Research Proposal The efficacy of the milfoil weevil _Euhrychiopsis

							                                Research Proposal:




The efficacy of the milfoil weevil (Euhrychiopsis lecontei) in controlling Eurasian
 water milfoil (Myriophyllum spicatum), an invasive freshwater macrophyte in
                                  North America.




                                   Adam Lima




                                February 4, 2011




                              University of Ottawa
Introduction:

        The Eurasian Water milfoil is an invasive plant species which has become a problem in
freshwater lakes in both Canada and the United States. This plant species is aggressive,
displacing native species and can form dense mats at the surface of the water, depleting oxygen
levels in the lake (Barko et al, 1990). Several methods have been used to control this invasive
species; however a relatively new method has come into interest. The use of biological controls
has become one of the most effective methods in controlling the Eurasian water milfoil and has
been seen to cause the least amounts of damage to existing native aquatic communities (Roley et
al, 2006). The milfoil weevil (Euhrychiopsis lecontei), as a biological control, could prove to be
the most efficient and effective way to control the fresh water invasive species of Eurasian Water
milfoil in comparison to other commonly used methods (Roley et al,). Some of these other
methods used in the past include: mechanical harvesting, herbicide use and other types of aquatic
insects. Results may supply evidence as to the efficiency of the milfoil weevil based on the
general success the insect will have in coping in different lake conditions as well as its benefits
in comparison to other control methods.

Background:

       When a species not native to a given region is introduced into a community, it becomes
invasive when there is evidence supporting the fact that its introduction has adversely affected
the environment, the economy and/or human health (Chadderton, 2008). Invasive species have
been proven to cause declines and extinctions in species that inhabit the communities which are
invaded (Clavero et al, 2005). A newly introduced species which becomes invasive generally
has no competition or natural predators. When a population is not controlled by internal or
external factors, such as competition, and given large amounts of resources, the species
population will continue to grow. These species explosions can potentially have large impacts on
whole ecosystems (Chadderton, 2008). Governments strive to remain in control of invading
populations by implementing chemical, mechanical or biological control methods.

        The Eurasian Watermilfoil has become one of the most detrimental invasive species in
North American aquatic environments (Barko et al, 1990). It is native to Europe, Asia and North
Africa; however the time and location of its introduction to North America is uncertain.
Before controlling methods had been implemented, the Eurasian watermilfoil had a distribution
throughout Lake George, New York of 5000m2 (Madsen et al, 1989). The Eurasian Watermilfoil
can begin growing earlier in the spring and in colder temperatures then other native aquatic
species. This allows them to develop large canopies which cover other slower growing aquatic
plants (Baro et al, 1990). These large dense canopies decrease the concentration of dissolved
oxygen in the water, impacting the recreational capacities of the lakes. Moreover, it can also clog
industrial and power generation water intakes (Eiswerth et al, 2000). Plant fragments which are
broken off or cut can re-root themselves and grow entirely new plants. They have also been
measured to grow up to one inch per day, making them very aggressive (Huehner, 2000).

        The milfoil weevil (Euhrychiopsis lecontei), is a potential biological control agent of the
invasive species, Earasian Watermifoil. The weevil is native to North America, however they are
not found in all freshwater lakes (Mazzei, 1999). Due to the fact that the weevil is native to
North American water bodies, it would likely be used a biological control. Studies have shown
that this type of weevil prefers the Erasian Watermilfoil over other native species and has
contributed to declines in stem and leaf carbohydrates of the invasive plant. These declines have
lead to the rehabilitation of other native aquatic plants and have shown an increase in sediment
ammonium (Newman, 2000).

        The milfoil weevil negatively impacts the watermilfoil during most stages of its life
cycle. Adult females lay their eggs on the tips of the milfoil leaves. When the eggs hatch the
larvae eat away the leaves then burrow into the stem to feed on the tissue within (Roley et al,
2006). The weevil cause the stems structural integrity to fail which in term leads to the plants
reduced capabilities to move nutrients throughout the plant and slows its growth. The pores
formed by the weevil also reduce the buoyancy of the leaves decreasing the sizes of the canopies
and allow for native aquatic plant species to thrive (Roley et al, 2006).

Purpose and Objectives:

        The milfoil weevil life cycle has been described in many articles and has proven how
effective the weevil is at destroying the invasive species. However, the milfoil has yet to be
described by its time effectiveness and possible future implications. The objective of this study
will be to assess the rate at which the Eurasian Watermilfoil is preyed upon by the milfoil
weevil to determine whether this aquatic insect is a good biological control for the invasive
Eurasian Watermilfoil. Every year there are millions of dollars spent on the control of this
invasive species and a single cost effective control has yet to be discovered (Eiswerth, 2000).

