Research objectives and content
The Mediterranean fruit fly (medfly), Ceratitis capitata, is rated as one of the world's most destructive agricultural pests. A native of eastern Africa, the fly has invaded most of the warmer parts of the world, causing immense devastation to more than two hundred fruit species. World-wide, the economic impact of this insect is estimated in hundreds of millions c dollars. The sterile insect technique (SIT) has been an effective method to control medfly. However, problems associated with the unavoidable release of females abound. The last years there has been an intensive interest in generating genetic sexing strains (GS) that would provide the means for the easy separation between the sexes and the release of male flies only.
Three are the major lines of research that have contributed to the understanding of the biology of the medfly and have helped address the aforementioned problems. First, the elaboration of the genetics of the medfly and the construction of genetic sexing strains useful for SIT. Second, the development of a system for the genetic transformation of the medfly Third, the analysis of the genetic structure and dynamics of medfly populations. With the present study we propose to build the fundamentals of an integrated tool for genetic, molecular and population analyses of the medfly based on microsatellite markers.
Microsatellite loci are regions of DNA containing tandem repeats of a short sequence motif. As molecular markers the! are particularly suitable for genetic and population studies because they occur abundantly in the genome, they are highly variable and can be easily scored using a combination of polymerase chain reaction (PCR) amplification of each locus followed by electrophoresis to separate alleles. In the case of medfly, there is the additional possibility of linking genetic with cytogenetic data due to the presence of well-defined polytene chromosomes. The goal of the proposed study is to generate an integrated tool for cytogenetic, genetic, molecular and population analyses of the medfly. Our objective is to produce a cytogenetic map of microsatellite polymorphisms covering all fives polytene chromosomes. Within the time limits of the present proposal we will first focus on chromosome 5, as it is the best characterized from a genetic and molecular point of view. On that map we intend to integrate pre-existing molecular and genetic markers, whose relative position will be determined either genetically or cytogenetically. Training content (objective, benefit and expected impact)
. The proposal is a combination of the research interests of the hosting team and of the previous experience of thee visiting researcher. The candidate will benefit from the exposure to the genetics of the medfly and his integration to the other research and educational activities of the host institution. In his turn, he will be able to introduce some of the most modern techniques for the genetic analysis of the organism. The construction of integrated genetic maps using molecular markers that are numerous, spontaneous and easily scorable by PCR, are extremely helpful in mapping genetic markers at a good average resolution. In addition, microsatellite markers are highly useful for studies of natural population structure and dynamics as well as for evolutionary studies, which are among our future goals. Such studies done with modern molecular tools, sensitive enough to uncover even cases of sympatric speciation, are among the main priorities of the Biotechnology Programme. In addition, these studies are essential in paving the ground for future genetic control of this agricultural pest. This is now a not so distant prospect after the recent development of a genetic transformation system for medfly. This makes part of biological control efforts that are among the priorities of several EU programmes, including co-operative programmes with developing countries.
Links with industry / industrial relevance (22)
The proposed project is relevant to agricultural industry, since the Mediterranean fruit fly is among the world's most destructive agricultural pests. The fly has invaded most of the warmer parts of the world, including all Mediterranean countries, causing huge devastation to fruit species. Large factories in Mexico and elsewhere are daily producing millions of sterile flies for releases under SIT programmes. Our results should have immediate contribution into the understanding of the population dynamics of released flies.
In addition, the host research group is collaborating with two Greek organizations, the Chania Institute of Subtropic Plants and Olive National Institute for Agricultural Research, and the Union of Agricultural Co-operatives of Apokorones and Sfakia.