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Cotton bollworm Helicoverpa armigera is one of the most polyphagous and cosmopolitan pests. Intracellular endosymbionts are widespread in Lepidoptera, often playing an important role in their dynamics. The prevalence of endosymbionts of cotton bollworm in Russia was not investigated. Cotton bollworm larvae and adults were collected in 2018–2020 in Krasnodar Area, and in Voronezh and Saratov Regions (from 131 to 170 insects) and analyzed by PCR using sets of group-specific primers for baculoviruses (locus lef8), bacteria of the genus of Wolbachia (locus wsp), and microsporidia (locus SSU rRNA). Level of infection with baculoviruses was 16 % for the sample of 32 individuals collected in Temryuk District of Krasnodar Area in 2018. The infection rate of the entire sample of 170 individuals was 2.9 %. The lef8 locus demonstrated 98.7–99.6 % of sequence similarity to the nuclear polyhedrosis virus isolates from the cotton bollworm and American bollworm. Among the tested 131 insects, bacteria of the genus of Wolbachia were not detected. PCR screening for microsporidia revealed one positive larvae among 19 insects collected in Krasnoarmeysk District of Krasnodar Area in 2019, which corresponded to the prevalence of 5 %. Partial sequencing of the genes coding for SSU rRNA and largest subunit RNA polymerase II made it possible to identify the new isolate as N. bombycis.

Beet webworm Loxostege sticticalis is a notorious pest widely distributed on the territory of Eurasia. Its outbreaks cause severe damage to crops in Russia and China. Here Wolbachia infection is reported for the first time in L. sticticalis. Larvae were sampled in Rostov, Saratov, Irkutsk Regions and Republic of Buryatia in 2005–2013. Primers targeting the wsp gene were used for the PCR screening of Wolbachia. Among 148 larvae, 35 were Wolbachia positive. Wolbachia prevalence rate ranged from 21 to 40 % in the Asian and from 0 to 47 % in the European part of Russia. The combined sample subsets were compared for European versus Asian part of Russia and 2005–2009 versus 2010–2013 timeframes. The prevalence rates of Wolbachia were not significantly different between two parts of Russia, but the endosymbiont presence (estimated for the total dataset) increased with time within the observation period.

The beet webworm Loxostege sticticalis (LS) has eruptive type of population dynamics and high migratory activity. The LS outbreaks are therefore difficult to predict and the pest belongs to the category of highly dangerous pests. However, during periods of depressions this insect is not observed within the most of its range and is very susceptible to infection by pathogens, including various species of microsporidia, some of which are not specific parasites of the order Lepidoptera. The distribution of LS microsporidia in Eurasia is quite extensive. During the study period of LS from 2003 to 2019, we have found 6 species of microsporidia. The parasite list includes not only species known for Lepidoptera such as Nosema sp. and Vairimorpha thomsoni, but also Vairimorpha (Nosema) ceranae as the typical pathogen from Apis mellifera, as well as Endoreticulatus cf poecilimonae, a pathogen similar to Endoreticulatus poecilimonae from Poecilimon thoracicus. Moreover, two isolates from the genus Tubulinosema identified in LS belong to the group of parasites with a very wide host range, including humans. In laboratory experiments, LS proved high sensitivity to microsporidia N. pyrausta from Ostrinia nubilalis and N. tyriae from Tyria jacobaeae. Its susceptibility to Paranosema locustae from Locusta migratoria has also been discovered.

Zophobas morio is a tropical darkling beetle which is widely exploited for commercial large-scale insect growing. Outbreaks of a disease may occur causing total devastation of cultures. In the present paper, samples of diseased Z. morio were obtained and used for establishment of a laboratory model as they were found infective to the larvae of the same insect species from another source. It took about 1 month to develop symptoms of acute disease in mid-age larvae and about twice as much when younger larvae were used for infection. Affected larvae perished quickly, and within several days up to 90–100% of the colony could perish. Both in healthy and diseased larvae a virus was detected using PCR with degenerate primers specific for a gene coding for a non-structural protein (ORF3). The sequenced gene fragment (Genbank accession #MN732869) confirmed allocation of the virus to Densoviridae, with maximal similarity of 97.2% to Blatella germanica densovirus-like virus (#JQ320376) and 66.2% to B. germanica densovirus (#AY189948). Genomic DNA samples of Z. morio larvae from an independent colony devoid of symptoms of a disease were also positive for this virus with a slightly different (99.7% sequence similarity to the former sequence of the Z. morio densovirus) genotype (#MN732870).

