Durham E-Theses Aspects of the ecology of the Lepidoptera associated with heather Calluna vulgaris. Fielding, Carol How to cite: Fielding, Carol (1992) Aspects of the ecology of the Lepidoptera associated with heather Calluna vulgaris., Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/962/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk Aspects of the ecology of the Lepidoptera associated with heather Calluna vulgaris by Carol Fielding B. Sc. (Dunelm) The copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. A thesis presented in candidature for the degree of Doctor of Philosophy. Department of Biological Sciences, University of Durham. 1992. 1 3 JAN 1995 I certify that all material in this thesis which is not my own work has been identified and that no material is included for which a degree has previously been conferred on me. © The copyright of this thesis rests with the author. No quotation from it should be published without her prior written consent and information derived from it should be acknowledged. Ab stract Aspects of the ecology of the assemblage of lepidopteran herbivores associated with heather (Calluna vulgaris) were investigated on northern heath and blanket bog habitats in the northern Pennines, England. The results of a literature search revealed 86 macrolepidopteran species to feed as larvae on Calluna in Britain although only 26 of these were recorded during this study. Information on the instar development of 15 species is presented. An investigation of the phenology of larval utilisation of the Calluna plant revealed spring and autumn peaks in macrolepidopteran species richness. This pattern is related to the different life-cycles exhibited by the Geometridae and Noctuidae families. The effect of altitude on the relationship between macrolepidoptera and Calluna was investigated along an altitude gradient from 290 to 650m. Approximately three species were lost for every 100m rise in altitude, of which one species was a Geometridae and two were of the Lasiocampidae, Saturniidae, Lymantriidae and Arctiidae families. There was no observed decline in the species richness of Noctuidae species on Calluna with altitude. The density of Lepidoptera species varied greatly within the altitudinal distribution with individual species exhibiting increases and decreases in density with elevation. There was an absence of upland specialists with the majority of Lepidoptera species present at higher altitudes also recorded at lower altitudes. The species richness of the lepidopteran fauna varied little between Calluna stands of different ages, although individual species exhibited preferences for different aged stands. An abundant geometrid species was found to remove 50% of the current year's foliage in mature aged stands. The lepidopteran herbivores on Calluna were compared and contrasted with those on Vaccinium myrtillus. During the spring V. myrtillus had a higher density of lepidopteran larvae than Calluna which mainly consisted of microlepidopteran species. Species richness of Lepidoptera on the two plant species was similar. There was evidence for certain lepidopteran species of disparities in larval development on the two plant species. 111 Acknowledgements I am grateful to my supervisor John Coulson for his encouragement and help throughout the progress of this study. Eric Henderson assisted with fieldwork and technical problems and was a source of support. I should also like to thank Michael Bone and Jack Warner for technical assistance. Professor P.R. Evans provided facilities in the Department of Biological Sciences and Durham University financed the work via a Research Studentship. I am indebted to Gilbert Roberts for advice and help with computing, Paul Sydney and David Hutchinson for photographic work and Stella Henderson for binding the thesis. Access to fieldsites was provided by Stuart Scott, Lambton Estates, the Stanhope Syndicate, Raby Estates, the Nature Conservancy Council and Durham County Council. The gamekeepers and farmers of these areas especially Dennis Dodd, David Liddle and David Dixon deserve many thanks for their patience and goodwill while fieldwork was in progress. I am grateful to Tom Dunn of Chester-le-Street for sharing his wisdom on the identification of the Lepidoptera and Adrian Riley of Rothamstead Experimental Station who identified the Eupithecia adults. Many thanks are due to Susan Fielding and Andrew Moon for helping with