Ba. Hawkins et Pc. Marino, THE COLONIZATION OF NATIVE PHYTOPHAGOUS INSECTS IN NORTH-AMERICA BY EXOTIC PARASITOIDS, Oecologia, 112(4), 1997, pp. 566-571
Classical biological control could have a major environmental cost if
introduced natural enemies colonize and disrupt native systems. Althou
gh quantifying these impacts is difficult for systems already colonize
d by natural enemies, the a priori condition for such impacts can be e
valuated based on the extent to which exotics have acquired native hos
ts. We use native host records for exotic parasitoids introduced into
North America for biological control to document the number of exotic
species that have been recorded from at least one native insect specie
s. We also evaluate the ability of six biological and ecological varia
bles to predict whether or not a parasitoid will move onto natives. Si
xteen percent of 313 parasitoid species introduced against holometabol
ous pests are known from natives. Further, the likelihood that a paras
itoid had colonized native hosts was largely unpredictable with respec
t to the independent variables. We conclude that given the quality of
the data available either now or in the foreseeable future, coupled wi
th inherent stochasticity in host shifts by parasitoids, there are no
rules of thumb to assist biological control workers in evaluating if a
n introduced parasitoid will colonize native insect communities.