Achiasmate male meiosis in two Cymatia species (Hemiptera,Heteroptera, Corixidae)

The karyotype and male meiosis, with a particular focus on the presence or absence of chiasmata between the homologs, were studied in the water boatman species Cymatia rogenhoferi (Fieber) and Cymatia coleoptrata (Fabricius) (Corixidae, Cymatiainae). It is shown that the species have 2n = 33 (28A+2m+X₁X₂Y) and 2n = 24 (20A+2m+XY) respectively, post-reduction of sex chromosomes, and achiasmate meiosis of an alignment type in males. Cytogenetic and some morphological diagnostic characters separating Cymatia Flor from the rest of Corixidae are discussed.     

Preferred egg laying sites in Palmacorixa nana (Heteroptera : Corixidae)

Female Palmacorixa nana showed clear preference for wood oviposition substrates over Elodea and plexiglass in both laboratory and field experiments. Wood was chosen because of its rigidity and rough surface. These data raise the possibility that males could gain access to females by controlling localized resources.Present address: Department 0f Entomology University 0f Alberta Edmonton, Alberta, Canada T6 G 2E3Present address: Department 0f Entomology University 0f Alberta Edmonton, Alberta, Canada T6 G 2E3     

A novel adipokinetic peptide in a water boatman (Heteroptera, Corixidae) and its bioanalogue in a saucer bug (Heteroptera, Naucoridae)

The corpora cardiaca (CC) of two water bug species, the water boatman Corixa punctata and the saucer bug Ilyocoris cimicoides, contain a substance that cause hyperlipemia in the migratory locust. The primary sequence of one octapeptide belonging to the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family was deduced from the multiple MS(N) electrospray mass data of CC material from each species. Whereas the saucer bug contains the known octapeptide pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Anaim-AKH, the water boatman has a novel peptide identified as pGlu-Leu/Ile-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Corpu-AKH. The ambiguity about the amino acid at position 2, i.e. Leu or Ile, in Corpu-AKH was solved by isolating the peptide in a single-step by reversed-phase HPLC and establishing co-elution with the synthetic peptide containing Leu at position 2. Functionally, the peptides regulate lipid mobilization, as evidenced by an adipokinetic effect after injecting synthetic Anaim-AKH and Corpu-AKH into the respective acceptor species. Swimming activity of I. cimicoides also causes hyperlipemia.     

Distributional Patterns of Chacoan Water Bugs (Heteroptera: Belostomatidae,Corixidae, Micronectidae and Gerridae)

Distributional patterns of South American species of aquatic and semiaquatic Heteroptera from the Chaco biogeographic province were analyzed. Based on a track analysis of 60 species of Belostomatidae, Corixidae, Micronectidae, and Gerridae, five generalized tracks were found:(1) Bolivia, and northwestern and central Argentina (Belostoma dallasi, Ectemnostega montana, E. quechua, E. stridulata, E. venturii, Sigara tucma, S. yala, Tenagobia pulchra, Eurygerris fuscinervis, and Trepobates taylori); (2) southern Brazil, eastern Bolivia, Paraguay, and northeastern Argentina (Belostoma bosqi, Heterocorixa brasiliensis, Tenagobia selecta tarahui, and T. schadei); (3) southeastern Brazil and northeastern Argentina, determined by Belostoma candidulum, B. testaceopallidum, Heterocorixa nigra, Sigara hungerfordi, Brachymetra furva,Halobatopsis spiniventris, Metrobates plaumanni plaumanni, and M. vigilis; (4) southeastern Brazil, Uruguay, and central western Argentina (Belostoma cummingsi, B. martini, Sigara argentiniensis, Tenagobia fuscata, and T. carapachay); and (5) southern (Trichocorixa milicorum, Sigara santiagiensis, and S. forciceps). Three panbiogeographic nodes have been determined:(1) northeastern Argentina, in the intersection of generalized tracks 2 and 3; (2) central Argentina, in the intersection of generalized tracks 1 and 4; and (3) central Argentina, in the intersection of generalized tracks 4 and 5. In spite of these complex patterns, these results show that the Chaco province appears to be a natural biogeographic area.     

The ecology of the Corixidae (Hemiptera: Heteroptera) in the Corrib catchment,Ireland

Two surveys were carried out in the Corrib catchment (Ireland) to determine the physical and chemical factors that govern the distribution of Corixidae. Of the twenty one species recorded, five species, Sigara scotti (Fieber), S. distincta (Fieber), S. fossarum (Leach), S. fallenoidea (Hungerford) and Cymatia bonsdorffii (Sahlberg) comprised 82% of the numerical total. Although individual species occurred in chemically diverse sites species assemblages and changes in the relative abundance of the majority of species and in species richness and diversity were evident in the progression from hard to soft water. High altitude soft water sites had a much lower number of species compared with chemically similar low altitude sites. In Lough Corrib, the main body of water in the catchment, most species were abundant only in sheltered areas with mud substrates and high percentage vegetation cover. Species diversity was high in these areas and either C. bonsdorffii, S. fossarum, S. fallenoidea or Callicorixa praeusta (Fieber) dominated numerically. However, S. scotti, S. dorsalis (Leach) and Arctocorisa germari (Fieber) were more abundant in exposed areas with sand, gravel or mearl substrates. In temporary ponds and in lotic water species diversity was also high but species composition (mainly C. praeusta, Sigara nigrolineata (Fieber), Corixa punctata (Illiger), C. panzeri (Fieber), C. bonsdorffii) was different to that of temporally stable lentic habitats.     

