Oviposition, life cycle, and parasitoids of the spruce cone maggot, Strobilomyia anthracina (Diptera: Anthomyiidae), in the Alps

The life cycle of Strobilomyia anthracina (Czerny) which exploits Norway spruce seed cones was investigated in 1992 and 1993 in the Alps at c. 1800 m at Torgnon (Valle d'Aosta, Italy) and Lac de Tseuzier (Valais, Switzerland) by sampling cones at fortnightly intervals. Oviposition occurred primarily singly in the basal third of cones at the beginning of June when cone scales were open for pollination. Infestation rates were higher when cone crops were poor. Most larvae left the cones in August to pupate in the litter beneath trees, usually at a depth of 1-4 cm. Prolonged diapause of pupae coincided with failed or poor cone crops. Parasitism was investigated at these two and 27 additional sites in the Swiss, French and Italian Alps. Among several hundred host eggs only one was parasitized by Trichogramma sp. (Trichogrammatidae). Among the larval-pupal endoparasitoids, the figitid Sarothrus areolatus Hartig was more common than an ichneumonid, Atractodes sp., but parasitism by both was commonly below 10%. Parasitism by an ichneumonid larval ectoparasitoid, Scambus sp., also rarely exceeded 10%. Puparia of S. anthracina that were buried in the litter to detect pupal parasitoids revealed the gregarious pteromalid Tritneptis sp. near lophyrorum (Rushka). This is the first record of a pupal parasitoid of Strobilomyia species. Information on the biology of the three larval parasitoids is presented. The potential for biological control of North American Strobilomyia neanthracina Michelsen and S. appalachensis Michelsen by importation of natural enemies of S. anthracina appears limite

Population management of cone and seed insects in spruce seed orchards

Seed orchards have been established in order to produce high quality seeds for reforestation and forestation. However, seed production in spruce (Picea abies (L.) Karst.) seed orchards is severely hampered by cone- and seed-feeding insects. Therefore it is of great importance to find methods to reduce damages from insects. This thesis summarizes and discusses results presented in four papers concerning various methods and chemicals (insecticides and a pheromone) for damage reductions in spruce seed orchards. Area-wide application of the biological insecticide Turex 50 WP was shown to reduce damage by two of the four most serious pest species. Concerns were then raised that feeding by insects that are not affected by this insecticide may increase following its application, in response to the consequent increases in the availability of food and space, resulting in little no or difference in overall damage. A follow up study indicated that there would probably not be any problem with increased feeding by the larvae survived and that spraying of an insecticide not affecting all species would probably be cost effective. However, various species-related and abiotic factors (e.g. rain and temperature) affect the efficacy of insecticide treatments, both among and within years, and thus should be taken into account. A system that would be less sensitive to weather and also may affect all pest species and at the same time avoid affecting the surrounding environment is injectable systemic insecticides. In order to increase the cost efficiency a study was performed where insecticide was combined with the flower stimulating hormone gibberellin and successfully reduced damages and increased number of flowers. In order to know if and when an insecticide application should be carried out, pheromone for trapping insects is a useful tool. But in order to do so there must be a pheromone available. During the spring of 2009 a pheromone for C. strobilella was identified and synthesized. The study showed that the amount of pheromone released from the female was extremely low, 1 pg, so the male antenna is supersensitive in order to find females. This implies also that this species can be a good candidate for mating disruption

An Investigation of the Cone and Seed Insects of Whitebark Pine and Alpine Larch Emphasizing the Western Conifer Seed Bug (Hemiptera: Coreidae) and the Larch Cone Fly (Diptera: Anthomyiidae)

Laboratory and field feeding tests with Leptoglossus occidentalis Heidemann proved that both immature and mature seed bugs can use cones and foliage of whitebark pine, Pinus albicaulis Engelmann, as a food source for 1- to 2-week periods. Damage to unprotected whitebark pine cones by seed bugs ranged from 0.3 to 2.1 % of seeds per cone, and for bagged cones averaged 0.7% of seeds per cone. Total insect damage ranged from 0.4 to 7.2% of seeds per cone. A seed chalcid, Megastigmus sp., was documented for the first time on whitebark pine and damaged 4.7% of examined seeds at one site. Four out of five upper elevation subsites had an average of 24.9% fewer filled seeds per cone than lower elevation subsites. Within-site elevation differences had no significant effect on cone length, number of seeds per cone, percentage of potential seeds per cone, or percentages of seed bug and insect-damaged seeds per cone. The larch cone fly Strobilomyia macalpinei Michelsen was found in cones of alpine larch, Larix lyallii Parl., in the Bitterroot Range of Montana. This is the first record of this species in the United States and the first since its description in 1988. Ninety-four percent of a sample of alpine larch cones were damaged by cone fly larvae, and 64% contained larvae or puparia. Colored traps did not succeed in trapping adult cone flies in an alpine larch stand with no cone crop

