How plant reproductive success is determined by the interplay
of antagonists and mutualists
Agroecology, Department of Crop Sciences, University of Goettingen, Grisebachstraße 6, 37077 G
Centre of Biodiversity and Sustainable Land Use (CBL), University of Goettingen, Platz der G
ottinger Sieben 5, 37073 G
Citation: Grass, I., V. Bohle, T. Tscharntke, and C. Westphal. 2018. How plant reproductive success is determined by the
interplay of antagonists and mutualists. Ecosphere 9(2):e02106. 10.1002/ecs2.2106
Plant reproductive success is often the outcome of mutualistic and antagonistic plant–animal
interactions, which can be moderated by landscape composition. Studies addressing single plant–animal
interactions are common, but studies simultaneously considering multiple plant–animal interactions in a
landscape context are still scarce. We selectively excluded ﬂower-visiting insects on phytometer plants and
quantiﬁed how mutualistic and antagonistic interactions shaped the reproductive success of a common
annual plant, wild mustard (Sinapis arvensis). Floral herbivory by larvae of rape pollen beetles (Meligethes
spp.) strongly reduced fruit production, but could be minimized by insecticide application. Total seed pro-
duction (the product of fruit production and seeds per fruit) strongly increased with pollinator visitation.
On average, pollinator access to plants enhanced seed numbers by 754%. Insecticide treatment almost
redoubled this number. The landscape composition (proportion of semi-natural habitats in 1000 m radius)
surrounding phytometer plants did not affect plant–animal interactions, presumably due to the high dis-
persal ability of both the pollen beetles and the major pollinators (syrphid ﬂies, bumblebees). In conclusion,
pest control increased reproductive success only in the case of sufﬁcient pollination.
Key words: Brassicaceae; exclusion experiment; ﬂorivory; herbivory; landscape; plant–animal interaction; pollination;
reproductive ﬁtness; Sinapis arvensis.
Received 10 December 2017; accepted 9 January 2018. Corresponding Editor: Dawn M. Browning.
Copyright: © 2018 Grass et al. This is an open access article under the terms of the Creative Commons Attribution
License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
The reproductive success of plants is often the
outcome of mutualistic and antagonistic plant–
animal interactions. Animal-mediated pollina-
tion plays a key role for the sexual reproduction
of 88% of global angiosperm plant species and
70% of the major global crop species (Klein et al.
2007, Ollerton et al. 2011). At the same time,
plant reproduction is often impaired by negative
plant–animal interactions (Zhang et al. 2007).
Among these, pest damage can severely reduce
plant reproductive output such as the number of
produced fruits or seeds.
Many studies have emphasized the importance
of landscape composition for pollination services
(Steffan-Dewenter et al. 2001, Ricketts et al. 2008,
Holzschuh et al. 2012). Besides honeybees (Apis
mellifera), wild bees (Hymenoptera: Apoidea)
are major pollinators in agricultural systems
(Garibaldi et al. 2013). Wild bees depend on high-
quality nesting sites and continuous food supply,
which are often subject to the availability of semi-
natural habitats (Steffan-Dewenter and Tscharn-
Ockinger and Smith 2006). Agricultural
expansion and intensiﬁcation at the expense of
(semi-)natural habitats can cause reductions in
wild bee abundance and species richness, putting
the reproductive success of animal-pollinated
plants situated in simpliﬁed agricultural land-
scapes at risk (Steffan-Dewenter et al. 2001,
Tscharntke et al. 2005, Holzschuh et al. 2012).