Susan D. McCombs

The piggyBac transposon mediates germ-line transformation in the Oriental fruit fly and closely related elements exist in its genome

Germ‐line transformation of a white eye strain of the Oriental fruit fly, Bactrocera dorsalis, was achieved with the piggyBac vector, derived from a transposon originally isolated from the cabbage looper moth, Trichoplusia ni. The vector was marked with the medfly white+ gene cDNA, and three transgenic lines were identified at a frequency of approximately 2% per fertile G0. Vector integrations were verified by Southern DNA hybridization, which also revealed the presence of endogenous genomic elements closely related to piggyBac. Approximately 10–20 elements per genome were evident in several B. dorsalis strains, and sequence analysis of 1.5 kb gene amplification products from two wild strains and the white eye host strain indicated 95% nucleotide and 92% amino acid sequence identity among resident elements and the T. ni element. PiggyBac was not evident by hybridization in other tephritid species, or insects previously transformed with the transposon. This is the first discovery of piggyBac beyond T. ni, and its existence in a distantly related species has important implications for the practical use of the vector and insects transformed with it.

Mating competitiveness of male oriental fruit flies from a translocation strain (Diptera: Tephritidae)

Abstract A major advance in sterile insect release programs against tephritid fruit fly pests has been the development of genetic sexing strains, which allow the production of males-only lines for field release. Genetic sexing strains both reduce the costs associated with mass rearing and enhance the mating effectiveness of sterile males. Research and application of genetic sexing strains has been limited largely to the Mediterranean fruit fly. However, translocation-based genetic sexing strains based on pupal color mutants have been constructed in the oriental fruit fly, Bactrocera dorsalis (Hendel). Here, we describe the results of laboratory tests on B. dorsalis that compared the relative success of males from a translocation-based sexing strain and wild males in mating competition for wild females. Additional tests examined the effect of irradiation and exposure to methyl eugenol on the mating frequency of males from the genetic sexing strain.

Comparison of Wild-Type and Mutant white eye Alleles in Melon Fly (Diptera: Tephritidae)

Abstract The DNA sequence of the coding region of the wild-type and mutant alleles of the white eye gene from the melon fly, Bactrocera cucurbitae Coquillett, was obtained. The mutant white eye allele had a single base pair mutation at the 5′ end of intron 4b in the RNA splice recognition site. Due to the disrupted splice recognition site, intron 4b was not removed from the mutant RNA transcript. The resulting mRNA transcript was 68 bp longer than that of the wild type, containing a frameshift and premature stop codon. Transport of pigment precursors would be blocked, resulting in a lack of pigmentation deposition consistent with the known mutant phenotype.