Phenology of apple leafcurling midge ( Dasineura mali) in relation to parasitism by Platygaster demades

Abstract

The phenology of apple leafcurling midge (ALCM Dasineura mali) and that of its parasitoid Platygaster demades was monitored in orchards over several years in the Nelson district There were 45 generations of ALCM the first two being distinct while the following generations tended to overlap Host and parasitoid populations were generally synchronized except for the second generation when parasitoid numbers were low and parasitism levels dropped Midge populations increased rapidly at this time and remained high in subsequent generations despite moderate levels of parasitism Laboratory studies on the effect of temperature on host and parasitoid pupal development rates combined with weather station data and actual soil temperatures were used to develop a model to predict generation timing Platygaster demades adults had a longer development period and emerged later than ALCM adults The influence of host and parasitoid phenology on parasitism levels and biological control of ALCM is discussed