fieldwork and proof reading. For general help and encouragement I would like to thank Cath Todd, Norman Cobley, Patrick Thompson, Shirley Goodyer, Lewis Davies, Tusi Butterfield and Karen Haysom. I should like to thank all my family, especially my mother, for their support and encouragement over the years. Finally this thesis is dedicated to all the caterpillars who perished during its progression and never got the chance to fly. iv Table of Contents Abstract Acknowledgements iv Table of contents Chapter 1. Introduction 1 Chapter 2. The study areas and sample sites 6 2.1. Location and characteristics of study areas 6 2.2. Description of sample sites 8 2.3. Description of Calluna at sample sites 8 2.4. Annual use of sample sites. 17 Chapter 3. Methods of sampling Lepidoptera 18 3.1. General objectives 18 3.2. Identification of Lepidoptera 18 3.3. Sampling techniques 18 3.3.1. Berlese funnel extraction 18 3.3.2 Sweep-netting 19 3.3.3. Searching 22 3.3.4. Light trapping 24 3.4. General conclusions on sampling 25 3.5. The calculation of densities from samples 29 Chapter 4. The Lepidoptera associated with Ericacea 35 4.1. Introduction 35 4.2. The Lepidoptera associated with Calluna vulgaris, Vaccinium myrtillus and Erica species in Britain 36 4.3. The number of Lepidoptera species associated with Calluna vulgaris in County Durham 45 4.4. Discussion 53 Chapter 5. The phenology of the macrolepidoptera associated with Calluna vulgaris 56 5.1. Introduction 56 5.2. The phenology of Calluna vulgaris 58 5.3. General methods 60 5.4. The overwintering stages of the macrolepidoptera associated with Calluna vulgaris 60 5.4.1. Methods 60 5.4.2. Results 61 5.5. The phenology of the species richness of macrolepidoptera present as larvae on Calluna vulgaris 64 5.5.1. Methods 64 5.5.2. Results 65 5.6. The larval phenology of the different families of macrolepidoptera associated with Calluna vulgaris 68 5.6.1. Methods 68 5.6.2. Results 70 5.7. Discussion 77 vi Chapter 6. Aspects of the growth and development of the Lepidoptera associated with Calluna vulgar& 81 6.1. Determination of the instar development 81 6.1.1. Introduction 81 6.1.2. Methods 82 6.1.3. The results of instar development 84 Chapter 7. The effect of altitude on the Lepidoptera associated with Calluna vulgaria 112 7.1. Introduction 112 7.2. The effect of altitude on macrolepidopteran species richness 116 7.2.1. Methods 116 7.2.2. Macrolepidoptera species richness 116 7.2.3. Species richness of the individual taxonomic groups of macrolepidoptera 117 7.2.4. The species richness of Lepidoptera within each of the separate years of the study 125 7.3. The effect of altitude on the distribution of the macrolepidopteran species 125 7.4. The effect of altitude on the density of the individual macrolepidopteran species 130 7.4.1. Methods 130 7.4.2. Results 134 7.5. The effects of altitude on the parasitism of the macrolepidoptera associated with Calluna vulgaris. 146 7.5.1. Methods 146 7.5.2. Results 146 vii 7.6. Other aspects of the effects of altitude on the macrolepidoptera associated with Calluna vulgaris 150 7.6.1. Introduction and methods 150 7.6.2. Results 150 7.7. Discussion 154 Chapter 8. The effect of Calluna vulgaris stand age on the macrolepidopteran herbivores associated with the plant 158 8.1. Introduction 158 8.2. General methods 161 8.3. The species richness of macrolepidoptera in Calluna vulgaris stands of the different life-history phases 161 8.4. The abundance of macrolepidoptera in different ages and phases of Calluna vulgaris stands 163 8.4.1. Methods 163 8.4.2. The abundance of macrolepidoptera and the individual taxonomic groups in Calluna vulgaris stands of the different life-history phases 163 8.4.3. The abundance of the individual macrolepidopteran species in Calluna stands of the different ages and life history phases 167 8.5. The distribution of Hydriomena furcata larvae within Calluna vulgaris stands of mature age 176 8.5.1. Methods 176 8.5.2. Results 176 8.6. Discussion 186 viii Chapter 9. A comparison between the Lepidoptera associated with Calluna vulgaris and Vaccinium myrtillus 194 9.1. Introduction 194 9.2. General methods 195 9.3. The species richness of Lepidoptera on Calluna and V. myrtillus. 195 9.3.1. As assessed from the literature 195 9.3.2. As assessed from samples taken in the field 195 9.4. The relative importance of the various taxonomic groups of Lepidoptera on Calluna vulgaris and Vaccinium myrtillus 196 9.4.1.