Diamondback moth

The diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), is the most important insect pest of crops of the cabbage family throughout the world. The cost of its chemical control exceeds one billion US dollars annually. In many countries, the diamondback moth has become resistant to all synthetic insecticides used against it in the field and also to toxins from the bacterium Bacillus thuringiensis. In South Africa, consumption of cabbage crops as a staple vegetable, especially in rural and peri-urban areas, is steadily increasing, and the pest status of the diamondback moth is rising.

The only method currently used by farmers in South Africa to control the diamondback moth is the application of synthetic pesticides. However, most resource-poor farmers cannot afford these insecticides. Affordable, alternative, non-chemical and sustainable control methods for the diamondback moth are under investigation, with the emphasis on biological control.

Twenty-three indigenous parasitoids associated with the diamondback moth have been recorded so far on cabbage in South Africa. The economic threshold level for chemical control of diamondback moth in cabbage was also determined. The large numbers of indigenous plants from the Brassicaceae in South Africa on which diamondback moth can develop, and the richness and diversity of the fauna of diamondback moth parasitoids, suggest that the pest may have originated in southern Africa.

Origin of the diamondback moth

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), feeds only on plants belonging to the family Brassicaceae. It is assumed that the diamondback moth evolved on plants from this family. Because cultivated brassicas are considered of European origin, it was suggested and since then widely accepted that the diamondback moth had also originated in the same area and spread with the cultivated brassicas around the world. (read more)

Monitoring of diamondback moth and its natural enemies

The pest status of diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), in South Africa is lower than in other countries with similar climates. A project was initiated to investigate possible reasons for this. (read more)

Diamondback moth in canola

Canola is a relatively new crop in South Africa. Several insect pests including diamondback moth (DBM), Lepidoptera: Plutellidae, that attack cruciferous vegetables, also attack canola. (read more)

Indigenous natural enemies of diamondback moth

Larvae and pupae of diamondback moth, (Lepidoptera: Plutellidae), were collected weekly for two years on unsprayed cabbage plots. (read more)

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