Is male back space limiting? An investigation into the reproductive demography of the giant water bug,Abedus indentatus (Heteroptera: Belostomatidae)

Because male giant water bugs in the subfamily Belostomatinae provide parental care by brooding eggs on their back, an accurate assessment can be made of both the actual and potential reproductive capacity of males. Two operational sex-ratio (OSR) indices were developed and empirically measured for a population of giant water bug, Abedus indentatus,in California. One index was based on reproductive rates measured in the laboratory; the other index was based on reproductive resources observed in the field. Both OSR indices suggest that the operational sex ratio fluctuates between maleskewed ratios in the summer and femaleskewed ratios in the winter. This pattern appears to be the consequence of two factors. First, the adult sex ratio is significantly female biased. Second, although males can outreproduce females at high ambient temperatures, the reverse is true at low temperatures. Possible reasons for the female-skewed adult sex ratio are examined, including differential recruitment, differential mortality, and sampling bias.     

Sex chromosome pre-reduction in male meiosis of Lethocerus patruelis (St?l, 1854) (Heteroptera,Belostomatidae) with some notes on the distribution?of?the species

The karyotype and meiosis in males of giant water bug Lethocerus patruelis (Heteroptera: Belostomatidae: Lethocerinae) were studied using standard and fluorochrome (CMA₃ and DAPI) staining of chromosomes. The species was shown to have 2n = 22A + 2m + XY where 2m are a pair of microchromosomes. NORs are located in X and Y chromosomes. Within Belostomatidae, Lethocerus patruelis is unique in showing sex chromosome pre-reduction in male meiosis, with the sex chromosomes undergoing reductional division at anaphase I and equational division at anaphase II. Cytogenetic data on the family Belostomatidae are summarized and compared. In addition, the structure of the male internal reproductive organs of Lethocerus patruelis is presented, the contemporary distribution of Lethocerus patruelis in Bulgaria and in the northern Aegean Islands is discussed, and the first information about the breeding and nymphal development of this species in Bulgaria is provided.     

Is egg carrying attractive? Mate choice in the golden egg bug (Coreidae,Heteroptera)

In several species of fish, females select males that are already guarding eggs in their nests. It is a matter of debate as to whether a female selects a good nest site for her offspring (natural selection) or a male for his attractiveness (sexual selection). The golden egg bug, Phyllomorpha laciniata Vill, resembles fish in the sense that mating males carry more eggs than single males, but in the bugs, female mate choice is decoupled from egg site choice. The sexual selection hypothesis predicts that if females select males using male egg load as a cue for male quality, they should not mate with a male when eggs are removed, regardless of his mating attempts. When individual females were enclosed with an egg-loaded male and an unloaded male, they mated equally often with both males, although the loaded males courted more. In addition, when only successful males were used, females mated equally often with the loaded male and the unloaded male irrespective of sex ratio. Male choice rather than female choice affected mating frequency when sex ratio was equal. Therefore, females do not select the male by the eggs he carries, but successful males may receive many eggs due to egg dumping by alien females while they mate or as a consequence of mate guarding.     

The salivary secretions of a plant-sucking bug,Oncopeltus fasciatus (Dall.) (Heteroptera: Lygaeidae)—III Origins in the salivary glands

The physical and chemical properties of the contents of the salivary glands are discussed in relation to the properties of the emitted salivary secretions, and the following conclusions are drawn. Sheath material originates as two distinct secretions, produced respectively in the anterior and lateral lobes. The precursors are elaborated as concentrated solutions of critical composition, and withdrawal or addition of water causes coagulation with hydrogen bonding; but the action of the oxidase secreted by the accessory gland is probably necessary to confer the final chemical and physical stability shown by sheath material. The watery saliva which is ejected independently of sheath material originates in the posterior lobe, but it may also contain mucoids secreted by the accessory gland or by the ducts generally.     

Good bug, bad bug: in the case of enteric inflammatory disease does the epithelium decide?

