EFFECTS OF ENTOMOPATHOGENIC NEMATODES ON INSECT PESTS OF AVOCADO

The withdrawal of several chemical pesticides from the market for pest management has diverted research attention from reliance on chemical control towards developing alternative biological control strategies. Growing concern about environmental contamination with pesticides, and insecticide resistance of the pests themselves, have also caused us to seek new biological control agents. For example, several strains of the bacterium Bacillus thuringiensis have been successfully used in insect pest management programs. The growing number of instances where nematodes are being successfully used in controlling insect pests prompted us to assess the viability of these nematodes in controlling key pests of avocado. The mutualistic bacterium Xenorhabdus sp uses the nematodes from two families (Steinernematidae and Heterorhabditidae) as vectors to enter the insect hosts ' hemocoel and cause tissue degradation and subsequent septicemia. Bacterial gene products are thought to confer the pathogenicity of the nematodes to the insects through this tripartite association. A long term goal of our research program is to develop the bacteria or bacterial gene products as control agents alone or in combination with other pathogens such as viruses. In the short-term, we are testing efficacy of the nematodes themselves. This report describes the effects of entomopathogenic nematodes on the lepidopteran pest, amorbia (Amorbia cuneana). Experiments were conducted by Ph.D student Ashok Pullikuth with two widely used nematode species, Steinernema carpocapsae and Heterorhabditis bacteriophora, to assay pathogenic effects on the larval and pupal stages of A. cuneana