Durham E-Theses Studies on the auchenorrhyncha (hemoptera insecta) of Pennine moorland with special reference to the ceropidae Whittaker, John B. How to cite: Whittaker, John B. (1963) Studies on the auchenorrhyncha (hemoptera insecta) of Pennine moorland with special reference to the ceropidae, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/10475/ 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 2 ABSTRACT Studies on the Auchenorrhyncha (Heina>ptera - insecta) of Pennine Moorland with special reference to the Cercopidae. Notes on the autecology of 32 species of Auchenorrhyncha from the Moor House National Nature Reserve are given. Studies were made of the microclimates of the common vegetation types on which these occur and it is shown that the size and function as a temperature regulator of the spittle (produced by nymphs of the Cercopidae) is associated with these gradients. Cercopid nymphs are shown to change feeding sites after moulting. The need to change host plants and thus leave protective spittle is thought to result In an increased mortality of nymphs (up to 3 per cent per day)* Overall nymphal mortality is not dependent on population density. In two cercopids (Neophilaenus lineatus and Neophilaenus exclamationls), there are marked changes in population density in each year (1961 to 1963) and these are partly attributed to climatic factors. The hatch of Cercopidae is delayed, and development is retarded at high altitudes. Nymphal mortality rates in a cicadellid (Macrosteles sexnotatus) and a delphacid (Conomelus anceps) did not differ from those of the Cercopidae studied, although they have no protective spittle. It is concluded that cercopid spittle is of some survival value at Moor House by enabling the nymph to avoid parasites, if not predators, and unfavourable climatic conditions encountered whilst remaining stationary on the host plant during feeding. These advantages are not sufficient to give the Cercopidae a significantly higher survival rate than other Auchenorrhyncha at Moor House. Non-density dependent factors are thought to be responsible for a major part of the changes in population density* A compensatory mechanism at other stages of the life cycle has not been demonstrated* Local extinction at the edge of the range is a result of climatic factors* The population studied is probably below the density level at which regulating mechanisms may occur. JOHN B. WHITTAKER, ZOOLOGY DEPARTMENT, DURHAM UNIVERSITY. STUDIES ON THE AUG HEN ORRHYiT CHA (lILLIFTERA - INSECTA) OF PENNINE MOORLAND WITH SPECIAL REFERENCE TO THE CERCOPIDAE "by John B. v/hittaker, B.Sc. (University College) ... "being a thesis presented in candidature for the degree of Doctor of Philosophy in the University of Durham, 1963. AZKNOWLEDGBffiNTS The writer wishes to express his sincere thanks to Professor J. B. Cragg and Dr. J. C. Coulson who supervised the work and offered helpful advice and criticism, and Professor D. Barker for continued facilities in the Department of Zoology, Durham* Thanks are also due to : Members of the Department of Zoology for helpful discussion, the staff of the Moor House Research Station, and particularly