In the laboratory, not all females of the seed bug Lygaeus simulans Deckert, 1985, produced fertilized eggs after copulation: 26.7% of the females were not inseminated and 5% were inseminated but did not lay fertilized eggs; only in 40% of the couples did copulation result in fertile eggs. The remaining 28.3% of couples refrained from mating. Duration of copulation was associated with insemination and fertilization: (i) fertile eggs were produced by only one couple that copulated for less than 60 min and all those that copulated for more than 360 min, (ii) probability of fertilization increased steadily with duration of copulation between 60 and 360 min, and (iii) duration of copulation was significantly different for couples that showed different insemination status.
A possible morphological explanation for this rime dependency was revealed by examining the genitalia of 69 couples freeze-fixed in copula after different periods in copulation. Because of the intricate structure of the genitalia in L. simulans, a male takes a long time to manoeuver its intromittent organ into the narrow insemination duct of the female. Only if completely inserted is the tip of the intromittent organ close enough for successful ejaculation of sperm into the spermatheca. The freeze-fixing experiment revealed that it usually took the male more than 30 min to locate the entrance to the insemination duct and another 30 min for full penetration. This explains why copulations that lasted less than 60 min failed, since insemination began only after intromission was complete.
The experiments, therefore, indicated that there is a relationship between the complex morphology of the genitalia and the low rates of insemination and fertilization in L. simulans., Thomas Micholitsch, Peter Krügel, Günther Pass, 7 obrázků, 1 tab., and Lit.
The Coreidae (Heteroptera) have holokinetic chromosomes and during male meiosis the autosomal bivalents segregate reductionally at anaphase I while the sex chromosomes do so equationally. The modal diploid chromosome number of the family is 2n = 21, with a pair of m-chromosomes and an X0/XX sex chromosome system. A 2n = 24/26 (male/female) and an X1X20/X1X1X2X2 sex chromosome system were found in Spartocera batatas (Fabricius). C-banding and fluorescent-banding revealed the presence of AT-rich heterochromatic bands medially located on all the autosomes, and one telomeric band on both the X1 and X2 chromosomes. This banding pattern differed from the telomeric heterochromatin distribution found in most other heteropteran species. The X1 and X2 chromosomes were intimately associated during male meiosis and difficult to recognize as two separate entities. Based on a comparison with the behaviour of sex chromosomes in other coreids and other heteopterans with multiple sex chromosomes it is suggested that the particular behaviour of X1 and X2 chromosomes in coreid species with multiple sex chromosome systems evolved as an alternative mechanism for ensuring the proper segregation of the sex chromosomes during meiosis.
In Mormidea paupercula (n = 6 + XY in males), the presence of a CMA3-bright band in the telomeric regions on both sex chromosomes allowed the analysis of the kinetic activity of the sex univalents and XY pseudobivalent at the first and second meiotic divisions, respectively. The separation of the sister chromatids of the sex chromosomes occurs from a pair of telomeric regions (with or without a band), with opposite telomeric regions remaining associated with each other at meiosis I; the behaviour of both sex chromosomes differs, on the X chromosome both telomeric regions are similarly active, while on the Y chromosome the telomeric region without a band is more frequently active. At the second division, the most frequent associations in the pseudobivalent occur between the telomeric regions of both sex chromosomes with bands or without bands. Therefore, in both meiotic divisions, the same telomeric region on the sex chromosomes could lead the migration, in contrast to that observed usually in autosomal bivalents. These results provide evidence that the sex chromosomes of Heteroptera show more than one pattern of attachment to the spindle.