The microsporidium Nosema pyrausta is an important mortality factor of the European corn borer, Ostrinia nubilalis. The present study was aimed at N. pyrausta virulence testing to the beet webworm (BW), Loxostege sticticalis. This agricultural pest, L. sticticalis, was highly vulnerable to N. pyrausta. The parasite’s spores were located in salivary glands, adipose tissue, and Malpighian tubules of the infected specimens. Infection was transmitted transovarially through at least 3 laboratory generations, in which BW fitness indices were lower than in the control, and moth emergence and fertility decreased prominently. Transovarial infection was most detrimental to female egg-laying ability, resulting in zero fertility in F3. When propagated in BW, the microsporidium tended to increase its virulence to L. sticticalis, as compared to the Ostrinia isolates. The parasite’s ability to infect this host at low dosages and transmit vertically should guarantee its effective establishment and spread within BW populations. In conclusion, N. pyrausta is a promising agent against BW, which is a notorious polyphagous pest in Eurasia.

Loma acerinae is a xenoma-forming fish microsporidium described from common ruffe Gymnocephalus cernua (Perciformes: Percidae) and also found in Ponto-Caspian gobies (Gobiiformes: Gobiidae). This casts doubt on the strict host specificity of this parasite. The largest subunit RNA polymerase II (rpb1) was used as a genetic marker of the parasite isolated from six host species of Perciformes (G. cernua from the Baltic Sea), Atheriniformes (Atherina boyeri from the Azov Sea) and Gobiiformes (Neogobius spp. and Zosterisessor ophiocephalus from the Black Sea and Ponticola kessleri from the Caspian Sea basin). Two major rpb1 haplogroups were found with 98.5% identity between the groups. Notably, Haplogroup I was associated with Neogobius spp. samples (n = 6) only, whereas Haplogroup II included the samples from other host species (n = 7). These findings confirm the broad distribution and host range of L. acerinae, but also indicate that certain patterns of host-driven intraspecific polymorphism may exist. Furthermore, the study revealed low similarity between the ribosomal RNA gene sequences of L. acerinae and the type species, Loma morhua (as well as other species of the genus). This suggests loose genetic association within the genus, and may raise the need for the taxonomic revision of L. acerinae.

Two species of microsporidia, Nosema apis and Nosema ceranae, occur regularly and cause significant losses in apiculture throughout the world. N. ceranae is thought to be an emerging pathogen of the European honey bee which is replacing N. apis. Microscopic analysis of honey bees collected in Tyumen region, South-Western Siberia, suggested presence of two microsporidial pathogens slightly differing in spore size and shape. PCR detection using species-specific primer sets 312APIS and 218MITOC followed by PCR product sequencing confirmed the diagnosis of N. apis and N. ceranae, respectively. Microsporidia were present in private apiaries through 2008-2010, and among 21 colonies from 7 localities, two colonies were infected with both pathogens, while infections with N. apis only were detected in 8, and with N. ceranae only in 13 colonies. These data suggest that N. ceranae is widely spread in South-Western Siberia alongside with N. apis and is able to persist in the regions with average January temperatures below –18°C.

Chorthippus loratus collected in Krasnodar Territory in 2017 was infected at 15% rate with a microsporidium possessing ovocylindrical binucleate spores, 2.6 × 1.2 μm in size. SSU RNA gene typing (Genbank accession # MH396491) showed its allocation to the genus Liebermannia. Degenerate primers based upon largest subunit RNA polymerase II (RPB1) sequences of closest relatives allowed amplifying the respective gene fragment of Liebermannia sp. (# MH396492). The present finding indicates worldwide distribution of the Liebermannia genus and parasitism in hosts with nonoverlapping geographic ranges (representing Neotropical versus Palearctic fauna), while previous observations were restricted to Acridoidea endemic for South America.

Analysis of the prevalence rates of the endosymbiotic bacterium of the Wolbachia genus in the populations of corn borers of the Ostrinia genus was carried out. Samples of genomic DNA were extracted from field-collected larvae. The PCR analysis for the presence of Wolbachia infection was performed independently using three diagnostic loci: 16SrRNA, gatB, and fbpA. A positive signal for Wolbachia was obtained for 13.5% of the Ostrinia nubilalis larvae (N = 141) and 31.9% of the Ostrinia scapulalis larvae (N = 138). The infection rate ranged from 2.9% (N = 34) to 65.8% (N = 38) in different geographical populations. At the same time, a significantly higher infection rate of O. scapulalis than O. nubilalis was observed in three out of four habitats. It was also found that the Wolbachia infection was more common for O. scapulalis individuals feeding on hemp than for those collected from mugwort.

