Lily pad beetle
| Lily pad beetle | ||||||||||||
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Lily pad beetle ( Galerucella nymphaeae ) |
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| Galerucella nymphaeae | ||||||||||||
| ( Linnaeus , 1758) |
The lily pad beetle ( Galerucella nymphaeae ) is a beetle from the family of leaf beetles (Chrysomelidae).
features
The beetles are about six to seven millimeters long, light to dark brown in color, usually with a lighter, orange to yellow-orange or light brown border around the thorax and wing . Legs and head are also lighter. But there are also almost monochrome brown specimens. The head is round, the eyes round and black. The head and thorax are clearly separated, the scutellum is dark.
The larvae are dark brown to black and between the segments orange to yellow (only visible when stretched). They are cylindrical, slightly flattened and wider at the front than at the back. In the first stage, the larvae are about three millimeters long.
The egg packets consist of approx. 12 light yellow to orange, round eggs, which are tacked next to each other on the top of the leaf.
Occurrence
The lily pad beetle occurs in most of Europe , in the north to Scandinavia and in the south to northern Spain and northern Italy, tied to the occurrence of forage plants. The populations found in North America may be a species of their own .
Way of life
The beetle is oligophagous, which means that it only feeds on very few plant species. It is very likely to be found on the white water lily ( Nymphaea alba ), yellow pond rose ( Nuphar lutea ) and knotweed ( Polygonum amphibium ). Further forage plants are common arrowhead ( Sagittaria sagittifolia ), swamp blood-eye ( Potentilla palustris ), river dock ( Rumex hydrolapathum ) and strawberry ( Fragaria spec. ). Galerucella nymphaeae is therefore also known as the strawberry beetle . Due to the very different forage plants, the beetles each specialize in a family of host plants . In the following, the way of life of the beetles that feed on the white water lily and the yellow pond rose is discussed .
All stages of the species, i.e. eggs, three larval stages, pupae and beetles live on the floating leaves . They eat irregular trenches in the upper leaf layers but leave the lower epidermis intact so that the leaf does not flood or sink. The beetles spend the winter in fallen leaves or under pieces of bark on the ground. The beetle does not have any adaptations that are necessary for swimming or breathing underwater, but egg packets as well as beetles and larvae that cling to the leaf can survive brief immersion. If a larva - due to the leaf change of the host plant - has to leave one leaf and migrate to another, this is done by passive drifting. If it gets under the surface film , it goes under immediately.
Reproduction
In spring (April – May), the beetles that have overwintered populate the young leaves as soon as they float on the surface and begin to mate quickly. The females mate more than once and have a spermatheca to store the sperm . During the egg-laying phase of around five weeks, each female lays an average of one egg packet per day. Then this generation dies . The new generation completes the pupal stage after about 30 to 40 days, mates and produces another generation that can mate again from August to September. However, the females of this generation will no longer lay eggs this year. Both the spring and summer generations can overwinter.
swell
Individual evidence
- ↑ Galerucella nymphaeae in Fauna Europaea
- ↑ a b c d Kouki, J. (1991): Small-scale distributional dynamics of the yellow water-lily and its herbivore Galerucella nymphaeae (Coleoptera: Chrysomelidae). Oecologia 88: pp. 48-54
- ↑ Nokkala, C .; Nokkala, S .; Nordell-Paavola, A. (1998): European and North American populations of Galerucella nymphaeae (Coleoptera: Chrysomelidae): Two separate species revealed by chorion polypeptide analysis. European Journal of Entomology 95: 269-274.
- ↑ a b c Pappers, S .; (2001): Evolution in action: Host Race formation in Galerucella nymphaeae . ISBN 90-9015225-3
- ↑ a b Almkvist, P. (1984): Ecological studies of the leaf beetle Galerucella nymphaeae in south-western Sweden. PhD thesis, University of Götenborg
- ↑ Kouki, J. (1991): Tracking spatially variable resources: An experimental study on the oviposition of the water-lily beetle. Oikos 61: 243-249
Web links
- Galerucella nymphaeae at Fauna Europaea