1 The cultivated tomato, Lycopersicon esculentum, is an economically important worldwide crop. Current pest management techniques rely heavily on pesticides but trichome-based host-plant resistance may reduce pesticide use. 2 A review of the literature is provided on trichomes of wild Lycopersicon species and the effects of trichome-based host-plant resistance on arthropods. Solvents have been used to remove glandular trichome exudates and the resulting dimminution of their effects quantified. Correlational approaches to assess the relationship between the different trichome types and effects on pests have also been used. 3 Most studies have focused on Lepidoptera and Hemiptera, although some work has included Coleoptera, Diptera and Acarina, and both antibiotic and antixenotic effects have been demonstrated. 4 Natural enemies are a cornerstone of international pest management and this review discusses how the compatibility of this approach with trichome-based host-plant resistance is uncertain because of the reported negative effects of trichomes on one dipteran, one hemipteran and several Hymenoptera. 5 For trichome-based host-plant resistance to be utilized as a pest management tool, trichomes of wild species need to be introgressed into the cultivated tomato. Hybrids between the cultivated tomato and the wild species Lycopersicon hirsutum f. glabratum, Lycopersicon pennellii and Lycopersicon cheesmanii f. minor have been produced and useful levels of resistance to Acarina, Diptera and Hemiptera pests have been exhibited, although these effects may be tempered by effects on natural enemies. 6 This review proposes that studies on genetic links between fruit quality and resistance, field studies to determine the compatibility of natural enemies and trichome-based host-plant resistance, and a strong focus on L. cheesmanii f. minor, are all priorities for further research that will help realize the potential of this natural defence mechanism in pest management.

Summary1. An increase in pesticide resistance in many pest species is promoting interest in biological control. Much remains to be learned about natural enemy immigration into and persistence within crops at specific times and how to maximize suppression of pest populations. Therefore this study was conducted to test a novel biological control approach, 'attract and reward' which combines two aspects of applied insect ecology: synthetic herbivore-induced plant volatiles (HIPVs) to improve immigration of beneficial taxa into crops and nectar plants to maintain their populations. 2. The 'attract and reward' approach was tested in sweetcorn, broccoli and wine-grapes with several HIPV formulations at 1AE0% (v ⁄ v) as attractants and buckwheat (Fagopyrum esculentum Moench) as reward. Abundance of insects was assessed with non-attractive sticky traps for up to 22 days after the HIPV spray application. 3. In sweetcorn, Eulophidae were more numerous in the attract treatments: methyl anthranilate, methyl jasmonate (MeJA), methyl salicylate (MeSA) and HIPV mix. Encyrtidae were more abundant near MeJA-treated plants. In broccoli, Scelionidae were more abundant in MeSA treatments with reward and near cis-3-hexenyl acetate-treated plants without reward whilst Ceraphronidae were more numerous near MeSA and predators were more abundant near HIPV mix-treated plants. Nectar plant reward increased catches of parasitoids from several families in all three tested crop species and increased predators in sweet corn and broccoli. 4. Increases in natural enemy numbers were correlated with effects at the first and second trophic levels. Significantly fewer larvae of the sweetcorn pest Helicoverpa spp. were found on sweetcorn plants from plots with reward and significantly less Helicoverpa spp. damage was evident to cobs for one of the HIPV treatments. 5. Synthesis and applications. Results suggest that applications of synthetic HIPVs can enhance recruitment of natural enemies and buckwheat was a suitable resource subsidy plant for increasing abundance and residency. Whilst both of these approaches offer potential to enhance biological control, further work is required to realize fully synergistic effects from their combination as an 'attract and reward' approach.

1 The cultivated tomato, Lycopersicon esculentum , is an economically important worldwide crop. Current pest management techniques rely heavily on pesticides but trichome-based host-plant resistance may reduce pesticide use. 2 A review of the literature is provided on trichomes of wild Lycopersicon species and the effects of trichome-based host-plant resistance on arthropods. Solvents have been used to remove glandular trichome exudates and the resulting dimminution of their effects quantified. Correlational approaches to assess the relationship between the different trichome types and effects on pests have also been used. 3 Most studies have focused on Lepidoptera and Hemiptera, although some work has included Coleoptera, Diptera and Acarina, and both antibiotic and antixenotic effects have been demonstrated. 4 Natural enemies are a cornerstone of international pest management and this review discusses how the compatibility of this approach with trichome-based hostplant resistance is uncertain because of the reported negative effects of trichomes on one dipteran, one hemipteran and several Hymenoptera. 5 For trichome-based host-plant resistance to be utilized as a pest management tool, trichomes of wild species need to be introgressed into the cultivated tomato. Hybrids between the cultivated tomato and the wild species Lycopersicon hirsutum f. glabratum , Lycopersicon pennellii and Lycopersicon cheesmanii f . minor have been produced and useful levels of resistance to Acarina, Diptera and Hemiptera pests have been exhibited, although these effects may be tempered by effects on natural enemies. 6 This review proposes that studies on genetic links between fruit quality and resistance, field studies to determine the compatibility of natural enemies and trichome-based host-plant resistance, and a strong focus on L. cheesmanii f. minor , are all priorities for further research that will help realize the potential of this natural defence mechanism in pest management.