A comparison of the small subunit rRNA gene sequences of the microsporidian isolates from corn borers of the Ostrinia genus from Russia and Belarus indicates that they belong to the Nosema pyrausta species. In order to analyze genetic polymorphism, the nucleotide sequences of the molecular clones of the rRNA intergenic spacer (IGS) of the N. pyrausta isolates from Ostrinia nubilalis and Ostrinia scapulalis (Krasnodar territory), as well as from O. nubilalis (Gomel region, Belarus), are determined. Based on the information obtained and available in Genbank, a high level of divergence of the IGS locus between the isolates of different species and populations of microsporidia, as well as between the molecular clones within individual isolates of parasites, is shown.

A microsporidium was found in a Mediterranean cricket Gryllus bimaculatus from a pet market in the UK and a lab stock at the Moscow Zoo (originating from London Zoo). The spores were ovoid, uninucleate, 6.3 × 3.7 μm in size (unfixed), in packets by of 8, 16, or 32. The spores were easily discharged upon dessication or slight mechanical pressure. The polar tube was isofilar, with 15-16 coils arranged in 1-2 rows. The polaroplast was composed of thin lamellae and occupied about one third of the spore volume. The endospore was 200 nm thick, thinning over the anchoring disc. The exospore was thin, uniform, and with no ornamentation. Phylogenetics based upon small subunit ribosomal RNA (Genbank accession # MG663123) and RNA polymerase II largest subunit (# MG664544) genes placed the parasite at the base of the Trachipleistophora/Vavraia lineage. The RPB1 locus was polymorphic but similar genetic structure and identical clones were found in both isolates, confirming their common geographic origin. Due to in insufficient ultrastructural data and prominent divergence from described species, the parasite is provisionally placed to the collective taxon Microsporidium.

Background . Endosymbiotic bacteria of the genus Wolbachia are widespread in arthropods and often cause reproductive abnormalities in lepidopteran insects, including corn borers of the genus Ostrinia . Wolbachia - Ostrinia is a promising model for studies of parasite-host interactions yet parasite prevalence in natural insect host populations remains unknown. Materials and Methods . Molecular genetic screening and statistical analysis is applied to evaluate prevalence rates of Wolbachia in sympatric populations of two corn borer species. Individual genomic DNA samples were extracted from last instar larvae collected in nature from different forage plants. For each sample of DNA showing positive signal with insect-specific primers the detection is performed using three diagnostic loci of Wolbachia : 16SrRNA, gatB and fbpA. Results . Wolbachia -positive signal is obtained for 13.5% larvae of Ostrinia nubilalis (N = 141) and 31.9% larvae of Ostrinia scapulalis (N = 138). In different localities the Wolbachia prevalence ranged from 2.9% (N = 34) to 65.8% (N = 38). Significantly higher rates of Wolbachia prevalence in insects from mugwort and hemp ( O. scapulalis ) as compared to those from corn ( O. nubilalis ) are revealed in three out of four localities. Conclusions . Endosymbiotic bacteria of the genus Wolbachia are revealed in natural populations of corn borers for the first time for Eastern Europe. The prevalence rates can be high and this should be taken into consideration when reproductive isolation is examined in population of these hosts as well as establishment of laboratory cultures is performed.

Background. Microsporidia are ubiquitous parasites of animals, most abundant in arthropods and fishes. Many species of these parasites are important from standpoints of medicine, veterinary and agriculture. Microsporidium Nosema pyrausta is an important disease agent in corn borer populations causing adverse effect on host fitness. Genotyping of this parasite is necessary for proper species identification and intraspecific polymorphysm studies. Materials and Methods. Microsporidia-infected larvae of corn borers of the genus Ostrinia were recovered from Krasnodar Territory in Russia and Gomel Region in Belarus. Small subunit ribosomal RNA (SSU rRNA) was amplified and sequenced directly, while intergenic spacer (IGS) was amplified, cloned and sequenced (1-5 clones per sample) for four isolates of microsporidia. Sequences were aligned and compared using standard bioinformatics tools (Clustal W and BLAST). Results. SSU rRNA genotyping showed allocation of all four isolates to N. pyrausta with 100% identity to each other and 99.7% similarity to Nosema bombycis, the type species of the genus Nosema. High levels of IGS sequence variation (61-74%) is observed both between isolates of different species and populations of microsporidia as well as between molecular clones within parasite isolates from individual hosts. Conclusion. N. pyrausta is widespread in corn borer populations and its genetic structure is complicated, as in other species of these parasites. Further studies of molecular markers are needed for genetic differentiation of geographic isolates of N. pyrausta.

