Ground-nesting insects could use visual tracking for monitoring nest position during learning flights

Ants, bees and wasps are central place foragers. They leave their nests to forage and routinely return to their home-base. Most are guided by memories of the visual panorama and the visual appearance of the local nest environment when pinpointing their nest. These memories are acquired during highly structured learning walks or flights that are performed when leaving the nest for the first time or whenever the insects had difficulties finding the nest during their previous return. Ground-nesting bees and wasps perform such learning flights daily when they depart for the first time. During these flights, the insects turn back to face the nest entrance and subsequently back away from the nest while flying along ever increasing arcs that are centred on the nest. Flying along these arcs, the insects counter-turn in such a way that the nest entrance is always seen in the frontal visual field at slightly lateral positions. Here we asked how the insects may achieve keeping track of the nest entrance location given that it is a small, inconspicuous hole in the ground, surrounded by complex natural structures that undergo unpredictable perspective transformations as the insect pivots around the area and gains distance from it. We reconstructed the natural visual scene experienced by wasps and bees during their learning flights and applied a number of template-based tracking methods to these image sequences. We find that tracking with a fixed template fails very quickly in the course of a learning flight, but that continuously updating the template allowed us to reliably estimate nest direction in reconstructed image sequences. This is true even for later sections of learning flights when the insects are so far away from the nest that they cannot resolve the nest entrance as a visual feature. We discuss why visual goal-anchoring is likely to be important during the acquisition of visual-spatial memories and describe experiments to test whether insects indeed update nest-related templates during their learning flights. © 2014 Springer International Publishing Switzerland

The learning walks of ants (Hymenoptera: Formicidae)

When transitioning from in-nest duties to their foraging life outside the nest, ants perform a series of highly choreographed learning walks around the nest entrance, before leaving to forage for the first time. These learning walks have been described in detail only for a few species of ants, but a pattern of similarities and differences is emerging that we review here with an emphasis on understanding the functional significance of this learning process for efficient homing in ants. We compare the organization of learning walks in ants with that of the learning flights in bees and wasps and provide a list of key research questions that would need to be tackled if we are to understand the role of learning walks in the acquisition of nest-location information, the evolution of this highly conserved learning process, and how it is controlled.We acknowledge financial support to JZ from the Australian Research Council’s Discovery Program (DP150101172 and DP150102699) and to PNF from a Scientia-Scholarship, University of Würzburg, and the Deutsche Forschungsgemeinschaft (project FL1060/1-1)

The Effects of Landscape and Experience on the Navigation and Foraging Behaviour of Bumblebees, Bombus terrestris

Bumblebees live in an environment where the spatial distribution of foraging resources is always changing. In order to keep track of such changes, bumblebees employ a variety of different navigation and foraging strategies. Although a substantial amount of research has investigated the different navigation and foraging behaviours of bumblebees, much less is known of the effects that landscape features have on bumblebee behaviour. In this thesis, a series of experiments were conducted in order to investigate the role that landscape features have on the navigation and foraging behaviour of Bombus terrestris and whether individuals’ experience influences such behaviour. A hedgerow situated next to the colony was not found to significantly shape the flight paths or foraging choices of naïve bumblebees. Homing success was investigated and used as a proxy for foraging range in different environment types. Both the release distance and the type of environment were found to have a significant effect on the homing success of Bombus terrestris workers. Previous experience of the landscape was also found to significantly affect the time it took bumblebees to return to the colony (homing duration) as well as the likelihood of staying out overnight before returning to the colony. When focusing on the first five flights of a naïve bumblebee worker, experience was not found to significantly affect flight duration. Experience, however, significantly affected the weight of pollen foraged. The observed behaviour of bumblebee gynes provisioning their maternal colony with pollen was also investigated. The influx of pollen into the colony was found to affect this behaviour, suggesting that gynes will provision the maternal colony in response to its nutritional needs. The overall results are also discussed within the context of informing landscape management practices. The results presented in this thesis point to the critical role that factors such as the physical landscape and individual experience play in influencing bumblebee behaviour.South Devon Area of Outstanding Natural Beauty (AONB) Uni

Spatio-temporal dynamics of landscape use by the bumblebee Bombus pauloensis (Hymenoptera: Apidae) and its relationship with pollen provisioning

