Why do pollinators visit proportionally fewer flowers in large patches

By Dave Goulson. 2000

140 citations recorded by the source corpus.

Pollinators collect resources that are patchy, since flowers are usually aggregated on several spatial scales. Empirical studies have established that pollinators almost invariably visit a smaller proportion of flowers as patch size increases. This has not been adequately explained. Here I present data on the payoff curve achieved by bumblebees, Bombus lapidarius, when visiting patches containing different numbers of inflorescences, and use the marginal value theorem to predict the optimum duration of stay within patches. The data demonstrate that visiting a declining proportion of inflorescences as patch size increases is an optimal strategy, if we assume that bees are attempting to maximise their rate of reward acquisition. I argue that this occurs because searching for the remaining unvisited inflorescences is easier in a small patch. On large patches, bees visited more inflorescences per patch than predicted (although still visiting a declining proportion). I suggest that this may occur because bees are using simple departure rules which result in near-optimal behaviour. I show that a departure rule based on two successive encounters with empty inflorescences closely predicts observed behaviour.

Subfields: Ecology, Evolution, Behavior and Systematics, Genetics, Plant Science

View Paper: https://www.semanticscholar.org/paper/1fab8ab1698f65776a946303c206e5e9d6d17338

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In Ecology, Evolution, Behavior and Systematics

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Citations in the corpus

Consequences of clonal growth for plant mating (2001, background): “…of geitonogamy increases with plant size, i.e., number of open flowers per individual (e.g., de Jong et al., 1992b; Harder and Barrett, 1995; Vrieling et al., 1999) although this trend also depends on flower phenology and pollinator foraging behavior (e.g., Goulson, 2000; Ishii and Sakai, 2001).”
Effects of experience and weather on foraging rate and pollen versus nectar collection in the bumblebee, Bombus terrestris (2005, background): “…and predictions of foraging models and the interplay between learning, memory constraints and foraging rate in a complex and unpredictable environment (e.g. Heinrich 1979; Cresswell 1990; Dukas and Real 1993a, 1993b, 1993c; Goulson 1994, 1999, 2000a, 2000b; Dreisig 1995; Cresswell et al. 2000).”
The influence of Mimulus ringens floral display size on pollinator visitation patterns (2004, background): “…for why bumble bees probed more flowers but a declining proportion of flowers on plants with large floral displays (Ohashi χ32 χ 22 122 R. J. Mitchell et al. © 2004 British Ecological Society, Functional Ecology, 18, 116–124 & Yahara 1998, 2001, 2002; Pappers et al. 1999; Goulson 2000).”
Pollinator visitation, stigmatic pollen loads and among‐population variation in seed set in Lythrum salicaria (2004, background): “Second, pollinator foraging behaviour may change with the size and density of the population (Zimmerman 1981; Sih & Baltus 1987; Cresswell 1997; Kunin 1997; Goulson 2000), thereby affecting the composition of the pollen deposited.”
Visit larger displays but probe proportionally fewer flowers: counterintuitive behaviour of nectar-collecting bumble bees achieves an ideal free distribution (2002, background): “As has been observed repeatedly for other species (reviewed by Goulson 2000; Ohashi & Yahara 2001), the number of heads that bumble bees probed per plant increased less than proportionally with floral display size, so that the proportion of flower heads probed per bee (tc/F ) declined with display…”
Indirect effects of an introduced ungulate on pollination and plant reproduction (2004, background): “In fact, several studies show that, although pollinators tend to visit more flowers and stay longer in larger floral patches, they tend to visit a smaller proportion of flowers there than in smaller patches (Totland and Matthews 1998, Comba 1999, Goulson 2000, Mustaja ¨rvi et al. 2001).”