The microsporidian genera Nosema and Vairimorpha comprise a clade described from insects. Currently the genus Nosema is defined as having a dimorphic life cycle characterized by diplokaryotic stages and diplosporoblastic sporogony with two functionally and morphologically distinct spore types ("early" or "primary" and "environmental"). The Vairimorpha life cycle, in addition to a Nosema-type diplokaryotic sporogony, includes an octosporoblastic sporogony producing eight uninucleate spores (octospores) within a sporophorous vesicle. Molecular phylogeny, however, has clearly demonstrated that the genera Nosema and Vairimorpha, characterized by the absence or presence of uninucleate octospores, respectively, represent two polyphyletic taxa, and that octosporogony is turned on and off frequently within taxa, depending on environmental factors such as host species and rearing temperature. In addition, recent studies have shown that both branches of the Vairimorpha-Nosema clade contain species that are uninucleate throughout their life cycle. The SSU rRNA gene sequence data reveal two distinct clades, those closely related to Vairimorpha necatrix, the type species for the genus Vairimorpha, and those closely related to Nosema bombycis, the type species for the genus Nosema. Here, we redefine the two genera, giving priority to molecular character states over those observed at the developmental, structural or ultrastructural levels and present a list of revised species designations. Using this approach, a series of species are renamed (combination novum) and members of two genera, Rugispora and Oligosporidium, are reassigned to Vairimorpha because of their phylogenetic position. Moreover, the family Nosematidae is redefined and includes the genera Nosema and Vairimorpha comprising a monophyletic lineage of Microsporidia.

The experiments were aimed at evaluation of the effect of feeding with wheat colonized by the fungus Beauveria bassiana on the development of locusts. The seeds were treated with fungal conidia and 90 days after sowing, the plant parts were fed to II instar nymphs of laboratory colonies of migratory and desert locusts within the period of 18 days. The mortality levels between experimental and control (fed with untreated wheat) groups were not significantly different though a tendency of an increase in variants with contaminated fodder was observed. Two weeks after the beginning of the bioassay, insect mortality was 20-30% and 15% in control. As many as 50% of migratory locust and 40% of desert locust cadavers were covered by a fungal mycelium. Sequencing of two diagnostic DNA loci has confirmed attribution of the reisolate to the genotype of the initial Beauveria bassiana strain BBK-1. It can be therefore concluded that the endophyte fungus is capable of causing classical pathogenesis of mycosis in locust nymphs. Moreover, the nymphal development was retarded by feeding with the fungus-colonized plants.

Hexokinase (HK) is a core glycolytic enzyme of Microsporidia which regulates host cell metabolic processes. The goal of the present study was to test for the utility of HK for molecular phylogenetics, species identification and molecular detection of microsporidia in infected insects. HK sequence-based reconstructions were essentially similar to those based upon largest subunit RNA polymerase (RPB1) gene sequences, as well as previously published rRNA gene and genome-based trees. Comparing HK sequences allowed clear differentiation of closely related taxa, such as Nosema bombycis and Nosema pyrausta. In Nosema ceranae, unique SNPs were found for an isolate from wild colonies of the Burzyan dark honey bee as compared with the isolates from domesticated European honey bee. Similarly, in Encephalitozoon cuniculi, HK was as effective as RPB1 for discrimination of isolates belonging to different ITS genotypes. Amplification using species-specific primers flanking short fragments at the 3′-end of HK gene showed the presence of infection in insect tissues infected with N. pyrausta, Nosema ceranae and Paranosema (Antonospora) locustae. For the latter parasite species, HK expression was also demonstrated at early stages of infection using total mRNA extracts of locust larvae. These results indicate the suitability of HK as a novel tool for molecular genetic studies of Microsporidia.

