oa African Entomology - The phenology of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), Tortrix capensana (Walker) and Cryptophlebia leucotreta (Meyrick) (Lepidoptera: Tortricidae) on citrus at Zebediela, South Africa



A long-term study of the population cycles of Helicoverpa armigera (Hubner), Tortrix capensana (Walker) and Cryptoph/ebia leucotreta (Meyrick) on citrus at Zebediela was undertaken to establish a phenological model for the planning and implementation of control strategies. Helicoverpa armigera and T. capensana were monitored with light-traps and orchard scouting. In H. armigera the relationships between adult activity, oviposition on citrus blossoms, the presence of larvae on citrus trees and the correlation between moth activity and climatic factors were determined. A correlation between moth activity in autumn and pest status in the following spring was demonstrated. Although the oviposition levels on Navel blossoms were higher than on Valencia, both cultivars were subject to an ovipoSition peak in the first week of September. The larval population peaked on both cultivars in the third week of September during full bloom. Larvae appeared earlier on Navel and but persisted longer on Valencia.


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