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General Introduction 24 from laying eggs on host plants and the feeding deterrents will render the plant inedible. The best approach as yet is the integrated pest management (IPM) system which was developed to increase the use of biological resources (biological control and mating disruption) and supplement its use with reduced amounts of chemicals such as pesticides (Wearing, 1993; Jones, 1998). 1.7 Light brown apple moth The light brown apple moth, Epiphyas postvittana, is a species of leafroller moth, a member of the order Lepidoptera and belongs to the family Tortricidae (Wearing et al., 1991). E. postvittana is endemic to Australia but has also invaded Hawaii, California and parts of Europe (Suckling and Brockerhoff, 2010). The first report of this moth in New Zealand was in 1891 (Danthanarayana, 1975). E. postvittana has a wide host range, from pipfruit (apples and pears) to citrus, grapes, kiwifruit and even some vegetables. E. postvittana attack pipfruit in all the fruit growing regions of New Zealand and is found in very high numbers in Nelson (Wearing et al., 1991). The moth does not have a winter dormancy stage and the number of generations in a year differs in different regions of the country, with the far north having four generations, central parts of the country having three and two generations in the southern region. If the optimum temperature for larval development, 20°C is provided, it will take approximately 32–40 days for the completion of all the larval developmental stages. The larvae feed on leaves and fruits by creating silken shelters on either a single leaf by rolling or between a leaf and fruit (Geier and Briese, 1980). Pupae turn from a green to brown colour with maturation and male moth emergence occurs before females. The female moth mates only once in her life, and the eggs are laid in several batches of 30 eggs each so one female moth can lay between 150–900 eggs. Most of these eggs hatch into larvae as predation of the eggs is very low. Even though some biological control agents were imported from Australia, the zero tolerance requirement of this moth on exported fruits has still not been attained (Wearing et al., 1991). The damage causing stage of E. postvittana is the larva, which feeds on the buds, foliage, shoots and fruits (Suckling, 1998; Markwick et al., 2002). The rolling of
General Introduction 25 leaves and webbing of leaves to fruits to make protective shelters causes calluses on the fruits and leaves (Lo et al., 2000). The export market requires nil tolerance of both insect and insect damage on fruits. These stringent measures put in place calls for the development of better and sustainable control measures for this pest. From the 1960s, chemical control was used in the form of pesticide sprays. The major chemicals used were azinphos-methyl and chloropyrifos sprayed on fruits. However, these chemicals are toxic to some natural enemies of the moth and in 1980s, populations resistant to the chemicals were reported. This called for alternative control measures. Bacillus thuringiensis (B.t) was looked into but due to high UV radiation in New Zealand, this microbial insecticide is easily deactivated (Suckling et al., 1994; Suckling et al., 1999; Markwick et al., 2002). The naturally occurring baculovirus enemy of the moth that kills the larvae, nucleopolyhedrovirus was used as sprays to some success. However, the most sustainable control came from the use of mating disruption and pheromone trapping of the adult moths. Small scale mating disruption showed that the best results were achieved through integrated pest management (IPM), by using the 20:1 ratio of the sex pheromone components together with a few applications of insecticide (Suckling and Shaw, 1990). Scale up of this mating disruption showed similar results in larger fields (Suckling and Shaw, 1995). The efficiency of this system is however hindered by factors such as migration of mated females from nearby untreated sources, or a high population density requiring a second application (McLaren et al., 1998). The biggest issue facing mating disruption is the high concentration of pheromone required hence the high cost of this pest control method. The limited knowledge of actual pheromone mechanism hinders the success of this system. Understanding the underlying mechanisms of receptor adaptation to different compounds, the actual behaviour that mating disruption targets and whether males respond to any remaining pheromone plumes will enhance its success. Reviewed in Suckling and Brockerhoff (2010). The sex pheromone of E. postvittana is released at night or during the dark period, and has been identified to be a 20:1 ratio of (E)-11-tetradecenyl acetate (E11-14:OAc) and (E,E)-9,11-tetradecadienyl acetate (E9,E11-14:OAc), respectively (Bellas et al., 1983) shown in Figure 1.6. The components on their own do not produce any response in male moths but when present in the specific ratio, the blend produced response in both field trials and laboratory bioassay. The biosynthetic pathways
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Page 3 and 4: Abstract Abstract Olfaction or the
Page 5 and 6: Acknowledgements Acknowledgements I
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Page 11 and 12: List of Figures List of Figures Fig
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Page 15 and 16: List of Abbreviations gDNA Genomic
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The roles of Epiphyas postvittana G
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4.1 Introduction 4 Identification o
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Identification of putative odorant
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Microarray OR 454 Transcriptome OR
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5.1 Introduction 5 Concluding Discu
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Concluding Discussion 127 VOBA sett
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Concluding Discussion 129 redundant
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Concluding Discussion 131 against t
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Concluding Discussion 133 sequencin
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Appendix B 135 Buffered TB (Sambroo
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Appendix C 137 C. Appendix C - Clus
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Appendix D 139 D. Appendix D - Solu
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Appendix E 141 I II
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Appendix E 143 V
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Appendix E 145 VII continued Figure
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References 147 Ansebo, L., Ignell,
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References 149 Butenandt, A., Beckm
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References 151 Fedurco, M., Romieu,
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References 153 Große-Wilde, E., St
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References 155 Hrdy, I., F. Kuldova
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References 157 Kaissling, K. E. (19
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References 159 Krieger, J., Große-
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References 161 Lopez-Gomez, R. and
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References 163 Miura, N., Nakagawa,
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References 165 Pell, J. K., Macaula
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References 167 Røstelien, T., Stra
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References 169 Stowers, L. and Loga
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References 171 Turner, C. T., Davy,
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References 173 Vogt, R. G., Riddifo
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References 175 Widmayer, P., Heifet
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