Biological control of exotic plant populations with native
organisms appears to be increasing, even though its success
to date has been limited. Although many researchers and
managers feel that native organisms are easier to use and
present less risk to the environment this may not be true.
Developing a successful management program with a native
insect is dependent on a number of critical factors that need
to be considered. Information is needed on the feeding preference
of the agent, agent effectiveness, environmental regulation
of the agent, unique requirements of the agent,
population maintenance of the agent, and time to desired
impact. By understanding these factors, researchers and
managers can develop a detailed protocol for using the native
biological control agent for a specific target plant.
. We found
E. lecontei
in 14 waterbodies,
most of which were in eastern Washington. Only one lake
with weevils was located in western Washington. Weevils were
associated with both Eurasian (
Myriophyllum spicatum
L.) and
northern watermilfoil (
M. sibiricum
K.). Waterbodies with
E.
lecontei
had significantly higher (
P
< 0.05) pH (8.7
±
0.2)
(mean
±
2SE), specific conductance (0.3
±
0.08 mS cm
-1
) and
total alkalinity (132.4
±
30.8 mg CaCO
3
L
-1
). We also found
that weevil presence was related to surface water temperature
and waterbody location ( = 24.3,
P
≤
0.001) and of all
the models tested, this model provided the best fit (Hosmer-
Lemeshow goodness-of-fit = 4.0,
P
= 0.9). Our results suggest
that in Washington State
E. lecontei
occurs primarily in
eastern Washington in waterbodies with pH
≥
8.2 and specific
conductance
≥
0.2 mS cm
-1
. Furthermore, weevil distribution
appears to be correlated with waterbody location (eastern
versus western Washington) and surface water temperature