Messrs* A* Eddy and D* Welch for Botanical information concerning the Moor House Reserve, Dr. W. E. China for permission to study the collection of the British Museum (Natural History), Mrs* A* Simpson for typing the final draft, Messrs. D. Kelly, D* Hutchinson and D. Whittaker for photographic assistance, and Miss H. M. Thorley for help in checking references. The work was carried out whilst holding a Nature Conservancy Studentship* CONTENTS Page I INTRODUCTION 1 II THE STUDY AREA AND SAMPLING- SITES 3 1. LOCATION AND GENERAL PHYSIOGRAPHY 3 2. THE SAMPLING SITES k a) THE JUNCUS SQUARROSUS SITE k b) THE NARDUS SITE 5 c) THE LIMESTONE GRASSLAND SITE 6 d) THE DORTH GILL TRANSECT 8 e) THE MIDDLE TONGUE TRANSECT 8 f) OTHER SAMPLE SITES 9 3. THE CLIMATE AT MOORHOUSE 10 III TAXONOMY AND AUTECOLOGY OP THE MOOR HOUSE AUCHEN ORRHYNCHA 13 1. TAXONOMY 13 a) GENERAL 13 b) THE CERCOPIDAE 16 2. CHECK LIST OP MOOR HOUSE AUCHENQRRHYNCHA 17 3. AUTECOLOGY OP THE MOOR HOUSE AUCHENORRHYNCHA 20 U. PARASITES OP MOOR HOUSE AUCHENORRHYNCHA 26 5. AFFINITIES OF THE MOOR HOUSE AUCHENORRHYNCHA 27 IV SAMPLING TECHNIQUES 29 1* QUANTITATIVE SAMPLING OF CERCOPID NYMPHS 29 a) INTRODUCTION 29 b) PRELIMINARY SAMPLING 30 Page c) GRID SAMPLING 32 d) ERRORS IN THE GRID SAMPLING 33 i Destruction of spittles by the observer 33 ii Migrating nymphs or very small spittles 3k iii Relative efficiency of sampling instars 35 e) EFFECT OF SAMPLING ON THE NEXT YEAR'S POPULATION 37 f ) ESTIMATION OF POPULATION DENSITY BY PERCENTAGE 38 ABSENCE 2. SAMPLING OF JASSIDAE, DELPHACIDAE AND ADULT CERCOPIDAS k2 a) SWEEP NET SAMPLING k2 b) SUCTION SAMPLING k3 i Operation of the apparatus kk ii Efficiency of the apparatus 1+6 V THE MICROCLIMATES IN THE VEGETATION OF THE SAMPLE SITES kl 1. INTRODUCTION 1+7 2. COMPARISON OF JUNCUS AND LIMESTONE GRASSLAND SITES 1+7 3. COMPARISON OF HUMMOCKS AND HOLLOWa ON LIMESTONE GRASSLAND 50 k. THE MICROCLIMATE OF CERCOPID SPITTLE 52 5. THE EFFECT OF A HIGH TEMPERATURE GRADIENT 58 ON AUCHENORRHYNCHA OTHER THAN NYMPHAL CERCOPIDAE VI THE BIOLOGY OF NEOPHILAENUS LINEATUS 59 A. THE NYMPHAL INSTARS 59 1. INTRODUCTION 59 2. DETERMINATION OF INSTARS 60 Page 3. DESCRIPTIONS OP THE INSTARS 63 k. DURATION OP INS TARS 65 a) IN THE FIELD 65 b) THE EFFECT OF TEMPERATURE ON THE DURATION OF INS TAR ONE 68 i In the laboratory 68 ii In the field 68 5. DENSITIES AND COMPOSITIONS OF THE N. LINEATUS POPULATIONS 69 60 HOST PLANTS OF NYMPHS AT MOOR HOUSE 73 B. THE SPATIAL DISTRIBUTION OF NYMPHS, AND THEIR uORTALITY 75 1. INTRODUCTION 75 2. STATISTICAL TREATMENT OF TIL, DATA 76 3. THE VARIANCE MEAN RATIO 78 k. VARIATIONS IN THE COEFFICIENT OF DISPERSION OF THE NYMPHS 79 a) THE JUNCUS SITE 79 b) THE NARDUS SITE 82 5. VARIATIONS IN THE COEFFICIENTS OF DISPERSION OF THE SPITTLES 85 a) THE JUNCUS SITE 85 b) THE NARDUS SITE 86 6. THE SPITTLE/NYMPH RATIO 86 a) THE SITUATION IN 1961 87 b) THE SITUATION IN 1962 87 7. THE NATURE OF THE INCREASE IN PERCENTAGE OF NYMPHS ON JUNCUS 89 Page 8. REASONS FOR THE MOVE FROM FESTUCA TO JUNCUS 91 9. CONCLUSIONS 92 10. NYMPHAL MORTALITY ON THE SAMPLING- AREA 97 a) INTRODUCTION 97 b) METHODS AND RESULTS 97 c) DISCUSSION 100 11. NYMPHAL