ABSTRACT The honeybee (Apis mellifera L.) is an important pollinator worldwide. Beekeepers have experienced an increasing loss of colonies in recent years and pathologies including viruses and intestinal parasites such as Nosema ceranae are among those held responsible for this decline. The aim of this study was to determine the prevalence and distribution, using the real time PCR method, of six honeybee viruses including Deformed Wing Virus (DWV), Black Queen Cell Virus (BQCV), Sacbrood Virus (SBV), Acute Bee Paralysis Virus (ABPV), Chronic Bee Paralysis Virus (CBPV) and Israeli Acute Paralysis Virus (IAPV) in addition to three intestinal parasites, N. ceranae, N. apis and Lotmaria passim in Chilean beehives distributed between the Metropolitan Region and La Araucanía Region. Among the viruses, BQCV was the most prevalent in the analyzed hives, ranging from 72% to 100%, N. ceranae was detected between 19% to 53% and L. passim showed infections ranging from 45% to 73%. Similarly, BQCV (96%) and N. ceranae (42%) were more prevalent in spring-summer whilst DWV (37%) and L. passim (68%) were more frequents in autumn-winter seasons. Furthermore, mixed infections were also detected, wherein viruses were found along with L. passim or viruses with N. ceranae and L. passim, which proved to be the most prevalent. Of the 467 hives analyzed, 97.2% were infected with one or more of the studied pathogens, indicating that they are widely spread in Chile.

Crown rot pathogens are associated with higher losses for wheat crop farmers, but information about the distribution and prevalence of these pathogens in Chile is inadequate. Distribution and prevalence of wheat (Triticum aestivum L.) crown rot pathogens were examined in a survey of 48 commercial fields from December 2011 to February 2012 in southern Chile. These fields were located between Collipulli (37°56’00" S; 72°26’39" W) and Purranque (40°50’30" S; 73°22’03" W). Severity of crown rot disease was determined through visual assessment of the first internode of 20 tillers obtained from each field. Incidence of crown rot pathogens per field was determined by plating the 20 tillers on Petri plates with 20% potato dextrose agar amended with lactic acid (aPDA) medium. Resulting fungal colonies from monoxenic culture were identified by morphological or molecular-assisted identification. Severity of crown rot varied between 11.3% and 80% for individual fields. Culture plate analysis showed 72.2% of stems were infected with some fungus. Fusarium avenaceum, F. graminearum, and F. culmorum, pathogens associated with Fusarium crown rot disease were isolated from 13.5% of tillers. Gaeumannomyces graminis, causal agent of take-all disease in cereals, was isolated from 11.1% of culms. Phaeosphaeria sp., an endophyte and possibly a non-pathogenic fungus, was isolated from 13.9% of tillers. Pathogenic fungi such as Rhizoctonia spp. and Microdochium nivale, other saprophyte, and several unidentified non-sporulating fungi were isolated at frequencies lower than 3% of the total. Fusarium crown rot and take-all were the most prevalent and distributed crown rot diseases present in wheat crops in southern Chile.

Extracts of many plant species have shown nematicide activity attributable to phytochemicals present in their tissues or formed during a degradation process. Nevertheless, before the application of plant compounds in the field, it is necessary to know their effect on plant hosts. Three concentrations (1, 2.5 and 5% w/w) of dry leaves of Buddleja globosa, Drymis winteri, Eucalyptus globulus, Gevuina avellana, Laurelia sempervirens and Ugni molinae were evaluated on growth parameters (plant height, root length and leaf dry matter) in plants of Lactuca sativa infested with Meloidogyne hapla. Lettuce growth parameters were significantly affected by the interaction between the species and dry leaf tissues concentrations. Drymis winteri showed the biggest reductive effect on the evaluated parameters, but not significantly different as the effects from E. globulus. Independently of nematode infestation in lettuce plants, the incorporation of greater than 5% of dry leaves of D. winteri, E. globulus, G. avellana, L. sempervirens and U. molinae into the substrate had an important effect in the reduction of aerial biomass, estimating that the increase of dry leaf concentration explained about 60% of the reduction of this parameter. This suggests that the plant species evaluated have common active components with phytotoxic activity on lettuce plants, even though no complete information are available for concentrations, interactions and synthesis of derivatives during the degradation process of these tissues.

