The leaf beetle ''Chrysomela lapponica'' is found in central and northern Europe feeding on leaves of

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

s and

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...

. The adult beetles are about 8 mm long and beetles in different regions can have different colour patterns on their

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

Colour forms and host plants

Beetles from different populations can be distinct in their biology, like coloration or behaviour. The larvae and adults from northern Europe (e.g. Finland, Sweden, Norway, Russia, and the Baltic states) feed and oviposit only on some willow species. The Central European populations, which are patchily distributed in Germany, Czech Republic, Poland, northern Italy and France, are mostly

monophagous A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of env ...

on birch. Development of the insect is impaired if beetles are reared on their non-natural host, that is beetles from northern Europe are fed with birch leaves, or beetles from Central Europe with willow leaves. The elytra colouration consists of red and black marks. Black marks predominate in the northern populations while in the central European population the colours red and black are about equally represented on the elytra. The darker forms heat up more quickly and might be an adaptation to the colder environment in northern Europe.

Pest status

In the

Kola Peninsula sjd, Куэлнэгк нёа̄ррк , image_name= Kola peninsula.png , image_caption= Kola Peninsula as a part of Murmansk Oblast , image_size= 300px , image_alt= , map_image= Murmansk in Russia.svg , map_caption = Location of Murmansk Oblas ...

of north-west Russia, outbreaks of ''Chrysomela lapponica'' resulted in severe defoliation of the willow species ''

Salix borealis Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...

'' in August 1993 and then again in 1994 and 1995. Studies showed that plants stressed by defoliation the previous year were less favourable for the development of the leaf beetles. Therefore, the decline of the outbreaks appears to be linked to the development of resistance in the willow hosts.

Natural enemies

Like other insects, ''Chrysomela lapponica'' is attacked by a variety of natural enemies, mainly other types of insects which prey on or parasitize the larvae. ''Chrysomela lapponica'' has developed defenses against such natural enemies. The larvae possess defensive glands filled with volatile compounds which deter attacking natural enemies and have antimicrobial activity. There are also differences in the chemical composition of these defensive compounds among geographically separated populations, apparently linked to the host plant the beetles feed on. Although the defensive compounds are usually repellents, some natural enemies are actually attracted to them and use them to locate their prey or host. This has been shown for the predaceous hoverfly ''Parasyrphus nigritarsis'' and the phorid fly ''Megaselia opacicornis''.

References

{{Taxonbar, from=Q1310025 Chrysomelinae Beetles of Europe Taxa named by Carl Linnaeus Beetles described in 1758