Many studies demonstrate that intestinal inflammation is either initiated or exaggerated by a component of the normal microbiota, most likely commensal bacteria or products derived from these organisms. We review the nature of human inflammatory bowel disease, the evidence for the involvement of the normal bacterial flora in these disorders and the relevance of maintaining the integrity of the epithelial barrier. Moreover, we, and others, have shown abnormal mitochondria structure in tissue resections from patients with inflammatory bowel disease and tissues from rodents that demonstrated psychological stress-induced increases in epithelial permeability. Thus, we also consider the possibility that a defect in epithelial mitochondrial function would predispose an individual to respond to their commensal bacteria flora--no longer considering them as a beneficial passive inhabitant, but rather perceiving them as a threatening and pro-inflammatory stimulus. In support of this postulate, we discuss our recent findings from an in vitro model showing that the human colon-derived T84 cell line exposed to the metabolic stressor, dinitrophenol, and the non-pathogenic, non-invasive, Escherichia coli (strain HB101) display a loss of barrier function, increased signal transduction and increased production of the chemokine, interleukin 8.     

The Nabidae (Insecta,Hemiptera, Heteroptera) of?Argentina

In Argentina, five genera and 14 species are recorded in the subfamilies Prostemmatinae and Nabinae: Hoplistoscelis sordidus Reuter, Lasiomerus constrictus Champion, Metatropiphorus alvarengai Reuter, Nabis argentinus Meyer-Dür, Nabis (Tropiconabis) capsiformis Germar, Nabis faminei Stål, Nabis paranensis Harris, Nabis punctipennis Blanchard, Nabis roripes Stål, Nabis setricus Harris, Nabis tandilensis Berg, Pagasa (Pagasa) costalis Reuter, Pagasa (Lampropagasa) fuscipennis Reuter and Pagasa (Pagasa) signatipennis Reuter.     

Should the mirid,Eccritotarsus catarinensis (Heteroptera: Miridae), be considered for release against water hyacinth in the United States of America?

Between one and seven biological control agents have been released against water hyacinth (Eichhornia crassipes (Mart.) Solms) in at least 30 countries, with varied success. A mirid, Eccritotarsus catarinensis (Carvalho) (Heteroptera: Miridae), the most recent agent released, is damaging to the plant on the African continent. It could be useful in the USA where water hyacinth remains a problem, but its introduction remains in doubt because during host specificity trials, it developed on Pontederia cordata L. (pickerelweed), indigenous to the USA. However, it did not establish on pickerelweed monocultures during South African field trials, and only light spillover feeding occurred where the two plants coexisted suggesting that the use of P. cordata as a host is a laboratory artefact and it may be suitable for use in the USA, if its thermal physiology allows establishment. We reran models developed for South Africa using CLIMEX to predict whether the mirid will establish where water hyacinth and pickerelweed co-occur, but not where pickerelweed occurs in the absence of water hyacinth. The models suggest that the mirid's distribution will be limited by cold winter temperatures and insufficient thermal accumulation to the southern states of the USA, within the main distribution of water hyacinth. Even though some spillover feeding on pickerelweed might result where the two plants co-occur, the risk of population level effects seems minimal and the risk to more northern pickerelweed negligible. The benefits, including improved habitat for pickerelweed, associated with further suppression of water hyacinth, outweigh the minimal risk of collateral damage to pickerelweed.     

Taxonomic review of the lace bug genus Omoplax (Hemiptera: Heteroptera: Tingidae) endemic to “Oriental Galapagos” (the Ogasawara Islands,Japan) with the description of its new allied genus and species

In this study, we revise the lace bugs (family Tingidae) from the Ogasawara Islands, Japan (also known as the “Oriental Galapagos”). Three species belonging to two endemic genera are recognized: Acanthomoplax tomokunii gen. et sp. nov. , Omoplax desecta (Horváth, 1912), and O. majorcarinae Guilbert, 2001. A key to species is provided to facilitate the identification of Ogasawaran lace bugs.     

The salivary secretions of a plant-sucking bug,Oncopeltus fasciatus (Dall.) (Heteroptera: Lygaeidae)—II physical and chemical properties

Histochemical tests indicate that the material which forms the stylet sheath contains a lipoprotein, is rich in tyrosine, and contains traces of tryptophan. Chitin and carbohydrate appear to be absent. There is no evidence that pectic substances can diffuse into the material from plant tissue. Sheath material is probably stabilized mainly by carbonyl-imino linkages, but there is evidence of additional aromatic bonding. The material shows similarities to the lipoprotein of the cockroach cuticle before the onset of final tanning and hardening, when it has been suggested that circular lipoprotein is ‘self-tanned”. The watery saliva appears to contain mucoprotein.     

