66 research outputs found
Individual foraging, activity level and longevity in the stingless bee Melipona beecheii in Costa Rica (Hymenoptera, Apidae, Meliponinae)
Foraging behaviour of individually marked workers of Melipona beecheii (Meliponinae) was
monitored in Costa Rica to investigate individual specialisation for different materials and how
this influences foraging longevity. The majority of the individuals harvested one commodity
(pollen, nectar or resin) during a single day. Half of the age-marked foragers specialised on nectar
or pollen during their complete foraging career, the other half collected two or three commodities.
Most members of the latter group switched daily from early morning pollen (or resin) collecting to
nectar collecting. Life-long foraging of one-material collectors was not more efficient than that of
two-material collectors. The groups of foragers differed significantly in activity patterns and
longevity: activity was traded off with longevity. Nectar foragers were active all day and died after
an average of 3 foraging days. Pollen foragers were active for 1-3 hours per day, but lived for
12 days on average. However, pollen foragers and nectar foragers performed a similar number of
flights in their career.
How bees become pollen, nectar or mixed foragers is not clear. Age and performance of
pre-foraging hive tasks did not influence forager specialisation in M. beecheii
Modelling collective foraging by means of individual behaviour rules in honey-bees
An individual-oriented model is constructed
which simulates the collective foraging behaviour of a
colony of honey-bees, Apis mellifera. Each bee follows
the same set of behavioural rules. Each rule consists of a
set of conditions followed by the behavioural act to be
performed if the conditions are fulfilled. The set of
conditions comprises the state of external information
available to the bee (e.g. the dancing of other bees) and
internal information variables (like memorised location
of a food source and homing motivation). The rules are
partly observational (i.e. they capture the observable
regularities between the present external information
and the individual bee's behaviour), and partly involve
hypothesised internal-state variables (e.g. abandoning
tendency and homing motivation), because no observ-
able (physiological) aspect has as yet been detected in the
bee which correlates with changes in the internal moti-
vation. Our aim is to obtain a set of rules that is nec-
essary and sufficient for the generation of the collective
foraging behaviour observed in real bees. We simulated
an experiment performed by Seeley et al. in which a
colony of honey-bees chooses between two nectar
sources of different profitabilities which are switched at
intervals. A good fit between observed and simulated
collective forager patterns was obtained when the model
included rules in which the bees (1) relied on the infor-
mation acquired from previous fiights to a source (e.g.
profitability and time of day when the source was
found), (2) used positional information obtained by at-
tending recruitment dances and (3) did not abandon a
(temporarily) deteriorated source too fast or too slowly.
The significance of the following issues is discussed: the
role of internal and external information, source prof-
itability, the spatial precision of the dance communica-
tion, the ability to search for a source after the source
position has been transmitted, the tendency to abandon
a deteriorated source, and the concepts of scout, recruit,
(un)employed forager, and foraging history
Exploration and exploitation of food sources by social insect colonies: a revision of the scout-recruit concept
Social insect colonies need to explore and exploit
multiple food sources simultaneously and efficiently.
At the individual level, this colony-level behaviour
has been thought to be taken care of by two types of individual:
scouts that independently search for food, and
recruits that are directed by nest mates to a food source.
However, recent analyses show that this strict division of
labour between scouts and recruits is untenable. Therefore,
a modified concept is presented here that comprises
the possible behavioural states of an individual forager
(novice forager, scout, recruit, employed forager, unemployed
experienced forager, inspector and reactivated
forager) and the transitions between them. The available
empirical data are reviewed in the light of both the old
and the new concept, and probabilities for the different
transitions are derived for the case of the honey-bee. The
modified concept distinguishes three types of foragers
that may be involved in the exploration behaviour of the
colony: novice bees that become scouts, unemployed experienced
bees that scout, and lost recruits, i.e. bees that
discover a food source other than the one to which they
were directed to by their nest mates. An advantage of the
modified concept is that it allows for a better comparison
of studies investigating the different roles performed by
social insect foragers during their individual foraging
histories
Symmetry breaking in collective honeybee foraging: a simulation study
Symmetry breaking is the phenomenon that the numbers of foragers exploiting two equally profitable food sources will diverge. This
phenomenon has been investigated in ants [1,4,5], but hardly in honeybees. It is even not clear whether in honeybees symmetry breaking
can occur [3, p.190]. We present results of an individual-oriented simulation model showing that under specific circumstances symmetry
breaking in the numbers of honeybee workers exploiting two or four identical nectar sources can occur. We studied factors that influence
the occurrence of symmetry breaking, which include: size of the forager pool, number of bees initially exploiting the sources, and size of
the flower patch. This study is part of an ongoing study which aims at developing an individual-oriented simulation model capturing the
necessary and sufficient behavioural rules to generate the collective foraging patterns observed in bee
Possible chemical mimicry of the European lady’s slipper orchid (Cypripedium calceolus)
