Suppression of reproductive characteristics of the invasive plant Mikania micrantha by sweet potato competition.
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 m(2) plots over 2 years.



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.



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.
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
Shicai
S
Shen
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
Gaofeng
G
Xu
Biology Department, Trinity Western University, 7600 Glover Road, Langley, BC, V2Y1Y1, Canada. clements@twu.ca.
David Roy
DR
Clements
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
Guimei
G
Jin
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
Shufang
S
Liu
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
Yanxian
Y
Yang
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
Aidong
A
Chen
Agricultural Environment and Resource Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China. fdzh@vip.sina.com.
Fudou
F
Zhang
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, 761-0795, Japan.
Hisashi
H
Kato-Noguchi
D000818:Animals; D001516:Bees / Q000502:physiology; D004175:Diptera / Q000502:physiology; D027723:Ipomoea batatas / Q000254:growth & development / Q000502:physiology*; D035742:Mikania / Q000254:growth & development / Q000502:physiology*; D012098:Reproduction
Biological control; Competition; Flowering and fruiting phenology; Mikania micrantha; Reproductive suppression; Sweet potato