1_The young larvae of insects living on dry food produce large amounts of water by the metabolic combustion of dietary lipids. The metabolic production of water needed for larval growth, previously known as hypermetabolic responses to juvenile hormone (JH), is associated with a 10- to 20-fold increase in the rate of O2 consumption (10,000 µl O2/g/h in contrast to the usual rate of 500 µl O2/g/h). Growing and moulting larvae are naturally hypermetabolic due to the endogenous release of JH from the corpora allata. At the last, larval-pupal or larval-adult moult there is no JH and as a consequence the metabolic rate is much lower and the dietary lipid is not metabolized to produce water but stored in the fat body. At this developmental stage, however, a hypermetabolic response can be induced by the exogenous treatment of the last larval instars with a synthetic JH analogue. In D. vulpinus, the JH-treated hypermetabolic larvae survive for several weeks without moulting or pupating. In T. castaneum and G. mellonella, the JH-treated hypermetabolic larvae moult several times but do not pupate. All these larvae consume dry food and the hypermetabolic response to JH is considered to be a secondary feature of a hormone, which is produced by some subordinated endocrine organ., 2_The organ is most probably the controversial prothoracic gland (PG), which is a typical larval endocrine gland that only functions when JH is present. According to our hypothesis, PG activated by JH (not by a hypothetical PTTH) releases an adipokinetic superhormone, which initiates the conversion of dietary lipid into metabolic water. This type of metabolic combustion of dietary lipid produces large quantities of endothermic energy, which is dissipated by the larvae in the form of heat. Thermovision imaging revealed that the body of hypermetabolic larvae of G. mellonella can be as hot as 43°C or more. In contrast, the temperature of "cold" normal last instar larvae did not differ significantly from that of their environment. It is highly likely that thermovision will facilitate the elucidation of the currently poorly understood hormonal mechanisms that initiate the production of metabolic water essential for the survival of insects that live in absolutely dry conditions., Karel Sláma, Jan Lukáš., and Obsahuje seznam literatury
Diglyphus isaea Walker (Hymenoptera: Eulophidae) is an important ectoparasitic wasp of many leaf miners. Ability of D. isaea to find hosts placed in artificial mines and for its larvae to pupate when the larva is not in a mine was studied. Artificial mines consisted of slits cut in index card sandwiched between two cover slips. Almost 80% of the neonate larvae of D. isaea located host larvae in artificial mines compared to only 50% of those not in a mine. Mature larvae removed from mines did not construct normal pupal chambers. Nonetheless, they pupated and emerged successfully. Larvae of Liriomyza sativae Blanchard (Diptera: Agromyzidae) in mines are more likely to be attacked than those not in mines. Moreover, when close to a host larva this parasitoid can use vibrational cues to locate the larva in a mine. In addition, this parasitoid also did not always use volatile and gustatory cues for short range location of hosts. However, adult females of D. isaea more quickly located L. sativae larvae in the presence of the odour of juice extracted from an uninfested host plant. We conclude by proposing that the host mine is the medium by which the vibrations generated by the host larva are transmitted, which are probably the most important cue used by female D. isaea searching for hosts. That is this parasitoid first perceives mines not host larvae. These results will be helpful for developing techniques for the mass rearing of D. isaea in the future., De Yu Zou, Hong Yin Chen, Li Sheng Zhang., and Obsahuje seznam literatury