Honey bee orientation behaviour and the influence of flower distribution on foraging movements

ABSTRACT.

• 1 Directional movement by foraging honey bees (Apis mellifera L.) was studied on several flower arrays. The most frequent move among equidistant flower stalks was straight ahead from stalk to stalk with frequencies decreasing for increasing turn angles. Turns to the left were about equal in frequency to turns to the right.
• 2 Bees maintained directionality when moving from flower stalks that had been rotated 90° counterclockwise while the bee was on the stalk (no difference between moves from rotated stalks and unrotated controls). Thus, directionality is maintained by the bee and is not an artefact of flower distribution.
• 3 Bees also maintained directionality when the entire array was rotated around the flower stalk the bee was on. Thus, bees use an external cue to orientate in a given direction rather than fixing on an inflorescence within the flower array.
• 4 Bees foraging on very different flower arrays differed in patterns of directionality and in distances flown between flower stalks. Therefore, even though bees maintain directionality using external cues, flower distribution can nevertheless influence flight patterns.

     

Can honey bees change foraging patterns?

Abstract. 1. Foraging patterns were studied using honey bees on artificial flower patches to determine if given individuals could change behaviours under differing conditions.
2. Two types of flower patches were used; those simulating a population of flowers, dimorphic for colour, and grids simulating a single colour-dimorphic inflorescence.
3. In the simulated population of flowers bees were individually constant to colour over a range of reward volumes and flower patch sizes.
4. Each bee remained individually constant to a flower morph when visiting a population-type grid but changed to random visitation on the simulated inflorescence.
5. On the simulated inflorescence, with morphs providing unequal qualities of reward, most bees foraged on the higher molarity morph.
6. Most, but not all bees, failed to minimize uncertainty on the simulated inflorescence.
7. On the simulated inflorescence, bees failed to optimize when one morph provided a greater reward volume than did the other.
8. In the population of flowers bees flew from flower to flower, whereas, they walked on the simulated inflorescence.     

The foraging decisions of a central place foraging seabird in response to fluctuations in local prey conditions

During reproduction, seabirds need to balance the demands of self- and offspring-provisioning within the constraints imposed by central place foraging. To assess behavioral adjustments and tolerances to these constraints, we studied the feeding tactics and reproductive success of common murres (also known as common guillemots) Uria aalge , at their largest and most offshore colony (Funk Island) where parents travel long distances to deliver a single capelin Mallotus villosus to their chicks. We assessed changes in the distance murres traveled from the colony, their proximate foraging locations and prey size choice during two successive years in which capelin exhibited an order of magnitude decrease in density and a shift from aggregated (2004) to dispersed (2005) distributions. When capelin availability was low (2005), parental murres increased their maximum foraging distances by 35% (60 to 81 km) and delivered significantly larger capelin to chicks, as predicted by central place foraging theory. Murres preferred large (>140 mm) relative to small capelin (100–140 mm) in both years, but unexpectedly this preference increased as the relative density of large capelin decreased. We conclude that single prey-loading murres target larger capelin during long foraging trips as parents are 'forced' to select the best prey for their offspring. Low fledgling masses suggest also that increased foraging time when capelin is scarce may come at a cost to the chicks (i.e. fewer meals per day). Murres at this colony may be functioning near physiological limits above which further or sustained adjustments in foraging effort could compromise the life-time reproductive success of this long-lived seabird.     

Spatial foraging patterns of the African honey bee,Apis mellifera scutellata

Recruitment patterns were investigated for the African honey bee in the Okavango River Delta, Botswana. The waggle dances of two observation colonies maintained in the field were monitored and used to construct maps of daily recruitment activity. These maps revealed that the African colonies frequently adjusted the allocation of recruits among food patches, recruited for 16–17 different food sites/day over areas of 55–80 km ² ,and concentrated the majority of recruitment within 1 km of the hives (median foraging distances for the two colonies were 295 and 563 m). In both colonies pollen foragers were more abundant than nectar foragers, and pollen sources indicated by waggle dancers were significantly closer to the hives than nectar sources. Compared to the recruitment patterns of temperate climate colonies, the African colonies had smaller recruitment areas, smaller mean recruitment distances, and a greater emphasis on pollen foraging. These differences may be related to the contrasting survival strategies followed by tropical-versus temperate-climate honey bees.     

