Sequence and expression analysis of potential spermatogenesis-specific gene cognates in the Caribbean fruit fly, Anastrepha suspensa.

The sterile insect technique (SIT) is a highly effective biologically-based method for the suppression of many insect pest populations. SIT efficacy could be improved by methods of male sterilization that avoid the use of irradiation that can result in diminished fitness and mating competitiveness. Alternative sterilization methods include conditional disruption of genes for male fertility, or using their sperm-specific promoters to drive the expression of genes for lethal effectors. Testing has begun for the testis-specific β2-tubulin gene, though additional male fertility genes are required for redundancy or replacement, and for species where the β2-tubulin isoform does not exist or is not testis-specific. Here we had the goal of identifying and characterizing the sequence and transcriptional expression of two genes in the caribfly, Anastrepha suspensa, that are cognates of D. melanogaster spermatocyte-specific male fertility genes. In Drosophila, wampa encodes a coiled-coil dynein subunit required for axonemal assembly essential to microtubule-based sperm motility, while Prosα6T is a proteasome subunit gene required for spermatid individualization and nuclear maturation. In A. suspensa a cognate to wampa exhibited testis-specific transcript expression, which was minimal in both male and female body tissue. A Prosα6T cognate was not apparent in A. suspensa, but its constitutive isoform, Prosα6, expresses in male testes, but also in male and female body tissue. Thus, for A. suspensa, wampa remains a strong candidate gene for male sterility strategies for SIT including a direct target for gene-editing knockout and use of its promoter for testis-specific toxicity or cell death in conditional expression systems.