Taimiuutiset 3/2008

Taimi- ja metsänviljelyalan ammattileht

Taimiuutiset 4/2005

Taimi- ja metsänviljelyalan ammattileht

L'entomofaune des cônes de sapin baumier (Abies balsamea (L.) Mill) et son impact sur la régénération

Les conophytes sont un groupe d'insectes spécialisés dans l'exploitation des cônes: leur développement est lié obligatoirement à la présence de ceux-ci. Plusieurs espèces conophytes se nourrissent du cône et des graines et ont un impact important sur la production semencière. Les espèces s'attaquant au sapin baumier (Abies balsamea) sont mal connues, tout comme leur impact sur la production de graines et sur la régénération des peuplements. Le présent projet vient pallier le manque de connaissances. Il présente l'inventaire des insectes présents et la structure de la communauté, fait la relation entre les périodes de colonisations de conophytes et le développement du cône et établit certaine interactions entre les différentes espèces de conophytes. Au niveau de la production semencière, le projet a permis d'évaluer l'impact des conophytes sur la production semencière du sapin baumier. Il constitue également une première tentative de relier les pertes observées au niveau des cônes et la densité des émergents de sapin baumier. Un dispositif d'échafaudage, installé dans une sapinière boréale, a permis l'accès aux cimes des arbres, permettant la récolte des cônes sur une base périodique. Ces récoltes ont permis 1) d'identifier les insectes qui parasitent les cônes du sapin baumier, en forêt boréale, 2) d'estimer les périodes d'attaques des conophytes, 3) d'établir des relations entre les différentes espèces et 4) d'évaluer leur impact sur la production semencière. Les trois premiers points sont traités dans le chapitre 2, alors que l'impact des conophytes sur la production de graines fait l'objet du chapitre 3. Un deuxième dispositif, comprenant des grilles de trappes à graines et des quadrats pour le suivi de l'émergence des semis, a été installé dans huit sapinières (chapitre 4). Il a été possible d'établir un lien entre la prédation prédispersion et la régénération, en se concentrant essentiellement sur l'émergence des semis. Au cours des années 2003 et 2004, les conophytes ont colonisé l'ensemble des cônes récoltés à l'aide du dispositif d'échantillonnage. Douze espèces ont été inventoriés, principalement des espèces phytophages. Si trois de ces espèces sont abondantes (Dasineura sp., Earomyia aterrima et Megastigmus specularis), les autres demeurent relativement rares. La communauté est par conséquent très peu diversifiée. Les périodes d'attaque s'échelonnent sur plus de deux mois, par contre, la plupart des espèces colonisent le cône avant la lignification de celui-ci. Malgré la cohabitation de plusieurs espèces au sein d'un même cône, peu de relations de compétition ont pu être établies entre les espèces phytophages. Les tests ont toutefois permis de faire ressortir, en 2004, une relation négative entre Dasineura sp. et Earomyia aterimma, et une relation positive entre Dasineura sp. et Megastigmus specularis. La présence des conophytes, dans les cônes, a engendré des pertes au niveau de la production semencière. Ces pertes sont relativement faibles en 2003, alors que 26,6 % des graines produites ont été endommagées. Par contre, le taux de prédation a augmenté significativement en 2004. La faible production semencière en 2004 a concentré les larves dans peu de cônes: l'abondance des larves a doublé et le taux de prédation a atteint 89,3 % de la production de graines. Par conséquent, très peu de graines pleines ont été produites cette année-là. Les données de prédation, obtenues à l'aide du dispositif de trappes à graines, reflètent ce qui a été observé dans les cônes. Les deux dispositifs permettent de constater qu'il existe une relation entre la production semencière et l'abondance des larves. Les variations interannuelles dans la production semencière engendrent des variations inverses dans l'abondance des conophytes et les dégâts associés. Ainsi les taux de prédation sont faibles lors des années de forte production semencière. Par contre, les dégâts sont très importants en 2004, une année de faible production semencière. Cet effet se répercute au niveau des semis puisque la densité des émergents est quasiment nulle lors de ces faibles années de production semencière. Cela résulte de l'effet combiné d'un très faible taux de graines pleines et d'un important taux de prédation. Les conophytes ont donc, non seulement un effet sur la production de graines pleines, mais également sur la densité des émergents de sapin baumier. Il est cependant peu probable, dans des sapinières naturelles, que cet impact se répercute sur l'établissement des semis et donc sur la régénération des peuplements. Dans ces peuplements, la régénération est assurée par la présence d'une banque de semis permanente. Pour que les conophytes aient un impact sur la régénération, il faudrait que des taux de prédation élevés soient atteints au cours de plusieurs années consécutives, au moment de la constitution de la banque de semis permanente. Il serait toutefois intéressant d'étudier l'effet de ces insectes dans des sapinières en phase de régénération. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Abies balsamea, Conophytes, Prédation, Prédispersion des graines, Production semencière, Régénération, Sapin baumier

