Predation of codling moth eggs, Cydia pomonella, the predators responsible and their alternative prey.
In a study in an unsprayed cider-apple orchard in Bristol, England, on the importance of egg predation in the population dynamics of Cydia pomonella (L.), it was found that 12-86% of Cydia eggs glued to the leaves and fruits at weekly intervals throughout the summer were sucked out, and 3-29% disappeared. The mortality of the natural egg population is estimated to be lower than this, because tests in the laboratory showed that predators were less likely to feed on naturally deposited eggs than on artificially placed ones. The numbers and biomass of 6 species of Heteroptera and of 1 mite species capable of sucking out the contents of Cydia eggs, and the numbers of Forficula auricularia L., which is considered responsible for egg disappearance, were recorded in the foliage. Because of their low numbers when distributed naturally, Cydia eggs are not thought to be an important food source for these predators. The major prey of Heteroptera is probably Panonychus ulmi (Koch), since their numbers and weights are known from previous work to fluctuate in relation to the abundance of this prey only. It is concluded that the predators of P. ulmi also usefully reduce the abundance of Cydia eggs and subsequent damage to the fruit.