Christmas Island, outbreak densities of scale insects
associated with Anoplolepis supercolonies appear to cause
dieback in the canopies of large trees (cf. Bach 1991), and may
further impair tree performance through the deposition of
excess honeydew on their leaf surfaces. Honeydew encourages
the development of sooty moulds (Capnodiaceae),
which reduce photosynthesis (Wood et al. 1988). Ant-scale
associations are often adventive and generalized, and need
not be generated by a coevolutionary history (Simberloff &
Von Holle 1999). Invasive impacts may depend upon serial
introductions of different scale insect species capable of
establishing mutualism with Anoplolepis. Positive populationlevel
consequences magnify impacts of both.