Costs to foraging bumble bees of switching plant species

1994 ◽  
Vol 72 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Terence M. Laverty

Many pollinators tend to move between flowers of the same species of plant even when flowers of other species are available. Reasons for this behaviour (known as flower constancy) are unclear. One possible explanation (proposed by Darwin) is that flower handling methods learned on one plant species interfere with previously learned handling methods of other plant species. Darwin's hypothesis was tested by measuring the constancy of bumble bees (Bombus fervidus) foraging in the field and looking for evidence of interference (increased handling times and flower handling errors) when bees switched among four species with relatively simple flowers (Prunella vulgaris, Trifolium pratense, T. hybridum, and Vicia cracca) and two species with more complex flowers (Aconitum napellus and Impatiens capensis). Bees foraging on simple flowers showed no tendency towards flower constancy, and switching between species did not increase handling times or handling errors. Foragers displayed strong constancy when visiting the species with more complex flowers and there was also some evidence of increased handling times and error frequencies following switches. However, the time costs of switching were small (about 1 s over the first flower visit after a switch) and are unlikely to account for flower constancy by bumble bees foraging under natural conditions.

1995 ◽  
Vol 73 (11) ◽  
pp. 2052-2058 ◽  
Author(s):  
Robert J. Gegear ◽  
Terence M. Laverty

Pollinators often forage sequentially among the flowers of the same plant species while bypassing flowers of other rewarding species. Darwin proposed that it is more efficient for pollinators to remain constant to one plant species because switching to a second species interferes with their ability to recall a previously learned flower-handling technique. This interference hypothesis was tested using Bombus impatiens workers. Bees that had learned to handle one type of flower (species A) were retested on species A after they had learned to handle a second type of flower (species B). Interference effects were detected by comparing flower access times (time to insert the tongue into the flower) during the retesting period with initial access times on species A. Bees retested on both simple (red clover, Trifolium pratense) and complex (toadflax, Linaria vulgaris) flowers showed no evidence of interference after learning simple-flowered plant species (blueweed, Echium vulgare; purple loosestrife, Lythrum salicaria). However, bees relearning the complex flowers of toadflax showed a 2.2-s (81%) increase over their initial access time after switching to a second complex-flowered species (orange touch-me-not, Impatiens capensis). These results suggest that the interference effects incurred by bees switching between toadflax and orange touch-me-not under biologically realistic conditions are relatively small, and are unlikely to account for flower constancy in bumble bees.


2004 ◽  
Vol 82 (4) ◽  
pp. 587-593 ◽  
Author(s):  
Robert J Gegear ◽  
Terence M Laverty

We assessed the flower constancy of Italian honey bees (Apis mellifera ligustica Spinelli, 1808) and bumble bees (Bombus impatiens Cresson, 1863) by presenting individual foragers with a mixed array of equally rewarding yellow and blue flowers after they were trained to visit each colour in succession. All honey bees showed a high degree of flower constancy to one colour and rarely visited the alternate colour, whereas most bumble bees indiscriminately visited both colours. Foraging rates (flowers visited per minute) and flower handling times did not differ between honey bee and bumble bee foragers; however, bumble bees tended to fly farther between consecutive flower visits and make fewer moves to nearest neighbouring flowers than honey bees. When bees were forced to specialize on one of two previously rewarding flower colours by depleting one colour of reward, honey bees required almost twice as many flower visits to specialize on the rewarding flower colour as bumble bees. Together, these results suggest that the relationship between individual flower constancy and colour differences is not a general behavioural phenomenon in honey and bumble bees, perhaps because of differences in the ability of each group to effectively manage multiple colours at the same time and location.


