Monday, March 21, 2011

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.

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