Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Suppression of reproductive characteristics of the invasive plant Mikania micrantha by sweet potato competition.

Abstract

Background: As a means of biologically controlling Mikania micrantha H.B.K. in Yunnan, China, the influence of sweet potato [Ipomoea batatas (L.) Lam.] on its reproductive characteristics was studied. The trial utilized a de Wit replacement series incorporating six ratios of sweet potato and M. micrantha plants in 25 m2 plots over 2 years. Results: Budding of M. micrantha occurred at the end of September; flowering and fruiting occurred from October to February. Flowering phenology of M. micrantha was delayed (P<0.05), duration of flowering and fruiting was reduced (P<0.05) and duration of bud formation was increased (P<0.05) with increasing proportions of sweet potato. Reproductive allocation, reproductive investment and reproductive index of M. micrantha were significantly reduced (P<0.05) with increasing sweet potato densities. Apidae bees, and Calliphoridae or Syrphidae flies were the most abundant visitors to M. micrantha flowers. Overall flower visits decreased (P<0.05) as sweet potato increased. Thus the mechanism by which sweet potato suppressed sexual reproduction in M. micrantha was essentially two-fold: causing a delay in flowering phenology and reducing pollinator visits. The number, biomass, length, set rate, germination rate, and 1000-grain dry weight of M. micrantha seeds were suppressed (P<0.05) by sweet potato competition. With proportional increases in sweet potato, sexual and asexual seedling populations of M. micrantha were significantly reduced (P<0.05). The mortality of both seedling types increased (P<0.05) with proportional increases in sweet potato. Conclusions: These results suggest that sweet potato significantly suppresses the reproductive ability of the invasive species M. micrantha, and is a promising alternative to traditional biological control and other methods of control. Planting sweet potato in conjunction with other control methods could provide a comprehensive strategy for managing M. micrantha. The scenario of controlling M. micrantha by utilizing a crop with a similar growth form may provide a useful model for similar management strategies in other systems.