Science Facing Aliens - Invasive Alien Species in Belgium - Belgian ...

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Ladybirds sampled
From the 20 sites sampled, 13 species of adult ladybirds were collected (Figure 1). The most
abundant species was H. axyridis: it was present in 18 out of the 20 sites sampled and was
also the most abundant with 791 specimens collected. Next, but 15 times less abundant and
each present on half of the sites, were 4 natives species: 3 aphidophagous tree species, A.
decempunctata (L.), Calvia quatuordecimguttata (L.) and Calvia decemguttata (L.), and 1
mycetophagous species: Halyzia sedecimguttata (L.). Further, 2 generalist species and 2 tree
species were caught: A. bipunctata (L.), Propylea quatuordecimpunctata (L.) and Exochomus
quadripustulatus (L.), Oenopia conglobata (L.), respectively. Anatis ocelata (L.), Myrrha
octodecimguttata (L.) and Aphidecta obliterata (L.) live in coniferous trees and are not
associated with lime trees, which explains the low catch of these species.
Anatis ocelata (1/20)
Myrrha 18-guttata (1/20)
Psyllobora 22-punctata (1/20)
Oenopia conglobata (1/20)
Aphidecta obliterata (2/20)
Propylea 14-punctata (2/20)
Exochomus 4-pustulatus (2/20)
Adalia 2-punctata (7/20)
Halyzia 16-guttata (11/20)
Calvia 10-guttata (11/20)
Calvia 14-guttata (12/20)
Adalia 10-punctata (15/20)
Harmonia axyridis (18/20)
1
1
1
1
2
2
2
9
39
47
52
52
791
0 100 200 300 400 500 600 700 800 900
No adults/ 1540 beatings
Figure 2. Numbers of adult ladybirds collected. In brackets: number of sites in which they
were caught.
An even lower number of species was present as larvae (Figure 2). Again, H. axyridis was the
dominant species, present in all sites with 737 larvae. To the contrary, only 33 native
coccinellids larvae (C. quatuordecimguttata, Adalia spp., C. decemguttata and P.
quatuordecimpunctata) were collected in 7, 5, 2 and 1 out of 20 sites, respectively. All these
aphidophagous species are in competition for food and are potential intraguild prey for H.
axyridis.