Laboratory and field investigations using indigenous entomopathogenic nematodes for biological control of Plutella xylostella in Kenya

Abstract

This study was undertaken to determine the potential utility of entomopathogenic nematodes for management of diamondback moth (DBM) larvae in Kenya. Five Kenyan EPN isolates, Heterorhabditis indica, Steinernema karii, Steinernema weiseri, Steinernema sp. and Heterorhabditis taysearae were tested for their ability to penetrate DBM and their speed of kill (LT₅₀). Heterorhabditis indica and S. weiseri were found to have the quickest rate of kill and S. weiseri was found to have the largest proportion of nematodes penetrating. Three of the isolates, Steinernema sp. (95), S. weiseri and H. indica, were used in a field experiment to test their ability to reduce DBM populations and damage to kale. All three nematodes caused significant reductions in populations of DBM and DBM damage, with the population reductions being similar to those caused by application of Bacillus thuringiensis ssp. kurstaki. This study shows that EPNs have great potential that should be exploited in the management of DBM in Kenya.

Keywords:

• diamond back moth
• Plutella xylostella
• entomopathogenic nematodes
• Steinernema
• Heterorhabditis
• biological control

Acknowledgements

We would like to thank Shelmith Mwaniki for supplying cultures of Heterorhabditi taysearae; Steinernema weiseri; and Steinernema sp. (95) that she isolated as part of her PhD studies. Collaboration between the Universities of Aberdeen and Nairobi has been funded through a British Council Higher Education Link Grant ‘Novel and Molecular Methods in Crop Pest Control’.