Effects of the Neotyphodium endophyte fungus on dormancy and germination rate of Lolium multiflorum seeds

Abstract Neotyphodium frequently occurs as an endophyte in grasses. Evidence shows enhanced fitness of endophyte infected grasses relative to non‐infected ones. Some studies of seed germination show endophyte enhancement of plant fitness in various environments, but inconsistent results indicate that further studies are needed. So far, experiments have failed to separate the confounded effects of population origin and seed management. For this reason, we evaluated the effects of endophyte infection on seed dormancy and germination in Lolium multiflorum using an experimental design controlling these factors. Depending on the year of seed production, endophyte infection modified seed response to light quality, affecting predominantly seed dormancy levels. Nevertheless, the endophyte did not affect base temperature or thermal time of germination. We concluded that endophytes were not a strong influence on germination behaviour. We speculate from our results that the presence of the endophyte changes germination by an indirect effect, in extending growth of the maternal plant during seed development and ripening. The direct effect of hyphae in the seed on seed behaviour was disregarded, because the difference between infected and non‐infected seed varied within the year of seed production. Future experiments should focus on effects of the endophyte on the canopy of parent plants during seed production and ripening, and, hence, on subsequent dormancy and germination of the seeds.     

Esterases A5-B5 in organophosphate-resistant Culex pipiens from Italy

Abstract. Culex pipiens mosquitoes from Lignano city, Udine province, northeast Italy, were found to carry over-produced non-specific esterases Al, A2-B2 and A4-B4 or A5-B5, detected by starch gel electrophoresis, giving multiple resistance to organophosphorus insecticides. In order to differentiate between A4-B4 and A5-B5 esterases, the latter known only from Cyprus whereas the former is widespread in Italy and elsewhere, restriction fragment length polymorphism (RFLP) analysis was performed at the esterase B locus. Both B4 and B5 haplotypes were found. This is the first record of A5-B5 esterase-mediated resistance in continental Europe.     

Morphological,molecular and biological evidence reveal two cryptic species in Mecinus janthinus Germar (Coleoptera,Curculionidae), a successful biological control agent of Dalmatian toadflax,Linaria dalmatica (Lamiales,Plantaginaceae)

A combined morphological, molecular and biological study shows that the weevil species presently named Mecinus janthinus is actually composed of two different cryptic species: M. janthinus Germar, 1821 and M. janthiniformis To?evski & Caldara sp.n. These species are morphologically distinguishable from each other by a few very subtle morphological characters. On the contrary, they are more readily distinguishable by both molecular and biological characters. A molecular assessment based on the mitochondrial DNA cytochrome oxidase subunit II gene revealed fixed differences between the two species with p‐distances between samples of both species ranging from 1.3 to 2.4%. In addition to this, the larvae of the two species are found to develop on different species within the genus Linaria (Plantaginaceae): M. janthinus is associated with yellow toadflax (L. vulgaris) and M. janthiniformis with broomleaf toadflax (L. genistifolia) and Dalmatian toadflax (L. dalmatica). Molecular and host use records further suggest the occurrence of a third species associated with L. vulgaris within M. janthinus, sampled from north Switzerland, central Hungary and east Serbia. The significance of these new findings is of particular importance because species of the M. janthinus group are used, or are potential candidates, for the biological control of invasive toadflaxes in North America.     

Colleterial glands of Sesamia nonagrioides as a source of the host-recognition kairomone for the egg parasitoid Telenomus busseolae

Abstract.  The maize stemborer Sesamia nonagrioides glues its egg masses under the leaf sheaths or ear bracts using colleterial gland secretion. In spite of such concealed oviposition sites, these eggs are parasitized by Telenomus busseolae. The colleterial glands of S. nonagrioides are investigated as a possible source of the host-recognition kairomone for T. busseolae . This secretion, applied on glass beads, elicits intense antennal drumming and oviposition probing behaviour in the parasitoid. Through an histochemical study, neutral and acid glycoconjugates are identified as components of the secretion. Finally, using ultrastructural techniques, the colleterial glands are described and classified as comprising class 3 secretory cells.     

Bottom‐up effects on a plant‐endophage‐parasitoid system: The role of flower‐head size and chemistry

The effects of water and nutrient addition on a trophic chain were studied in a plant‐endophage‐parasitoid system comprised of insects associated with flower heads of Chromolaena squalida (Asteraceae). Nine species of endophages associated with C. squalida flower heads were found, belonging to two families of Diptera – Tephritidae (Cecidochares sp1, Cecidochares sp2, Xanthaciura biocellata, X. chrysura, X. sp. and Neomyopites sp.) and Agromyzidae (Melanagromyza sp.), and two families of Coleoptera – Apionidae (Apion sp.) and Anthicidae (Anthicidae sp.). A factorial field experiment with water and nutrient addition showed that resource availability can affect the developmental process of flower heads. Fertilization increased flower‐head diameter and nitrogen and alkaloid concentrations. Although nutrient availability affected the size and chemistry of flower heads, endophage species did not respond consistently to the experimental treatments. This is contrary to other studies where endophages showed preference for larger flower heads. Thus, the plant vigour hypothesis was not corroborated for our study system. Our results also showed that coupled responses of plants to resource availability (i.e. tissue nutritional quality and investment in growth of the structure that serves as shelter for endophages) can represent distinct kinds of indirect interactions with opposing effects on the herbivore‐parasitoid interaction.