Mortality factors affecting immature stages of codling moth, Cydia pomonella (Lepidoptera: Tortricidae), and the impact of parasitoid complex

摘要

Codling moth, Cydia pomonella Linnaeus (Lepidoptera: Tortricidae), is a serious pest of apples worldwide. This study aimed to evaluate the mortality rate of codling moth eggs, larvae and pupae in the field in commercial and neglected apple and walnut orchards over two years, and to investigate the biodiversity and intensity of parasitoids associated with codling moth in the orchards. Five patches of wax paper containing 1-day-old codling moth eggs were placed in a neglected orchard in order to evaluate parasitism rates. Corrugated cardboard bands were placed around the trunk of 15 trees during late spring and the beginning of summer through to fruiting season to capture and measure parasitism of codling moth larvae. 5285 larvae in total were collected during this study. Mortality rate (egg + larvae + pupae) varied between the commercial and neglected orchards, reaching a maximum of (42.89% and 66.67%) in neglected apple orchards and (61.03% and 74.76%) in the neglected walnut orchard in 2003 and 2004, respectively. Trichogramma cacoeciae (Hymenoptera: Tichogrammatidae) was the only egg parasitoid recorded. Eight hymenopteran larval and pupal parasitoids belonging to several subfamilies were recorded: Cheloninae, Agathidinae, Cremastinae, Haltichellinae, Chalcidinae, Anomalinae, and Pteromalinae and one dipteran belonging to Tachininae. In conclusion, mortality factors, mainly by parasitoids, are contributing to a general reduction in codling moth larvae populations particularly in neglected orchards. The hymenopteran Ascogaster quadridentata and the dipteran Neoplectops pomonellae can contribute to biological control programmes against codling moth in the coastal region and other regions.