Climate change will affect the ability of forest management to reduce gaps between current and presettlement forest composition in southeastern Canada

Landscape Ecology - Forest landscapes at the boreal–temperate ecotone have been extensively altered. Reducing the gap between current and presettlement forest conditions through...     

Optimizing aphid biocontrol with the predator Aphidoletes aphidimyza,based on biology and ecology

Aphidoletes aphidimyza is one of the most important predators used in the augmentative biological control of aphids, key pests of many crops worldwide. Adult females are very efficient in locating aphid infestations over a relatively long range, up to 45 m, and deposit eggs near or within aphid colonies. The predatory larvae are aphid generalists preying on several agriculturally important aphid species. The successful use of this biocontrol agent in agricultural systems depends on several biotic and abiotic factors. Among biotic factors, aphid species, plant structure, interspecific competition and intraguild predation may significantly impact the predator´s population dynamics. Key abiotic conditions include day lengths (above a critical threshold to prevent diapause), availability of mating sites in the crop, temperature (above 15 °C to enable egg laying), air relative humidity (above 70%) and availability of pupation sites. Although several successes have been reported in open field crops with naturally occurring or released populations, commercial releases are primarily used in protected crops. Optimized emergence boxes combining provisioning of food sources for the adults, integration with the technological advances that occurred in the greenhouse environment lately, insights into the nutritional ecology in open field crops and exploration of the genetic variability are proposed as future directions to improve adoption and efficacy of A. aphidimyza in crop protection. © 2018 Society of Chemical Industry     

Hog Cholera: IV. Detection of the Virus in Tissue Culture Preparations by the Fluorescent Antibody Technique

The fluorescent-antibody technique was employed for detection of hog cholera virus in tissue cultures inoculated with spleens of infected animals. As controls, cultures were also inoculated with material from normal swine and from those infected with other agents. In the first series 71 of 73 infected spleens, or 97 per cent, were detected. There were no false positive reactions among the controls. Results obtained with the second series of pigs showed that spleens collected during advanced stages of the disease were more satisfactory specimens than those collected earlier during the high temperature phase of infection. Findings with the third series of older swine indicated that their spleens were less satisfactory as a source of virus than those from young pigs. Tissues from freshly killed animals provided better specimen material than those from animals which had died.     

Functional requirement for class I MHC in CNS development and plasticity

Class I major histocompatibility complex (class I MHC) molecules, known to be important for immune responses to antigen, are expressed also by neurons that undergo activity-dependent, long-term structural and synaptic modifications. Here, we show that in mice genetically deficient for cell surface class I MHC or for a class I MHC receptor component, CD3zeta, refinement of connections between retina and central targets during development is incomplete. In the hippocampus of adult mutants, N-methyl-D-aspartate receptor-dependent long-term potentiation (LTP) is enhanced, and long-term depression (LTD) is absent. Specific class I MHC messenger RNAs are expressed by distinct mosaics of neurons, reflecting a potential for diverse neuronal functions. These results demonstrate an important role for these molecules in the activity-dependent remodeling and plasticity of connections in the developing and mature mammalian central nervous system (CNS).     

Improvements in the modified direct complement fixation test and its application in the detection of bluetongue antibodies in cattle and sheep sera.

In this study, improvements were made in the technique and the preparation of the antigen. It was possible to perform three extractions and elutions resulting in a soluble reactive preparation from each batch of infected mouse brain. This led to an appreciable increase in the yield of highly reactive antigen. The presence of bluetongue antibodies was not detected in 13,210 sheep sera. Of the 13,486 bovine sera tested, only three questionable reactions were obtained. It was possible to determine that two of these animals were imported. Various isolation methods, including transmission trials to susceptible sheep followed by serological tests on the sheep sera, failed to confirm the infection in the three reactors.     

Transmissible gastroenteritis: demonstration of the virus from field specimens by means of cell culture and pig inoculation.

Isolation of transmissible gastroenteritis virus was attempted from segments of jejunum collected from piglets submitted for diagnosis of transmissible gastroenteritis. The virus was isolated more frequently in susceptible piglets than in pig kidney or pig thyroid cells. Practically, both cell systems were equally capable of demonstrating the virus when the tissue suspensions were sonicated. The pig thyroid cells prepared with glands collected from minimal disease pigs were preferred to the pig kidney cells for initial virus isolation because of their ability to respond to transmissible gastroenteritis virus with a progressive cytopathic effect. However, the pig thyroid cells, prepared from pool of glands collected in abattoirs, were often contaminated with parvoviruses and could not be used for diagnostic work. Controlled ultrasound treatments of the inoculum increased the frequency of virus isolation in both cell systems.     

Studies on Bluetongue: II. Complement-Fxing Activity of Ovine and Bovine Sera

Sera of sheep and calves infected with the California type 10 and Cyprus type 3 viruses of bluetongue were tested by the regular and modified direct complement-fixation tests. To obtain satisfactory complement fixation it was necessary to use the latter test. Cross reactivity was found, therefore, the California type 10 antigen could be used in testing sera of animals infected with the Cyprus virus.