Recently, the distribution of the Mediterranean cedar bark beetle, Phloeosinus aubei Perris (Coleoptera: Scolytidae), has expanded to Central Europe. Reported mostly on cypress in the Mediterranean area, potential host plants in the invaded range include other scale-leafed conifers, such as cultivars of arborvitae, Thuja occidentalis L. To reveal potential kairomonal cues for P. aubei, volatiles of T. occidentalis were collected and analysed by gas chromatography with electroantennographic detection (GC-EAD). Assignments of chemical structures of antennally active components were carried out by gas chromatography linked to mass spectrometry (GC-MS) using authentic reference samples. Antennal responses to synthetic samples of the identified compounds were studied by electroantennography (EAG), with antennae of female and male P. aubei. GC-EAD analysis of head space volatiles of T. occidentalis revealed 22 antennally active compounds, of which 21 were identified. The most abundant components were a-and bthujone, fenchone, camphor, terpinen-4-ol, bornyl acetate and a-terpinyl acetate, all of which are oxygenated monoterpenes. When EAG activities of synthetic samples were compared, the most intensive responses from female antennae were elicited by a mixture of a-and b-thujone, followed by (-)-terpinen-4-ol, (+)-camphor, cis-4-thujanol, (+)-sabina ketone, (+)-terpinen-4-ol, isopulegone, (-)-fenchone, borneol, (3Z)-hexen-1-ol, (-)-1-octen-3-ol and (+)-sulcatol. Male antennae responded the most to (-)-terpinen-4-ol and cis-4-thujanol followed by the mixture of a-and b-thujone. The next highest responses were elicited by (+)-camphor, borneol, (+)-terpinen-4-ol, (+)-sulcatol and (+)-sabina ketone. Striking differences were found between responses to the enantiomers of fenchone, sulcatol and 1-octen-3-ol, whereas responses to the enantiomers of terpinen-4-ol did not differ significantly from each other. Several antennally active volatiles of T. occidentalis have also been reported from cypress and various other members of the Cupressaceae, suggesting that the sensory apparatus of P. aubei may recognize the shared components, which may enable rapid adaptation to new hosts in the invaded areas.
The cypress jewel beetle, Ovalisia festiva L. (Coleoptera: Buprestidae, Chrysochroinae), and the cypress bark beetle, Phloeosinus aubei Perris (Coleoptera: Curculionidae, Scolytinae), are invasive wood‐boring pests of scale‐leafed conifers (Cupressaceae), threatening tree nurseries and urban green areas. In order to reveal which volatile compounds of their common host, the American arborvitae, Thuja occidentalis L. cultivar ‘Smaragd’, they can perceive, we collected headspace volatiles from live attached twigs and screened them for bioactivity by gas chromatography coupled to an electroantennographic detector (GC‐EAD). Compounds eliciting antennal responses were identified by gas chromatography coupled to mass spectroscopy (GC‐MS). Synthetic samples of bioactive compounds were then screened by electroantennography. GC‐EAD analyses of volatile collections revealed that E–β–caryophyllene elicited antennal responses only from O. festiva (from both sexes), whereas borneol only from P. aubei. Electroantennography screening of synthetic compounds showed further differences between the two species. Even many of those compounds, which elicited responses from both species, differed in the relative intensities of responses they evoked. This indicates that O. festiva and P. aubei probably use different key compounds in the Thuja volatile blend for host recognition.
Pheromone biosynthesis activating neuropeptide (PBAN) is a member of the pyrokinin (FXPRLamide) insect neuropeptides. Here, we report the cloning of the gene Ostnu-PBAN from the E and Z pheromone strains of the European corn borer (ECB), Ostrinia nubilalis (Lepidoptera: Crambidae), a major pest of maize. The Ostnu-PBAN genomic sequence is > 5 kb in length and consists of six exons. The deduced amino acid sequence revealed a 200-residue precursor protein including a signal peptide, a 24-amino acid (aa) diapause hormone, a 37-aa PBAN and three other FXPRLamide neuropeptides. Our in vivo assays suggest that the 37-aa synthetic Ostnu-PBAN is hormonally active in the pheromone gland. It restores sex pheromone production to normal levels in mated females and decapitated virgins of both E and Z cultures. The results of a real-time PCR analysis indicated that Ostnu-PBAN mRNA levels reached a plateau in the brain-suboesophageal ganglion complexes 1 day after eclosion, and mating did not affect the mRNA expression. Three size classes of Ostnu-PBAN mRNA (1.9, 2.0 and 2.1 kb) were obtained, differing only in the length of the 3' untranslated region. However, there was no correlation between sequence divergence and the pheromone composition, voltinism or geographical origin (Hungary, Slovenia, Sweden, Turkey) of ECB moths.
