Mosquitoes & Salvinia Weevils survive extreme cold

BATON ROUGE, LA (WAFB) - If you were hoping this week's hard freeze would mean fewer mosquitoes this spring, think again.  The director of East Baton Rouge Mosquito Abatement & Rodent Control said the majority likely survived.

"They're out there breeding in the ditches. Right now they're just kinda holed up in a warm place waiting for it to warm up more," Dr. Todd Walker said.

Walker said some likely did die over the past few days, but the duration of the deep freeze was too short to make a dent in the population. Mosquito larvae can survive in water underneath frozen surfaces.

"They are actually respiring through their cuticle and getting oxygen that way and that's how they survive in the cold weather with ice on the water, he said.

Walker said even in freezing temperatures control crews are out looking for larvae and treating the ditches where they find them.

There's another insect that scientists hope survived the freeze. The Salvinia weevil is native to South America, but millions have been released into Louisiana waterways to control the invasive Salvinia plant.

According to the LSU Ag Center Salvinia can double its coverage area every 36 hours, and a single plant has been described to cover 40 square miles in three months. It does damage by displacing other vegetation, blocking sunlight and depleting oxygen levels, which can kill fish and other animals.

"In 2010 we made a huge release of weevils and we lost 100% of them [to the cold]. That was a lot of lost effort by Wildlife & Fisheries and the Ag Center," said Ag Center researcher Dearl Sanders.

Sanders said this year he's confident the majority of the weevils survived.

"We have a big task force going out Tuesday to start collecting [weevils]. This actually may be a benefit for us," he said.

That's because the Ag Center is trying to find a weevil that's tolerant of the cold. This week mother nature provided researchers with the perfect experiment.

"What we're hoping to find are colonies of weevils that are doing well. We'll take those in and start reproducing those and turn them back out," Sanders said.

Meaning this cold snap could eventually mean less of the out-of-control plant. Sanders said it takes about three years for a population of weevils and their larvae to kill a large area of Salvinia. The weevils then die once the plant is gone.