I am grateful to David Bloomfield for pointing out the Spanish paper on the Atinian Elm that
started off this investigation.
References:
Coleman, M. (2002) British Wildlife 13: 390.
Columella,J.M. (c.AD50) De re Rustica, v.6. quoted from L. Junius Moderatus Columella
Of Husbandry. London. 1745.226 f.
Gil, L et al, (2004) English Elm is a 2,000-year-old Roman Clone. Nature 431: 1053.
Pliny (the elder), (c.AD70) Natural History. XVII: 35. from the Bostock & Riley translation
(London 1885, vol:III. p.512).
Harmonia axyridis - a potential ecological disaster in Britain?
Paul Mabbott 49 Endowood Road Sheffield S7 2LY paulmabbott@blueyonder.co.uk
I noted (Essex Field Club Newsletter May, 2004) that "new" ladybirds were likely to be
found in Britain and expressed concern about one species. Harmonia axyridis (the
multicoloured, multivariate, southern, Japanese, harlequin, hallowe'en, Asian ladybird, -
beetle,-bug) was introduced into S.E. USA to control pest aphids: it is a very efficient at
this but has some less fortunate properties. Like most ladybirds it can reproduce at a
prodigious rate so millions are regularly seen, often entering buildings and becoming a
nuisance. It has spread throughout the USA and Canada.
It out-competes other ladybirds for aphids. Furthermore, it has a very wide prey range:
when there are no more aphids it will eat other insects including ladybirds. Most native
ladybird species eat each other, but there is a balance without net gain or loss between
species. Unfortunately, other ladybirds cannot eat H. axyridis because of its chemical
defences. In America native species are in decline from both competition and predation.
Other insects are also eaten including butterfly eggs: it is not only ladybirds which are
threatened.
To release the animal in America was foolish. Worse was to allow its use in Europe: it is
now established, particularly in the Low Countries where it seems to be elbowing out
local ladybirds. On the scale of continental America and Europe the species is a big
problem: it could be disastrous on a small island. In its native ecosystem (N.E. Asia), H.
axyridis is a helpful ladybird because its population level is controlled by predators and
pathogens. These do not exist in America but most are present in Europe.
The first British report of the species came from North Essex: Ian Wright found it in the
garden of the White Lion at Sible Hedingham during September. It was hoped that this
was an isolated vagrant, but within weeks more were found in south-east England,
particularly in S.W. London. One of the earliest records was in fact from Dovercourt
where Chris Gibson had photographed an odd ladybird from his light trap on the night
of 21/22 August (see Plate 1). Subsequently there have been other isolated, mainly coastal,
Essex Field Club Newsletter No. 46, January 2005
17