Following the first incident in Belgium, the second European record of the honeybee hive inhabiting mite, Neocypholaelaps apicola Delfinado-Baker et Baker, 1983, is presented from Budapest, Hungary. In contrast to the original host in Pakistan (Apis cerana indica Fabricius, 1793) and the host in Belgium (Apis mellifera carnica Pollmann, 1879), the Hungarian specimens were associated to Apis mellifera mellifera Linnaeus, 1758. New knowledge about the morphology and the first Genbank sequences (cytochrome oxidase subunit I) are given with new drawings and scanning electron micrographs. Distinguishing characters between the two European Neocypholaelaps species are also presented.
The European corn borer moth, (ECB), Ostrinia nubilalis (Lepidoptera: Crambidae, Pyraustinae) is one of the most destructive pests of maize worldwide. ECB has two pheromone-strains, separated by specific ratios of isomers of E- and Z11-tetradecenyl acetates (E11- and Z11-14Ac), but appearing morphologically identical. Accordingly, E- and Z-ECB pheromone traps are available for the respective populations for practical monitoring of the flight, however, traps for Z-strain are unreliable for practical usage in some parts of Central-Europe. E- and Z-ECB populations occur in sympatry in some areas, while in allelopatry in other areas. Determining the strains before the flight of adults, when difference in the composition of their respective pheromones is manifested, would be of practical interest for early warning. In addition to the known fatty-acyl-reductase (FAR) marker, further markers would allow more comprehensive studies. We screened the following common markers for mitochondrial and nuclear DNA regions: partial cytochrome c oxidase I (COI), cytochrome B (CytB), the second spacer of the internal transcribed spacer (ITS2), Elongation factor 1a (EF1a) and actin gene (Act). In addition, a marker of the Δ11-desaturase gene (11desat), linked to biosynthesis of female-produced sex pheromone, was also included, because we reported earlier a differential expression for this site. Three Z-ECB populations locating at distant sites within Hungary, an area where only Z-strain occurs, and an E-ECB population in Slovenia, known as the closest-occurring E-strain, were included into the study. Separate laboratory colonies were established from each population, and F1 generations were sampled to verify the identity of pheromone strains, by analysing the composition of sex pheromone by gas chromatography linked to an electroantennographic detector (GC-EAD). Molecular studies were conducted using specimens taken from the F2 generations. Results of genetic studies showed that there were no differences between the Z and E populations for the common markers. In contrast to this, several nucleic acid changes (11 nt in 4 positions) were found between the three Z-populations (Hungary) and the E-population (Slovenia) in the desaturase marker. Further study is required to reveal whether the differences found in this study are consistent across E-populations, thus making these markers suitable for diagnostic purposes.
The cypress bark beetle, Phloeosinus aubei (Coleoptera, Curculionidae, Scolytinae) prefers to build breeding galleries in decaying host trees. However, volatile cues specific to decaying or actively infested trees have not yet been reported. Any such information would be useful for the management of this invasive, wood-boring species that has become established across Europe in the temperate zone and is now a key pest of ornamental Cupressaceae in nurseries and urban landscapes. Our objective was to reveal key components in host volatiles specific to stressed trees, which could be potential signals for the pest of its suitability for colonisation. Volatile profiles of arborvitae, Thuja occidentalis ‘Smaragd’ suffering from either dehydration or fresh infestation of P. aubei was collected and compared to that samples from healthy control trees. Analyses of volatiles by gas chromatography coupled to an electroantennographic detector revealed substantial differences between healthy, dehydrated and infested trees. Structural elucidation of the major antennally active components revealed that both α-pinene and α-thujene were prevalent in the volatiles of infested trees, whilst α-thujone was the major component in volatiles of healthy trees. In volatiles collected from trunks housing fresh P. aubei female nuptial chambers, sharp increases of β-pinene, myrcene, limonene, and p-cymene were noticed, alongside trace amounts of camphene and fenchene. Volatiles collected from fresh frass showed a similar profile, but with a somewhat smaller amount of limonene. Fenchone was present in each type of volatiles, however, only in low amounts. Further studies should be directed to reveal the behavioural role of these components, which could be helpful in developing kairomone-based techniques for monitoring the flight of the pest in stands of scale-leafed trees.
Invasive stink bug species, such as Halyomorpha halys (Stål, 1855) (Hemiptera: Heteroptera: Pentatomidae), are serious agricultural pests worldwide. During autumn dispersal, adults aggregate in large numbers in human-made structures, homes and on walls of buildings. Preferred overwintering sites are sun-warmed, well-protected shelters. Exploiting a new concept, we developed a new collection method for monitoring and controlling them in their pre-overwintering period. Our trap design exploits the heat preference of stink bugs seeking overwintering sites. As a result, significantly greater numbers of H. halys adults moved into our black box traps, equipped with a heating apparatus, than into unheated ones. Experiments were performed in October during the pre-overwintering autumn dispersal period. Traps were placed next to a building that served as an overwintering site, where stink bugs usually aggregate in large numbers. Heated traps were operated on sunny afternoon hours when stink bugs were found to be active by visual observations. Our results represent the first example of an effective collection method based on artificially heated traps placed in natural conditions.
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