GALL INDUCTION BY PEGOMYA CURTICORNIS (STEIN) (DIPTERA: ANTHOMYIIDAE) WITHIN THE ROOTS OF SPURGES EUPHORBIA VIRGATA WALDST. AND KIT. AND E. ESULA L. (EUPHORBIACEAE)

The anthomyiid fly Pegomya curticornis (Stein), introduced into Alberta from Europe for the biocontrol of leafy spurge (Euphorbia esula L.), normally induces simple galls on subterranean stems. Here we describe the anatomy of galls collected in Europe that had been induced by P. curticornis on horizontal roots of spurges. Four mature galls were found on the roots of E. virgata Waldst. and Kit. and 10 on the roots of E. esula. Tissues of the root galls were composed of gall parenchyma that had proliferated from feeding sites near the outside edge of secondary xylem. It is assumed that some larvae inadvertently tunnel beyond the base of stems into the roots and that similar galls will form on Alberta spurge

STRUCTURAL DAMAGE AND GALL INDUCTION BY PEGOMYA CURTICORNIS AND PEGOMYA EUPHORBIAE (DIPTERA: ANTHOMYIIDAE) WITHIN THE STEMS OF LEAFY SPURGE (EUPHORBIA × PSEUDOVIRGATA) (EUPHORBIACEAE)

Leafy spurge (Euphorbia × pseudovirgata [Schur]) is an herbaceous perennial and serious weed of European origin that has been accidently introduced into North America. The European anthomyiid flies Pegomya curticornis (Stein) and Pegomya euphorbiae (Kieffer) are found on several spurge species in Europe and also attack leafy spurge. The two flies induce identical galls on the subterranean stems of their host plants, and the shoots wilt and die. Eggs are laid on the shoot tip, and the larvae bore into the stem by eating pith which is later replaced by callus. This is a rare example of an insect with both boring and gall-inducing feeding strategies. Galls are induced when larvae feed on the ring of vascular tissue. There is no proliferation of nutritive cells but instead thick layers of gall parenchyma are produced. The vascular connections are broken at the gall level and concentric vascular bundles appear in the cortical and gall parenchyma. After pupation an inner periderm differentiates around the chamber surfac

Multiple Organ System Defects and Transcriptional Dysregulation in the Nipbl+/− Mouse, a Model of Cornelia de Lange Syndrome

Cornelia de Lange Syndrome (CdLS) is a multi-organ system birth defects disorder linked, in at least half of cases, to heterozygous mutations in the NIPBL gene. In animals and fungi, orthologs of NIPBL regulate cohesin, a complex of proteins that is essential for chromosome cohesion and is also implicated in DNA repair and transcriptional regulation. Mice heterozygous for a gene-trap mutation in Nipbl were produced and exhibited defects characteristic of CdLS, including small size, craniofacial anomalies, microbrachycephaly, heart defects, hearing abnormalities, delayed bone maturation, reduced body fat, behavioral disturbances, and high mortality (75–80%) during the first weeks of life. These phenotypes arose despite a decrease in Nipbl transcript levels of only ∼30%, implying extreme sensitivity of development to small changes in Nipbl activity. Gene expression profiling demonstrated that Nipbl deficiency leads to modest but significant transcriptional dysregulation of many genes. Expression changes at the protocadherin beta (Pcdhb) locus, as well as at other loci, support the view that NIPBL influences long-range chromosomal regulatory interactions. In addition, evidence is presented that reduced expression of genes involved in adipogenic differentiation may underlie the low amounts of body fat observed both in Nipbl+/− mice and in individuals with CdLS

Biological control of Rhamnus cathartica: is it feasible? A review of work done in 2002-2012

Rhamnus cathartica (common buckthorn) is a shrub (or small tree) of Eurasian origin, which has become invasive in North America. Internal feeders and sap suckers were prioritized for biological control from over 30 specialized insects identified from the target plant in its native European range. Five leaf-feeding moths were also considered for further investigations. Field observations and preliminary host range tests with the stem-boring beetle Oberea pedemontana, the root-boring moth Synanthedon stomoxiformis, the shoot-tip-boring moth Sorhagenia janiszewskae and the leaf-feeding moths Ancylis apicella, A.unculana, Triphosa dubitata, Philereme transversata and P.vetulata confirmed that all of these species were lacking host specificity in no-choice conditions. Choice oviposition tests carried out with most of the prioritized species to assess their ecological host range yielded unreliable results. Three psyllids, Trichochermes walkeri, Cacopsylla rhamnicolla and Trioza rhamni are promising in terms of host specificity, but are infected with the plant disease Candidatus Phytoplasma rhamni'. Fruit- or seed-feeding insects may present the best potential for biological control of buckthorn in directly reducing seed set and thus seedling establishment. However, it was not possible to obtain adult fruiting trees of native North American Rhamnus species for testing. It is concluded that there are no promising arthropod agents based on what is known to date. Pathogens could offer new opportunities for biological control of R.cathartica in North America

Biology and host specificity of Chamaesphecia hungarica and Ch. Astatiformis (Lep.: Sesiidae) two candidates for the biological control of leafy spurge, Euphorbia esula (Euphorbiaceae) in North America

