Mechanisms of the suppression of gonadotropic activity of the corpus allatum (CA) in macropterous females were compared with those previously reported for either diapause or starving non-diapause brachypterous females by reciprocal transplantations of the neuroendocrine complexes (comprising the brain-suboesophageal ganglion-corpora cardiaca-CA). The denervated CA stimulated reproduction in most females of all experimental groups suggesting an inhibition of the CA via nervous connections with the brain. The inhibition of the CA within the transplanted neuroendocrine complex was measured by the reproductive performance of feeding recipient females deprived of their own CA. The complex from starving non-diapause brachypterous females stimulated reproduction in 58.3-78.9% of recipients suggesting that the inhibition of the CA was mostly overcome by the stimulating internal milieu of feeding females. In contrast, the "macropterous" complex stimulated reproduction in only 18.8-37.5% of recipients, similar to the "diapause brachypterous" complex (32.0%). The results indicate that the "macropterism", similar to the diapause, is associated with a considerably lower responsiveness of the neuroendocrine complex to humoral stimulation by feeding compared to the responsivenes of the "starving" complex from brachypterous non-diapause females. On the other hand, the CA of macropterous females is of intermediate size between that of the feeding non-diapause and diapause brachypterous females, similar to the CA of the non-diapause brachypterous females deprived of food. Overall, the data suggest that the suppression of the CA activity results from a combination of the diapause-like refractoriness of the neuroendocrine complex with the starvation-like inhibition of the CA growth. Regulation of the CA activity is discussed in relation to the "oogenesis-flight syndrome" recorded for flying wing-polymorphic species of insects.
We studied the development of the indirect flight muscles and reproductive organs in long-winged (macropterous) adults of the flightless bug Pyrrhocoris apterus (L.) and the factors involved in flight muscles histolysis by means of total protein analysis. Both the extirpation of the corpus allatum, an endocrine gland that is the sole source of juvenile hormone, and sham operation accelerated histolysis and decreased the level of the total protein content of the flight muscles to the same extent. Degeneration of flight muscles was not a result of allatectomy but rather a consequence of injury, followed by resumption of enhanced food intake, because it was stimulated also by the removal of wings. Transfer of penultimate instar larvae to a diapause-inducing short-day photoperiod did not prevent imaginal growth and histolysis of flight muscles, but inhibited growth of ovaries in females and maturation of accessory glands in adult males. Thus inactivation of the corpus allatum in diapausing macropters does not prevent imaginal growth of their flight muscles. Application of a high dose of methoprene to the surface of intact long-day macropterous adults induced precocious histolysis of flight muscles and growth of ovaries in females and accessory glands in males. Prolonged starvation of macropterous adults had only a small effect on the histolysis of their flight muscles. The results indicate that imaginal growth and histolysis of indirect flight muscles in macropterous individuals of P. apterus are largely juvenile hormone-independent processes that are programmed to occur spontaneously, but can be affected by various internal and external factors.
n this study we addressed a question of whether experimental manipulations that increase life span also reduce physical activity and molecular oxidative damage. We used three phenotypes of male and female Pyrrhocoris apterus that survive for different lengths of time, diapausing insects, reproductive insects and insects from which the corpus allatum, the source of juvenile hormone, was surgically removed. Protein carbonyl content of the thoracic muscles was used as an index of molecular oxidative modification. Diapause or ablation of the corpus allatum (allatectomy) was associated with an extended life span of both sexes, but only those individuals that were in diapause were less active. The carbonyl content, both relative (per protein unit) and absolute (per thorax) increased with age in reproductive insects of both sexes. However, the associations between the carbonyl content and diapause and allatectomy differed in males and females. In males, the carbonyl content was not associated with either diapause or allatectomy. There was no age-related increase in the relative and absolute carbonyl levels in diapausing females, while only the increase in the relative carbonyl level was absent in allectomized females. Overall, the results indicate that both allatectomy and diapause prolonged life span, but had different and sex-specific effects on locomotor activity and carbonyl content. Only the extension of the life span of diapausing females was correlated with both reduced locomotor activity and reduced carbonyl content., Marcela Buricova, Magdalena Hodkova., and Obsahuje seznam literatury