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Why Big Species of Ladybird Beetles are Not Melanic
L. A. Stewart and A. F. G. Dixon
Functional Ecology
Vol. 3, No. 2 (1989), pp.
165-171
(article consists of 7 pages)
Stable URL:
http://www.jstor.org/stable/2389297
Functional Ecology © 1989 British
Ecological Society
Abstract
Melanic forms occur commonly in small species of coccinellid
like Adalia bipunctata (L.) but are rare or absent in large species like
Coccinella septempunctata L. Under direct irradiation coccinellids that are
melanic show a greater temperature excess than non-melanic individuals. This was
demonstrated for naturally occurring morphs of A. bipunctata and the normal
non-melanic and artificial melanic forms of C. septempunctata. Temperature
excess was shown to be a function of the elytral surface area that is coloured
black. It is suggested that large species of coccinellid are not melanic because
if they were their body temperatures would frequently reach deleterious levels
on sunny days.