Numerosas especies vegetales y/o sus extractos muestran propiedades nematicidas, atribuibles a los compuestos fitoquímicos presentes en sus tejidos o formados durante el proceso de degradación. Sin embargo, previo a su aplicación en el campo es necesario conocer su efecto sobre las plantas hospedantes. Se evaluó el efecto de la incorporación al sustrato de tres contracciones (1, 2,5 y 5% peso/peso) de hojas secas trituradas de Buddleja globosa, Drymis winteri, Eucalyptus globulus, Gevuina avellana, Laurelia sempervirens y Ugni molinae sobre variables de crecimiento (altura de la planta, largo radical y materia seca foliar) en plantas de Lactuca sativa infestadas con Meloidogyne hapla. Los parámetros de crecimiento de las lechugas fueron afectados significativamente por la interacción entre la especie y las concentraciones de tejido, mostrando D. winteri el mayor efecto reductivo, aún cuando similar a E. globulus. Independientemente del efecto de la infestación del nemátodo en las plantas, la incorporación al sustrato de concentraciones superiores al 5% de hojas secas de D. winteri, E. globulus, G. avellana, L. sempervirens y U. molinae, redujeron la biomasa aérea, estimándose que el aumento de concentración de hojas secas explica alrededor de un 60% la reducción de este parámetro. Esto sugiere, que las especies vegetales evaluadas presentarían componentes activos comunes, teniendo actividad fitotóxica hacia plantas de lechuga, aún cuando, se carece de información de la concentración, interacciones y síntesis de derivados durante su proceso de degradación de esos tejidos.

Murta (Ugni molinae Turcz.) and common chaura (Gaultheria phillyreifolia (Pers.) Sleumer) are native species of Chile. Plants of both species have shown over-branching like witches’ broom. The causal agents of these symptoms in many plants are phytoplasma. To verify the presence of these microorganisms, DAPI (4’,6-diamidino-2-phenylindole) staining analysis and polymerase chain reaction (PCR) were performed in symptomatic and asymptomatic plants. Positive PCR samples were sequenced to identify the pathogens involved. In individuals of both species with witches’ broom symptoms, DAPI staining showed fluorescent bodies in the phloem tissues, but not in asymptomatic plants. Verification by nested-PCR, phytoplasmatic DNA was amplified from diseased murta and chaura, but not in apparently healthy plants. Sequencing of amplified products allowed locating phytoplasma within the ash yellows group (16SrVII) and related to Candidatus phytoplasma fraxini. This is the first report of phytoplasma in Chilean native species. Considering the diversity of plant species infected by the ash yellows group suggests that G. phillyreifolia and U. molinae could be a phytoplasma reservoir for other economically important agricultural crops.

La murta (Ugni molinae Turcz.) y la chaura común (Gaultheria phillyreifolia (Pers.) Sleumer) son especies nativas de Chile. En plantas de ambas especies se ha observado una sobre-ramificación de tipo "escoba de bruja". En muchas plantas los agentes causales de esta sintomatología son fitoplasmas. Para verificar la presencia de estos microorganismos se analizaron plantas con y sin síntomas mediante tinciones DAPI ( 4’,6-diamidino-2-fenilindol) y reacción en cadena de la polimerasa (PCR). Muestras positivas en la PCR fueron secuenciadas para identificar al fitopatógeno implicado. En individuos de ambas especies con síntomas de escoba de bruja, la tinción DAPI permitió observar cuerpos fluorescentes en los tejidos del floema, situación que no ocurrió en plantas asintomáticas. En la verificación mediante PCR-anidada, se logró amplificar ADN fitoplasmático en plantas de murta y chaura enfermas, pero no en plantas aparentemente sanas. La secuenciación de los productos amplificados permitió localizar al fitoplasma dentro del grupo "ash yellows" (16SrVII) y relacionado al "Candidatus Phytoplasma fraxini". Éste es el primer reporte que caracteriza a un fitoplasma en especies nativas chilenas. Considerando la diversidad de especies de plantas infectadas por el grupo ash yellows, sugiere que G. phillyreifolia y U. molinae podrían constituir un reservorio de fitoplasmas para otros cultivos agrícolas de importancia económica.

