The ecology of Harmonia axyridis in Great Britain
Brown, P.M.J.; Ware, R.L.; Roy, D.B.; Roy, H.E.. 2010 The ecology of Harmonia axyridis in Great Britain. In: International Symposium on Ecology of Aphidophaga 11, Perugia, Italy, 19-24 September 2010.Full text not available from this repository.
Native to Asia, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is an invasive non-native ladybird in Europe. The objective of the study was to investigate the habitat use and phenology of H. axyridis in Great Britain in the first five years since establishment, using data collected in a web-based public survey (www.harlequin-survey.org) and association with a national land cover dataset. Over 10000 verified records of H. axyridis between 2004 and 2008 were analysed. Evidence of bi-voltinism was found, with a spring peak in larval records in weeks 22-25 (i.e. late May – late June) and an autumn peak most frequently in weeks 42-43 (i.e. mid-late October). Harmonia axyridis had a mean activity period of 30.75 (range 26 to 34) weeks per year (based on the difference between the start and end of overwintering in buildings). There was a very strong positive relationship (R2 = 0.977) between the length of activity period per year and the mean annual temperature in Britain. Mean occurrence on arable/horticultural land was 18.8%. Occurrence in built-up areas and gardens decreased each year, from 70.2% in 2005 to 53.4% in 2008. Conversely, occurrence in grassland increased, from 6.0% in 2005 to 20.4% in 2008. Occurrence in woodland was greater in later years (2006-8 mean = 5.6%) than in earlier years (2004-5 mean = 2.5%). Thus although H. axyridis was very common in urban habitats, it increasingly used semi-natural habitats. Mean occurrence of H. axyridis on plants was: deciduous trees/shrubs 55.9%; herbaceous plants 29.1%; evergreen trees/shrubs 11.2%; grass/rush/sedge/fern 3.7%. The species was increasingly found on herbaceous plants. Harmonia axyridis was recorded from 75 families of flowering plant and three families of coniferous plant. 53.5% of records were reported from the six most represented plant families (Aceraceae, Rosaceae, Malvaceae, Urticaceae, Asteraceae and Fabaceae). Harmonia axyridis larvae were recorded from 50 plant families (with 50.2% of all larval records reported from Aceraceae, Malvaceae and Rosaceae). These data show that H. axyridis has a broad habitat range in Britain and has the capacity to dominate coccinellid assemblages in semi-natural, as well as urban, habitats.
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