Does fungal endophyte infection improve tall fescue's growth response to fire and water limitation?

Invasive species may owe some of their success in competing and co-existing with native species to microbial symbioses they are capable of forming. Tall fescue is a cool-season, non-native, invasive grass capable of co-existing with native warm-season grasses in North American grasslands that frequently experience fire, drought, and cold winters, conditions to which the native species should be better-adapted than tall fescue. We hypothesized that tall fescue's ability to form a symbiosis with Neotyphodium coenophialum, an aboveground fungal endophyte, may enhance its environmental stress tolerance and persistence in these environments. We used a greenhouse experiment to examine the effects of endophyte infection (E+ vs. E-), prescribed fire (1 burn vs. 2 burn vs. unburned control), and watering regime (dry vs. wet) on tall fescue growth. We assessed treatment effects for growth rates and the following response variables: total tiller length, number of tillers recruited during the experiment, number of reproductive tillers, tiller biomass, root biomass, and total biomass. Water regime significantly affected all response variables, with less growth and lower growth rates observed under the dry water regime compared to the wet. The burn treatments significantly affected total tiller length, number of reproductive tillers, total tiller biomass, and total biomass, but treatment differences were not consistent across parameters. Overall, fire seemed to enhance growth. Endophyte status significantly affected total tiller length and tiller biomass, but the effect was opposite what we predicted (E->E+). The results from our experiment indicated that tall fescue was relatively tolerant of fire, even when combined with dry conditions, and that the fungal endophyte symbiosis was not important in governing this ecological ability. The persistence of tall fescue in native grassland ecosystems may be linked to other endophyte-conferred abilities not measured here (e.g., herbivory release) or may not be related to this plant-microbial symbiosis.

Pachybrachis (coleoptera, chrysomelidae, cryptocephalinae) of eastern Canada.

Seventeen Pachybrachis species occurring in eastern Canada [Ontario (ON), Québec (QC), New Brunswick (NB), Nova Scotia (NS), and Prince Edward Island (PE)] are treated by the authors. Two new national records were discovered, both from southernmost Ontario: P. cephalicus Fall and P. luctuosus Suffrian. Four species were new provincial records: P. cephalicus (ON), P. luctuosus (ON, QC), P. obsoletus Suffrian (NB), P. peccans (PE). A fully illustrated key to the Pachybrachis of eastern Canada is provided and supported with extensive photographs, distribution maps, and plant associations. Three species were distributed from southern Ontario into at least one province in the Maritimes (P. nigricornis (Say), P. obsoletus Suffrianand P. peccans Suffrian). Six species were distributed along the shores of the Great Lakes (Erie, Michigan, and Ontario) and rivers (Ottawa, Saguenay and St. Lawrence), but unknown from central and northern ON and QC (P. bivittatus (Say), P. hepaticus hepaticus (F. E. Melsheimer), P. othonus othonus (Say), P. pectoralis (F. E. Melsheimer), P. spumarius Suffrianand P. trinotatus (F. E. Melsheimer)). Seven species were rare, five being found exclusively from southern ON (P. calcaratus Fall, P. cephalicus, P. luridus (Fabricius), P. subfasciatus (J. E. LeConte)and P. tridens (F. E. Melsheimer)), with two having, in addition, a disjunct population in QC (P. atomarius (F. E. Melsheimer)and P. luctuosus). One species was found to be the northern most extension of an eastern United States (US) distribution into the eastern townships of QC (P. m-nigrum (F. E. Melsheimer)). There were no Pachybrachis that could be considered arctic, subarctic, or boreal species; no specimens were found from Labrador and Newfoundland, and all species had southern affinities. Pachybrachis atomarius, P. calcaratus, P. luridus, P. subfaciatus, and P. tridens, not seen over the last 30-70 years, may be extirpated from eastern Canada.

RésuméLes auteurs traitent des 17 espèces de Pachybrachis présentes dans l'est du Canada [Ontario (ON), Québec (QC), Nouveau-Brunswick (NB), Nouvelle-Écosse (NS), Île-du-Prince-Édouard (PE)]. Deux espèces en provenance de l'extrême sud de l'Ontario sont nouvelles pour le pays: P. cephalicus Fall et P. luctuosus Suffrian. Quatre espèces représentent de nouvelles mentions provinciales: P. cephalicus (ON), P. luctuosus (ON, QC), P. obsoletus Suffrian (NB) et P. peccans (PE). La clé d'identification des espèces de l'est du Canada s'appuie sur de nombreuses illustrations en plus d'inclure des cartes de répartition et les associations avec les plantes. Trois espèces se répartissent du sud de l'ON jusqu'à au moins l'une ou l'autre des provinces Maritimes (P. nigricornis (Say), P. obsoletus Suffrianet P. peccans Suffrian). Six espèces sont limitées aux rives des Grands-Lacs (Érié, Michigan et Ontario), du fleuve Saint-Laurent et des grandes rivières (des Outaouais, Saguenay) sans atteindre le centre et le nord de l'ON et du QC (P. bivittatus (Say), P. hepaticus (F. E. Melsheimer), P. othonus (Say), P. pectoralis (F. E. Melsheimer), P. spumarius Suffrianet P. trinotatus (F. E. Melsheimer)). Cinq, parmi les sept espèces rares, proviennent exclusivement du sud de l'ON (P. calcaratus, P. cephalicus, P. luridus (Fabricius), P. subfasciatus (J. E. LeConte) et P. tridens (F. E. Melsheimer)), alors que les deux autres possèdent, en outre, une population disjointe au QC (P. atomarius et P. luctuosus). Une espèce, présente seulement en Estrie (QC), se trouve à la limite septentrionale de sa répartition dans l'est des États-Unis (P. m-nigrum (F. E. Melsheimer)). Aucune espèce, parmi les Pachybrachis étudiés, n'est arctique, subarctique ou boréale, mais toutes présentent des affinités méridionales. Aucun spécimen en provenance de Terre-Neuve et du Labrador n'a été observé. Les espèces Pachybrachis atomarius, P. calcaratus, P. luridus, P. subfaciatus et P. tridens n'ont pas été vues depuis les 30­70 dernières années de sorte qu'elles sont probablement disparues de la faune de l'Est du Canada.