Evaluation of Steinernema carpocapsae Weiser for Control of Carrot Weevil Adults, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), in Organically Grown Carrots

Under controlled conditions, application of Steinernema carpocapsae using a baiting method consistently reduced the oviposition of Listronotus oregonensis adults at all moisture regimens. At 80 and 95% relative humidity, soil applications at 10 4 infective juveniles (IJs) cm-2 and 10 5 infective stages (400 IJs cm-2) per pot reduced the survival and oviposition of L. oregonensis adults; soil applications were ineffective at relative humidity lower than 80%. When timed correctly, soil application at the rate of 2 105 IJs/linear meter of row (4.4 109 IJs ha-1) reduced damage by up to 59%.     

Biocontrol of the apple sawfly,Hoplocampa testudinea,with entomogenous nematodes

Four types of experiments were conducted to assess the pathogenicity of entomogenous nematodes against the apple sawfly,Hoplocampa testudinea Klug (Hymenoptera: Tenthredinidae). In Petri dish,Steinernema carpocapsae (Weiser) DD 136 strain,S. carpocapsae All strain,S. feltiae (Filipjev) andHeterorhabditis bacteriophora Poinar caused 100% larval mortality 72 h after the treatments. In semi-field conditions under dwarf apple trees, a single treatment with either 40 or 80S. carpocapsae All strain/cm² caused significant (>80%) larval mortality. No significant increase in mortality was obtained with a second application. In 1990, late treatment with 80S. carpocapsae All strain/cm² caused significant (39.1%) pupal mortality. In 50×50 cm quadrats under dwarf apple trees, treatment with 40 and 80S. carpocapsae All strain/cm² were done in spring 1989. In spring 1990, respectively 22 and 25 apple sawfly adults emerged from quadrats treated with 40 and 80S. carpocapsae All strain/cm², whereas 78 adults emerged from untreated quadrats. In a foliar application experiment, a single treatment withS. carpocapsae All strain significantly reduced the percent of fruit showing secondary damage. The possibility of using entomogenous nematodes as part of an integrated pest management in apple orchards is discussed, with particular reference to the integration of programs aimed at managing plum curculio,Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) populations.      

Oscillations in cyclical neutropenia: new evidence based on mathematical modeling

We present a dynamical model of the production and regulation of circulating blood neutrophil number. This model is derived from physiologically relevant features of the hematopoietic system, and is analysed using both analytic and numerical methods. Supercritical Hopf bifurcations and saddle-node bifurcations of limit cycles are shown to exist. We make the estimation of kinetic parameters for dogs and then apply the model to cyclical neutropenia (CN) in the grey collie, a rare disorder in which oscillations in all blood cell counts are found. We conclude that the major cause of the oscillations in CN is an increased rate of apoptosis of neutrophil precursors which leads to a destabilization of the hematopoietic stem cell compartment.     

Threats to and conservation of North African wetlands: the case of the Ramsar site of Beni-Belaid (NE Algeria)

Because of their biogeographical and geomorphological context, the northeastern Algeria wetlands present high species and community richness. The vegetation study of the Ramsar site of Beni-Belaid (Kabylia) showed the existence of four main communities, distributed along gradients of hydrology and disturbance. The obtained results reveal worrying threats on short term: overgrazing results in the lake invasion by the sand eroded from the coastal dune; agriculture induces illegal cutting, water pollution and excessive groundwater pumping; finally, hunting and fishing are illegally practiced into the Ramsar site. The awareness of public authorities is needed in order: (1) to completely protect the wetland with the aim of restoring a riparian forest belt; and (2) to initiate a campaign for increasing the local population awareness, and its involvement in conservation programs.     

Production of acetone and conversion of acetone to acetate in the perfused rat liver

The utilization of millimolar concentrations of [2-14C]acetone and the production of acetone from acetoacetate were studied in perfused livers from 48-h starved rats. We devised a procedure for determining, in a perfused liver system, the first-order rate constant for the decarboxylation of acetoacetate (0.29 +/- 0.09 h-1, S.E., n = 8). After perfusion of livers with [2-14C]acetone, labeled acetate was isolated from the perfusion medium and characterized as [1-14C]acetate. No radioactivity was found in lactate or 3-hydroxybutyrate. After 90 min of perfusion with [2-14C]acetone, the specific activity of acetate was 30 +/- 4% (n = 13) of the initial specific activity of acetone. We conclude that, in perfused livers from 2-day starved rats, acetone metabolism occurs for the most part via free acetate.     