An isolate of the microsporidium Vairimorpha ephestiae (originally isolated from Ephestia kuhniella) from collection of Prof. J. Weiser was propagated in a laboratory culture of Galleria mellonella. Only disporoblastic sporogony was observed and formation of octospores, characteristic of the genus Vairimorpha, never occurred. A partial nucleotide sequence of the small subunit rRNA gene (1247 bp) for this microsporidium showed 100% identity to the homologous sequences of Vairimorpha (Nosema) necatrix (Genbank accession # U11051 and # DQ996241), a microsporidium with a broad host range within the Lepidoptera. Sequence similarity of protein-coding genes (RPB1, HSP70 and actin) between V. ephestiae and V. necatrix was about 98–100%. The level of genetic polymorphism in the RPB1 locus between these two species was essentially the same as between isolates of V. necatrix. It is therefore concluded that V. ephestiae is in fact an isolate of V. necatrix and the former species should be synonymized with the latter. Though described later, V. necatrix has prevailing usage and its precedence over V. ephestiae is proposed to conserve stability and avoid confusion.

Three species of Microsporidia were identified from a population of the beet webworm Loxostege sticticalis at prevalence rates of 35, 4, and 3%. The most prevalent parasite (Tubulinosema sp.) was similar to Tubulinosema acridophagus (99.8% ssrDNA sequence similarity) and was also isolated from the parasitoid Lydella thompsoni (Diptera, Tachinidae) that emerged from the beet webworms. In laboratory assays, spores of this Tubulinosema sp. showed an infection rate of up to 80% for both L. sticticalis and Galleria mellonella larvae. The spores were viable after 12 months of storage in dried infected cadavers. The second most prevalent parasite was closely related to Nosema furnacalis and Nosema granulosis (98.7% similarity). Fresh spores showed a 50% infection rate under laboratory conditions. The third most abundant parasite was identified as the honeybee pathogen Nosema ceranae (100% ssrDNA and 95–100% IGS similarity). In the laboratory, fresh spores of N. ceranae isolated from beet webworm and honey bee were infective to L. sticticalis larvae at the rates of 5 and 2%, respectively.

Genomic DNA samples from larvae of the beet webworm Loxostege sticticalis collected in the south-western Russia were used to amplify mitochondrial cytochrome oxidase unit I (COI) gene. In a small proportion of samples, the sequenced product showed considerable heterogeneity due to admixture of a minor sequence. A preliminary BLAST analysis of a 100-bp-long fragment of this minor sequence showed its maximal similarity to the COI gene region of Cotesia, a genus of braconid larval endoparasitoids of Lepidoptera. An additional primer was designed to specifically amplify ca 300 bp of the COI gene region from Braconidae. As many as seven of 25 samples were positive by PCR. Sequencing of the amplified products in all these samples showed nucleotide sequence identity to the COI region of Cotesia vestalis (Cotesia plutellae) and the presence of two molecular haplotypes among individual parasitoid samples.

The beet webworm, Loxostege sticticalis L., is a very dangerous polyphagous insect pest whose outbreaks periodically occur in southern Russia and northern China. The aim of our work was to describe the photoperiodic response of beet webworm populations from western (Krasnodar Territory and Rostov Province) and eastern [Buryatia and China (Hebei Province)] parts of the pest range. The insects were reared under constant photoperiods of 12–18 h and constant temperatures of 19–25°C. Incidence of diapause at different photoperiods did not show any considerable geographic differences, and the critical day length at which 50% of prepupae arrested their development was about 14–15 h in all the populations studied at experimental temperatures. The results obtained agree with the hypothesis on the existence of an area (or areas) where the pest survives during adverse periods and wherefrom it spreads when an outbreak begins (Saulich et al., 1983; Goryshin et al., 1986). Presumably, the larger part of the pest native habitats (to the north of the steppe zone) is occupied by temporary populations, incapable of surviving for long periods without an inflow of migrants from more southerly steppe regions.

Population dynamics of the beet webworm Pyrausta sticticalis L. was studied in 2003–2005 in Krasnodar Territory (Slavyansk-on-Kuban District) during the period of low population density of the pest. In the period examined, the adult death rate was high, fecundity was low; the low rate of hatchability and high rate of mortality was typical of larvae reared in the laboratory. Analysis of life tables has demonstrated that the observed population density of adults could be explained only by a constant flow of migrants. Low viability of insects from the local population could be explained by the infection with pathogenic microorganisms, including viruses of the Polyhedrosis and Granulosi groups of Baculovirus, and microsporidia, including Nosema sticticalis and Microsporidium sp. Reproduction of the pest can also be influenced by unfavorable weather conditions reducing population density in the subsequent generation. It is demonstrated that the model of the beet webworm population density dynamics based on indices of female fertility, changes in the offspring viability, and the rate of infection with microsporidia is more reliable than models based only on meteorological factors.

