Effects of domestication on quality control parameters of the Queensland fruit fly Bactrocera tryoni (Diptera: Tephritidae)

Abstract

The Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt), is a major horticultural pest in Australia. Sterile insect technique (SIT) is increasingly used in area-wide integrated management of Q-fly, as well as for eradication of outbreaks in Q-fly-free regions. Quality control (QC) procedures are important to monitor and maintain high standards of mass-reared insects for SIT. Effective use of QC procedures, and the setting of meaningful standards, requires a clear understanding of the short-term factors that can cause changes in key parameters, such as failures in production systems, and also of the longer-term effects of domestication on the performance of mass-reared colonies. Artificial rearing conditions impose substantial selection pressures that can lead to changes in performance, and hence changes in the expected baseline values in QC assays. We investigated the effects of domestication on QC parameters of old and young Q-fly colonies originating from three distant geographical locations in Australia: Sydney (Generation >100 and 7), Brisbane (Generation 59 and 14) and Cairns (Generation 29 and 9). Standard QC parameters including development time, pupal recovery, pupal weight, adult emergence, sex ratio, flight ability, fecundity, egg hatchability and longevity were assessed. Regardless of their origin, older Q-fly colonies had lower egg hatchability, shorter developmental time, higher fecundity, higher survival under stress and greater longevity. We emphasize the importance of understanding the effects of continued domestication on QC measures when setting standards for assessment of fruit fly strains used in SIT programmes, particularly when using strains that are regularly replaced or infused with wild stock.