Klein, Barrett
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Applying human brain image processing methods to honeybee calcium image data
Methods developed for analyzing human brain fMRI data have great potential for application to brain imaging data of different spatial and temporal scales, different imaging methods, and different species. In this work, we demonstrate a simple analysis of honeybee (Apis mellifera) brain image data using the Python programming language.
To our knowledge, this is the first application of human brain imaging techniques to an invertebrate. These techniques provide advantages when analyzing intra-individual phenomena, and invertebrates such as the honeybee offer the advantage of harboring a simpler, experimentally more accessible nervous system.
Work or sleep? : honeybee foragers opportunistically nap during the day when forage is not available
Shifts in work schedules test humans’ capacity to be flexible in the timing of both work and sleep. Honeybee, Apis mellifera, foragers also shift their work schedules, but how flexible they are in the timing of sleep as they shift the timing of work is unknown, despite the importance of colony-level plasticity in the face of a changing environment. We hypothesized that sleep schedules of foragers are not fixed and instead vary depending on the time when food is available. We trained bees to visit a food source made available for several hours in the early morning (AM) or several hours in the late afternoon (PM), then monitored their sleep behaviour for 24 h after training, specifically comparing their sleep during the AM and PM periods previously designated as training periods. Following AM training, honeybee foragers slept more during the afternoon than during the morning, but following PM training, the same bees ‘slept in’ the next morning, and so slept more in the morning than in the afternoon. Although foragers did not change the total amount of time devoted to each of their behaviours (including sleep), the timing of their sleep did change. Thus, plasticity in timing of foraging was matched by plasticity in timing of sleep. The apparent correlation between the timing patterns of foraging and sleeping demonstrates temporal plasticity of sleep under ecologically realistic conditions in an invertebrate. Testing how shift work affects the health and performance of honeybees may shed light on the role of sleep in a nonhuman social animal.
Quantifying the symbiont contribution to essential amino acids in aphids : the importance of tryptophan for Uroleucon ambrosiae
A complete amino acid budget was constructed using the aphid Uroleucon ambrosiae (Strecker), feeding on a suboptimal host, Tithonia fruticosa. The availability of amino acids was estimated from phloem analyses and phloem intake rates at each stage of development. Requirements for amino acids were estimated from gravimetric studies and from analyses of body amino acids. Because the budget was found to be well balanced, estimates of specific needs and shortfalls of essential amino acids were calculated, thus quantifying the role of symbiotic bacteria in fulfilling needs for these amino acids. The most dramatic shortfall was for tryptophan, consistent with the amplification of relevant genes in the symbiont.
Multimodal signal variation in space and time : how important is matching a signal with its signaler?
Multimodal signals (acoustic+visual) are known to be used by many anuran amphibians during courtship displays. The relative degree to which each signal component influences female mate choice, however, remains poorly understood. In this study we used a robotic frog with an inflating vocal sac and acoustic playbacks to document responses of female túngara frogs to unimodal signal components (acoustic and visual). We then tested female responses to a synchronous multimodal signal. Finally, we tested the influence of spatial and temporal variation between signal components for female attraction. Females failed to approach the isolated visual cue of the robotic frog and they showed a significant preference for the call over the spatially separate robotic frog. When presented with a call that was temporally synchronous with the vocal sac inflation of the robotic frog, females did not show a significant preference for this over the call alone; when presented with a call that was temporally asynchronous with vocal sac inflation of the robotic frog, females discriminated strongly against the asynchronous multimodal signal in favor of the call alone. Our data suggest that although the visual cue is neither necessary nor sufficient for attraction, it can strongly modulate mate choice if females perceive a temporal disjunction relative to the primary acoustic signal.
Sleep deprivation impairs precision of waggle dance signaling in honey bees
Sleep is essential for basic survival, and insufficient sleep leads to a variety of dysfunctions. In humans, one of the most profound consequences of sleep deprivation is imprecise or irrational communication, demonstrated by degradation in signaling as well as in receiving information. Communication in nonhuman animals may suffer analogous degradation of precision, perhaps with especially damaging consequences for social animals. However, society-specific consequences of sleep loss have rarely been explored, and no function of sleep has been ascribed to a truly social (eusocial) organism in the context of its society. Here we show that sleep-deprived honey bees (Apis mellifera) exhibit reduced precision when signaling direction information to food sources in their waggle dances. The deterioration of the honey bee’s ability to communicate is expected to reduce the foraging efficiency of nestmates. This study demonstrates the impact of sleep deprivation on signaling in a eusocial animal. If the deterioration of signals made by sleep-deprived honey bees and humans is generalizable, then imprecise communication may be one detrimental effect of sleep loss shared by social organisms.
