Agriculture Reference
In-Depth Information
Brachiacantha ursina
(Fab.) were more abundant in those that included decidu-
ous forest habitats. Overall, coccinellid species richness increased in sites con-
taining uncultivated habitats, demonstrating the importance of these habitats in
shaping predator communities (Woltz and Landis 2014).
Documenting Invasive Species
Long-term sampling at KBS has also been important for documenting the arrival of
exotic coccinellids and their impacts on the predator community. When the MCSE
was initiated in 1989,
C. septempunctata
was concluding its initial outbreak phase
(Sirota 1990) and was the dominant coccinellid species. Subsequent observations
show that this species exhibits roughly a 5-year population cycle (Fig. 8.4). In 1994
the KBS LTER trap network was the first to detect the occurrence of the exotic
species
H. axyridis
in Michigan (Colunga-Garcia and Gage 1998) (Fig. 8.5). In
contrast to
C. septempunctata
, which primarily inhabits field crops and herbaceous
plants in old-field habitats,
H. axyridis
is considered a semi-arboreal species (Koch
and Galvan 2008), inhabiting both trees and herbaceous habitats. These flexible
habitat requirements allowed
H. axyridis
to become a dominant species in all
MCSE habitats. Its occurrence in forested habitats was associated with a decline
in the abundance of
B. ursina, Cycloneda munda
(Say), and
C. stigma—
all species
that prefer wooded habitats—suggesting that competitive displacement may have
been occurring. In 2005 another exotic coccinellid,
H. variegata
, was reported in
Michigan for the first time at KBS and in three additional counties (Gardiner and
Parsons 2005), although a subsequent search of KBS LTER records showed it was
first detected in 2000. Finally, in 2006, the exotic 14-spotted lady beetle (
P. quatu-
ordecimpunctata
) was discovered in Michigan (Gardiner et al. 2009a). This species
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
Year
Figure 8.4
. Mean number of
Coccinella septempunctata
ladybird beetle adults caught per
trap over week-long deployments at the MCSE between 1989-2009.
