Effects of invasive plant haplotypes on a biological control agent (Lepidelphax pistiae) fecundity and impact

Pistia stratiotes L. is an invasive floating plant that alters native habitats in Florida by forming thick mats that shade out submerged vegetation and obstruct navigation. Multiple genotypes of this plant have been identified from locations across its native and adventive ranges including types from throughout the Americas, the Caribbean, Asia, and Australia. We investigated the performance of a known monophagous insect, Lepidelphax pistiae, on nine P. stratiotes haplotypes (from four clades) in no-choice experiments and found that while L. pistiae performance varied on different haplotypes, there was considerable overlap in fitness and impact among haplotypes. Lepidelphax pistiae did not distinguish between purported 'native' and 'non-native' haplotypes and did not perform better or cause more damage to South American haplotypes specifically, which would have supported its utility as a biocontrol agent on the exotic haplotypes found in Florida. While L. pistiae is monophagous on P. stratiotes, it was not specific enough to differentiate consistently among the tested haplotypes and thus, may not be suitable as a biological control agent because of the potential threat they pose to native haplotypes of P. stratiotes in Florida.