A model of ant route navigation driven by scene familiarity

In this paper we propose a model of visually guided route navigation in ants that captures the known properties of real behaviour whilst retaining mechanistic simplicity and thus biological plausibility. For an ant, the coupling of movement and viewing direction means that a familiar view specifies a familiar direction of movement. Since the views experienced along a habitual route will be more familiar, route navigation can be re-cast as a search for familiar views. This search can be performed with a simple scanning routine, a behaviour that ants have been observed to perform. We test this proposed route navigation strategy in simulation, by learning a series of routes through visually cluttered environments consisting of objects that are only distinguishable as silhouettes against the sky. In the first instance we determine view familiarity by exhaustive comparison with the set of views experienced during training. In further experiments we train an artificial neural network to perform familiarity discrimination using the training views. Our results indicate that, not only is the approach successful, but also that the routes that are learnt show many of the characteristics of the routes of desert ants. As such, we believe the model represents the only detailed and complete model of insect route guidance to date. What is more, the model provides a general demonstration that visually guided routes can be produced with parsimonious mechanisms that do not specify when or what to learn, nor separate routes into sequences of waypoints

Group-wise 3D registration based templates to study the evolution of ant worker neuroanatomy

The evolutionary success of ants and other social insects is considered to be intrinsically linked to division of labor and emergent collective intelligence. The role of the brains of individual ants in generating these processes, however, is poorly understood. One genus of ant of special interest is Pheidole, which includes more than a thousand species, most of which are dimorphic, i.e. their colonies contain two subcastes of workers: minors and majors. Using confocal imaging and manual annotations, it has been demonstrated that minor and major workers of different ages of three species of Pheidole have distinct patterns of brain size and subregion scaling. However, these studies require laborious effort to quantify brain region volumes and are subject to potential bias. To address these issues, we propose a group-wise 3D registration approach to build for the first time bias-free brain atlases of intra- and inter-subcaste individuals and automatize the segmentation of new individuals.Comment: 10 pages, 5 figures, preprint for conference (not reviewed

The Role of Landscapes and Landmarks in Bee Navigation: A Review.

The ability of animals to explore landmarks in their environment is essential to their fitness. Landmarks are widely recognized to play a key role in navigation by providing information in multiple sensory modalities. However, what is a landmark? We propose that animals use a hierarchy of information based upon its utility and salience when an animal is in a given motivational state. Focusing on honeybees, we suggest that foragers choose landmarks based upon their relative uniqueness, conspicuousness, stability, and context. We also propose that it is useful to distinguish between landmarks that provide sensory input that changes ("near") or does not change ("far") as the receiver uses these landmarks to navigate. However, we recognize that this distinction occurs on a continuum and is not a clear-cut dichotomy. We review the rich literature on landmarks, focusing on recent studies that have illuminated our understanding of the kinds of information that bees use, how they use it, potential mechanisms, and future research directions

Plain Meaning, Precedent, and Metaphysics: Interpreting the “Point Source” Element of the Clean Water Act Offense

This Article, the fourth in a series of five, examines the continuing struggles to define “point source” and “nonpoint source” under the Clean Water Act. State regulation of nonpoint sources is neither pervasive nor robust, and most continuing water pollution problems can be traced primarily to nonpoint sources. EPA should define nonpoint sources by regulation and begin to expand the definition of point source by incorporating established case law and Agency practice to bring more nonpoint sources into the point source definition

Association between neotropical burrowing spiders (araneae: nemesiidae) and mites (acari: heterostigmata, scutacaridae)

Whilst collecting burrowing spiders of the family Nemesiidae from 16 localities in Argentina, phoretic mites were found on Stenoterommata iguazu, Stenoterommata platense and Stenoterommata uruguai. These mites are described here: Scutacarus (S.) araneophilus n. sp. and Scutacarus (S.) adgregatus n. sp. Assocations between spiders and scutacarids were not previouly known. Aspects of the biology of the spiders and the interactions between mites and spiders are reported and discussed.Durante colectas de arafias cavadoras de la familia Nemesiidae en I 6 localidades de Argentina, se encontraron acaros foreticos sobre Stenoterommata iguazu, S. platense, and S. uruguai. Se describe aqui a estos acaros, como Scutacarus ( S.) araneophilus n. sp. and Scutacarus ( S.) adgregatus n.sp. Ninguna asociaci6n entre arafias y escutacaridos se conocia previamente. Se discute la interacci6n entre Ios acaros y las arafias, tomando en cuenta Ios datos conocidos de la biologia de ambos.Fil: Ebermann, Ernst. Karl Franzens University; AustriaFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; Argentin

TGLE Vol 50 nos. 3 & 4 full issue

The Great Lakes Entomologist Volume 50 Numbers 3 & 4 Fall/Winter full issue

Using an insect mushroom body circuit to encode route memory in complex natural environments

Ants, like many other animals, use visual memory to follow extended routes through complex environments, but it is unknown how their small brains implement this capability. The mushroom body neuropils have been identified as a crucial memory circuit in the insect brain, but their function has mostly been explored for simple olfactory association tasks. We show that a spiking neural model of this circuit originally developed to describe fruitfly (Drosophila melanogaster) olfactory association, can also account for the ability of desert ants (Cataglyphis velox) to rapidly learn visual routes through complex natural environments. We further demonstrate that abstracting the key computational principles of this circuit, which include one-shot learning of sparse codes, enables the theoretical storage capacity of the ant mushroom body to be estimated at hundreds of independent images

An exploration of the social brain hypothesis in insects.

The "social brain hypothesis" posits that the cognitive demands of sociality have driven the evolution of substantially enlarged brains in primates and some other mammals. Whether such reasoning can apply to all social animals is an open question. Here we examine the evolutionary relationships between sociality, cognition, and brain size in insects, a taxonomic group characterized by an extreme sophistication of social behaviors and relatively simple nervous systems. We discuss the application of the social brain hypothesis in this group, based on comparative studies of brain volumes across species exhibiting various levels of social complexity. We illustrate how some of the major behavioral innovations of social insects may in fact require little information-processing and minor adjustments of neural circuitry, thus potentially selecting for more specialized rather than bigger brains. We argue that future work aiming to understand how animal behavior, cognition, and brains are shaped by the environment (including social interactions) should focus on brain functions and identify neural circuitry correlates of social tasks, not only brain sizes.This work was supported by the Australian Research Council (Mathieu Lihoreau and Tanya Latty) and the Natural Sciences and Engineering Council of Canada (Tanya Latty)