Visual resolution of the orientation cue by the honeybee (Apis mellifera)

Bees were trained to discriminate between a pattern with two or more black bars and a similar pattern with the bars at right angles. Earlier measures of the resolution of oblique black and white regular gratings of different periods were confirmed. The positions of the training bars were shifted every 5 min to prevent the bees from using their locations as cues. To measure the length of the detectors of edge orientation, the trained bees were tested with targets filled with parallel short black/white edges of various lengths. The minimum individual length of edge required to discriminate the orientation cue was found to be near 3 degrees, and similar for vertical, horizontal and oblique edges. This is the first time that this kind of resolution has been measured in an invertebrate. The bees learn and recognize the edge orientation, not the lay-out of the pattern.     

Energetic state during learning affects foraging choices in starlings

We investigated the influence of energetic state at the timeof acquaintance with a new food source on preference for thatsource on later encounters, using wild-caught European starlingsas subjects. Twelve birds learned to obtain food rewards bypecking at either of two keys identified by color. The keyswere encountered in different sessions, while the subjects werefood deprived or prefed. Food rewards from both sources werealways identical. After an equal number of reinforced trialswith each source, the birds were presented with choices betweenthem. The birds significantly preferred the source that hadpreviously delivered food under higher deprivation. We relatethese results to findings reported elsewhere of preferencesfor options previously associated with greater effort. We hypothesizethat subjects may attribute value to an option according tothe marginal fitness gain associated with this option in thepast. Although this process may be adaptive under many circumstances,it violates the assumptions of normative models of choice thatimply mechanisms of valuation sensitive to the absolute propertiesof a payoff or to expected absolute changes in state.     

The interplay between dancing and trophallactic behavior in the honey bee Apis mellifera

The interplay between the recruitment dance and food-giving trophallactic contacts of returning Apis mellifera foragers was analyzed. Dancing and trophallactic events were recorded for bees returning from a rate feeder that provided 50% weight on weight sucrose solution at a constant flow rate of 5 μl min⁻¹. Bees that had danced immediately before their trophallactic contact had more recipients per trophallaxis compared with bees that did not dance before. Thus, besides information coded in dancing behavior, dance maneuvers could serve as a stimulus to increase attention of bees located on the dance floor to receive nectar. In addition, the number of bees receiving food during a trophallaxis showed a positive correlation with the probability of dancing immediately after contacting. The time from arrival at the hive to when the first or the subsequent contacts took place presented no correlation with the probability of dancing after trophallaxis. Also, the duration of a trophallaxis was positively correlated with the number of recipients per trophallaxis. These results suggest that returning foragers could receive information during a trophallactic contact with their hive mates that modify thresholds for dancing. Dance maneuvers and trophallactic contacts performed by foraging bees seem to be “mutually” affected. Accepted: 29 November 1999     

Optimal foraging and fitness in Columbian ground squirrels

Summary Optimal diets were determined for each of 109 individual Columbian ground squirrels (Spermophilus columbianus) at two sites in northwestern Montana. Body mass, daily activity time, and vegetation consumption rates for individuals were measured in the field, along with the average water content of vegetation at each ground squirrel colony. I also measured stomach and caecal capacity and turnover rate of plant food through the digestive tract for individuals in the laboratory to construct regressions of digestive capacity as a function of individual body mass. Finally, I obtained literature estimates of average daily energy requirements as a function of body mass and digestible energy content of vegetation. These data were used to construct a linear programming diet model for each individual. The model for each individual was used to predict the proportion of two food types (monocots and dicots) that maximized daily energy intake, given time and digestive constraints on foraging. Individuals were classified as optimal or deviating, depending on whether their observed diet was significantly different from their predicted optimal diet. I determined the consequences of selecting an optimal diet for energy intake and fitness. As expected, daily energy intake calculated for deviators (based on their observed diet proportion) was less than that for optimal foragers. Deviating foragers do not appear to compensate for their lower calculated energy intake through other factors such as body size or physiological efficiency of processing food. Growth rate, yearly survivorship, and litter size increase with calculated energy intake, and optimal foragers have six times the reproductive success of deviators by age three. Optimal foraging behavior, therefore, appears to confer a considerable fitness advantage.     