Populations of European corn borer (Ostrinia nubilalis Hubner) from Krasnodar Territory (Southwestern Russia) become regularly infected with Nosema-like microsporidia. To identify the parasite, it was subjected to electron microscopy and small subunit ribosomal RNA (SSU rRNA) gene sequencing. The spore ultrastructure of the parasite was highly similar to Nosema bombycis from China and Nosema pyrausta from the USA. The nucleotide sequence of SSU rRNA gene was identical to a microsporidium isolated from O. nubilalis in southern France (GenBank accession no. HM566196) and closely related to Nosema bombycis (no. AY209011, 99.7 % sequence similarity) from Bombyx mori of Chinese origin and N. pyrausta (no. AY958071) from O. nubilalis of North American origin. As the molecular haplotype of SSU rRNA is fixed for the parasite infecting O. nubilalis across Europe and N. pyrausta was initially described in France as Perezia pyraustae (Paillot CR Acad Sci Paris 185: 673–675, 1927), we conclude that the parasite examined under the present study correspond to the type isolate of N. pyrausta. The microsporidium from O. nubilalis in North America (no. AY958071) corresponds therefore to a closely related, yet distinct haplotype.

A number of microscopic techniques and dyes are available to diagnose microsporidian infections in invertebrate and vertebrate hosts. Among these, DNA-specific fluorochrome DAPI is widely used to stain DNA in prokaryotic and eukaryotic cells, alone or in combination with other histochemical or fluorescent dyes. Moreover, this dye also binds to membraneous structures and protein complexes. In our studies, DAPI was used to stain spores of microsporidia infecting orthopteran, coleopteran, dipteran and lepidopteran insect hosts. DAPI staining of diplokarya helped to discriminate the Nosema-like microsporidian spores from spore-shaped bodies lacking this characteristic staining. It was found, moreover, that non-DNA staining occurred in many cases and other components of the spores were stained: the exospore, the cytoplasm, the extruded polar filament and the polaroplast. Staining of these structures was feeble as compared to DNA and in most cases did not interfere with nuclear apparatus staining. Feebly stained cytoplasm and exospore clearly indicated unstained zone of endospore, making it easier to diagnose both mono- and diplokaryotic spores. Staining of extruded polar filament allowed to demonstrate viability and to observe some stages of extrusion process of microsporidian spores.

International audience; Trilobed uncus taxa of the genus Ostrinia (Lepidoptera, Crambidae) illustrate the complex relationship, at early stages of speciation, between reproductive isolation and differentiation in morphology, resource use and genetic variation. On the basis of behaviour and ecology, we recently hypothesized that individuals with small mid-tibiae belong to two distinct species depending on host plant-O. nubilalis and O. scapulalis sensu Frolov et al. (2007) feeding on maize and on a number of dicotyledons, respectively. Individuals with small, medium or massive mid-tibiae would all belong to O. scapulalis as long as they feed on these dicotyledons. This contrasts with previous taxonomy, which distinguished three species by male mid-tibia morphology, regardless of host plant. Here, we test our hypothesis by examining the genetic structure of Ostrinia populations from regions with mid-tibia polymorphism Western Russia and Kazakhstan and comparing it with that of French populations where only small mid-tibiae occur. Results support two predictions: (1) maize- and dicotyledon-collected populations are genetically differentiated from each other like in France, and (2) dicotyledon-collected populations show no genetic evidence of consisting of more than one species. Between-species differentiation was unrelated to geographic distance, despite significant isolation by distance within species. The distinction between two and only two species differing by host plant thus holds at continental scale. Interestingly, one microsatellite locus contributed 10 times more than the others to differentiation between both taxa. This deserves further investigation, as it might reveal a linkage between this outlier and loci involved in host-plant adaptation and/or reproductive isolation.