1998 ◽  
Vol 76 (7) ◽  
pp. 1358-1365 ◽  
Author(s):  
R J Gegear ◽  
T M Laverty

Bumble bees often restrict their foraging behaviour to the flowers of two plant species on a single foraging trip ("a major and a minor" sensu Heinrich), perhaps because learning additional flower-handling techniques interferes with their ability to recall previously learned flower-handling skills. This hypothesis was tested with bumble bees (Bombus impatiens) foraging on arrays of artificial flower types. Test bees were first trained on one flower type, then retested on the same flower type after learning one, two, or three different types. The number of flower types selected by bees on a mixed array consisting of several types was also tested. Interference effects increased with the number and complexity of interfering flower types: a 0% increase for one simple flower type; 278% for two simple flower types; 357% for three simple flower types; and 565% for two complex flower types; switching among more than two flower types caused substantial interference. On the mixed array of three flower types, none of the 20 foragers tested randomly visited all three types, 67% primarily visited two types, and 33% primarily visited one type. These findings suggest that the bees limited the number of flower types to two because of the substantial costs incurred when a third flower type was included in their foraging repertoire.


1997 ◽  
Vol 8 (3) ◽  
pp. 239-249 ◽  
Author(s):  
Lars Chittka ◽  
Andreas Gumbert ◽  
Jan Kunze
Keyword(s):  

1959 ◽  
Vol 39 (4) ◽  
pp. 505-511 ◽  
Author(s):  
P. Pankiw ◽  
C. R. Elliott

Pollination studies involving zero, one and three colonies of honey bees per acre, on commercial alsike clover fields ranging in size from 15 to 75 acres, were conducted in 1954, 1955, and 1957 in the Hinton Trail district of the Peace River Region of Alberta. These studies indicated that in large fields one colony of honey bees per acre is sufficient to pollinate alsike clover, consideration being given to competition of other crops and to the climatic conditions. The influence of competing crops was such that 65- to 75-acre fields, with one colony per acre, were similar in honey bee populations and seed production to 15- to 20-acre fields with three colonies per acre. Competing plant species accounted for 15 to 36 per cent of the pollen collected by honey bees. Fields with the higher populations of pollinators matured earlier than fields deficient in pollinators. A population of 3400 honey bees per acre (0.7 bee per sq. yd.) throughout the flowering period resulted in seed sets up to 82 per cent and seed yields to 375 lb. per acre. Check fields, where no honey bees were supplied, ranged in production from 29 lb. per acre, with a low native pollinator count, to 293 lb. where a pollinator equivalent of 1300 bumble bees per acre was observed. Bumble bees worked alsike clover at the rate of 28.6 florets per minute, as compared to 20.0 for leaf-cutter bees and 18.7 for honey bees.


2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Margaret J. Couvillon ◽  
Chandra M. Walter ◽  
Eluned M. Blows ◽  
Tomer J. Czaczkes ◽  
Karin L. Alton ◽  
...  

We quantified insect visitation rates by counting how many flowers/inflorescences were probed per unit time for five plant species (four native and one garden: California lilac, bramble, ragwort, wild marjoram, and ivy) growing in Sussex, United Kingdom, by following individual insects (n=2987) from nine functional groups (honey bees (Apis mellifera), bumble bees (Bombusspp.), hoverflies, flies, butterflies, beetles, wasps, non-Apidae bees, and moths). Additionally, we made a census of the insect diversity on the studied plant species. Overall we found that insect groups differed greatly in their rate of flower visits (P<2.2e-16), with bumble bees and honey bees visiting significantly more flowers per time (11.5 and 9.2 flowers/minute, resp.) than the other insect groups. Additionally, we report on a within-group difference in the non-Apidae bees, where the genusOsmia, which is often suggested as an alternative to honey bees as a managed pollinator, was very speedy (13.4 flowers/minute) compared to the other non-Apidae bees (4.3 flowers/minute). Our census showed that the plants attracted a range of insects, with the honey bee as the most abundant visitor (34%). Therefore, rate differences cannot be explained by particular specializations. Lastly, we discuss potential implications of our conclusions for pollination.


Ethology ◽  
2004 ◽  
Vol 110 (10) ◽  
pp. 793-805 ◽  
Author(s):  
Robert J. Gegear ◽  
James D. Thomson
Keyword(s):  

2004 ◽  
Vol 70 (8) ◽  
pp. 4766-4774 ◽  
Author(s):  
Liz J. Shaw ◽  
Richard G. Burns

ABSTRACT Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-14C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/α-ketoglutarate dioxygenase (tfdA) were investigated. The rhizosphere effect on [14C]2,4-D mineralization (50 μg g−1) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g−1) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of α-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway.


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