The fecundity of spring and summer adults and mortality of the egg, larval and pupal stages of codling moth, Cydia pomonella (L), were studied in sleeve cages in an apple orchard not treated with insecticides. There was a significant difference between the overall fecundity of the spring (137.2 eggs/female) and summer (159.3 eggs/female) moths. During the first third of October, spring moths produced significantly fewer eggs than in November. Egg mortality in spring was 8.2 %, and in summer 21.2%. The increased summer egg mortality was due to the egg parasitoid, Trichogramma luteum Girault (Hymenoptera: Trichogrammatidae). During spring and summer, mortality due to infertile and fertile but unhatched eggs was less than 5 %. In the absence of entomophagous insects, the failure of first instar larvae to penetrate the fruit ranged from 4.9 to 19.5 %. The mortality of larvae from egg hatch to emergence from the fruit ranged from 29.7 to 43.8 %. Mortality of fifth instar larvae in cocoons spun in corrugated cardboard after emerging from the fruit was low, ranging from 0 to 8.7 %. Pupal mortality varied from 0 to 3.5 %. These studies indicate that codling moth in South Africa probably has a higher biotic potential than in most other apple-producing countries.
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Vol. 20 • No. 2