Studies of the male reproductive system of the amphipod Orchestia platensis Kr?yer (Crustacea: Amphipoda)

Morphological details of the testis, seminal vesicles and vas deferens of Orchestia platensis are described. The follicular lumen of the mature testis contains spermatogonia, spermatocytes, spermatids and spermatozoa. The histochemical nature of the testis and the vas deferens is elucidated. The spermatozoa and vas deferens contain acid sulphated mucopolysaccharides and neutral mucopolysaccharides. In addition, they contain basic proteins, disulphide groups, lipids, phospholipids, RNA and DNA.     

Is period gene causally involved in the photoperiodic regulation of reproductive diapause in the linden bug, Pyrrhocoris apterus?

Earlier experiments demonstrated a strong up-regulation of per mRNA in wild-type (Wt) females of Pyrrhocoris apterus reared under diapause-inducing short days, while per mRNA levels were low in females of two non-diapause mutant strains (Nd), irrespective of photoperiod. In the present study, different sequences of per DNA in two strains of geographically different origin enabled us to analyse genetic linkage between the per gene and the Nd phenotype. Crosses between Wt females originating from C. Budejovice (Czech Republic) and Nd males originating from Lyon (France) resulted in F(2) progeny where 411 females entered diapause under short days and 120 females were reproducing. Thus, the segregation was very close to the 3:1 ratio in favour of diapause females, suggesting that the Nd trait behaves as a single autosomal recessive. Analysis of DNA in 20 females of the F(2) progeny revealed that their phenotype was not linked to the per genotype. We conclude that the per gene is not primarily responsible for the block to diapause photoresponsiveness in Nd mutants and its role, if any, is downstream from other gene(s) controlling diapause. This is the first attempt at genetic linkage analysis between a bona fide circadian clock gene and photoperiodism in a "non-drosophilid" species.     

Is the replication of somatic coliphages in water environments significant?

Somatic coliphages are amid several groups of bacteriophages that have been suggested as indicators in water quality assessment. One of the limitations frequently endorsed to somatic coliphages as indicators is that they can replicate in the water environment. This review intends to evaluate the significance of this potential replication. In view of: the threshold densities of somatic coliphages and host bacteria needed for productive infection to occur, the densities of both host cells supporting somatic coliphages replication and these phages in water environments, and the poor contribution of lysogenic induction to the free somatic coliphage numbers in water, it can be concluded that replication of somatic coliphages in waters is very unlikely. Consequently, the contribution of replication in the environment of somatic coliphages is expected to have a non-noticeable influence on the numbers of somatic coliphages detected in water environments. Thus, the replication in the environment should not be argued as a limitation to the use of somatic coliphages as indicators.     

Are semi-aquatic bugs (Heteroptera: Nepomorpha) indicators of hydrological stability of permanent ponds?

The composition of semi-aquatic bug communities from eight permanent ponds from southern Transylvania was investigated between 2001 and 2004. Three of the ponds were sampled repeatedly throughout the active period of the year, while the other five were sampled only once. Microvelia reticulata (Burmeister, 1835) and Gerris argentatus Schummel, 1832 were the dominant species from the thoroughly investigated habitats. Statistical analysis proved that each of the sampled species has specific habitat preferences in relation to the modifications of the hydrological regime of the ponds (reflected by the modifications of open water areas, station sizes, and percentages of vegetation coverage). The results, obtained from the three habitats investigated throughout the active period, were confirmed by the samples taken from the other five habitats opening the discussion about the use of semi-aquatic bug communities as bioindicators of the hydrological regime for permanent ponds.     

Evolution of body colouration in killifishes (Cyprinodontiformes: Aplocheilidae,Nothobranchiidae, Rivulidae): Is male ornamentation constrained by intersexual genetic correlation?

