ANALYSIS OF MORTALITY IN THE APPLE MAGGOT, RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE), IN QUEBEC

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Abstract
Life tables were constructed for populations of R. pomonella (Walsh) in two abandoned, heavily infested apple orchards near Como, Quebec. All life stages were sampled and the results expressed in terms of the apple as a unit. Twenty-five life tables, each based on one tree, covered two successive generations on both early and late maturing varieties.Natality was of no value in predicting variation in numbers of emerging adults, whereas the early pupal stage estimates explained over 80% of the variation. Parasitism of larvae and pupae was more common than previously recorded but parasites were not significant in the population dynamics of their host. Nutritionally based larval mortality, predation on mature larvae and pupae, and movements of adults between trees were key factors in population variation. Early variety trees appeared to maintain apple maggot population levels. These results were supported by experimental studies on the effects of temperature treatments and predation on larval and pupal mortality.