Microbial control of insect pests in temperate orchard systems: Potential for incorporation into IPM

Due to their selectivity and safety, microbial control agents (MCAs) appear to be ready made components of IPM systems that do not pose a threat to applicators or the environment and allow other natural enemies to function. Control of several orchard pest insects using MCAs, including viruses, Bacillus thuringiensis, fungi and entomopathogenic nematodes have been demonstrated in apple, pear, stone fruits, citrus and several nut crops. Bacillus thuringiensis is the most used MCA for control of lepidopteran orchard pests. Significant use of entomopathogenic nematodes in citrus for control of root weevils is also reported. The granulovirus of codling moth is increasingly being used in apple and pear by organic growers with interest also shown by conventional growers. Although some success has been achieved, in most orchard systems MCAs account for a relatively small proportion of the pest control tactics employed, and in some systems they are not used at all. Research toward improving MCA efficacy and economic competitiveness is required to enhance the role of MCAs in IPM.