The chemical ecology of armyworms

Moths of the genus Spodoptera are economically important pest insects. The necessity to develop novel control strategies which may be included in integrated pest management schemes has led to the study of chemical communication in several species within the genus. The polyphagous nature of most Spodoptera species makes it an interesting model to study the way in which different odor profiles are processed and interpreted by the insect brain and how this reflects upon the behavior and ecological interactions which may be of importance in agricultural systems. As such, armyworms have become a model organism in olfactory insect chemical ecology. Here, I attempt to give an overview of what is known about Spodptera chemical ecology to date and present perspectives and directions for future research

A Time for Atlases and Atlases for Time

Advances in neuroanatomy and computational power are leading to the construction of new digital brain atlases. Atlases are rising as indispensable tools for comparing anatomical data as well as being stimulators of new hypotheses and experimental designs. Brain atlases describe nervous systems which are inherently plastic and variable. Thus, the levels of brain plasticity and stereotypy would be important to evaluate as limiting factors in the context of static brain atlases. In this review, we discuss the extent of structural changes which neurons undergo over time, and how these changes would impact the static nature of atlases. We describe the anatomical stereotypy between neurons of the same type, highlighting the differences between invertebrates and vertebrates. We review some recent experimental advances in our understanding of anatomical dynamics in adult neural circuits, and how these are modulated by the organism's experience. In this respect, we discuss some analogies between brain atlases and the sequenced genome and the emerging epigenome. We argue that variability and plasticity of neurons are substantially high, and should thus be considered as integral features of high-resolution digital brain atlases

Multimodal information processing and associative learning in the insect brain

The study of sensory systems in insects has a long-spanning history of almost an entire century. Olfaction, vision, and gustation are thoroughly researched in several robust insect models and new discoveries are made every day on the more elusive thermo- and mechano-sensory systems. Few specialized senses such as hygro- and magneto-reception are also identified in some insects. In light of recent advancements in the scientific investigation of insect behavior, it is not only important to study sensory modalities individually, but also as a combination of multimodal inputs. This is of particular significance, as a combinatorial approach to study sensory behaviors mimics the real-time environment of an insect with a wide spectrum of information available to it. As a fascinating field that is recently gaining new insight, multimodal integration in insects serves as a fundamental basis to understand complex insect behaviors including, but not limited to navigation, foraging, learning, and memory. In this review, we have summarized various studies that investigated sensory integration across modalities, with emphasis on three insect models (honeybees, ants and flies), their behaviors, and the corresponding neuronal underpinnings

Drosophila type II neuroblast lineages keep Prospero levels low to generate large clones that contribute to the adult brain central complex

Tissue homeostasis depends on the ability of stem cells to properly regulate self-renewal versus differentiation. Drosophila neural stem cells (neuroblasts) are a model system to study self-renewal and differentiation. Recent work has identified two types of larval neuroblasts that have different self-renewal/differentiation properties. Type I neuroblasts bud off a series of small basal daughter cells (ganglion mother cells) that each generate two neurons. Type II neuroblasts bud off small basal daughter cells called intermediate progenitors (INPs), with each INP generating 6 to 12 neurons. Type I neuroblasts and INPs have nuclear Asense and cytoplasmic Prospero, whereas type II neuroblasts lack both these transcription factors. Here we test whether Prospero distinguishes type I/II neuroblast identity or proliferation profile, using several newly characterized Gal4 lines. We misexpress prospero using the 19H09-Gal4 line (expressed in type II neuroblasts but no adjacent type I neuroblasts) or 9D11-Gal4 line (expressed in INPs but not type II neuroblasts). We find that differential prospero expression does not distinguish type I and type II neuroblast identities, but Prospero regulates proliferation in both type I and type II neuroblast lineages. In addition, we use 9D11 lineage tracing to show that type II lineages generate both small-field and large-field neurons within the adult central complex, a brain region required for locomotion, flight, and visual pattern memory

Sensory Organ Morphogenesis in Caenorhabditis Elegans

Sensory organs are the gates through which information flows into the nervous system. In most animals, such organs consist of sensory neurons, which can transform stimuli into changes in their membrane potential, and glial cells, which establish a niche important for the morphogenesis and function of the neurons. Although similar glial compartments are seen throughout the nervous system, their morphogenesis is poorly understood. In the work presented here, I use the main sensory organ of Caenorhabditis elegans, the amphid, as a model system for understanding how glia form these compartments. First, by the interpretation of electron microscopy reconstructions of the developing amphid, I was able to uncover a role for daf-6/Patched, an established regulator of amphid morphogenesis, in restricting the size of the sensory compartment. Second, I sought to identify genes acting in the opposite direction, in expanding the sensory compartment, by cloning and characterizing suppressors of daf-6. Through this approach I discovered that lit-1/Nlk acts within glia, in counterbalance to daf-6, to promote sensory compartment expansion. Although LIT-1 has been shown to regulate Wnt signaling, my genetic studies demonstrate a novel, Wnt-independent role for LIT-1 in sensory compartment size control. The LIT-1 activator MOM-4/TAK1 is also important for compartment morphogenesis and both proteins line the glial sensory compartment. LIT-1 compartment localization is important for its function and requires neuronal signals. Furthermore, the conserved LIT-1 C-terminus is necessary and sufficient for this localization. Two-hybrid and co-immunoprecipitation studies demonstrate that the LIT-1 C-terminus binds both actin and the Wiskott-Aldrich syndrome protein (WASP), an actin regulator. I show that actin also lines the sensory compartment, and that WASP is important for compartment expansion, potentially by functioning in the same pathway as LIT-1. These results suggest that the daf-6 and lit-1 glial pathways constitute a rheostat used to control sensory compartment size. Finally, I also identify a role for the retromer complex, a module involved in the recycling of transmembrane proteins and membrane material from the endosomes to the Golgi apparatus, in amphid morphogenesis. Similar to lit-1, mutations of retromer components suppress daf-6, suggesting that the retromer could also act in promoting sensory compartment expansion