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The spotted asparagus beetle, Crioceris duodecimpunctata (L.) is an invasive host-specific pest of asparagus cultivations. To contribute to the understanding of the role of plant volatiles in host-finding by this species, behavioural and electrophysiological tests were carried out. Y-tube olfactometer bioassays, testing intact or mechanically-damaged cladophylls vs. clean air, revealed sexually-dimorphic responses with males being the only sex attracted to both plant materials. Electroantennographic (EAG) assays showed that antennae of both sexes can perceive a wide range of asparagus volatiles. Male and female EAG profiles were almost similar and (Z)-3-hexen-1-ol was by far the most EAG-active compound. (E)-2-hexenal, (±)-linalool, and 3-heptanone elicited the strongest EAG amplitude within the corresponding chemical groups. Eight of the most EAG-active compounds elicited dose-dependent responses indicating the sensitivity of male and female olfactory systems to changes in stimulus concentration. In a Y-tube olfactometer bioassay, (Z)-3-hexen-1-ol at the doses of 1, 10, and 50 μg did not elicit female attraction whereas a significant attraction at the 10 μg dose and a repellent effect at the 50 μg dose was induced in males. Sexual dimorphism of male behavioural response to host plant volatiles is discussed. This study provides a basis for future investigations that could contribute to the development of semiochemical-based monitoring and management strategies for this pest.

Intracellular bacteria of the genus Wolbachia (a-Proteobacteria) are the most widespread endosymbionts of insects. Host infection is usually associated with alterations in reproduction, such as cytoplasmic incompatibility, the induction of parthenogenesis and offspring sex ratio bias: all phenomena that may infl uence host speciation. In the present study, by using wellestablished molecular tools, we investigated the presence of Wolbachia in leaf beetles of the genus Crioceris and their host plants, which are various species of Asparagus. Multilocus sequence typing of bacterial genes showed that despite their occurrence in the same habitat and feeding on the same plant, two species of Crioceris, C. quinquepunctata and C. quatuordecimpunctata, are infected by two different strains of Wolbachia. C. asparagi, C. paracenthesis and C. duodecimpunctata, which are sympatric with the infected species, do not harbour the bacterium. Interestingly, DNA of Wolbachia was detected in host plant tissues that are exploited by the beetles, providing evidence for the horizontal transmission of the bacterium between beetles and their host plants. Moreover, Wolbachia was detected in species of Crioceris that are not closely related.

The cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), is an emerging pest of cereal crops in the Prairie Provinces of Canada. In other regions with a history of this pest, it is managed primarily through biological control with the parasitoid Tetrastichus julis (Walker) (Hymenoptera: Eulophidae). In this paper we report a study conducted during the summers of 2007 and 2008 in Pullman, Washington (USA), and 2010 and 2012 in Lethbridge, Alberta (Canada) assessing potential non-target effects of T. julis . The chrysomelid species tested included the following native and introduced species of leaf beetles (Chrysomelidae): Cassida azurea Fabricius, Chrysolina quadrigemina (Suffrian), Crioceris duodecimpunctata (L.), Deloyala guttata (Olivier), Galerucella calmariensis (L.), Gastrophysa cyanea Melsheimer, Gastrophysa polygoni L., Jonthonota nigripes (Olivier), Lema daturaphila Kogan & Geode, Leptinotarsa decemlineata (Say), Lilioceris lilii (Scopoli), and Xanthogaleruca luteola (Müller) (Coleoptera: Chrysomelidae). Tetrastichus julis did not parasitize any of these potential non-target species. Thus the occurrence and relocation of T. julis in the Prairie Provinces of Canada and northwestern USA poses a relatively low risk to biodiversity.

The influence of drip irrigation of 10 European asparagus cultivars on the occurrence of Crioceris duodecimpunctata (L.) and Crioceris asparagi (L.) was studied. We tested 5 German cultivars (‘Ravel’, ‘Rambo’, ‘Rally’, ‘Ramada’, ‘Rapsody’), 2 Spanish cv. (‘Cipres’ and ‘Plaverd’), 2 Dutch cv. (‘Backlim’ and ‘Grolim’) and French cv. ‘Orane’ in the field conditions. The field experiment was carried out in two consecutive years (2005-2006) at Kruszyn Krajeński near Bydgoszcz on a sandy soil. Adults and larvae of C. duodecimpunctata (twelvespotted asparagus beetles - T-SAB) and C. asparagi (common asparagus beetles - CAB) reached over 91% of all insects settled on asparagus summer stalks. The German cultivars ‘Rambo’ and ‘Rally’ were considerably settled by adults and larvae of T-SAB. The highest number of individuals (adults and larvae) of CAB on the Dutch cv. ‘Backlim’ were observed. However, German cv. ‘Rapsody’ were significantly less numerous (both CAB and T-SAB). Moreover Dutch cv. ‘Backlim’ was more occupied by adults and larvae of CAB in drip irrigation plots than all five tested German cultivars. Also adults and larvae of T-SAB as well as CAB often prefer drip irrigated asparagus summer stalks. Badano wpływ nawadniania kroplowego 10 europejskich odmian szparaga na występowanie Crioceris duodecimpunctata (L.) i Crioceris asparagi (L.). W warunkach polowych badano 5 niemieckich odmian szparaga (‘Ravel’, ‘Rambo’, ‘Rally’, ‘Ramada’, ‘Rapsody’), 2 hiszpańskie (‘Cipres’, ‘Plaverd’), 2 holenderskie (‘Backlim’, ‘Grolim’) i 1 francuską (‘Orane’). Badania polowe prowadzono w latach 2005-2006 w Kruszynie Krajeńskim koło Bydgoszczy na glebie lekkiej. Osobniki dorosłe i larwy dwóch gatunków poskrzypek stanowiły 91% wszystkich oznaczonych owadów zasiedlających rośliny szparaga. C. duodecimpunctata najchętniej zasiedlały niemieckie odmiany ‘Rambo’ i ‘Rally’. Zaobserwowano najwyższą liczebność C. asparagi na holenderskiej odmianie ‘Backlim’, jednakże na niemieckiej odmianie ‘Rapsody’ było istotnie najmniej, zarówno C. duodecimpunctata, jak i C. asparagi. Ponadto holenderska odmiana ‘Backlim’ była chętniej zasiedlana przez larwy i osobniki dorosłe C. asparagi na poletkach nawadnianych niż testowane odmiany niemieckie. Zarówno dorosłe osobniki, jak i larwy C. duodecimpunctata i C. asparagi preferowały nawadniane pędy asymilacyjne szparaga.