Neocorynurella, a new genus of augochlorine bees from South America (Hymenoptera: Halictidae)
Neocorynurella Engel gen. n., a new sweat bee genus of the tribe Augochlorini (Halictidae), is described and figured from high altitudes in Colombia and Venezuela. The genus is distinguished from other augochlorine genera by the following combination of characters: galeal comb absent, epistomal sulcus obtuse, mouthparts not narrowed, preoccipital ridge rounded, pronotal dorsal and lateral ridges not carinate, pectinate inner hind tibia1 spur, strong basitibial plate, truncated marginal cell, and penis valve without a ventral prong. Two species are currently recognized in the group, Neocorynurella SPPleyi Engel et Klein sp. n. and N. viridis Engel et Klein sp. 11. Modified key couplets are provided for Eickwort's key to the genera of Augochlorini in order to facilitate recognition of the new genus. The position of Neocorynurella in augochlorine phylogeny is briefly discussed.
Intersignal interaction and uncertain information in anuran multimodal signals
Disentangling the influence of multiple signal components on receivers and elucidating general processes influencing complex signal evolution are difficult tasks. In this study we test mate preferences of female squirrel treefrogs Hyla squirella and female túngara frogs Physalaemus pustulosus for similar combinations of acoustic and visual components of their multimodal courtship signals. In a two-choice playback experiment with squirrel treefrogs, the visual stimulus of a male model significantly increased the attractivness of a relatively unattractive slow call rate. A previous study demonstrated that faster call rates are more attractive to female squirrel treefrogs, and all else being equal, models of male frogs with large body stripes are more attractive. In a similar experiment with female túngara frogs, the visual stimulus of a robotic frog failed to increase the attractiveness of a relatively unattractive call. Females also showed no preference for the distinct stripe on the robot that males commonly bear on their throat. Thus, features of conspicuous signal components such as body stripes are not universally important and signal function is likely to differ even among species with similar ecologies and communication systems. Finally, we discuss the putative information content of anuran signals and suggest that the categorization of redundant versus multiple messages may not be sufficient as a general explanation for the evolution of multimodal signaling. Instead of relying on untested assumptions concerning the information content of signals, we discuss the value of initially collecting comparative empirical data sets related to receiver responses.
Caste-dependent sleep of worker honey bees
Sleep is a dynamic phenomenon that changes throughout an organismʼs lifetime, relating to possible age- or task-associated changes in health, learning ability, vigilance and fitness. Sleep has been identified experimentally in many animals, including honey bees (Apis mellifera). As worker bees age they change castes, typically performing a sequence of different task sets (as ʻcell cleanersʼ, ʻnurse beesʼ, ʻfood storersʼ and ʻforagersʼ). Belonging to a caste could differentially impact the duration, constitution and periodicity of a beeʼs sleep. We observed individually marked bees within observation hives to determine castedependent patterns of sleep behavior. We conducted three studies to investigate the duration and periodicity of sleep when bees were outside comb cells, as well as duration of potential sleep when bees were immobile inside cells. All four worker castes we examined exhibited a sleep state. As bees aged and changed tasks, however, they spent more time and longer uninterrupted periods in a sleep state outside cells, but spent less time and shorter uninterrupted periods immobile inside cells. Although cell cleaners and nurse bees exhibited no sleep:wake rhythmicity, food storers and foragers experienced a 24 h sleep:wake cycle, with more sleep and longer unbroken bouts of sleep during the night than during the day. If immobility within cells is an indicator of sleep, our study reveals that the youngest adult bees sleep the most, with all older castes sleeping the same amount. This in-cell potential sleep may compensate for what would otherwise indicate an exceptional increase of sleep in an aging animal.