Effects of Cropping Sequences on Population Densities of Meloidogyne hapla and Carrot Yield in Organic Soil

The influence of various cropping sequences on population densities of Meloidogyne hapla and carrot yield was studied in organic soil under microplot-and field conditions. Spinach, radish, barley, oat, and wheat were poor or nonhosts for M. hapla. Population densities of M. hapla were maintained or increased on cabbage, celery, lettuce, leek, marigold, and potato. Marketable percent-age and root weight of carrots were greater following spinach, oat, radish, and fallow-onion than those following two crops of onion or carrot in microplots. Under field conditions, the carrot-onion-oat-carrot cropping sequence decreased M. hapla population densities and provided a 282% increase in marketable yield of carrot compared to a carrot monoculture. Two consecutive years of onion increased M. hapla population densities causing severe root galling and a 50% yield loss in the following crop of carrot. Based on root-gall indices, carrots could be grown economically for 2 years following radish, spinach, and oat, but not following onion and carrot without the use of nematicides.     

Alder forests of Numidia (N.E. Algeria): floristic biodiversity, vulnerability and conservation

The phytoecological study of the alder forests of north-east Algeria shows that these habitats with boreal affinities harbour very high species richness (> 400 species) and complex structures, which suggest their ancient origin. They correspond phytosociologically to two syntaxa, the Campanulo alatae-Alnenion glutinosae (riparian alder forests) and the Rusco hypophylli-Alnetum glutinosae (peat-forming alder carrs), respectively. Their degraded state and their regressive dynamics, observed during the 14 years of the study, reveal their precarious situation and their rapid ongoing decline under the influence of human-induced uncontroled disturbances (cutting, burning, draining, dumping…). With regard to their ecological, historical and patrimonial importance, the alder forests of Algerian Numidia should be urgently protected, with the aim of assuring the perennity of their exceptional floristic corteges.     

Life Cycle of the Golden Cyst Nematode,Globodera rostochiensis,in Quebec,Canada

In 2006, the golden cyst nematode, Globodera rostochiensis, was discovered in the province of Quebec, Canada. We report here the life cycle of G. rostochiensis under the climatic conditions of southwestern Quebec. Only one full generation was completed per year under these latitudes. On susceptible potato cv. Snowden, G. rostochiensis needed a minimum of 579 growing degree units (GDU) (base 5.9°C) to complete its life cycle and the first mature cysts were observed 42 to 63 days after planting (DAP). In soil, second-stage juveniles (J2) were first observed 14 to 21 DAP, whereas both white females on roots and males in soil appeared synchronously after 35 to 42 days. The duration of the life cycle was affected by temperature but not by soil type. A second wave of hatching systematically occurred later in the season and a second generation of males was observed during the 2011 growth season. No complete second cycle was observed before plant senescence. Climate change and later maturing cultivars/crops could allow the development of a full second generation in the future.     

Virulence of entomopathogenic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) against Tipula paludosa (Diptera: Tipulidae), a turfgrass pest on golf courses

The European crane fly (ECF), Tipula paludosa Meigen feeds on leaves, crowns, and roots of cool-season turfgrasses causing damage to residential lawns and golf courses. A laboratory study was conducted to determine the susceptibility of ECF larvae to four commercial entomopathogenic nematode (EPN) species (Heterorhabditis marelatus, H. megidis, Steinernema carpocapsae and S. feltiae). The virulence of four S. feltiae isolates recovered from golf courses in Quebec and Ontario were also compared to a commercial strain. LC₅₀ values of EPN against late instar ECF larvae were 152, 562, 763, and 3584 for S. feltiae, H. megidis, H. marelatus and S. carpocapsae, respectively. When non-feeding (without grass seedling), ECF larvae mortalities decreased for all nematode species and concentrations tested. At 25°C, LC₅₀ values for the two most virulent indigenous S. feltiae were 129 and 187 nematodes/larva, not different from the commercial strain. At 5°C, the commercial S. feltiae was more effective than both BIC14A and RE6A isolates against ECF larvae. However, at 15°C, BIC14A was the most virulent at the low concentration of 200 IJs/larva.