Understanding how bees use resources at a landscape scale is essential for developing meaningful management plans that sustain populations and the pollination services they provide. Bumblebees are important pollinators for many wild and cultivated plants, and have experienced steep population declines worldwide. Bee foraging behavior can be influenced by resource availability and bees’ lifecycle stage. To better understand these relationships, we studied the habitat selection of Bombus pauloensis by tracking 17 queen bumblebees with radio telemetry in blueberry fields in Entre Ríos province, Argentina. To evaluate land use and floral resources used by bumblebees, we tracked bees before and after nest establishment and estimated home ranges using minimum convex polygons and kernel density methods. We also classified the pollen on their bodies to identify the floral resources they used from the floral species available at that time. We characterized land use for each bee as the relative proportion of GPS points inside of each land use. Bumblebees differed markedly in their movement behavior in relation to pre and post nest establishment. Bees moved over larger areas, and mostly within blueberry fields, before nest establishment. In contrast, after establishing the nest, the bees preferred the edges near forest plantations and they changed the nutritional resources to prefer wild floral species. Our study is the first to track queen bumblebee movements in an agricultural setting and relate movement changes across time and space with pollen resource availability. This study provides insight into the way bumblebee queens use different habitat elements at crucial periods in their lifecycle, showing the importance of mass flowering crops like blueberry in the first stages of queen’s lifecycle, and how diversified landscapes help support bee populations as their needs changes during different phases of their lifecycle.EEA ConcordiaFil: Cavigliasso, Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concordia; ArgentinaFil: Phifer, Colin C. Michigan Technological University. School of Forest Resources and Environmental Science; Estados UnidosFil: Adams, Erika M. Michigan Technological University. School of Forest Resources and Environmental Science; Estados UnidosFil: Flaspohler, David J. Michigan Technological University. School of Forest Resources and Environmental Science; EstadosFil: Gennari, Gerardo Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Licata, Julián Andrés. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concordia; ArgentinaFil: Chacoff, Natacha Paola. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecología Regional; Argentin

Unmanned Aerial Vehicles (UAVs) in environmental biology: A Review

Acquiring information about the environment is a key step during each study in the field of environmental biology at different levels, from an individual species to community and biome. However, obtaining information about the environment is frequently difficult because of, for example, the phenological timing, spatial distribution of a species or limited accessibility of a particular area for the field survey. Moreover, remote sensing technology, which enables the observation of the Earth’s surface and is currently very common in environmental research, has many limitations such as insufficient spatial, spectral and temporal resolution and a high cost of data acquisition. Since the 1990s, researchers have been exploring the potential of different types of unmanned aerial vehicles (UAVs) for monitoring Earth’s surface. The present study reviews recent scientific literature dealing with the use of UAV in environmental biology. Amongst numerous papers, short communications and conference abstracts, we selected 110 original studies of how UAVs can be used in environmental biology and which organisms can be studied in this manner. Most of these studies concerned the use of UAV to measure the vegetation parameters such as crown height, volume, number of individuals (14 studies) and quantification of the spatio-temporal dynamics of vegetation changes (12 studies). UAVs were also frequently applied to count birds and mammals, especially those living in the water. Generally, the analytical part of the present study was divided into following sections: (1) detecting, assessing and predicting threats on vegetation, (2) measuring the biophysical parameters of vegetation, (3) quantifying the dynamics of changes in plants and habitats and (4) population and behaviour studies of animals. At the end, we also synthesised all the information showing, amongst others, the advances in environmental biology because of UAV application. Considering that 33% of studies found and included in this review were published in 2017 and 2018, it is expected that the number and variety of applications of UAVs in environmental biology will increase in the future

Spatial aspects of foraging behaviour in Eastern honeybees, Apis cerana

The majority of plants in Asian tropical ecosystems depend on bee pollination. However, there is a substantial lack of knowledge of the behaviour and ecology of native tropical bees. In the present study I explored how the Eastern honeybee, Apis cerana, distributes its foragers in the local environment analysing waggle dances of foragers in four rural and urban locations in Kerala, South India. Similar to their well-studied close relatives, the Western honeybee A. mellifera, returning A. cerana foragers recruit nest mates through these dances communicating the distance and direction from the hive to a food source. I decoded the locations of food sources for which pollen and nectar foragers danced. The results suggest that the bees tend to forage over shorter distances as compared to the Western honeybees. Furthermore, I have found that the foraging distances, in which dancing foragers have travelled, can notably differ for pollen and nectar resources. However, there is no significant difference in the direction in which nectar and pollen foragers travel. The results also show that despite floral abundance in the proximity of the hive in the rubber plantation, foragers travelled significantly further in this location when compared to the distance that they travelled in the other locations. This may indicate that these floral resources might actually represent a nutritionally poor floral resource for the honeybees. Throughout all of the four locations, the honeybee colonies showed variable patterns of foraging distribution, focusing their recruitment towards areas which seemed to offer both pollen and nectar rewards. This is likely to be in response to the spatial clustering of their food sources, which may be a characteristic of landscapes that are dominated by human agri- and horticultural activities.The UK-India Education and Research Initiative (British Council, UK and DST, India)