Corixidae (Hemiptera,Heteroptera) in acidic mining lakes with pH ≤3 in Lusatia,Germany

Corixids are common members of the invertebrate communities of acidic mining lakes. Different qualitative and quantitative sampling methods to capture corixids are introduced. The occurrence of corixids is recorded from mining lakes of Lusatia, Germany, with pH <3, and data on their ecology are summarized.     

The ultrastructure of the flight muscle polymorphism in Cenocorixa bifida (Hung.) (Heteroptera,Corixidae)

Adult Cenocorixa bifida (Heteroptera: Corixidae) emerging early in the year in British Columbia are all able to fly. Insects emerging in the late autumn look similar externally, but are incapable of flight: the ultrastructure of their indirect flight muscles resembles that of immature tissue, indicating a block in the normal myogenetic sequence.     

Sound production and mating in a waterboatman, Palmacorixa nana (Heteroptera: Corixidae)

Both male and female Palmacorixa nana stridulate by rubbing fields of pegs on the fore femora over thickened flanges on the maxillary plates. I sugges that the head is the sound-radiating structure and is driven into oscillation when its edges are plucked by rows of femoral pegs. P. nana males produce spontaneous, courtship, mounting and copulatory signals. The latter tow signals are produced by a new mechanism which constitutes only the third record of inter-individual stridulation in insects. The known acoustic behaviour of the female is limited to a signal indicating readiness to mate. Mating behaviour was observed and copulatory success found not to rely on a complete exchange of acoustic signals. Comparison of data from several sources indicates that corixids capable of singing can either have an obligatory or optional exchange of signals.     

Review of water bugs of the genus Micronecta Kirk. (Heteroptera,Corixidae) of the fauna of the Northwestern Caucasus

A review of the species of the genus Micronecta from the Northwestern Caucasus with a key is provided. The regional distribution of Micronecta griseola Horváth, M. poweri (Douglas et Scott), and M. pusilla (Horváth) is clarified. Micronecta anatolica anatolica Lindberg is recorded from Russia for the first time.     

Observations on the natural diet of Cymatia bonsdorfi (C. Sahlb.) (Heteroptera: Corixidae): an immunological analysis

Immunological analyses of the gut contents of 1769 adult and 486 nymphal instars of the lesser waterboatman, Cymatia bonsdorfi, from Lough Corrib, western Ireland, were performed using a double immunodiffusion technique. Antisera against six potential prey categories (Oligochaeta, Cladocera, Copepoda, Gammarus, Diptera and Ephemeroptera), identified on the basis of field and laboratory observations, were utilized. Diptera larvae formed over 90% of the diet of adult bugs and were also the principal prey group of all nymphal instars.     

Revision and description of water boatmen from the Middle-Upper Jurassic of Northern and Northeastern China (Insecta: Hemiptera: Heteroptera: Corixidae)

Four adult and immature water boatmen from the Middle Jurassic and uppermost Middle Jurassic or lowermost Upper Jurassic Jiulongshan, Haifanggou and Daohugou formations in the northern and northeastern China are described as Yanliaocorixa chinensis (Lin, 1976), Jiulongshanocorixa genuina gen. et sp. nov., and Daohugocorixa vulcanica gen. et sp. nov., referred to the extinct subfamily Velocorixinae, and Karataviella popovi sp. nov., referred to the extant subfamily Diaprepocorinae. All the forms have previously been identified as one species, Yanliaocorixa chinensis. This species, found only in the Haifanggou Formation, is absent from the Jiulongshan Formation and other sites in China. The systematic position of corixids recorded earlier from the Mesozoic of China is reviewed and reassessed. Assemblages of dominant aquatic insects from various Jurassic nonmarine sedimentary basins in northern and northeastern China are described for the first time. They are entirely different between the Jiulongshan, Haifanggou, and Daohugou formations. The first formation is probably older than the other two.     

The Stenopodainae (Hemiptera,Heteroptera) of Argentina

In Argentina, 10 genera and 33 species of Stenopodainae (Hemiptera: Reduviidae) have been recorded. Diagnoses of the genera, subgenera and species are given, and an illustrated key to genera is provided. Six species are new records for Argentina and an additional seven species represent new records for provinces.     

Replacement analysis of non-equilibrium competition between rock pool Corixids (Hemiptera,Corixidae)

Summary The resource use of rock pool Corixids Arctocorisa carinata (Sahlb.) and Callicorixa producta (Reut.) was compared in single-species and mixed populations established in the natural environment. The experimental recruitment consisted of daily transfer of newly moulted first-stage larvae to the study pools. The changes in numbers of larvae and the increase of the biomass corresponded closely to the changes in natural populations. The growth of populations was limited by elimination of the youngest individuals. The maximal biomasses attained per unit of pool surface area were same in all cases. This indicates that the species have completely overlapping resources and use them with nearly equal efficiency. The strong interference by A. carinata is an additional reason for the unstability of the competitive interaction.