        Based on past studies, it is predicted that the milfoil weevil will have a preference for the
invasive species in comparison to the native aquatic plants (Solarz et al 2001). It is also
predicted that the predation of the invasive species is drastic enough to see some declines in
population sizes. The results of this study may yield a timely cost-effective biological control
that will drastically reduce the invasive species and at the same time maintain the natural
ecosystems.
Experimental Design:

        The experiment will be conducted in order to determine the average time it takes for the
milfoil weevil to show that it is diminishing the integrity and overall health of the Eurasian
Watermilfoil. In order to determine the health of the Eurasian Watermilfoil, certain health
characteristics will be watched for such as; the decreased buoyancy of leaves. If the leave of the
Eurasian Watermilfoil cannot reach the surface of the water, the plant will not be able to
reproduce and will have less effectively created a canopy blocking sunlight to the other aquatic
plants (Creed et al, 1993). These signs would undoubtedly show a decrease in the plants fitness.

        The experiment will take place in a lake located in Southern Ontario and will be based on
four mesocosms. Two of these mesocoms will have to be manipulated in order for them to be
placed at the shoreline of a freshwater lake where there will be an average depth of 2.5 meters in
water as well as incorporating a portion of dry land. They will have to be an average of
approximately 2.5 meter deep due to the fact that the native and invasive milfoil species inhabit
these depths (Caffrey et al, 2007). The incorporation of dry land would be to allow for wintering
in the soils on shore for the milfoil weevil. The other two mesocosms will be able to only remain
in the water and no extra enclosures will be necessary. The size of the mesocosms will be 6
meters by 5 meters to ensure enough aquatic summer growing area and wintering shoreline. The
mesocosms that will be used as controls (mesocosm 1 and 2) will be approximately 4 meters by
5meters to only incorporate the amount of water area enclosed by mesocosms three and four.
Organic debris will also be added on the shoreline to ensure proper conditions. The mesocosm
locations must be absent of any growth exceeding 1 inch to allow for accurate initial plant
biomass calculations. There must be limited exchange with water and soil exterior to the
mesocosm to avoid contamination of other aquatic plants.

        In each of the mesocosms there will be a different combination of organisms. The first
mesocosm will contain only the invasive species Eurasian Watermifoil. This mesocosm will act
as a control. The second mesocosm will contain a combination of the Eurasian Watermilfoil and
a native species the North American water milfoil (Myriophyllum exalbescens). The species has
been chosen becasue it had been the primary diet of the milfoil weevil before the introduction of
the invasive species (Grace et al, 1978). This mesocosm will also serve as a control. The third
mecosom will have only the Eurasian Watermilfoil species in it however the milfoil weevil will
also be introduced into the system. The fourth mesocosm will contain both plant species and the
milfoil weevil to see whether the presence of another food sources would affect the rate at which
the Eurasian Watermilfoil is destroyed.

       The plants will be grown at a different location and will be removed once they are
experiencing similar stages of their life cycles to ensure there is no timing advantage to their
growth stages. This would occur towards the middle of May after the plants had begun to grow
in the early spring. The plant species will be planted by hand. By measuring the biomass before
planting, using a dry scale, we will be able to determine the initial biomass. Approximately 15
individual plants of each species will be planted in their respective mesocosms. The amount of
each species will be the same when added to their mesocosms. Equal amounts of native and
invasive species will be added to mesocosms two and four. The plants will be left alone for
several weeks to ensure that they have been planted correctly and will be able to show natural
growth responses. The milfoil weevils will be purchased. Twenty to twenty five weevils will be
added to the mesocosms 3 and 4 towards the end of May early June to allow for the milfoil
weevil population to grow in size before overwintering in the soil (Huehner, 2000).

        The experiment will be designed to last approximately 3 years and after the first year a
replication of the experiment may begin in a different location on the same lake with similar
depths to ensure proper final results. Mesocosm assessments should be completed 2-3 times a
week. If the mesocosm shows dramatic results earlier than anticipated, the time line of the
experiment may be altered. At the end of the experiment the plants and the weevils would be
removed. The plant biomass would be measured and compared to its original biomass. The data
analyses of the results would mimic a factorial design. We would compare the effects of the
milfoil weevil being present in the mesocosm and comparing them to the results obtained from
the mesocosms that did not contain the weevil. These results should indicate that the presence of
the milfoil weevil decreased the overall biomass of the Eurasian Watermilfoil in both mesocosms
three and four. The results from the third and fourth mesocosms would be able to give a general
idea as to the rate of deterioration the milfoil weevil has on a given population density of
Eurasian Watermilfoil.

