Field observations on oviposition of codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Olethreutidae), in an unsprayed apple orchard in South Africa

Abstract

Oviposition of the codling moth, Cydia pomonella (Linnaeus), was studied from 1985 to 1989 in unsprayed apple orchards on the Elgin Experiment Farm, Grabouw, Western Cape Province. There was a significant difference in the site of oviposition, more eggs being recorded from the bottom half of the western and southern aspects of the tree. There was also contingency between the time of year and level (upper half, lower half) in the tree. Moths of the first generation preferred the bottom half of the tree and second and third generation moths the top half of the tree. The preferred oviposition sites on Granny Smith (GS) and Golden Delicious (GD) cultivars, in order of preference, were leaves, fruit and wood. More eggs were laid on the fruit of GS spurs (35.6 %) than on those of GD spurs (10.7 %). On fruit spurs, there was a Significant increase in the number of eggs on GD leaves, and GS fruit over the season, whereas the number of eggs on GS leaves and GD fruit remained constant. On branches, there was an increase in the number of eggs on GD and GS leaves, but not on the fruit or wood. The distribution within different fruit-bearing classes (1-4 fruit per spur) was random only for one fruit per spur, while on the other spur classes clustering occurred.