Geoscience Reference
In-Depth Information
Figure 2
The primary parasitoid wasp, Trioxys angelicae, oviposits inside the 'black-
bean aphid', Aphis fabae. Photo taken by Dirk Sanders.
C. The Importance of Host-Parasitoid Networks in
Ecological Research
Host-parasitoid interactions are prevalent within natural ecosystems,
and parasitoid organisms are considered to be the most important biological
control agents used in agriculture and conservation, with parasitoid wasps
saving the U.S. agriculture industry, through the control of crop pests, an
estimated $20 billion a year (
Mills and Wajnberg, 2008; Pennacchio and
Strand, 2006; Pennisi, 2010
). The prevalence and importance, as well as key
differences in structure compared to food webs, of host-parasitoid networks
have lead to important studies across a range of key ecological issues (
Ings et al.,
2009; Lafferty et al.,2008
). Further, the inclusive study of multiple networks is
important as different network types do not exist separately of one another and
the structure of one network type can have important effects upon species
composition and interaction strength in other network types (
Ings et al.,
2009; Oleson et al., 2010
). For example, studies of the mutualistic protection
of honey-dew producing aphids by ant species have shown that defensive
behaviour differentially excludes parasitoid species and significantly affects
the functional composition of both primary and secondary parasitoid species
communities (
Mackauer and Volkl, 1993; Sanders and Van Veen, 2010
).
