Eriophyid mite Floracarus perrepae reduces climbing ability of the invasive vine Lygodium microphyllum.
Invasive vines often grow rapidly, smothering native vegetation and causing extensive ecosystem damage. Despite these impacts, the growth rates of individual stems of multi-stemmed vines and the effects of biological control agents on these growth rates are poorly understood. Here, we quantified the growth rates of individual rachises of Lygodium microphyllum (Lygodiaceae; Old World climbing fern), a noxious invasive vine undergoing range expansion in Florida. Our objectives were to (1) quantify L. microphyllum rachis growth under varied light conditions and seasons; and (2) determine the effect of damage by the biological control mite Floracarus perrepae (Eriophyidae) to the apical meristem on rachis growth. We experimentally grew plants onto trellises to isolate, track, and measure individual rachises of the plant during 3 seasons (spring, summer, winter). Healthy (undamaged) rachises of L. microphyllum grew fastest in spring (2.22 ± 0.13 cm/day), particularly in shade where rachises grew nearly 1.5 times faster than in full sun. Mite damage reduced rachis growth rates 3.7 fold and greatly increased plant investment in rachises that did not climb. Furthermore, 85% of rachises damaged by mite feeding did not attain normal growth rates following mite damage. Our findings are the first to quantify the rapid climbing ability of individual L. microphyllum rachises, as well as the potential for F. perrepae to substantially curb rachis growth. Importantly, the ability to impede a vine's climbing may be critical in determining the efficacy of a biological control agent, and future work on vines should focus on developing such agents.