Developing apple leafcurling midge rearing techniques

Abstract

Apple leafcurling midge (Dasineura mali; ALCM) is considered a quarantine pest in some of New Zealand’s valuable export markets. Research into alternatives to methyl bromide as a fumigant requires a mass rearing programme to provide large numbers of all life stages. Our aim was to focus on developing an understanding of the environmental conditions that break ALCM diapause and facilitate ALCM oviposition. A trial was conducted comparing ALCM oviposition rates on apple seedlings in a controlled temperature room versus a shade house in ambient conditions over the summer months. Additionally, long day length and high humidity conditions were tested to break the diapause of ALCM cocooning larvae. Oviposition rates on young apple seedlings were similar in the controlled environment room and the shade house; however, apple seedlings grew better in the shade house due to lower incidence of powdery mildew. Adults emerged from ALCM cocoons that had been in diapause for five months and then held at 20.9°C for seven days. Conditions to break ALCM diapause have been determined. Seedlings at the six- to eight-leaf stage have the potential to provide an oviposition substrate. Further investigations are required into artificial oviposition substrates and the development of a larval diet to mass rear ALCM larvae.