Studies on the effect of varying light intensity on the spatial distribution of flying insect communities are rare, particularly in complex ecosystems like forests. The horizontal and vertical distribution of Heteroptera was studied at different scales in a large deciduous forest area, the "Steigerwald", in southern Germany. Diversity was affected by (1) vertical position: it was significantly higher near the ground than in the canopy of beech-dominated forests but similar in oak-dominated forests; within the canopy of beech-dominated forests, diversity was significantly higher in the upper than in the lower canopy of intermixed oak trees but similar in beech trees; (2) canopy cover, but in oak forests the response depended on the vertical position: increasing significantly close to the forest floor with decreasing canopy cover, but showing an opposite trend in the canopy; so that in sparse stands (little canopy cover) diversity was significantly higher near the ground, whereas where the forest canopy was medium or dense diversity was higher in the canopy. Moreover, community composition of Heteroptera near the ground differed from that in the canopy in both forest types and near the ground between stands in oak-dominated forest that had canopies of different densities. Results clearly indicate that light intensity is an important direct or indirect factor structuring Heteroptera communities. While in the canopy differences in leaf quality and microhabitats might be important, near the forest floor it is more likely to be the diversity of herbaceous plants.
The mating behaviour of Pyrrhocoris apterus in the laboratory is well studied, but little is known about it under natural conditions. In natural populations in Central Europe, overwintered adults start copulating in March and continue until their death. Caged females, kept under natural conditions in the permanent presence of males, copulated repeatedly. Their mating activity increased sharply until early April, then very slowly until the end of June and then declined as the females die-off. Half of copulations were short (< 5 h) and only 9% were longer than 1 day. By contrast, in natural populations, mating activity (percentage of individuals involved in copula) reached its maximum in April and then decreased until early July, when the overwintered adults die. The decline in mating frequency (percentage of adults involved in copula) was associated with a decrease in the availability of receptive females towards the end of the mating period. For a female, repeated copulation is necessary because sperm is nearly depleted after insemination of 3-5 egg batches.
Species of Pentatomidae are cytogenetically characterized by the presence of holokinetic chromosomes, a pre-reductional type of meiosis, and a great constancy not only in chromosome number (2n = 14 in 85% of the 250 species analyzed) but also in the sex chromosome determining system (XY/XX).
Edessa meditabunda and E. rufomarginata males have 2n = 14 = 12 + XY, and both species present small telomeric positively heteropycnotic bands which are DAPI and CMA bright. In E. meditabunda the NOR region is clearly revealed at the telomeric region of the largest autosomal pair by silver staining and CMA banding. Meiotic behaviour of both species follows the general pattern of the order: autosomes divide pre-reductionally, sex chromosomes are achiasmatic and divide postreductionally, and at both metaphase plates the autosomes become arranged in a circle with the sex chromosomes lying at its center. In E. meditabunda, however, the larger sex chromosome is generally observed at metaphase I forming part of the ring of autosomal bivalents. Bivalents with two chiasmata are frequently observed in E. meditabunda and E. rufomarginata; mean chiasma frequency (6.45 and 6.26, respectively) differ significantly between both species, but differences between populations within each species are not significant.
The metaphase plate arrangement of autosomes and sex chromosomes is rather constant in Heteroptera. However, our results in E. meditabunda together with previous reports in other species of the order led us to suggest that the metaphase plate arrangement is more liable to variation at the first meiotic division than at the second one, when it is almost constant. The presence of ring bivalents in both species here analyzed constitutes further evidence against the previous statement of only one chiasma per bivalent in Heteroptera.
Structures that assist in spreading secretions produced by the metathoracic glands were examined in Reduviidae and Pachynomidae (Heteroptera). The systematic distribution of a row of long and stout setae on the metacoxa, the metacoxal comb, was reinvestigated in a representative sample in both taxa. Observations on living Dipetalogaster maximus (Reduviidae: Triatominae) corroborated the interpretation of this metacoxal comb as an evaporatory device, which assists in atomizing the gland secretions. In addition to the metacoxal comb, a row of stout setae on the metacetabulum - a metacetabular comb - was found in several Reduviidae, which interacts with the metacoxal comb during rotation of the metacoxa. In addition to those atomizing devices, cuticular modifications surrounding the opening of the metathoracic gland, which presumably form evaporatoria, were discovered in Ectrichodiinae. The meshwork-like structure of this cuticle resembles the cuticular modifications found associated with the opening of the Brindley's gland in Reduviidae, but differs from the mushroom-like evaporatoria around the metathoracic glands in most Cimicomorpha and Pentatomomorpha. Thus, two fundamentally different mechanisms to spread secretions of the metathoracic gland - atomization and evaporation - are present in Reduviidae.
