Impact and Interaction of <i>Samea multiplicalis</i> (Lepidoptera: Pyralidae) and <i>Cyrtobagous salviniae</i> (Coleoptera: Curculionidae) on <i>Salvinia minima</i> in South Louisiana and the Foraging Behavior of <i>Solenopsis invicta</i> (Hymenoptera: Formicidae) on <i>Salvinia minima</i>

• Main Author: Tewari, Sunil
• Other Authors: Seth J. Johnson
• Format: Others
• Language: en
• Published: LSU 2007
• Subjects: Entomology
• Online Access: http://etd.lsu.edu/docs/available/etd-07032007-112751/

A field study was conducted in 2005 and 2006 to evaluate the impact and interaction of the herbivores <i>Cyrtobagous salviniae</i> Calder and Sands and <i>Samea multiplicalis</i> Guenee on common salvinia, <i>Salvinia minima</i> Baker in south Louisiana. It was a completely randomized experimental design in which treatments consisted of <i>C. salviniae</i> and <i>S. multiplicalis</i> feeding on common salvinia both independently and together along with a control. Our study revealed that treatments consisting of <i>C. salviniae</i> and <i>S .multiplicalis</i> feeding both independently and together had a significant impact on the biomass of common salvinia. Sampling done in October of both 2005 and 2006 showed that the lowest biomass was recorded for the treatment with both <i>C. salviniae</i> and <i>S. multiplicalis</i>. There was also a significant treatment by month interaction with a linear decrease in biomass for the treatment consisting of feeding by both <i>C. salviniae</i> and <i>S. multiplicalis</i> in 2005. Also, biomass showed a quadratic trend for the treatment with only <i>S. multiplicalis</i> in 2005. Percentage terminal damage (PTD) and percentage mat green (PMG) showed a significant treatment effect and a significant treatment by month interaction in 2005. Also, PTD showed a significant treatment effect and a significant treatment by month interaction in 2006. A field study was conducted in May of 2007 to document the foraging behavior of red imported fire ants (RIFA), <i>Solenopsis invicta</i> Buren, on common salvinia mats in flooded woodlands and dredged canals. RIFA mounds were found in flooded woodlands at the base of live trees and on dead tree stumps. The recruitment of RIFA to the bait stations was not uniform up to 100 m into the flooded woodlands and in most instances there was no linear relationship between distance from the levee and number of ants. Also, the recruitment at different times of the day was not the same. Results of this study provide evidence that RIFA forage extensively on common salvinia in both flooded woodlands and dredged canals, and could possibly have an adverse impact on the populations of native <i>S. multiplicalis</i> and also on the survival and establishment of <i>C. salviniae</i>.