Iowa State University has reared and released two European leaf-feeding beetle species to control purple loosestrife in Iowa wetlands. Expected reductions in loosestrife have not occurred, and biotic mortality factors may explain the failure of the beetles to curb the loosestrife.
Purple loosestrife is an invasive weed that impairs wetland functioning and biocontrol methods using beetles didn't seem to reduce the problem?
The research shows that the beetle eggs are probably eaten by other predators and they might survive better in more diverse wetlands.
Year of Grant Completion
Obrycki, John J., "Biotic interference of biological control of purple loosestrife" (2005). Leopold Center Completed Grant Reports. 249.