In the present study the temporal changes in the volume of the corpus allatum in three experimental groups of adult males (macropterous, reproductive brachypterous and diapausing brachypterous) of the flightless bug Pyrrhocoris apterus were determined and related to the size of male accessory glands. The results revealed wing morph- and age-dependent differences in the corpus allatum volume in males of this bug. In 4-14 day old males, the volumes of the corpus allatum and accessory glands were largest in long-day reproductive brachypters, intermediate in long-day macropters, and smallest in short-day diapausing brachypters. The smaller corpus allatum in young macropterous males than in same aged reproductive brachypterous males was due to the spontaneous fasting of the former. Later, starting on day 18 after adult emergence, i.e. when macropterous males were feeding normally, there were no significant differences in the volumes of the corpus allatum between long-day brachypterous and macropterous males. On the other hand, the corpus allatum of 18-28 day old diapausing brachypterous males was significantly smaller than that of same aged long-day macropterous and reproductive brachypterous males. The sizes of the corpus allatum and accessory glands were significantly positively correlated in macropterous and diapausing brachypterous males. This is the first report of corpus allatum volume-dependent wing morph-related differences in the rate of accessory gland maturation in males of insects with a non-functional macropterism. The role of differential activity of the corpus allatum in the different life history strategies of males of the two wing morphs in this wing-polymorphic insect is discussed.
The long-winged (macropterous) and short-winged (brachypterous) adult males of Pyrrhocoris apterus (L.) from temperate (Czech Republic) and Mediterranean (Israel) populations were analysed for the sexual activity and the functional activity of their accessory glands. The sexual activity of the males reared either under long-day (18L : 6D) or short-day (12L : 12D) conditions was determined by their capability to mate with 5-day-old reproductive females of the brachypterous morph and to fertilize the eggs. The functional activity of accessory glands was characterized by the presence of a specific immuno-marker. Sexual activity of fasting macropterous males from both temperate and Mediterranean populations was almost as high as that observed in the reproductive brachypterous ones. These findings were also confirmed by an immunotest. Contrary to the temperate macropterous males, the feeding arrest in temperate macropterous females was coupled with a non-diapause inhibition of reproduction in spite of long days. A similar kind of difference was observed also in the Mediterranean macropterous bugs reared under short-day conditions. The results showed the sexual difference in reproductive activity of the macropterous morph in P. apterus.
The aim of the present study was to test the hypothesis that short-winged (brachypterous) and long-winged (macropterous) adult males of a flightless bug Pyrrhocoris apterus differ in fertilization success. For this purpose, 5, 10 and 28 days old brachypterous and macropterous males were mated for the same period of time with reproductively active 5 days old brachypterous females. The average hatchability of five egg batches of these females was used as a measure of the fertilization success of the males. The results revealed significantly higher hatchability of the eggs laid by females that copulated with 5 or 10 days old brachypterous males than with same-aged macropterous males. In contrast, the average hatchability of eggs of females that copulated with 28 days old brachypterous males was significantly lower than of those mated with same-aged macropterous males. It is the first report of wing morph- and age-related differences in fertilization success of males in insects with a non-functional wing-polymorphism. The possible relationship between wing- and age-related differential fertilization and the mating success of P. apterus males, and differences in the amount of secretion transferred from their accessory glands into the reproductive tract of females during copulation, is discussed.