Three experimental groups of adult females of Pyrrhocoris apterus (reproductive brachypterous, diapausing brachypterous, and macropterous with non-diapause type of reproductive arrest) were analysed for their dose dependency of adipokinetic response, sensitivity of the fat body to Pya-AKH and locomotor activity during a 24 hour cycle. The greatest adipokinetic response (lipid elevation after hormonal treatment) was observed in macropterous, lower in diapausing brachypterous and the lowest in reproductive brachypterous females. Macropterous females also exhibited the highest activity of walking, while the lowest locomotor activity was found in diapausing brachypters. Diel changes of adipokinetic response were recorded in all three experimental groups, with maximal response occurring during the day at 6-7 h after the onset of light. On the contrary, the minimal adipokinetic response was found in the night and early after the onset of light. No significant differences in diel rhythms were observed between groups exposed to various day lengths. Diel changes in locomotor activity were found only in reproductive brachypterous females and females of macropterous morph, and showed a diurnal rhythm with only one peak of activity during a 24 hour cycle. In the latter, the rhythmic pattern of walking activity was positively correlated with diel changes of adipokinetic response. This indicates an important role of Pya-AKH in dispersal strategy of macropterous females of this heteropteran.
Velia currens (Fabricius, 1794) and V. gridellii Tamanini, 1947 are two South European species of Veliidae, whose ecology and behaviour are poorly known. The aims of this study were to investigate their life histories, quantify occurrence of wing polymorphism and gather information on their degree of co-occurrence. Nine different populations were regularly surveyed from April to November 2010. Furthermore, a dataset containing information on the occurrence of the two species and the presence of winged morphs at 294 sites was compiled from museum collections, private collections and published literature. No evidence for multivoltinism was detected in either species. However, oviposition and and/or hatching were protracted in time so that early-instar nymphs and adults co-occurred up to midsummer. Although their distributional ranges completely overlap at a large spatial scale, the two species co-occurred only rarely at the same sites and the degree of co-occurrence was lower than expected by chance. Winged specimens were rarely recorded. At least in V. gridellii, the numbers of winged individuals were inversely related to the altitudes of the sites. During the summer, when some of the streams surveyed dried up, several specimens were found in an apparent state of lethargy, under stones. It is hypothesized that the ability to aestivate, coupled with the ability to walk from one site to another may reduce the advantage associated with producing winged forms and account for the low rate of occurrence of macropterism in these species., Fabio Cianferoni and Giacomo Santini., and Obsahuje seznam literatury
The trade-off between flight capability and reproduction is well known in adult males of insects with wing dimorphism but the reproductive advantage of short-winged (SW) males over long-winged (LW) males appears to vary across insect taxa. In the present study, we determined the difference in the mating ability of SW and LW males of Velarifictorus ornatus (Orthoptera: Gryllidae) in order to evaluate whether the SW male morph has a reproductive advantage. We found that the choice of a mate depended on the female. Compared with LW males, SW males had an obvious mating advantage when both SW and LW males courted females simultaneously, and that dealation significantly enhanced the mating ability of LW males. Losing the ability to produce songs reduced the mating advantage of SW males, thereby indicating that the greater mating advantage of SW males was related to the attractiveness of the song. In addition, the difference in the mating ability of LW and SW males was not related to body size or age. These results indicate that SW males of V. ornatus have a mating advantage over their LW counterparts because their underdeveloped flight muscles allow them to devote more resources to reproduction., Lv-Quan Zhao, Huai-Lin Chai, Hong-Jun Wu, Dao-Hong ZhuU., and Obsahuje bibliografii
New aspects of the life-cycle of the flightless wing-polymorphic bug Pyrrhocoris apterus (L.) are described. It was found that 1.1-14.9% of the adult females of P. apterus in 11 samples collected from 4 populations in the South Bohemia had mated prior to entering diapause and their ovaries were in the pre-vitellogenic stage of development with viable sperm in their spermathecae. Some of these females successfully overwintered. The percentage of overwintering females that had been fertilized ranged from 1.1 to 7.2 % and depended on the month and year of collection. The results indicate that pre-diapause mating and overwintering of fertilized females is not unusual in populations of P. apterus in the Czech Republic and and that sperm in overwintering female survives for at least 7-8 months.