Individual foraging careers of the Jack Jumper ant, Myrmecia croslandi

A solitary foraging ant needs to rely exclusively on her navigational skill set to successfully navigate to and from goals such as the nest and food sites. Of interest is how ants are able to acquire this navigational information at a young age, before they become experienced workers and how this eventually shapes them into becoming efficient foragers. Ants of Myrmecia croslandi are highly visual, solitary foragers that exhibit no evidence of chemical trail following or recruitment. Therefore, a forager leaving the nest for the first time, must do so completely on her own, first by deciding where to go and second by utilising the information she has acquired from the environment to journey between sites. By identifying and individually following ants, I demonstrate that ants exhibit highly individual behaviour in most tasks, from early learning, and daily foraging to navigating from unfamiliar locations. First, I document the spatial and temporal variation in individual foraging behaviour at two nests of M. croslandi over a two-year period. Ants can take variable routes to the same food site and travel the longest distance when they forage on trees. Individual ants depart the nest at different times and a few ants perform multiple trips per day. Surprisingly, not a single ant foraged on consecutive days. By examining the behaviour of inexperienced ants at the nest, I provide a detailed analysis of the learning walks of M. croslandi. Most learning walks take place in the morning with a narrow time window separating the first two learning walks. There are no common bearing or gaze directions between ants, however, (a) in subsequent walks ants always explore directions that they have not previously visited and (b) ants engage in a systematic, saccadic scanning behaviour. I also discuss the significant differences between learning walks of M. croslandi and those previously studied in two other ant species, especially in relation the ‘turn back and look’ behaviour. In displacement experiments, I provide supporting evidence of a quick scanning behaviour that occurs as soon as ants are released. I examine the effect of a conflict in navigational information on successful homing by comparing full and zero vector ants. Zero vector ants are significantly better at navigating home, especially when released at unfamiliar sites. With the aid of the extensive individual foraging histories available to me, I show how in most cases, scene familiarity plays a role in driving ants home from unfamiliar displacement locations and discuss in detail behaviours that are exceptions to this. Finally, I provide the first evidence of the use of artificial landmarks near the nest in this species, which increases the accuracy with which ants pinpoint the nest entrance, even though they do not appear to make use of such landmarks in the wild and discuss my findings in relation to other ants. I also document the occurrence of re-orientation walks in response to an altered visual environment which show that ants are more directed as a result of re-learning

Head movements and the optic flow generated during the learning flights of bumblebees.

This is the final version of the article. Available from the publisher via the DOI in this recordInsects inform themselves about the 3D structure of their surroundings through motion parallax. During flight, they often simplify this task by minimising rotational image movement. Coordinated head and body movements generate rapid shifts of gaze separated by periods of almost zero rotational movement, during which the distance of objects from the insect can be estimated through pure translational optic flow. This saccadic strategy is less appropriate for assessing the distance between objects. Bees and wasps face this problem when learning the position of their nest-hole relative to objects close to it. They acquire the necessary information during specialised flights performed on leaving the nest. Here, we show that the bumblebee's saccadic strategy differs from other reported cases. In the fixations between saccades, a bumblebee's head continues to turn slowly, generating rotational flow. At specific points in learning flights these imperfect fixations generate a form of 'pivoting parallax', which is centred on the nest and enhances the visibility of features near the nest. Bumblebees may thus utilize an alternative form of motion parallax to that delivered by the standard 'saccade and fixate' strategy in which residual rotational flow plays a role in assessing the distances of objects from a focal point of interest.Financial support came from the EPSRC, Biotechnology and Biological Sciences Research Council (BBSRC) and The Leverhulme Trust. O.R. was supported by the Overseas Researc