Callum J. Macgregor1, Daniel J. Hoare2, Mark S. Parsons2 , and Owen T. Lewis3

Factors affecting the distribution and abundance of a rare British moth, Cucullia lychnitis Callum J. Macgregor1, Daniel J. Hoare2, Mark S. Parsons2 , and Owen T. Lewis3 [email protected] 1: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK. 2: Butterfly Conservation, Manor Yard, East Lulworth, Wareham, Dorset, BH20 5QP, UK. 3: Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK. @Macgregor_Cal Fig. 1: C. lychnitis Background imago (L; © David - The Striped Lychnis moth (Fig. 1), Cucullia lychnitis Rambur (Lepidoptera: Noctuidae), has Short, CC BY 2.0) been targeted for conservation effort in the UK1. and larva on V. - Larvae feed on flowers and seedheads of Dark Mullein Verbascum nigrum L. nigrum (R; Callum (Scrophulariaceae)2, which often occurs on road verges in patches varying from a single Macgregor). plant to several hundred. - C. lychnitis is readily found in some patches of V. nigrum but absent from others2. Methods - In this study3, we systematically searched road verges within the southern range of C. lychnitis (Fig. 2) for patches of V. nigrum. - At each patch (Fig. 3), we recorded a range of ecological variables: - Presence & abundance of C. lychnitis larvae - Abundance of V. nigrum - Isolation from neighbouring patches - Sward height and wind shelter - Density of weevil Cionus nigritarsis Reitter (Coleoptera: Curculionidae), a Fig. 2 (L): UK distribution of C. lychnitis. Black potential competitor whose larvae also feed on V. nigrum flowers circles show post-2000 records; white circles - At patches with several larvae of C. lychnitis present, we also recorded larval occupancy, show pre-2000 only. Box shows area in Fig. 3. number of flower spikes and height of the tallest flower spike for each V. nigrum plant. Fig. 3 (R): host-plant patches recorded in the - We tested the effect of these variables on C. lychnitis abundance and patch- and plant- study. Black circles indicate C. lychnitis presence level occupancy using generalized linear models (GLMs). and white circles indicate absence. The Striped Lychnis moth is range-restricted and declining… ...what factors determine its presence and abundance at host-plant patches? Among occupied patches, larvae of C. lychnitis were most abundant in Results patches of V. nigrum with low densities of C. nigritarsis (Fig 6, L), and in patches that were more isolated from other patches (Fig. 7, R). Solid lines show predicted larval abundance (dashed lines show standard error). Fig. 4: Larvae of C. lychnitis were most likely to occupy patches that were close to other patches and had high abundances of V. nigrum. In Figs 4 & 5, probability of larval occupancy is >50% for patches/plants above the solid line (dashed lines show 95% confidence interval). Conclusions - Efforts to conserve Cucullia lychnitis should focus on large patches close to other patches. Fig. 5: Larvae of C. - Increasing the size of small patches close to occupied patches may lychnitis were most facilitate dispersal and establishment of new local populations. likely to occupy - A balance between large patch size and low density of C. nigritarsis may plants that were be of most benefit. taller and had many - Ensuring patch persistence, through regular disturbance of patches flower-spikes. (outside the flowering period of V. nigrum), may also be important. References: 1. Natural Environment and Rural Communities Act 2006, Section 41. The Stationery Office, London. 2. Heath J, Emmet AM (1983) Moths and butterflies of Great Britain and Ireland. Harley Books, Colchester. 3. Macgregor CJ, Hoare DJ, Parsons MS, Lewis OT (2017) Host-plant patch qualities and presence of a likely competitor species affect the distribution and abundance of a rare British moth, Cucullia lychnitis. J. Insect Conserv., 21, 137-146. .

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