Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

Current developments in microbial control of insect pests and prospects for the early 21st century

Abstract: The role of microbial control in crop and forest protection and the abatement of insects of medical and veterinary importance has expanded considerably with the discovery and development of new microbial control agents and genetic improvement in bacterial and viral pathogens, and improvements in formulation, application options and compatibility with other interventions. A synopsis of the literature regarding the current use of bacteria, viruses, fungi, protozoans and nematodes as microbial control agents is presented along with speculation on their potential in the early 21st century. The most widely used of all microbial control agents isBacillus thuringiensis. The isolation within the past two decades of new strains that are larvicidal for certain Diptera and Coleoptera has increased the utility of the bacterium considerably. Further improvements in efficacy and broadening of its host range are in progress with the isolation of strains with new toxins and the manipulation ofB. thuringiensis genes that encode toxin production using both recombinant and nonrecombinant methods. Genetic manipulation of these genes has also enabled their incorporation into crop plants. The development and commercial availability of entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae expands the options for the control of insects, especially those with soil inhabiting stages. The results of natural epizootics of fungi and viruses often obviate the requirement for additional interventions. Breakthroughs in understanding the genetics ofBaculovirus and subsequent gene manipulation have increased their virulence and utility. Improved production methods that utilize insect cell culture technology may enable affordable use ofBaculovirus in the not too distant future. Fungi continue to offer the only control options using entomopathogens against plant sucking insects. Although fungi have great potential for development as microbial control agents, only a few have been used on an operational scale. Some factors that might limit the full range of entomopathogen potential, including development of resistance, are discussed. Because of their selectivity and minimal environmental impact, microbial control agents will be ideal components of integrated pest management programs in the early 21st century and beyond. However, if they are used merely as replacements for chemical pesticides, then eventually these agents will face some of the same fate as the chemicals they replace, particularly with respect to resistance.

Discrimination by Female Mice between the Odours of Parasitized and Non-Parasitized Males

Abstract: The detection and avoidance of parasitized males has been proposed to be a component of female mate choice. We investigated whether or not female laboratory mice, Mus musculus domesticus, could discriminate between parasitized and non-parasitized males on the basis of odour. Female mice were given a choice between the urine and other odorous secretions of either a male mouse sub-clinically infected for five days with the naturally occurring, enteric, single host, protozoan parasite, Eimeria vermiformis, or an uninfected male. Females showed a marked preference for the odours of non-parasitized male mice over those of the parasitized males; as measured by number of investigations, time spent per investigation, and total investigation time of the odours in a choice situation. Female mice also displayed an overwhelming initial, or first choice, preference for the odours of the non-parasitized male mice over those of the parasitized males. These observations show that female mice can distinguish between the odours of parasitized and non-parasitized males, and discriminate against parasitized males on the basis of odour. We suggest that the detection and avoidance of infected males by female mice through odour cues may function to reduce parasite transmission and potentially serve as a component of female mate selection or choice.

Genome analysis of Thinopyrum intermedium and Thinopyrum ponticum using genomic in situ hybridization

Abstract: Genomic in situ hybridization (GISH) using genomic DNA probes from Thinopyrum elongatum (Host) D.R. Dewey (genome E, 2n = 14), Thinopyrum bessarabicum (Savul. & Rayss) A. Love (genome J, 2n = 14), and Pseudoroegneria strigosa (M. Bieb.) A. Love (genome S, 2n = 14), was used to examine the genomic constitution of Thinopyrum intermedium (Host) Barkworth & D.R. Dewey (2n = 6x = 42) and Thinopyrum ponticum (Podp.) Barkworth & D.R. Dewey (2n = 10x = 70). Evidence from GISH indicated that hexaploid Th, intermedium contained the J, Js, and S genomes, in which the J genome was related to the E genome of Th. elongatum and the J genome of Th. bessarabicum. The S genome was homologous to the S genome of Ps. strigosa, while the Js genome referred to modified J- or E-type chromosomes distinguished by the presence of S genome specific sequences close to the centromere. Decaploid Th. ponticum had only the two basic genomes J and Js. The Js genome present in Th. intermedium and Th. ponticum was homologous with E or J genomes, but was quite distinct at centromeric regions, which can strongly hybridize with the S genome DNA probe. Based on GISH results, the genomic formula of Th. intermedium was redesignated JJsS and that of Th. ponticum was redesignated JJJJsJs. The finding of a close relationship among S, J, and Js genomes provides valuable markers for molecular cytogenetic analyses using S genome DNA probes to monitor the transfer of useful traits from Th. intermedium and Th. ponticum to wheat.