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The spotted wing drosophila, D. suzukii, is a serious agricultural pest attacking a variety of soft fruits and vegetables. Although originating from East Asia it has recently invaded America and Europe raising major concern about its expansion potential and the consequent economic losses. Since cytogenetic information on the species is scarce, we report here the mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of D. suzukii. The mitotic metaphase complement contains three pairs of autosomes, one of which is dot-like, and one pair of heteromorphic (XX/XY) sex chromosomes. The salivary gland polytene complement consists of five long polytene arms, representing the two metacentric autosomes and the acrocentric X chromosome, and one very short polytene element, which corresponds to the dot-like autosome. Banding pattern as well as the most characteristic features and prominent landmarks of each polytene chromosome arm are presented and discussed. Furthermore, twelve gene markers have been mapped on the polytene chromosomes of D. suzukii by in situ hybridization. Their distribution pattern was found quite similar to that of D. melanogaster revealing conservation of synteny although the relative position within each chromosome arm for most of the genes differed significantly between D. suzukii and D. melanogaster. The chromosome information presented here is suitable for comparative cytogenetic studies and phylogenetic exploration, while it could also facilitate the assembly of the genome sequence and support the development of genetic tools for species-specific and environment-friendly biological control applications such as the sterile insect technique.

The olive fruit fly, Bactrocera oleae, is the major pest of the olive tree. Despite its importance, very little genetic and molecular knowledge is available. The present study is a first attempt to identify and characterize B. oleae expressed sequence tags (ESTs). One hundred and ninety-five randomly selected cDNA clones were isolated and the obtained sequences were annotated through BLASTX similarity searches. A set of 159 unique putative transcripts were functionally assigned using Gene Ontology terms in broad categories of biological process, molecular function and cellular component based on D. melanogaster matches. Moreover, the cytogenetic location of 35 ESTs was determined by in situ hybridization to B. oleae polytene chromosomes. The resulting low-resolution EST map more than doubles the available entry points to the insect's genome and can assist syntenic comparisons with other distant species. The deduced codon usage of the isolated ESTs suggested a conserved pattern of B. oleae with its closest relatives. Additionally, the comparative analysis of B. oleae ESTs with the homologous D. melanogaster genes led to the development of 17 nuclear EPIC-PCR markers for the amplification of intron sequences of 11 Tephritidae species. Sequencing analysis of several cross-amplified intron sequences revealed a high degree of conservation among Bactrocera species and a varying transferability of the generated markers across the examined genera, suggesting that this method can provide a useful tool for the clarification of phylogenetic relationships among different species, particularly in cases of species complexes.

The Mediterranean fruit fly, Ceratitis capitata, is a pest of major economic importance and has become a model for the development of SIT control programs for insect pests. Significant information has been accumulated on classical and population genetics of this species during the past 2 decades. However, the availability of molecular markers is limited. Here, we present the isolation and characterization of 159 microsatellite clones and the development of 108 polymorphic microsatellite markers for this insect pest. Mapping by in situ hybridization to polytene chromosomes of 21 microsatellite clones enriched the cytogenetic map that was previously constructed by our group. The enriched map provides a large number of STSs for future genome mapping projects. Cross-species amplification of these microsatellite loci in 12 Tephritidae species and sequence analysis of several amplification products indicated a varying degree of transferability and their possible usefulness as molecular and genetic markers in these species where genetic and molecular tools are limited.