Giant Salvinia Article - Houston Chronicle

Interesting article from the Houston Chronicle regarding the issue of the invasive plant, Giant Salvinia.

http://www.chron.com/disp/story.mpl/outdoors/tompkins/7602063.html

Large-Scale Weevil Releases Begin

Over the past month, we've begun releasing the weevil infested material from our tanks onto the largest giant salvinia patches we can find on the lake. We have released large numbers of weevils at three locations and will be monitoring it consistently as summer progresses. We will be releasing at a fourth site in the near future which will complete the number of initial release sites required for the research protocol. Additional large-scale releases will be made as the weevils re-expand their numbers in the tanks and the giant salvinia begins to rapidly expand with the progressing summer heat.

To date, we've released a little over 70,000 weevils in the three locations (and an additional estimated 217,000 weevil larvae that would be within the released plant material). These weevils came from only two tanks in which we removed approximately 80% of the material of each tank. The two tanks had a spring weevil population "explosion" in which the adult weevil population density increased from 8 adults per pound to an estimated 85 weevils per pound! Consequently (and not surprisingly), the salvinia in the weevil tanks quickly began to crash due to this high number of weevils. As a result, every time we're on the water, we bring in fresh giant salvinia off the lake to keep our remaining weevils happy, well-fed, and reproducing. Hopefully, we'll be seeing some progress from the released weevils and will be able to report all findings.

Thanks to Bryan Higdon and Adam Fisher who volunteered their time to help with the weevil releases. Our next large-scale release will likely require more volunteers so we'll be putting the call out at some point later this summer.

Recent Media Regarding Invasives and Caddo Lake Efforts

LINKS TO THREE MEDIA STORIES:

http://www.thecherokeean.com/news/2011-04-20/Outdoors/Texas_Giant_Salvinia_Effort_Reaches_Boaters_Raises.html

http://outdoornews.com/state_news/article_97ed963e-6b6c-11e0-bfe4-001cc4c002e0.html

http://lubbockonline.com/texas/2011-05-01/henleys-work-paying-caddo-lake

Hurry Up...and Wait. Salvinia Still Recovering

In late March of 2011, we released approximately 1,500-2,000 weevils into a small area (less than an acre) of semi-green giant salvinia that persisted through the cold winter. We are closely monitoring this release site in hopes of collecting valuable data regarding early season weevil reproduction, weevil feeding activity, as well as environmental variables that may affect overall weevil success.

As of early May, there appears to be few, if any mats of giant salvinia that appear large and green enough for a large scale weevil release (however, the water hyacinth seems to be recovering rapidly). We know this situation will change quickly as we progress into May and early-June; as summer approaches, it's quite possible we'll have many covered areas that will be ideal for weevil releases.






Based upon the preliminary results of our ongoing "weevil egg-laying and larvae cage study", it's clear that lake temperatures are within range for weevil reproduction. This is critical because the larvae (pictured on the right), not the adults, are the most effective in controlling giant salvinia. These 1-2 mm larvae tunnel through the plant rhizome (rhizome is basically the stem connecting the leaves of the plant) causing massive damage to the plant. By dissecting the plants in our cage study, we are finding lots of these larvae doing their work. In fact, the giant salvinia in our weevil tanks are starting to show this larvae-induced damage (shown in the yellow/brown coloration in the bottom picture). Thus, the sooner we can get these bugs out and reproducing, the better.

We are hoping to do our first large scale release in the next 2-3 weeks. Of course, this is anticipating that we have some spots with adequate giant salvinia on the lake. If you are interested in assisting with this and other weevil releases, please email paireland@ag.tamu.edu to receive more information. As giant salvinia growth increases and CISE efforts ramp up, look for more updates on the blog and facebook page.

Caddo Lake Community Meeting - April 7th, 2011

The Caddo Lake Community Meeting, hosted by the Caddo Lake Clearinghouse will be on:

DATE: April 7th, 2011
TIME: 5:30 - 7:15 PM

Karnack Community Center
15593 FM 134 (at the intersection of FM 134 and T.J. Taylor Avenue)

HIGHLIGHTS:

• Aquatic Vegetation Control on Caddo Lake (including talks regarding the Giant Salvinia Eradication Project)
• Texas Master Naturalists Presentation
• Texas Mussel Watch Program Presentation
• Updates on Enviornmental Flows, Paddling Trails, LHAAP Cleanup, and paddlefish establishment

refreshments provided by Caddo Lake Institute

Spring Weevil Study Commences

It's documented that correct water temperature is critical for the development of salvinia weevils. As the water temperature increases from 62.6 F to 69.9 F many activities such as feeding, oviposition (egg-laying), and egg-hatch begin. However, spring temperatures (in a water body such as Caddo) at which these activities begin have apparently not been reported. Therefore, a study has begun to determine the temperature and date in which egg-laying occurs on Caddo Lake. It's hoped that the results will help further guide our efforts to control giant salvinia using weevils.

To do this, 30 cages (the same cages from the overwintering study) containing 12 adult weevils with fresh salvinia along with temperature loggers were placed on the lake last week. Each week for the next 10 weeks, three cages will be removed at random and the salvinia within will be extensively searched for adults, newly emerged adults (which will have a red color), and any larvae present (larvae will be found tunneling through the rhizome of the plant). We will be looking for the time and temperature at which "significant numbers' of larvae are present in all the cages.

Also, some recent local publicity regarding Caddo Lake and this project appeared in the Marshall News Messenger on March, 20, 2011.
http://www.marshallnewsmessenger.com/news/article_cca41eb6-52a3-11e0-bf42-001cc4c03286.html

Cold Winter Helped...Salvinia Expected To Recover

We've been fortunate this winter to have had a series of cold spells that knocked back the giant salvinia a great deal. It's expected that much of the dead, brown material that is floating will take several weeks to sink out of sight.
Despite this cold weather, we've found several very thick mats around the lake that show survival of green material under the insulating top layer. It's anticipated that these spots will be major expansion points as summer approaches. The first two pictures show the freeze damaged salvinia with green material showing through. These areas should provide good weevil sites for our early season stockings.


On another note, in late February, we completed the re-filling of our weevil tanks with Caddo Lake water. With the warm, sunny weather we've been experiencing lately, the giant salvinia in these tanks has been greening up nicely. Hopefully, our weevils will flourish and be ready for placement on the lake in the very near future!




















Finally, here is a recent article about the Caddo Lake salvinia project in the Winter 2011 edition of "TX H2O": http://twri.tamu.edu/publications/txh2o/winter-2011/controlling-invasive-weed