Efficacy of selected plant extracts against diamondback moth (Plutella xylostella L.) on round cabbage in situ

Abstract

Conventional application of synthetic insecticides to control Plutella xylostella (Diamondback moth) has been unsuccessful due to resistance within the pest. Garlic extract, Chili extract and Seasol® seaweed solution was tested for their efficacy against DBM. Both garlic and chili are locally abundant, possess insecticidal properties, cost-effective and compatible with natural enemies. Three concatenated parameters; DBM abundance, Defoliation (%) and Leaf Area Index (LAI) were measured to test the efficacy of these botanical extracts. Concerning DBM abundance, both seaweed extract (p=0.00) and chili extract (p=0.01) showed significant results (p 0.05). Defoliation (%) was low under all extract treatments; seaweed (p=0.00), garlic (p=0.00) and chili (p=0.00). However, there were no significant differences in LAI results. There was significant interaction effect between DBM abundance and extract treatments (p=0.00). Reduced number of DBM were found under Seaweed and chilli extract treatments.