Pollination based on insect deception has been debated in the scientific community since it was first reported over two hundred years ago. A vast majority of deceptive syndromes occur within the orchid family. While many cheating flowers have been described and are well known, there are still many curious cases that need further investigation. One prime example of such a case is Cypripedium calceolus, known as European lady’s slipper orchid. While the flower has been of interest to many prominent scientists for over a century, its pollination is still not fully understood. Both visual and olfactory cues seem to play an important role in pollinator attraction. In this study we focussed on the olfactory cues in order to explore their relationship (in future experiments) with floral visual cues, including the unique asymmetry of these flowers. Some of the plants’ floral fragrances were used in Electroantennography experiments. Eleven chemical compounds were applied to the antennae of Bombus terrestris and Apis mellifera. Even though these species are not regular visitors of C. calceolus, we were interested to see whether there were common principles in their responses to the flowers’ scent that might justify extrapolating to other pollinator species such as sand bees that get trapped in these orchids and fly out of the flowers afterwards with pollen smeared on their body. The results show that while both species react similarly to most of the odours, some of the tested acetates induced a significantly greater reaction in B. terrestris antennae. These acetates play an important role in bumblebee pheromones, but their relevance for the natural pollinators of C. calceolus remains to be confirmed to see whether chemical mimicry by these flowers is deliberately employed to attract pollinators
Biodiversiteitsonderzoek in het kader van de omgevingsvisie in Hart van Holland
Environmental Biolog
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Avoiding a bad apple: insect pollination enhances fruit quality and economic value
Insect pollination is important for food production globally and apples are one of the major fruit crops which are reliant on this ecosystem service. It is fundamentally important that the full range of benefits of insect pollination to crop production are understood, if the costs of interventions aiming to enhance pollination are to be compared against the costs of the interventions themselves. Most previous studies have simply assessed the benefits of pollination to crop yield and ignored quality benefits and how these translate through to economic values. In the present study we examine the influence of insect pollination services on farmgate output of two important UK apple varieties; Gala and Cox. Using field experiments, we quantify the influence of insect pollination on yield and importantly quality and whether either may be limited by sub-optimal insect pollination. Using an expanded bioeconomic model we value insect pollination to UK apple production and establish the potential for improvement through pollination service management. We show that insects are essential in the production of both varieties of apple in the UK and contribute a total of £36.7 million per annum, over £6 million more than the value calculated using more conventional dependence ratio methods. Insect pollination not only affects the quantity of production but can also have marked impacts on the quality of apples, influencing size, shape and effecting their classification for market. These effects are variety specific however. Due to the influence of pollination on both yield and quality in Gala, there is potential for insect pollination services to improve UK output by up to £5.7 million per annum. Our research shows that continued pollinator decline could have serious financial implications for the apple industry but there is considerable scope through management of wild pollinators or using managed pollinator augmentation, to improve the quality of production. Furthermore, we show that it is critically important to consider all production parameters including quality, varietal differences and management costs when valuing the pollination service of any crop so investment in pollinator management can be proportional to its contribution
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The identity of crop pollinators helps target conservation for improved ecosystem services
Insect pollinated mass flowering crops are becoming more widespread and there is a need to understand which insects are primarily responsible for the pollination of these crops so conservation measures can be appropriately targeted in the face of pollinator declines. This study used field surveys in conjunction with cage manipulations to identify the relative contributions of different pollinator taxa to the pollination of two widespread flowering crops, field beans and oilseed rape. Flower visiting pollinator communities observed in the field were distinct for each crop; while field beans were visited primarily by a few bumblebee species, multiple pollinator taxa visited oilseed, and the composition of this pollinator community was highly variable spatially and temporally. Neither pollinator community, however, appears to be meeting the demands of crops in our study regions. Cage manipulations showed that multiple taxa can effectively pollinate both oilseed and field beans, but bumblebees are particularly effective bean pollinators. Combining field observations and cage manipulations demonstrated that the pollination demands of these two mass flowering crops are highly contrasting, one would benefit from management to increase the abundance of some key taxa, whilst for the other, boosting overall pollinator abundance and diversity would be more appropriate. Our findings highlight the need for crop specific mitigation strategies that are targeted at conserving specific pollinator taxa (or group of taxa) that are both active and capable of crop pollination in order to reduce pollination deficits and meet the demands of future crop production
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