Inventory and review of quantitative models for spread of plant pests for use in pest risk assessment for the EU territory

This report considers the prospects for increasing the use of quantitative models for plant pest spread and dispersal in EFSA Plant Health risk assessments. The agreed major aims were to provide an overview of current modelling approaches and their strengths and weaknesses for risk assessment, and to develop and test a system for risk assessors to select appropriate models for application. First, we conducted an extensive literature review, based on protocols developed for systematic reviews. The review located 468 models for plant pest spread and dispersal and these were entered into a searchable and secure Electronic Model Inventory database. A cluster analysis on how these models were formulated allowed us to identify eight distinct major modelling strategies that were differentiated by the types of pests they were used for and the ways in which they were parameterised and analysed. These strategies varied in their strengths and weaknesses, meaning that no single approach was the most useful for all elements of risk assessment. Therefore we developed a Decision Support Scheme (DSS) to guide model selection. The DSS identifies the most appropriate strategies by weighing up the goals of risk assessment and constraints imposed by lack of data or expertise. Searching and filtering the Electronic Model Inventory then allows the assessor to locate specific models within those strategies that can be applied. This DSS was tested in seven case studies covering a range of risk assessment scenarios, pest types and dispersal mechanisms. These demonstrate the effectiveness of the DSS for selecting models that can be applied to contribute to EFSA Plant Health risk assessments. Therefore, quantitative spread and dispersal modelling has potential to improve current risk assessment protocols and contribute to reducing the serious impacts of plant pests in Europe

Red Squirrels Cause Balancing Selection on the Length of White Spruce Cones

Seed predators act as agents of selection on many conifer species through non-random foraging, but their effects on conifers that use mast seeding as a defense strategy are unknown. Optimal foraging models predict that when resources are scarce predators should act to maximize total energy, while when resources are abundant they should maximize efficiency. Here, I examined North American red squirrel (Tamiasciurus hudsonicus) seed predation on white spruce (Picea glauca). The length of white spruce cones exhibited a trade-off between total energy content and the rate of energy extraction. During mast years there was a low opportunity for selection and no evidence of selection on cone length. In non-mast years, squirrels disproportionately harvested longer cones farther from caches, but shorter cones closer to caches. Red squirrels harvested cones in a manner consistent with central-place foraging theory. However, these opposing relationships on cone length led to weak net selection.Northern Scientific Training ProgramOntario Graduate ScholarshipNatural Sciences and Engineering Research Council of Canad

Eine neue Art der Cyphon variabilis-Gruppe aus Nepal (Coleoptera, Scirtidae) (120. Beitrag zur Kenntnis der Scirtidae).

Eine neue Cyphon-Art aus Nepal wird beschrieben und mit Cyphon jaegeri Klausnitzer, 2005 verglichen. Sie gehört in die Cyphon variabilis-Gruppe. Eine Bestimmungstabelle für die Untergruppen der Cyphon variabilis-Gruppe wird vorgelegt.StichwörterScirtidae, Cyphon, Cyphon variabilis group, new species, new species group, Nepal.Nomenklatorische Handlungenweigeli Klausnitzer, 2005 (Cyphon), spec. n.A new Cyphon species from Nepal is described, attributed to the Cyphon variabilis group, and compared with Cyphon jaegeri Klausnitzer, 2005. An identification key to the sub-groups of the Cyphon variabilis group is presented.KeywordsScirtidae, Cyphon, Cyphon variabilis group, new species, new species group, Nepal.Nomenclatural Actsweigeli Klausnitzer, 2005 (Cyphon), spec. n