Implications:

        The results of the experiment may provide a cost effective biological control for the
invasive species of watermilfoil. As the milfoil weevil is a native species there are natural
controls for this species therefore once the Eurasian Watermilfoil is depleted there will not be a
second infestation and overpopulation that is uncontrollable. The removal of Eurasioan
Watermilfoil will have positive impacts on lakes that have been over-run by the invasive species
by allow for displaced native aquatic plants to regain resources and also allowing for biodiversity
increases. (Silverman, 2007). Governments and industries would be able to save money knowing
that the milfoil weevil works and will be able to give projected times as to when infested lakes
would be cleared up. Finding a biological control for this invasive species that does not cause
further damage to the environment would immediately yield benefits.
References:


Barko, J.W., & Smith, C.S. 1990. Ecology of Eurasion Watermilfoil. J.Aquat. Plant Manage. 28: 55-64.

Caffrey, A.J., Hoyer,M.V. & Canfield, D.E. 2007. Factors affecting the maximum depth of colonization
by submersed macrophytes in Florida lakes. Lake and Reservoir management. 23:287-297.

Chadderton, L. 2008. Aquativ Invasive Species. Nature.

Clavero, M. & Garcia-Berthou, E. 2005. Invasive species are a leading cause of animal extinctions.
Trends in Ecology and evolution. 20:3, 110.

Crowell, W., N. Troelstrup, L. Queen, and J. Perry. 1994. Effects of harvesting on plant communities
dominated by Eurasian watermilfoil in Lake Minnetonka, MN. Journal of Aquatic Plant Management 32:
56-60.

Creed, R.P, & Sheldon, P. 1993. The effect of feeding by a North American weevil, Euhrychiopsis
lecontei, on Eurasian watermilfoil (Myriophyllum spicatum). Aquatic Botany. 45(2-3), 245-256.

Eiswerth, M.E., Donaldson, S.G., Johnson, W.S 2000. Potential Environemental Impacts and Economic
Damages of Eurasian Wtermilfoil (Myriophyllum spicatum) in Western Nevada and Northeastern
California. Weed Technology. 14(3): 511-518.

Grace, J.B. & Wetel, R.G. 1978. The production Biology of Eurasian Watermilfoil (Myriophyllum
Spicatum L): A Review. J. Aquat. Plant Manage. 16: 1-11.

Huehner, M.K.. 2000. Eurasian Watermilfoil- Aquatic Weeds. EnviroScience.

Madsen, J.D, Eichler, L.W, Boylen, C.W. 1989. Vegetative Spread of Eurasian Watermilfoil in Lake
George, New York. J.Aquat. Plant Manage. 26:47:50.

Mazzei, K.C., Newman, R.M., Loos, A., Ragsdale, D.W. 1999 Developmental Rates of the Native Milfoil
Weevil, Euhrychiopsis lecontei, and Damage to Eurasian Watermilfoil at Constant Temperatures.
Biological Control. 16:2. 139-143.

Newman, R.M. & Biesboer, D.D. 2000. A decline of A Decline of Eurasian Watermilfoil in Minnesota
Associated with the Milfoil Weevil, Euhrychiopsis leconte. J. Aquat. Plant Manage. 38: 105-111.

Roley, S.S, Newman, R.M. 2006. Developmental Performance of the Milfoil Weevil, Euhrychiopsis
lecontei (Coleoptera: Curculionidae), on Northern Watermilfoil, Eurasian Watermilfoil, and Hybrid
(Northern × Eurasian) Watermilfoil. Environmental Entomology. 35(1): 121-126

Sheldon, S. P., and R. P. Creed. 1995. Use of a native insect as a biological control for an introduced
weed. Ecological Applications 5: 1122-1132.

Silverman, B.D. 2007. Modeling the effect of growth rate and survivability trade-offs on species
coexistence and spatial topology at a traveling invasive wave-front. Ecological Modeling. 202 (3-4):
454-464.
Solarz, S.L. and R.M. Newman. 2001. Variation in hostplant preference and performance by the milfoil
weevil Euhrychiopsis lecontei Dietz exposed to native and exotic watermilfoils. Oecologia 126: 66-75.