Tactile learning and the individual evaluation of the reward in honey bees (Apis mellifera L.)

Using the proboscis extension response we conditioned pollen and nectar foragers of the honey bee (Apis mellifera L.) to tactile patterns under laboratory conditions. Pollen foragers demonstrated better acquisition, extinction, and reversal learning than nectar foragers. We tested whether the known differences in response thresholds to sucrose between pollen and nectar foragers could explain the observed differences in learning and found that nectar foragers with low response thresholds performed better during acquisition and extinction than ones with higher thresholds. Conditioning pollen and nectar foragers with similar response thresholds did not yield differences in their learning performance. These results suggest that differences in the learning performance of pollen and nectar foragers are a consequence of differences in their perception of sucrose. Furthermore, we analysed the effect which the perception of sucrose reward has on associative learning. Nectar foragers with uniform low response thresholds were conditioned using varying concentrations of sucrose. We found significant positive correlations between the concentrations of the sucrose rewards and the performance during acquisition and extinction. The results are summarised in a model which describes the relationships between learning performance, response threshold to sucrose, concentration of sucrose and the number of rewards. Accepted: 14 April 1999     

Comportement de butinage des abeilles (Hymenoptera : Apoidea) sur les fleurs mâles et femelles du concombre (Cucumis sativus L.) (Cucurbitaceae) en région de Constantine (Algérie)

Les insectes butineurs de Cucumis sativus L. (Cucurbitaceae) ont été étudiés durant les floraisons de 2001 et de 2002 dans la région de Constantine (est algérien). Les observations ont montré que la majorité des visiteurs de la plante sont des hyménoptères apoïdes. Apis mellifera L., Ceratina cucurbitina Rossi, Megachile leachella Curtis et M. pilidens Alfken sont les espèces les plus fréquentes sur les fleurs. Les proportions de visites des abeilles sont plus élevées sur les fleurs staminées que sur les fleurs pistilées. En moyenne, les quatre espèces ont visité entre 6 et 8 fleurs par minute et leurs durées de visite sur les fleurs pistilées sont significativement plus lentes en comparaison avec les fleurs staminées.     

Larval juvenile hormone treatment affects pre-adult development,but not adult age at onset of foraging in worker honey bees (Apis mellifera)

Previous research has shown that juvenile hormone (JH) titers increase as adult worker honey bees age and treatments with JH, JH analogs and JH mimics induce precocious foraging. Larvae from genotypes exhibiting faster adult behavioral development had significantly higher levels of juvenile hormone during the 2nd and 3rd larval instar. It is known that highly increased JH during this period causes the totipotent female larvae to differentiate into a queen. We treated third instar larvae with JH to test the hypothesis that this time period may be a developmental critical period for organizational effects of JH on brain and behavior also in the worker caste, such that JH treatment at a lower level than required to produce queens will speed adult behavioral development in workers. Larval JH treatment did not influence adult worker behavioral development. However, it made pre-adult development more queen-like in two ways: treated larvae were capped sooner by adult bees, and emerged from pupation earlier. These results suggest that some aspects of honey bee behavioral development may be relatively insensitive to pre-adult perturbation. These results also suggest JH titer may be connected to cues perceived by the adult bees indicating larval readiness for pupation resulting in adult bee cell capping behavior.     