Color sticky traps are one of the main alternatives to collect insect vectors, as they are easy to handle and are inexpensive. We aimed to compare the effect of color and height of the traps on the attractiveness to potential cicadellids vectors of plant pathogens. Yellow and green colored stick traps were placed at two different heights in plant of Gaultheria phillyreifolia. Seventeen leafhopper species were identified, with Ribautiana tenerrima Herrich-Shäffer (49%), Carelmapu ramosi Linnavuori & DeLong (33%), Carelmapu aurionitens Linnavuori (5%) and Atanus sp. (6%) being the most common. All these species were significantly attracted by yellow sticky traps. Ribautiana tenerrima was the only species affected by the height of the sticky traps. However, this was also dependent on the sampling season. The phytoplasma vector candidate, C. ramosi, showed two population peaks in early and late summer, which may indicate two different generations. Males of this species were more abundant than females on sticky traps, but were both similarly attracted to yellow sticky traps. No differences were detected in the capture efficiency of both sexes at any height of the traps. The high proportion of C. ramosi captured suggests that the yellow sticky traps can be an important element for monitoring this species.

Las trampas pegajosas de colores son una de las principales alternativas en la captura de insectos vectores, debido a su bajo costo y su fácil implementación. El objetivo fue comparar las preferencias a los colores y la altura de colocación de trampas para los posibles cicadélidos vectores de fitopatógenos. Trampas pegajosas amarillas y verdes fueron colocadas en plantas de Gaultheria phillyreifolia a dos distintas alturas. Se diferenciaron 17 especies de cicadélidos, siendo Ribautiana tenerrima Herrich-Shäffer (49%), Carelmapu ramosi Linnavuori & DeLong, Carelmapu aureonitens Linnavuori (33 y 5%), Atanus sp. (6%) las especies más comunes. Todas estas especies se vieron significativamente atraídas por trampas de color amarillo. Ribautiana tenerrima fue la única especie afectada por la altura de las trampas pegajosas, aunque este efecto fue influenciado por la temporada de colecta. La especie candidato a vector, C. ramosi, presentó dos curvas de crecimiento al inicio y finales del verano, lo cual puede representar la emergencia de dos generaciones distintas. Machos de esta especie fueron más abundantes que las hembras en las trampas pegajosas, pero ambos con una similar preferencia hacia el color amarillo. Además, no se detectaron diferencias en la posición de las trampas en la captura de ambos sexos. La alta proporción capturada de C. ramosi, sugiere que trampas de color amarillo pueden ser um elemento importante en el monitoreo de esta especie.

The biological control of the root-knot nematode, Meloidogyne hapla , was evaluated through the addition of organic amendments of dry and chopped leaves of Buddleia globes, Dramas winter, Eucalyptus globules, Genuine aflame, Aurelia sempervirens, huma apiculata, Maytenus boaria and Ugni molinae to the soil substratum. The assays were carried out in pots seeded with lettuce plants (cv. Reina de Mayo). All pots were inoculated with 2000 eggs and juveniles of M. hapla, and then maintained under greenhouse conditions for 45 days. Control pots without foliage additions were also seeded with lettuce. The results show that the addition of dry leaves of L. sempervirens, G. avellana, M. boaria, D. winteri , and B. globosa significantly reduced root-knot nematode development in soil in which lettuce plants were grown. On the other hand, while all of the treatments significantly affected the development of eggs and juveniles of M hapla, the best inhibitory effect was found with dry leaves of U. molinae, D. winteri and L. sempervirens . For all plant species, an increase in the concentration of dry leaves incorporated into the substratum resulted in better control of nematode population.

Buscando alternativas biológicas para el control del nemátodo de las agallas radicales, Meloidogyne hapla, se evaluó la incorporación al sustrato de follaje seco y molido de Buddleja globosa, Drymis winteri, Eucalyptus globulus, Gevuina avellana, Laurelia sempervirens, huma apiculata, Maytenus boaria y Ugni molinae. Se utilizó como control un tratamiento sin follaje. El ensayo se realizó en macetas en las que se trasplantaron plantas de lechuga (cv Reina de Mayo). Todas las macetas se inocularon con 2000 huevos y juveniles de M. hapla y se mantuvieron por 45 días en invernadero. Los resultados indicaron que las plantas de lechuga desarrolladas en sustratos con hojas secas de L. sempervirens, G. avellana, M. boaria, D. winteri y B. globosa redujeron significativamente el agallamiento radical. Mientras que todos los tratamientos afectaron significativamente la formación de huevos y juveniles de M. hapla, destacando el efecto inhibitorio sobre este parámetro el follaje seco de U. molinae, D. winteri y L. sempervirens. En todas las especies, el incremento de la concentración de follaje incorporado al sustrato resultó en un mayor control en la multiplicación de M. hapla.