n African Entomology - Seasonal phenology of the diamondback moth, (L.), (Lepidoptera : Plutellidae), and its parasitoids on canola, (L.), in Gauteng province, South Africa

Volume 11, Issue 2
  • ISSN : 1021-3589



Canola, L. (Brassicaceae), is a relatively new crop in South Africa. Several insect pests, including diamondback moth, (L.) (Lepidoptera : Plutellidae), that attack cruciferous vegetables, also attack canola. The aims of this study were to determine the seasonal phenology of populations on canola, and the composition, relative abundance and seasonal phenology of parasitoids attacking on this crop. Diamondback moth adults were monitored with synthetic sex-pheromone traps. Larval and pupal populations of were monitored weekly for three years at Bapsfontein and Rietondale in Gauteng province. Samples of diamondback moth larvae, pupae and parasitoid cocoons were collected and transported to the laboratory. Parasitoids that emerged were identified and their incidence recorded. Berlese funnel catches were used as an indicator of the accuracy of the visual counts. The infestation level of larvae was high from May to August at Rietondale, while at Bapsfontein it was high from September to December. There was a high correlation (r=0.79, P<0.001) between pheromone trap catches and subsequent larval infestations at Bapsfontein. The pheromone traps indicated that diamondback moth adults were present throughout the year. Berlese funnel catches indicated that a large number of larvae, especially first instars, were overlooked during visual plant scouting. Parasitism rates were often very high, reaching 90-100 %. The following parasitoids were recorded from field-collected : the larval parasitoids (Kurdjumov) (Hymenoptera : Braconidae) and Ullyett (Hymenoptera : Braconidae), the larval / pupal parasitoids (Holmgren) (Hymenoptera : Ichneumonidae) and (Kurdjumov) (Hymenoptera : Eulophidae), the pupal parasitoid (Gravenhorst) (Hymenoptera : Ichneumonidae), and the hyperparasitoids sp. (Hymenoptera : Ichneumonidae) and sp. (Hymenoptera : Pteromalidae). was the most abundant parasitoid throughout the study.

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