Leafy spurge (Euphorbia esula (s.1.)) is an herbaceous perennial and serious weed of Eurasian origin that has been accidentally introduced into North America. The two European root-boring moths Chamaesphecia hungarica and Ch. astatiformis are univoltine and overwinter as mature larvae. Both species have a lower survival rate on leafy spurge than on their field hosts, and thus are not optimal candidates for the biological control of leafy spurge. However, the rate of larval development and larval growth on the target weed and on the two field hosts is nearly the same. The experimental host range of both species is restricted to a few species in the subgenus Esula within the genus Euphorbia. The two species occupy different habitats in the steppe biome and are targeted for similar leafy spurge habitats in North America

Description of European Chamaesphecia spp (Lepidoptera: Sesiidae) feeding Euphorbia (Euphorbiaceae), and their potential for biological control of leafy spurge (Euphorbia esula) in north America

The description of the ten Chamaesphecia species associated with Euphorbia in eastern and south-eastern Europe is based on external adult morphology, male and female genitalia, and the structure of the egg chorion. These species can be divided into two groups according to the shape of the setae of the dorso-basal part of the valvae in the male genitalia. Most Chamaesphecia species are associated with one species of host-plant and all are closely tied to one habitat type. The host-plant and the structure of the egg chorion are fundamental characteristics for the determination of a few species, and very helpful for the others. All species bore into the main root of their host-plant and overwinter as larvae. With the exception of two species which have an annual or biennial life cycle, all species are univoltine. The larvae of three of the eight Chamaesphecia spp. investigated feed and develop in the roots of North American leafy spurge, Euphorbia esula sensu late. Of these, the best candidate for the biological control of leafy spurge is C. crassicornis, because the larvae have a similar survival rate on the target weed and the European host-plant, E. virgata

Use of native range surveys to determine the potential host range of arthropod herbivores for biological control of two related weed species, Rhamnus cathartica and Frangula alnus

The buckthorn species, Rhamnus cathartica and Frangula alnus, are shrubs and small trees of Eurasian origin that have become invasive in North America. A program was initiated in 2001 to reassess the potential for biological control of these two species taking into consideration increasing concerns over potential non-target impacts of biological control agents. The key question was whether R. cathartica and F alnus are distantly enough related that they would not share the same arthropod complex in Europe, and, if so, which arthropod species Would be less likely to use native North American buckthorns as hosts. Some 1000 insect samples collected at 99 sites in Europe indicated that the arthropod -species richness is higher on R. cathartica than on F. alnus and includes more species that are presumed to be host-specific at the species or genus level. This discrepancy supports the hypothesis that the genus Rhamnus in the temperate Old World has evolved in isolation of the genus Frangula in the Neotropics and that taxonomic isolation has an effect on species richness of specialized herbivores. The fauna was dominated by Lepidoptera (22 species), followed by Hemiptera (8 species), Diptera (4 species), Acarina (4 species) and Coleoptera (I species). At least 12 arthropod species were found exclusively on Rhamnus, some of which may be specific to R. cathartica. Several species usually associated with Rhamnus were found rarely on F alnus but the field host range of these species still needs to be confirmed. Only one species was found exclusively on F. alnus. The findings indicate that, with one exception, there are no species or genus-specific agents available for biological control of F alnus at this stage. However, additional field surveys may reveal other host-specific species. (C) 2008 Elsevier Inc. All rights reserved

The occurrence of 'Candidatus phytoplasma rhamni' in Rhamnus cathartica L. without symptoms

Common buckthorn, Rhamnus cathartica L., is a small tree or shrub of Eurasian origin that has become invasive in North America. A survey was conducted during 2010 to evaluate occurrence of buckthorn witches' broom (BWB) disease symptoms induced by Candidatus Phytoplasma rhamni' in the native range of R. cathartica. The distribution of phytoplasma-infected trees was identified over a large expanse of Europe, from south-west Switzerland to north-east Serbia. Although 25% of analyzed buckthorn trees were infected with phytoplasma (34 out of 133 plants), all plants were symptomless, indicating a commensal relationship between the phytoplasma and its plant host without negative effects which would lead to disease development

PCR-RFLP-based method for reliable discrimination of cryptic species within Mecinus janthinus species complex (Mecinini, Curculionidae) introduced in North America for biological control of invasive toadflaxes

Several populations of the stem-mining weevil Mecinus janthinus Germar species complex (Mecinini, Curculionidae), identified based on morphological characteristics, have been introduced in North America for the biological control of invasive toadflaxes of European origin: Linaria vulgaris Miller and L. dalmatica (L.) Miller (Plantaginaceae). According to the mitochondrial cytochrome oxidase subunit II (COII) gene haplotype divergence of Mecinus janthinus species complex, a total of 20 M. janthinus s.s., 3 M. janthinus s.l. of the 'speciosa' genotype and 29 M. janthiniformis haplotypes have been recorded across their native range in central and southeastern Europe. A polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) diagnostic assay of COII gene using Hpy188III and MnlI enzyme-mix, was developed for fast and cost-effective discrimination of these morphologically very similar cryptic weevil species. It is shown that digestion generates unique 4-fragment restriction profile in M. janthinus s.s., 2-fragment profile in M. janthiniformis and 3-fragment profile in M. janthinus s.l. 'speciosa' group of haplotypes, allowing precise identification of each species or genotype. The proposed method represents a practical tool for fast and accurate identification of the target biocontrol agents and should prevent using inappropriate weevil species in redistribution programs for biological control of invasive toadflax species