Cuticular parts of the spermatheca and associated vaginal structures (chiefly the ring sclerites of the parietovaginal glands) have been examined and compared in 190 cydnid species representing 65 genera and all five subfamilies currently recognized in the family (Amnestinae, Cephalocteinae, Cydninae, Garsauriinae, Sehirinae). Four species belonging to genera formerly included within the Cydnidae (Dismegistus, Parastrachia, Thaumastella, Thyreocoris) were also examined. Morphology of the three main parts of the spermatheca [seminal receptacle (distal bulb), intermediate part (pump apparatus), spermathecal duct] is described. Four main types of spermathecae can be recognized from the distal receptacle and the intermediate part: the amaurocorine type (in Sehirinae: Amaurocorini), amnestine type (in Amnestinae), garsauriine type (in Garsauriinae), and "cydnoid" type (in Cephalocteinae + Cydninae: Cydnini, Geotomini + Sehirinae: Sehirini). No synapomorphy of these types was found which suggests that the currently conceived Cydnidae are not monophyletic. Moreover, out of these four types only the "cydnoid" is typically pentatomoidean due to the presence of an intermediate part usually well delimited by two flanges and having always an unsclerotized flexible zone as well as two internal cuticular structures (septum and fretum) partly obstructing the lumen. The simple tubular amaurocorine type is unusual and aberrant within all Pentatomoidea. The amnestine and garsauriine types display some similarities with taxa outside the Pentatomoidea, especially with some lygaeoid or coreoid spermathecae, mainly in the structure of the intermediate part not delimited proximally (absence of flanges) and devoid of the flexible zone. Within the "cydnoid" type, six spermathecal facies can be characterized principally according to the shape of both the apical reservoir along with the intermediate part, and the differentiations of the spermathecal duct. It has been impossible to find any synapomorphy for all species and for the six facies belonging to the "cydnoid" type of spermatheca. We suggest that the Cydnidae as defined presently are probably a polyphyletic group; moreover its main "cydnoid" branch, called by us Cydnidae sensu stricto (Cephalocteinae + Cydninae + Sehirinae: Sehirini) seems to be relatively recent among the Pentatomoidea. Nishadana and Nishocoris are transferred from Garsauriinae back to Cydninae: Cydnini and the tribe Amaurocorini (Sehirinae) is upgraded to a separate subfamily Amaurocorinae stat. nov. Moreover, we regard the Geotomini and the Sehirini both as non-monophyletic and we indicate that by appending them sensu lato (Geotomini "s. l.", Sehirini "s. l.")
As a part of ongoing cytogenetic studies on the bug family Nabidae (Heteroptera), the karyotypes and meiotic patterns of male Nabis (Aspilaspis) viridulus Spinola, 1837, N. (A.) indicus (Stål, 1873) (subfamily Nabinae) and Prostemma guttula (Fabricius, 1787) (subfamily Prostemmatinae) are described.
N. viridulus and N. indicus differ from P. guttula in their chromosome numbers, which are 2n = 32 + XY and 2n = 26 + XY, respectively, and behaviour of the sex chromosomes in male meiosis, which, respectively, show "distance pairing" and "touch-and-go pairing" in spermatocyte metaphase II. The karyotype of 2n = 34 and "touch-and-go pairing" are considered to be plesiomorphic characters in Nabidae. The evolutionary mechanisms that might underlie different chromosome numbers, the taxonomic significance of karyotype variation and the distribution of meiotic patterns in the family, are discussed.
Cephalic chaetotaxy of nymphal and adult stages of species from all the subfamilies of Cydnidae s. str. (sensu Froeschner, 1960 and Lis, 1994), namely Garsauriinae, Cephalocteinae, Cydninae, Sehirinae, and Amnestinae, was studied. Two types of setae, primary and secondary, are described, and changes they undergo during ontogeny reviewed. The adaptive, taxonomic and phylogenetic significance of the cephalic setae in the Cydnidae s. str. is discussed. A ground-plan of the original cephalic chaetotaxy of the family, and its evolution within the family Cydnidae s. str. are proposed.