Presented at the TWCA Fall Conference 2014 www.twca.org

1. GIANT SALVINIA:
A GROWING PROBLEM AND
A NATURAL CONTROL
Presented by:
Allie Cozad

2. WHAT’S TO COME?
Giant salvinia (Salvinia molesta)
• Basic biology
• Impacts on us and the environment
• How it got here and how we control it
The salvinia weevil (Cyrtobagous salviniae)
• Basic biology and life cycle
• Red River Waterway’s Research Center
• A few success stories (with pictures)
Continuing Research
Questions

3. What is Giant Salvinia?
• Free floating aquatic fern
• Pair of floating emergent
leaves
• 3rd submersed leaf acts
like a root
• Sporocarps appear in the
“mature” plants

4. THREE STAGES Primary
S
e
c
o
n
d
a
r
y
Tertiary

5. WHY IS GIANT SALVINIA
A PROBLEM?
• Highly invasive
• Doubles in 2-3 days
• Dominating waterways
– Makes navigation
difficult
– Devaluation of
property
– Irrigation systems
– Blocks natural air
exchange

6. How did this invasion begin???
• Brazilian native plant
introduced in the US as
ornamental plant
• 1970- federally listed as
prohibited noxious weed
• Mid 90s- invaded Louisiana
• Today- invaded almost
every water body across
the south

7. Methods of Control
• Mechanical removal
– Highly labor intensive
– Damages plants-promotes
growth
• Chemical control
– Not possibly in some areas
– Chemicals affect other plants
– Effective but expensive
• Bio-control
– Naturally occurring control
– Successful in over 15 countries
• “Endocide” --- more to come

8. Cyrtobagous salviniae : Giant
salvinia’s natural control
• Length: 1.5-3.1 mm
• Width: 1.2-1.6 mm
• Live for about 6 months
• Egg to adult in 6 weeks
• All stages are temperature
dependent
• Host specific

9. Life Cycle of the Weevil
 Females lay eggs only when
salvinia is in contact with
water
 Larvae feed on leaves and
new buds eventually
tunneling inside the rhizome
 Adult emerges primarily
feeding on leaves and leaf
buds
 Both active life stages
destroy salvinia

10. Aquatic Research Center
• Greenhouse construction
complete in Sept. of 2012
• Started with approx. 300
ADULTS in March of 2012
• Released 90,000 ADULTS
in 2013
• 2014 Greenhouses
yielded 110,000 ADULTS
West side of Red River
at Lock 3
8-18-12

11. Lake Moondarra, Queensland,
Australia
APPROX. 500 ACRES
INFESTED WITH S. MOLESTA
14 MONTHS AFTER RELEASE
C. SALVINIAE

12. Bayou Nicholas
November 2013
January 2014
June 2013

13. Continuing Research
• Backwater areas are most important
• Plant nurseries
• Goal to make weevil factories
• Fewer locations
• Cold tolerance and Integrated management approaches
• Key questions will be addressed in Master’s thesis
research
• RRWC is Exploring all options against our fight
• Dr Shiyou Li and staff working towards new approach
“ENDOCIDE”

14. Any Questions ???