MORTALITY IN EXPERIMENTAL POPULATIONS 10k C. THE ADULT 107 1. SEX RATIO 107 2. MORTALITY 107 3. COPULATION 108 k. OVARY DEVELOPMENT 109 5. OVIPOSITION 111 6. THE EGG 111 7. HATCHING 111 8. EGG MORTALITY 113 D. THE EFFECT OF ALTITUDE ON N. LINEATUS 115 1. INTRODUCTION H5 2. DORTH GILL TRANSECT I96I 116 3. MIDDLE TONGUE TRANSECT 1962 X18 VII THE BIOLOGY OF NEOPHILAENUS EXCLAMATIONIS 121+ 1. INTRODUCTION 121+ 2. THE DISTRIBUTION OF NEOPHILAENUS LINEATUS AND NEOPHILAENUS EXCLAMATIONIS 125 Page 3. THE NYMPHS 126 a) DETERMINATION OP INSTARS 126 ID) DURATION OP INSTARS IN THE FIELD 127 c) DISTRIBUTION OF THE NYMPHS 128 d) MORTALITY OF THE NYMPHS 129 k. THE ADULT 130 a) DISTRIBUTION 130 b) MORTALITY 131 VIII STUDIES ON PHILAENUS SPUMARIUS 135 1. INTRODUCTION 135 2. HOST PLANTS AT MOOR HOUSE 136 3. COLOUR VARIETIES 137 IX POPULATION STUDIES ON OTHER AUCHEN ORRHYNCHA lUl 1. INTRODUCTION Ikl 2. THE POPULATION DENSITY OF MACROSTELES SEX1T0TATUS li+2 3. THE POPULATION DENSITY OF CONOMELUS ANCEPS 110 k* COMPARISON OF THE MORTALITY IN THE NYMPHAL STAGES OF THE CERCOPIDAE, CICADELLIDAE, AND DELPHACIDAE STUDIED 1^5 X GENERAL DISCUSSION 1I4.7 SUMMARY 161 REFERENCES 166 APPENDIX 180 I APPARATUS 180 1. THE SUCTION SAMPLER 180 Page 2. APPARATUS FOR RECORDING- TEMPERATURES AND HUMIDITIES IN VEGETATION 180 a) THE RECORDING BRIDGE 180 b) THE THERMISTOR TYPES AND THEIR USE 182 i Temperature and humidity gradients in vegetation 182 ii Comparison of the Micro-hygrometer with an Assmann Psychrometer 1QU iii Type P thermistor for spittle temperature measurement 185 c) CALIBRATION OF THERMISTORS 186 1. I. INTRODUCTION Since 1952, studies of the fauna of the Moor House National Nature Reserve have been in progress. The need for detailed surveys of the animals of the Reserve has been pointed out by Cragg (1961), and the present study was undertaken with the aim of supplementing the general faunal data accumulating for the Reserve* Many authors have laid stress on the great severity of the climate at Moor House* An opportunity has therefore been taken to study the Cercopidae in more detail than the rest of the Horaoptera Auchenorrhyncha, because members of this group are able in the nymphal stages to provide themselves with a small enveloping micro• climate known as "cuckoo-spit". The existence of this spittle has also made possible quantitative sampling on a scale which would otherwise have been difficult under Pennine climatic conditions* The relatively low densities of Auchenorrhyncha at Moor House, com• pared with lowlands, has also limited the scope of the present study* The advantages of undisturbed study areas provided by a National Nature Reserve, and the usefulness of data collected on such a Reserve are, however, justifiable reasons for working there* The British Cercopidae are represented by ten species which are members of four genera* Apart from initial descriptions of the species and occasional habitat records, only one of these species has received much attention in the literature* Philaenus spumarius is widely distributed in the Palaearctic and Nearctic regions and ' 19 to ^ is a serious pest of alfalfa and other hay crops in the United States 2.