Infection of corn borers of the genus Ostrinia with microsporidia is found for the first time in Russia. Incidence rates of the last instar larvae of the second generation, sampled under natural conditions in the Krasnodar Territory, is ranged between 3.0 and 17.2%. When infection incidence rates have been compared between larvae, collected (a) on the western and eastern borders of the region and (b) on dicotyledonous (cocklebur, mugwort) and monocotyledonous plants (maize), no distinct differences were found. Infection rates were maximal in larvae of Ostrinia nubilalis when its population entered the depression phase, yet it did not differ significantly from the values of the previous years. Morphometric characters of the spores allows identifying the parasite species as Nosema pyrausta. These data demonstrate wide dispersal of microsporidia in the populations of stem borers on diverse forage plants within the boundaries of the Krasnodar Territory.

We examined whether maize offers enemy-free space (EFS) to its pest Ostrinia nubilalis, and may thereby have contributed to its divergence from the sibling species, Ostrinia scapulalis, feeding mainly on mugwort, when introduced into Europe five centuries ago. We collected Ostrinia larvae on maize (70 populations, 8425 individuals) and mugwort (10 populations, 1184 individuals) and recorded parasitism using both traditional (counting emerging parasitoids) and molecular methods (detection by specific polymerase chain reaction). The main parasitoid was Macrocentrus cingulum (Braconidae). On mugwort, parasitism was twice that on maize, and parasitoid-related mortality was 8 times higher. This suggests that maize affords substantial EFS to Ostrinia feeding on it. The lower Mortality:Infestation ratio in maize suggests that O. nubilalis' immune response might be stronger than that of O. scapulalis. If so, adapting to maize and diverging from O. scapulalis would decrease the impact of parasitism on O. nubilalis at both ecological and evolutionary levels.

Cooperative laser activities in Europe under the 'Eureka umbrella,' and their principle objectives, are summarized. The paper then discusses recent laser applications work within the Eureka EU113 CO EUROLASER Project using: a 1 kW laser at Heriot-Watt University, Edinburgh; a 3 - 4 kW (industrial prototype) Laser Ecosse laser (currently sited at TWI, Abington); and the high power laser facility at SBLT, Ekaterinburg. Finally, the potential for carbon laser processing is reviewed globally, in the light of experiments recently published by other workers.

Two high-power CO laser installations for industrial applications are being developed now in Russia within the framework of the Eureka Project EU113 (`CO-Eurolaser'). The electron- beam-controlled-discharge (EBCD) method for pumping those lasers is used. The first one, EBCD 10 kW CO laser, operates in continuous wave and `gentle' repetitively pulsed (RP) (peak power 20 kW, laser pulse duration 0.5 - 1 ms, pulse repetition rate 500 - 1,000 Hz) modes. The second laser, EBCD 5 - 10 kW CO laser will operate in `tough' RP mode (peak power 0.2 - 1.0 MW, single pulse energy 100 J, pulse duration 0.1 - 0.5 ms, repetition rate 50 - 100 Hz). A detander-compressor device, the main characteristics of which are reported, will be used for cooling the laser mixture of the second CO laser. Those high-power CO laser installations are supposed to be used for investigation of different laser materials processing methods on 5 micrometers wavelength for deep penetration welding, cutting, and surface treatment and also for comparative materials processing studies on CO and CO2 laser wavelengths.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper describes the evolution of a concept for a technological laser for industrial use. It consists of a collation of texts published by the authors and their colleagues in the U.S.S.R. over the past decade. A laser system which can run on multiple wavelengths, operate in CW, and long or short repetitive pulse modes, and which can operate economically was the design goal. Each section of this paper addresses one of the problems to be solved and indicates how it was solved. The end result is a laser system which uses a coupled turbocompressor and refrigerator to supply the gas flow and temperature control. The gas which expands and cools in the refrigeration turbine also supplies a portion of the power required by the turbocompressor. This system can operate on CO or CO 2 , thus serving as a source of mid-and far-infrared radiation in either the CW or pulse repetition mode. A five gas mixture (to conserve helium) and a silica gel gas purifier (in place of a catalytic converter) are proposed for their economic advantages.

An experimental study was made of the maximum field intensity and input energy that can be achieved in continuous electron-beam-controlled discharges in nitrogen and in active mixtures of CO2 and CO lasers. It was found that the maximum field intensity was governed by the specific input energy and by the degree of inhomogeneity of the pumping. In the case of CO laser mixtures the reduced input energy was 3–4 times higher than in electron-beam-controlled CO2 lasers because of the low proportion of the energy consumed in heating a gas (δ ≈ 0.25).

The first report is given of construction of a cw electron-beam-controlled CO laser with an output power of 10 kW, an efficiency of 24%, and a specific output energy of 65 J/g.