation and respiration

A palmitoyl conjugate of an insect pentapeptide that occurs in diapausing insects causes a reversible cell-cycle arrest and suppresses mitochondrial respiration. This peptide compound also causes growth arrest in murine leukemic cell line expressing human gene Bcr/Abl and a farnesoyl peptide induces embryonic diapause in Bombyx mori. These results demonstrate that the insect peptide compounds can lead to the understanding of a common pathway in developmental arrest in animals and may provide a new peptidominetic analog in the development of biopharmaceuticals and pest management.

Male reproductive maturity and diapause termination in the leaf beetle Gastrophysa atrocyanea

Male reproductive potential and growth of testes are studied in the leaf beetle Gastrophysa atrocyanea Motschulsky (Coleoptera: Chrysomelidae) that is exposed to mild temperatures after imaginal ecdysis. Continuous administration of the Juvenile Hormone (JH) in artificial diet is highly effective with respect to stimulating testes growth and mating behaviour. Female reproductive diapause can be induced under standard rearing conditions, although optimum reproductive maturity of males is achieved at 15 °C. Treatment of males with a JH analogue accelerates testes development up to the stage of spermiogenesis (the bundling of spermatozoa) but does not promote the formation of cysts with mature sperm. Treatment with 20‐hydroxyecdysone has no influence on diapause termination and testes function. These results suggest that male reproductive maturation in G. atrocyanea is independent of JH, and moderate temperatures may induce an unknown factor that is responsible for the maturation of sperm cysts.