As a Purdue Extension Specialist on Insects of Woody Ornamental Plants,
I am writing to comment on the Environmental Assessment for the proposed
release of 3 parasitoids against the emerald ash borer (docket:
APHIS-2007-0060).

With over 8 billion ash trees at risk, the country is in desperate need
of help for controlling the emerald ash borer. Research conducted on
insecticidal control to date has showed only ephemeral benefits when
applied in a timely manner on trees in urban areas. Insecticides that
have been identified are either too expensive or simply impractical to
apply to forested areas without undue cost or environmental impact.
Therefore, I strongly support the release of the 3 parasitoids for the
biological control of emerald ash borer.

The EA provides a very strong case for the release of all three natural
enemies. Each of the parasitoids has been shown to be associated with
population reductions of EAB in China. The most encouraging news is that
the *Oobius* egg parasitoid and the *Tetrastichus* larval parasitoid was
associated with the sympatric survival of a planting of North American
green ash (*Fraxinus* *pennsylvanica*) in and emerald ash borer in China
for over 25 years.

Despite the tremendous potential for success, the EA goes to great
lengths to address the very legitimate concerns for host specificity and
the potential impacts on non-target arthropods. The data presented
provide a strong argument for host specificity, documenting that the
larval parasitoids are largely restricted in their host range to only
some buprestid beetles in the same genus as emerald ash borer (Agrilus).
The egg parasitoid only attacks Buprestid eggs of similar size. In
total, the EA presents enough size and species restrictions to say that
these parasitoids pose a low risk at best to non-targets.

Another potential area of concern is whether the three larval
parasitoids are complementary or antagonistic in their contribution to
the mortality of EAB. Clearly, the the ability of the *Oobius* egg
parasitoids and the *Tetrastichus* larval parasitoid to provide enough
mortality to contribute to the survival of susceptible North America ash
suggest that at least these two parasitoids are compatible. The authors
do not address the issue of compatibility for the *Spathius* and
*Tetrastichus* larval parasitoids*.* Much of the literature of
biological control (eg Xiao et al. 2007) would argue that control of
exotic pests with few natural enemies like EAB would indeed be improved
by the presence of redundant sources of parasitoids. This would be
especially important in the case of emerald ash borer that is relatively
rare in its native ecosystem. Having redundancies would increase the
chances of conserving populations of beneficials if local extirpations
of pests result from the introductions.

In summary, the potential benefits from EAB far outweigh any rather
negligible risks that the authors may have failed to address in their
EA.

Xiao, Y., J.A. Qureshi and P.A. Stansly 2007. Contribution of predation
and parasitism to mortality of citrus leafminer Phyllocnistis citrella
Stainton (Lepidoptera: Gracillariidae) populations in Florida,
Biological control : theory and application in pest management. 40(3) p.
396-404.