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We provide scientists and decision-makers with up-to-date information on Megaplatypus mutatus (Coleoptera: Curculionidae: Platypodinae), a forest insect native to South America that has invaded other regions. Emphasis is given to information that may prove relevant for the development of early detection, containment and management programs and improved risk analyses. The increase in global movement of people and goods, coupled with expected climatic scenarios, suggests that M. mutatus may arrive and establish populations in new areas. The major impact of this forest pest has always been reported in exotic tree species, even within its native range. The absence of a coevolutionary history with ‘naïve’ host trees is a relevant factor when analyzing and understanding the magnitude of the problem posed by this beetle and fungi associated with it. Notably, among preferred hosts are the widely planted Eucalyptus and Populus spp., facilitating the invasion of this insect into new regions and posing a threat to commercial forestry.

Arboreal fungal endophytes are a highly diverse group of organisms associated with asymptomatic tissues and some of them are latent pathogens. The knowledge of fungal endophytes is limited, because previous studies mainly focused on foliar fungal endophytes of a limited number of host species and locations. We assessed the fungal endophyte diversity in twigs of congeneric native and exotic tree species belonging to eleven angiosperm and gymnosperm genera in mostly temperate regions of 32 countries on six continents. We describe how host taxonomy and geographic location affect endophyte diversity and how diversity differs between native and exotic trees. More than 400 samples were collected on both hemispheres and fungal communities were assessed by high-throughput sequencing. Sampling was done in winter, because trees are mostly traded in winter, when deciduous trees lack foliage. We found around 15, 000 fungal Exact Sequence Variants (ESVs) associated with the tree genera. ESV richness varied among sampled taxa, but did not differ between native and exotic hosts. ESV richness in most of the northern hemisphere tree genera peaked at 45-50 degrees of latitude, but the pattern for southern hemisphere genera was not clear. The endophyte communities of angiosperms and gymnosperms differed ; around 30% of all ESVs were found in a single genus and less than 1% was found in all genera. Distinct geographic patterns among and within continents were found and the similarity of the endophyte communities decreased with distance between sampling locations in most genera. This study reveals fungal endophyte diversity on an unprecedented scale as a result of the wide geographic and taxonomic diversity of the samples. The geographic differences in ESVs in particular suggest that international live plant trade can facilitate the exchange of geographically isolated fungal communities, which could threaten tree-based resources in importing countries.

Live plants are often traded in their dormant stage, among other reasons to reduce the introduction of new pests. However, the pests associated with this pathway are largely unknown. Risk mitigation relies on pest risk assessments which can only be performed for known pests. It is therefore important to identify potential pests before the introduction occurs. In addition, post arrival host shifts are very difficult to predict. Several studies attempted to estimate the likelihood of host shifts based on existing literature data on known pest-host associations, but the number of pests in these studies was often limited and the data were unlikely collected in the same place and at the same time. To overcome these problems, we performed a global study which aimed at detecting potential insect pests and fungal pathogens on selected congeneric native and exotic tree species in 33 countries. Samples were taken in botanical gardens and arboreta on the Northern and Southern hemisphere. At each location, twenty 50 cm long twigs were collected from tree species of up to six genera and kept in containers with water at room temperature for insect emergence. Emerged insects were collected and identified based on morphology and DNA barcoding of the mitochondrial DNA COI region. DNA was also extracted from pooled buds, twig parts and needles for the identification of fungi based on the ribosomal DNA ITS region using a high-throughput sequencing approach. Here, we present the first results of this study and discuss them in the context of pest risk assessment.

Un carnero infestado con M. ovinus fue introducido durante dos semanas en una majada de ovinos cruza Corriedale que se encontraba libre del parásito. La evolución de M. ovinus fue medida registrando los ovinos infestados y realizando conteos de parásitos sobre los animales en los días 0, 220 y 433. Los resultados de estas observaciones fueron utilizados para la elaboración de un modelo de crecimiento poblacional simple con el que se pudo estimar la curva potencial de crecimiento del parásito y compararla con los datos observados a campo. El hallazgo inicial de parasitismo, el día 0, fue de 4 melófagos y 3 pupas en una oveja de la majada; el día 220 se registró la presencia de parasitismo en el 100 % de los corderos y ese mismo porcentaje de infestación se observó en la siguiente generación de corderos revisados el día 433. Por otro lado, en los ovinos adultos las cargas parasitarias fueron menores y el porcentaje de infección fue aumentando lentamente hasta llegar al 91% el día 433. En esta fecha, la capacidad potencial de crecimiento de la población de melófagos, calculada por el modelo, fue aproximadamente 193 veces mayor al valor medido en los corderos en la misma fecha. La diferencia observada se atribuye a factores ambientales como las temperaturas y a las maniobras convencionales de manejo tales como esquila, venta de corderos y pariciones, que condicionan la abundancia y estacionalidad de las poblaciones de melófagos. An infested ram was introduced during mating (for 2 weeks) into a non-infested Corriedale sheep flock. The rate at which keds were disseminated, was measured by tallying number of infected sheep and counting ked burden on days 0, 220 and 433. To evaluate potential growth of Melophagus ovinus populations within the fixed-sized sheep flock during the study period, we built a simple population model. Initial counts (day 0), were of 4 M. ovinus adults and 3 pupae on a single sheep, whereas on day 220 parasitism reached 100% in lambs remaining at these values throughout the study period. In contrast, adult sheep showed low but rising counts, reaching 91% on day 433. According to the model, expected M. ovinus populations were 193 fold larger. We assign this difference to limitations on population growth set by environmental factors and sheep management such as shearing, lambing and lamb sales. EEA Bariloche Fil: Olaechea, Fermin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo Salud Animal; Argentina Fil: Corley, Juan Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; Argentina Fil: Larroza, Marcela Patricia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo Salud Animal; Argentina Fil: Raffo, Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentina Fil: Cabrera, Raul Francisco. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo Salud Animal; Argentina