Sexual selection drives the evolution of exaggerated traits in males of many animal species. Nevertheless, the response to this selective pressure can be constrained by genetic correlation between sexes. This hypothesis predicts that costly ornamental structures selected for only in males appear also in females, at least because both sexes share most of their genomes. If a trait bears no fitness advantages to females, its expression should reflect a compromise between selection for hypertrophy in males and natural selection favouring reduction of ornamentation in females. Therefore, extravagant male ornaments should evolve predominantly under weak intersexual genetic correlation. Here, we explore the role and evolutionary stability of the constraint imposed by intersexual genetic correlation in the evolution of body colouration in three species-rich families of killifishes. Across most killifish lineages, the evolutionary changes in male and female variegation were correlated, which identifies intersexual genetic correlation as an important factor in the evolution of killifish colouration. Several lineages overcame the constraining intersexual genetic correlation and evolved extremely conspicuous colouration in males together with plain colouration in females. Hormonal manipulations in two species from closely related genera (Nothobranchius and Fundulopanchax) differing in magnitude of sexual dichromatism suggest that pronounced sexual dimorphism in variegation evolved via disappearance of vivid body colours in females and extension of androgen-linked vivid colouration over body surface in males.     

Is Cooperative Breeding Associated With Bigger Brains? A Comparative Test in the Corvida (Passeriformes)

The cognitive demands of a social existence favour the evolution of relatively large brains and neocortices in primates. Comparable tests of sociality and brain size/structure in birds have not been performed, despite marked similarities in the social systems of birds and mammals. Here, we test whether one aspect of avian sociality, cooperative breeding, is associated with an increase in brain size across 155 species of the passeriform parvorder Corvida. Using conventional and phylogeny‐corrected statistics, we examined the correlated evolution of relative brain size and: the presence/absence of cooperative breeding, percentage of nests that are cooperative and cooperatively breeding group size. Most of the comparisons yielded non‐significant results, which suggests that cooperative breeding is not related to relative brain size in this parvorder. There are a number of potential explanations for our findings. First, changes in brain region size may be correlated with cooperative breeding without affecting overall brain size. Secondly, cooperatively breeding birds might not possess more complex social behaviour than non‐cooperatively breeding birds. Thirdly, relatively large brains might be ancestral in this parvorder. This may predispose them to evolve the range of complex behaviours found in this group, including extreme sociality. Finally, ecological and/or developmental factors might play a more significant role than social behaviour in the diversification of avian brain size. Assessing these alternatives requires more information on the neural and cognitive differences between bird species.     

Too hot to handle? Phenological and life‐history responses to simulated climate change of the southern green stink bug Nezara viridula (Heteroptera: Pentatomidae)

The effect of simulated climate change on Nezara viridula was studied close to the species' northern range limit in Japan. Insects from the same egg masses were reared for 15 months in 10 consecutive series under quasi‐natural (i.e. outdoor) conditions and in a transparent incubator, in which climate warming was simulated by adding 2.5 °C to the outdoor temperature. The warming strongly affected all life‐history and phenological parameters. In the spring, the simulated warming advanced the timing of postdiapause body colour changes and reproduction. In the early summer, it increased egg production and accelerated nymphal development. In the late summer (the hottest season), the effect of the simulated warming was strongly deleterious: nymphs developed slowly, suffered higher mortality and had difficulties during final moulting; the emerged females were smaller, some exhibited abnormal cuticle, produced fewer eggs and had a decreased life span. In the autumn, the warming accelerated nymphal development, resulted in larger female size, affected the timing of the diapause‐associated adult body colour change from green to russet and enhanced preparation for overwintering. Larger females had higher winter survival rate than smaller females. The warming strongly increased survival rate in both size classes and allowed smaller females to reach the same winter survival rate as larger females had under the quasi‐natural conditions. The winter survival also differed between the green and dark‐coloured females under the quasi‐natural, but not under the warming conditions. However, under the warming conditions, green females survived the winter even better than dark‐coloured females did under the quasi‐natural conditions. The warming also shortened the life span of females from the summer generations and prolonged it in those from the autumn generation. It is concluded that even a moderate temperature increase (+2.5 °C) in the future is likely to have a complex influence upon insects, strongly affecting many of their life‐history and phenological parameters.