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Enhancing the monitoring and trapping of protected crop pests by incorporating LED technology into existing traps Kevin McCormack Doctor of Philosophy – University of Edinburgh - 2015 Dedication To Patricia, my inspiration. I Declaration I certify that: (a) This thesis has been composed by me, and (b) Either that the work is my own, or, where I have been a member of a research group, that I have made a substantial contribution to the work, such contribution being clearly indicated, and (c) That the work has not been submitted for any other professional degree or professional qualification except as specified. Kevin McCormack ………………………… II Acknowledgements This research project was funded by the Horticulture Development Company (HDC) and Scotland’s Rural Colleges (SRUC). I would like to express my gratitude to my supervisors Dr Andy Evans (SRUC) and Dr Thomas Döring (Humboldt-Universität zu Berlin), as well as my University of Edinburgh supervisor Per Smiseth. Thank you to Professor John Allen of St Andrews University, for valuable technical assistance, and Koppert Biological Systems for providing yellow sticky traps. I would also like to thank the commercial growers and their staff, without their partnership this project would not have been possible. III Lay Summary The use of coloured light-emitting diodes (LED) attached to sticky traps has been shown to enhance the capture of some insect pests of protected crops to allow for more effective monitoring. For example green (540 nm wavelength) LEDs attached to yellow sticky traps tended to catch more fungus gnats than yellow sticky traps alone, and green (540 nm) or blue (480 nm) LEDs attached to yellow sticky traps caught significantly more diamondback moths than yellow sticky traps alone. The use of LEDs did not have a negative effect on the use of biological control agents such as Encarsia formosa (used for whitefly management). A naturally occurring parasitoid wasp (Kleidotoma psiloides) of shorefly was caught in fewer numbers when green LEDs (540 nm) were attached to yellow sticky traps. The potential for LEDs to enhance the monitoring of certain pests in protected crops without any effect on biological control agents has been demonstrated and warrants further development to make the use of LEDs with sticky traps more practical within protected cropping systems. Protected crops require significant pest management inputs in many cases, particularly with edible crops where insecticide use is discouraged where possible, and the use of biological control agents (BCA) is most often undertaken (e.g. tomatoes, cucumbers, peppers). To obtain the most efficient pest management using insecticides or BCAs (or in combination) requires precise timing of application to the crop and an assessment of their effectiveness post-application, to determine whether any further applications are required. Currently, sticky traps (often coloured) are used to detect the presence of many pests (e.g. thrips, whitefly, various aphid species, leaf miners, sciarid flies) and a decision on whether to begin application of insecticides and/or introduction of BCAs is often taken based on whether pests are being found on the traps. The efficacy of traps relies on their attractiveness to these pests, and exploits the behavioural attraction of the pests to their colour. It has been known for many years that specific colours are attractive to specific pests, such as blue for thrips, yellow for whitefly, white for sciarid flies. Recent research by others has indicated that traps can be made more effective through the use of light emitting diodes (LEDs) incorporated with the trap. For example, the capture of tobacco whitefly (Bemisia tabaci) was doubled through the addition of a lime-green LED (530 nm wavelength) to the trap. Similarly, a 2.5 times more western flower thrips (Frankliniella occidentalis) were captured on blue sticky traps that had a blue LED (465 nm wavelength) incorporated with the trap. IV Various researchers have looked at the use of LEDs to enhance the efficacy of insect trapping, particularly of biting pests such as mosquitoes, but there is relatively little work on exploiting this on a commercial scale to enable growers to incorporate these traps into their intergrated pest management (IPM) programmes. This project aimed to identify the light spectra that are most attractive to a range of protected crop pests and their biological control agents; screened LEDs of specific light wavelengths that can be used with traps to enhance the attractiveness of traps to pests; and evaluated the efficacy of LED/trap combinations for their use in trapping pests under protected crop conditions with a small group of growers. V Abstract Management of pest species is ordinarily required in the production of protected crops. Integrated pest management (IPM) is commonly used when controlling insects. The European Union Sustainable Use Directives states that "integrated pest management’ means careful consideration of all available plant protection methods and subsequent integration of appropriate measures that discourage the development of populations of harmful organisms and keep the use of plant protection products and other forms of intervention to levels that are economically and ecologically justified and reduce or minimise risks to human health and the environment. ‘Integrated pest management’ emphasises the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms.” Effectively monitoring pests is a key component of IPM, with decisions to use biological control agents (BCA) and insecticides often based on the presence of pests in traps. A commonly used monitoring tool is the sticky trap; these traps are coloured and rely primarily on their visual attractiveness to the pest. The capture efficiency of sticky traps can potentially be increased with the addition of light emitting diodes (LEDs). The objective of this project was to use LEDs to enhance the efficacy of yellow sticky traps for trapping a range of insect pests, to enable more effective timing of pest management by optimising pest monitoring. The addition of LEDs may also enable more effective mass trapping via yellow sticky traps, and minimize the trapping of beneficial insects. Comparisons between standard yellow sticky traps and those equipped with green (540 nm) or blue (480 nm) LEDs were carried out at four commercial growing facilities. Green (540 nm) LED equipped traps were compared with standard yellow traps in a mass release of the biological control agent Encarsia formosa Gahan (Hymenoptera: Aphelinidae), to determine if there are negative consequences to the addition of green (540 nm) LEDs when using this biological control agent. Relative spectral preferences of western flower thrips (Frankliniella occidentalis Pergande (Thysanoptera: Thripidea)) and Glasshouse whitefly (Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae)) were determined using a choice test comparing a range of wavelengths in 20 nm steps against a control wavelength. Green (540 nm), and blue (480 nm) LED equipped traps captured significantly more dark- winged fungus gnats (Bradysia difformis Frey (Sciaridae: Diptera)) and diamondback moths (Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae)) than those without. No significant VI differences were found between green (540 nm) LED equipped traps and those without for E. formosa, and a significant decrease in the capture of the shore fly parasitoid Kleidotoma psiloides Westwood (Hymenoptera: Figitidae) was observed. In behavioural experiments F. occidentalis showed a peak spectral preference at 360, 420, and 480 nm, and T. vaporariorum at 320, 340, and 380 nm. The addition of LEDs to yellow sticky traps enhanced their capture efficiency for some key pests in commercial protected crop growing environments, and has the potential to enable pest detection at an early stage, consequently optimising the timing of pest management options. VII Contents Acknowledgements .......................................................................................................... III Lay Summary .................................................................................................................. IV Abstract .......................................................................................................................... VI Contents ...................................................................................................................... VIII Chapter 1 General Introduction ....................................................................................... 1 Integrated Pest