A Meta-Analysis of Predation Risk Effects on Pollinator Behaviour

Abstract

Flower-visiting animals are constantly under predation risk when foraging and hence might be expected to evolve behavioural adaptations to avoid predators. We reviewed the available published and unpublished data to assess the overall effects of predators on pollinator behaviour and to examine sources of variation in these effects. The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators. The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary). However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera. Furthermore, larger pollinators showed weaker responses to predation risk, probably because they are more difficult to capture. Presence of live crab spiders on flowers had weaker effects on pollinator behaviour than presence of dead or artificial crab spiders or other objects (e.g. dead bees, spheres), suggesting that predator crypsis may be effective to some extent. These results add to a growing consensus on the importance of considering both predator and pollinator characteristics from a community perspective.

Giant Asian honeybees use olfactory eavesdropping to detect and avoid ant predators

“…Although such attack rates Table 1. may seem low, they can affect floral visits and pollination (Dukas, 2005). Moreover, the mere presence of predators on flowers reduces visits by insect pollinators by 36% (Romero et al, 2011). Thus, O. smaragdina probably reduces pollinator visits.…”

“…Predators can influence pollinator behaviour (Romero, Antiqueira, & Koricheva, 2011) and thereby influence pollination (Dukas, 2005), a key ecosystem service (Klein et al, 2007;Vanbergen & Initiative, 2013). To avoid predators, pollinators can use public information, arising from foragers, predators and their interactions (Chittka & Leadbeater, 2005;Goodale & Nieh, 2012;Romero et al, 2011).…”

“…To avoid predators, pollinators can use public information, arising from foragers, predators and their interactions (Chittka & Leadbeater, 2005;Goodale & Nieh, 2012;Romero et al, 2011). This information usage has cascading consequences for plantepollinator mutualisms because predators can deter pollinator visits, thereby reducing seed (Suttle, 2003) and fruit production (Dukas, 2005).…”

Competitive impacts of an invasive nectar thief on plant–pollinator mutualisms

“…Vespula aggressively patrolled M. polymorpha floral nectar, physically removed and, during several observations, directly preyed upon A. mellifera and Hylaeus from M. polymorpha inflorescences. Interference (Primack and Howe 1975) and predation (see Romero et al 2011) can result in the behavioral avoidance of flowers by foragers. Although A. mellifera and Hylaeus are known from the diets of Vespula in Hawaii (Wilson and Holway 2010), the significant increase in A. mellifera and Hylaeus visitation rates following the removal of V. pensylvanica was probably a behavioral response to removal, given that the time frame was shorter than the time required for populations of A. mellifera and Hylaeus to increase (Wilson and Holway 2010).…”

Weak trophic links between a crab-spider and the effective pollinators of a rewardless orchid

“…Yet, the impact of predation risk on flower visitors has been a neglected issue in pollination studies until the last decade (Dukas, 2001a;Dukas and Morse, 2003). Recently several empirical studies assessing predation risk, directly mediated by the presence of an ambush predator or indirectly mediated by dead prey found in flowers, have consistently reported changes in pollinator density and behavior such as increasing avoidance or reducing the frequency and/or duration of visits to flowers (reviewed by Romero et al, 2013). Furthermore, behavioral changes in the flower visitors' assemblage have shown to translate into strong negative effects of predators on plant fitness, decreasing plant reproductive success by 17%e25% (Knight et al, 2006;Romero and Koricheva, 2011).…”