Journal of Comparative Physiology A-Neuroethology Sensory Neural and Behavioral Physiology最新文献

Magnetoreception is the ability of animals to detect and use the geomagnetic field (GMF) for spatial orientation. Cataglyphis ants are experimental models for insect navigation and magnetoreception. At the beginning of their foraging life, Cataglyphis ants perform learning walks (LWs), explorative excursions around the nest, with pirouettes (tight turns about the ants' body axes). During a pirouette, an ant gazes to the nest entrance, an invisible hole in the ground. Until now, Cataglyphis nodus has been the only desert ant species shown to use the GMF to align their gazes to the nest entrance during LW pirouettes. In the present study, we show that Cataglyphis hellenica, phylogenetically distant from C. nodus, but inhabiting the same environment, also possesses a magnetic sense. When C. hellenica ants are exposed to an experimental alteration of the GMF (alteration of the horizontal component about 180° or + 120°), they gaze to the fictive position of the nest entrance. This study demonstrates that C. hellenica ants use the GMF to gaze back to the nest entrance, confirming the presence of magnetoreception in a second Cataglyphis species, in addition to C. nodus. This suggests that the use of the GMF for path integration is rather common than unique in Cataglyphis species.

Extracellular recordings from the sensory pits, conspicuous sensory organs on the cuticle of planthopper nymphs (suborder Fulgoromorpha), were performed. No responses to sound, ultrasound, direct mechanical stimulation, temperature changes, or magnetic fields were observed. They do, however, respond to stimulation with electric fields of very low intensity. Field strengths of less than 1 kV/m were sometimes sufficient to elicit responses. These responses, together with the arrangement of these special sensory structures on the body surface of planthoppers, imply that these sensory organs perceive electric fields in the environment. Our results correspond well with recently published observations and model calculations for treehoppers (Membracidae), another Auchenorrhyncha taxon. Our results corroborate these recent findings with direct electrophysiological evidence and support the notion that both treehoppers and planthoppers are able to perceive electric fields. The ecological importance for this kind of sensory system is discussed.

The sense of taste is crucial for butterflies and moths to accomplish important life tasks such as feeding or selecting suitable oviposition sites. In Lepidoptera taste is of special importance since they are constantly confronted with a vast amount of plant secondary metabolites combined with sugars, amino acids and other primary metabolites that they need to fuel their metabolism. The high importance of many tastants for feeding and oviposition gives these compounds a strong innate meaning for the animal. During associative learning this positive or negative valence often functions as reward or punishment, giving the sense of taste an important role during memory formation. In this review we first address some general mechanisms of gustatory detection before focusing on the taste system of caterpillars and adult Lepidoptera specifically. We list recent examples of receptor genes for which the main ligands have been identified, but place special emphasis on the neuronal and behavioral responses to different tastants. Thereafter the detection of primary and secondary metabolites is reviewed, with a focus on the role of secondary plant metabolites during host-plant choice. Finally, we compiled different results on the taste processing in the lepidopteran brain and highlight the role of taste during associative learning. In this review we combined information on the role of taste for both innate and learned responses of Lepidoptera to their environment, aiming to provide a starting point for further explorations into this essential sensory modality.

Animals live in diverse environments and have evolved to cope with environmental challenges in different ways. How such adaptations shape overall brain morphology is still unclear. Here, we test how two behavioural adaptations - circadian activity pattern and migratory behaviour - are reflected in the brains of moths and butterflies (Lepidoptera). We predicted that circadian activity pattern affects primary sensory regions, whereas migration impacts integrative centres. Using anti-synapsin immunostaining, we generated detailed 3D reconstructions of each species' brain and performed a phylogenetically corrected volumetric analysis. All lepidopteran brains, including early-diverging lineages, share a characteristic layout that differs from the caddisfly (Trichoptera) outgroup. Some brain regions proved highly evolvable - most notably, the anterior optic tubercle varied qualitatively among species. Most regions, however, differed quantitatively, with tissue volumes strongly shaped by phylogeny as well as behavioural traits. While activity pattern predominantly affected primary visual areas, migratory behaviour correlated with significant volume changes in the fan-shaped body, the accessory medulla and parts of the mushroom body. We also identified several small neuropils as evolutionary "hotspots", showing rapid, lineage-specific expansion or reduction. Finally, positive and negative correlations among neuropil volumes reveal coordinated evolution in defined neuropil groups, suggesting functional linkages and constraints beyond anatomically related regions. These findings generate testable hypotheses about poorly studied brain areas and highlight diverse evolutionary dynamics across the lepidopteran phylogeny.

The Australian Bogong moth (Agrotis infusa) is a small noctuid moth that undertakes annual, nocturnal migrations of up to 1000 km to escape the summer heat of its breeding grounds. The moths travel to cool alpine caves, where they enter a dormant state (aestivation) before returning to reproduce and die. During migration, their brains integrate magnetic and visual cues to guide their flight direction. While the Bogong moth's neurobiology is increasingly understood, its visual system has remained unexplored. Here, we describe the morphology, ultrastructure, optics, and visual opsins of the Bogong moth's compound eyes and ocelli. Using light and electron microscopy, micro-computed tomography, in situ hybridization, and spectral absorbance measurements, we show that the compound eyes are typical superposition eyes with a tiered rhabdom, similar to other noctuid moths. The ocelli are small but structurally complex, featuring a two-tiered retina with spectrally distinct receptor cells and a lens forming a focused image on the ocellar retina. At the molecular level, the Bogong moth expresses three canonical opsins (UV, blue, and long-wavelength) and an additional red-shifted long-wavelength opsin, suggesting enhanced sensitivity to long-wavelength light. These opsins exhibit distinct expression patterns across the compound eyes, indicating functionally distinct dorsal and ventral eye hemispheres. Overall, the Bogong moth's visual system displays multiple adaptations to nocturnal vision. These features, likely shared across noctuid moths, may have contributed to the evolution of the exceptional navigational abilities during long-distance migrations in dim light that define the Bogong moth, but which are also widespread across noctuid moths.