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.
Acidic methanolic extracts of haemolymph, cuticle and eyes of larvae and adults of the migratory locust, Locusta migratoria migratorioides (R. et L.), were subjected to thin layer chromatography. The Rf-values as well as the fluorescent colour of the spots under ultraviolet illumination at 350 nm, were compared to those of 12 pteridine standards. Most of the standards showed a major spot, as well as up to 3 additional minor spots, probably due to the presence of isomers and degradation products. The extract of the haemolymph of untreated larvae and adults yielded 6 different spots. Cuticle and eyes had their own specific pattern. Application of methoprene (analogue of juvenile hormone) induced solitary phase-like pigmentation of the cuticle and green-coloured haemolyph. The content of pterin, biopterin, leucopterin, isoxanthopterin, and probably also of lumazin, increased. The melanization of the cuticle nearly completely disappeared. Similar, but weak effects were observed in neem-oil treated locusts. Application of precocene caused a number of changes in the pigment pattern of all extracts. It also induced some melanization of the cuticle in particular in larvae. Many pigment spots were observed which did not correspond to any of the 12 standard pteridines. The classical concept about the pigment composition of locust haemolymph, namely that it is restricted to melanin, carotenes and biliverdin, needs modification.