Novel integrated pest management components for the control of the glasshouse whitefly (Trialeurodes vaporariorum) on glasshouse-grown tomatoes (Solanum lycopersicum)

Abstract

The glasshouse whitefly (Trialeurodes vaporariorum Westwood) is one of the most important U.K. pests. This phloem-feeding insect is a particular threat to glasshouse-grown crops, including the tomato (Solanum lycopersicum L.). Integrated Pest Management (IPM) involves applying a range of biological, cultural, physical and chemical control measures, with monitoring, to reduce pest and pathogen numbers on commercial crops below acceptable economic thresholds, with minimal environmental damage. Different IPM tools are used together to achieve an acceptable control level. Whilst IPM has been effectively utilised to control the glasshouse whitefly, greater knowledge of individual IPM components is still needed to continue to effectively protect greenhouse-grown tomatoes in the future, particularly with increasing pesticide resistance levels in whitefly populations. Therefore, this PhD thesis sought to advance knowledge of existing and novel IPM components for whitefly control on tomatoes. Several distinct IPM methods were investigated. A wild tomato species, Lycopersicon pimpinellifolium (L.) Mill, was assessed for enhanced whitefly resistance, with a novel dual method of resistance discovered, one pre- and one post-phloem penetration, which may be introduced into modern tomato cultivars to enhance whitefly resistance. The ‘push-pull’ method of intercropping tomatoes with whitefly-repellent species, and surrounding them with attractive host species, was investigated in a large scale glasshouse trial, with French marigolds revealed to be an effective intercrop plant to reduce whitefly numbers on tomatoes. The potential of whitefly-induced plant volatiles to enhance whitefly resistance in uninfested tomatoes was examined, with plant-plant communication shown to be an effective method at reducing settling and oviposition in volatile-exposed tomatoes, potentially by priming defences against a subsequent whitefly infestation. It is anticipated that these IPM tools could be combined to achieve control of the glasshouse whitefly in glasshouse-grown tomatoes, contributing to environmentally sustainable food production and reduced synthetic pesticide use, whilst managing whitefly pesticide resistance.