Impact of Archanara geminipuncta (Lepidoptera: Noctuidae) on aboveground biomass production of Phragmites australis

Management of invasive plants with biological control rests on the assumption of herbivores as structuring forces of plant community composition, but only 30% of programs achieve substantial plant suppression. Control is often caused by a few successful agents, and improvements in the ability to select the most promising species would greatly improve weed biocontrol programs. We evaluated impact of different larval stages and larval densities of the stem boring noctuid Archanara geminipuncta on height and biomass production of Phragmites australis in the field and in a common garden in the native European range. In the field, stem biomass was reduced 21.5–64.5% by A. geminipuncta attack with the largest reduction due to early larval feeding. In the common garden, P. australis performance declined linearly (stem height 40%, biomass 50%; and percentage of flowering stems 90%) as attack rates increased. Significant field and common garden impact and the large Eurasian distribution indicate great potential of A. geminipuncta for biocontrol of introduced P. australis in North America if host specificity tests produce favorable results. If approved for release, we anticipate that A. geminipuncta could establish throughout the range of introduced P. australis in North America. We also anticipate that this moth will build high populations with significant impact on height, aboveground biomass, and clonal expansion of P. australis. This attack is expected to reduce competitive ability of P. australis, favoring native wetland species and preventing further negative ecological impacts associated with the current spread of introduced P. australis in North America.