Honey Bees Avoiding Ant Harassment at Flowers Using Scent Cues

Abstract

Pollinators require resources throughout the year to maintain healthy populations. Along the urban-natural interface, floral resource availability may be limited especially when the system experiences extreme drought and fire threats. In such areas, succulents, such as Aloe spp., are commonly planted to serve as functional drought-tolerant, fire-protective landscaping, which can also support pollinator populations. However, access to this resource may be restricted by competition from other floral foragers, including invasive pests. We measured free-foraging honey bee (Apis mellifera L.) visitation rate and visitation duration to aloe flowers with and without Argentine ants (Linepithema humile (Mayr)) in a drought-stressed environment and found that bees actively avoided foraging on the ant-occupied flowers. To determine the mechanisms of avoidance, our subsequent experiments assessed visitation in the absence of ants and compared aloe flowers treated with ant pheromone to unmanipulated flowers lacking ant pheromone. Bees approached all flowers equally, but accepted flowers without ants at a higher rate than flowers with ants. Visitation duration also increased twofold on ant-excluded flowers, which suggests that Argentine ants may limit resource acquisition by bees. Honey bees similarly avoided flowers with Argentine ant pheromone and preferentially visited unmanipulated flowers at threefold higher rate. This study demonstrates that honey bees avoid foraging on floral resources with invasive Argentine ants and that bees use ant odors to avoid ant-occupied flowers. Resource limitation by this invasive pest ant may have serious implication for sustaining healthy pollinator populations at the urban-natural interface.

Scaling up our understanding of non-consumptive effects in insect systems

“…Shifts in insect prey traits in response to predators include behavioral changes [7][8][9][10][11], life history adjustments [12][13][14], and physiological changes [15][16][17][18][19] (See Table 1 & 2 for behavioral and physiological changes, respectively). The majority of studies to date link NCEs to changes in behavior, including changes in feeding [20][21][22], oviposition [23,24], colonization or dispersal [25][26][27], host-plant preference or habitat use [28][29][30] and increased predator avoidance [31,32]. As a whole, prey tend to respond to predators by modifying their behavior to become less apparent and reduce predator encounters (i.e.…”

“…It is well established that insect predators use chemical cues to locate prey [39] and more recently it has been shown that prey have the ability to eavesdrop on predator chemical cues [8,32,36,40]. Studies examining the role of chemical cues in NCEs have investigated isolated semiochemicals [9,28], chemicals associated with consuming conspecifics [33], footprints or previous foraging of predators [41], and crushed predators applied to plants as a slurry [40]. Using an experimental arena where predators had previously foraged and were subsequently removed, researchers can isolate specific contact chemical cues as a source of information for prey.…”

The role of ants in north temperate grasslands: a review

“…In their study, Cembrowski et al ( 2014 ) observed ants directly attacking bees visiting the artificial flowers and some bees having trouble flying after the interaction. Similarly, the invasive Argentine ants ( Linepithema humile ) are known to reduce pollinator foraging behavior within the temperate zone (Lach 2008 ; Sidhu and Wilson Rankin 2016 ). This aggressive invasive species holds the potential to reduce pollinator visitation duration by 50% and pollinator visitation is three times more likely on flowers without scent cues (Sidhu and Wilson Rankin 2016 ).…”

Agroecology of a salad crop pest in New Zealand

“…Many studies have shown that prey respond to predators by changing either their behaviour or physiology to reduce the risk of predation. These include increased predator avoidance (Wratten, 1976;Hoefler et al, 2012;Lee et al, 2014), reduced feeding (Rypstra & Buddle, 2013;Kaplan et al, 2014;Thaler et al, 2014), reduced oviposition (Wasserberg et al, 2013;Sendoya et al, 2009) and changes in host plant preference (Wilson & Leather, 2012;Sidhu & Wilson Rankin, 2016).…”