A guide to central place effects in foraging

We develop a general patch-use model of central place foraging, which subsumes and extends several previous models. The model produces a catalog of central place effects predicting how distance from a central place influences the costs and benefits of foraging, load-size, quitting harvest rates, and giving-up densities. In the model, we separate between costs that are load-size dependent, i.e. a direct effect of the size of the load, and load-size independent effects, such as correlations between distance and patch qualities. We also distinguish between predictions of between- and within-environment comparisons. Foraging costs, giving-up densities and quitting harvest rates should almost always increase with distance with these effects amplified by increases in metabolic costs, predation risk and load-costs. With respect to load-size: when comparing foraging in patches within an environment, we should often expect smaller loads to be taken from distant patches (negative distance–load correlation). However, when comparing between environments, there should be a positive correlation between average distance and load-size.     

Mating strategies based on foraging ability: an experiment with grasshoppers

Female mate choice and the benefits of this behavior are criticalaspects of Darwinian sexual selection, but they are seldom documentedbecause it is difficult to identify the male trait(s) that femalesmay be seeking. We conducted experiments with grasshoppers (Melanoplussangutnipes: Orthoptera, Acrididae) to examine this behavior.Males that feed more intensively and select a diet mix thatpermits greater food intake (food intake per body mass per time)in laboratory trials were preferentially selected by females.These better foraging males on average provide greater paternalinvestment (greater spermatophore mass) to the female, whichincreases her reproductive rate (eggs produced per body massper time). However, paternal investment may not entirely explainfemale choice of better foraging males, because these maleswere still selected even if they had their food intake restrictedor had been allowed to recently mate, which reduces spermatophoreproduction. Furthermore, males change their mating strategyin response to female choice and the foraging abilities of surroundingmales. Poorer foraging males attempt forcible copulation ratherthan displaying and allowing female choice. A male will facultativelyswitch between these strategies depending on the foraging abilitiesof the surrounding males. While females attempt to reject forciblecopulation, forcible copulation reduces the frequency with whichfemales successfully copulate with better foraging males. Therefore,males that are less "attractive" to females adopt alternativemating strategies to counter female choice which would excludethem from mating.[Behav Ecol 7: 438–444 (1996)]     

The effect of genotype, age, sex, and caste on response thresholds to sucrose and foraging behavior of honey bees (Apis mellifera L.)

Bees derived from artificially selected high- and low-pollen-hoarding strains were tested for their proboscis extension reflex response to water and varying sucrose concentrations. High-strain bees had a lower response threshold to sucrose than low-strain bees among pre-foragers, foragers, queens and drones. Pre-foraging low-strain workers showed ontogenetic changes in their response threshold to sucrose which was inversely related to age. High-strain foragers were more likely to return with loads of water compared to low-strain foragers. Whereas low-strain foragers were more likely to return with loads of nectar. Low-strain nectar foragers collected nectar with significantly higher sucrose concentrations than did the high-strain nectar foragers. Alternatively, low-strain foragers were more likely to return empty compared to high-strain foragers. These studies demonstrate how a genotypically varied sensory-physiological process, the perception of sucrose, are associated with a division of labor for foraging. Accepted: 27 October 1998     

Detection of Deformed wing virus, a honey bee viral pathogen, in bumble bees (Bombus terrestris and Bombus pascuorum) with wing deformities

Honey bees (Apis mellifera) productively infected with Deformed wing virus (DWV) through Varroa destructor (V. destructor) during pupal stages develop into adults showing wing and other morphological deformities. Here, we report for the first time the occurrence of bumble bees (Bombus terrestris, Bombus pascuorum) exhibiting wing deformities resembling those seen in clinically DWV-infected honey bees. Using specific RT-PCR protocols for the detection of DWV followed by sequencing of the PCR products we could demonstrate that the bumble bees were indeed infected with DWV. Since such deformed bumble bees are not viable DWV infection may pose a serious threat to bumble bee populations.