Studies in Neotropical Pseudophyllinae: A new genus of Cocconotini from the Colombian Andes and new subfamily assignment of the Dominican genus Anacaona (Tettigoniidae: Pseudophyllinae: Cocconotini).

Acuscercus eudaldoleondiazi n. gen et n. sp. from the Eastern slopes of the Colombian Andes is described, a typical long-winged member of the tribe Cocconotini, distinguished by peculiar morphology of male cerci. On the other hand, the Dominican genus Anacaona is moved from Cocconotini to the tribe Copiphorini (Conocephalinae). The status and tribal boundaries of Cocconotini and Eucocconotini are briefly discussed.

Archaeocercus gen. nov. (Hymenoptera, Chalcidoidea, Encyrtidae) from Late Eocene Rovno Amber.

Archaeocercus schuvachinae, gen. et sp. nov., is described and illustrated based on a female specimen from Rovno amber (Ukraine). This fossil genus is characterized by the apical position of cerci on metasoma, absence of filum spinosum on distal margin of linea calva on forewings, triangular hypopygium reaching metasomal apex, mesoscutum with incomplete notauli, long veins on forewings and apically expanded antennae. A brief comparative morphological analysis of some structures of the extinct and extant Encyrtidae is provided. The new genus is considered unplaced within Encyrtidae.

Functional morphology of the male caudal appendages of the damselfly Ischnura elegans (Zygoptera: Coenagrionidae).

Odonata are usually regarded as one of the most ancient extant lineages of winged insects. Their copulatory apparatus and mating behavior are unique among insects. Male damselflies use their caudal appendages to clasp the female's prothorax during both copulation and egg-laying and have a secondary copulatory apparatus for sperm transfer. Knowledge of the functional morphology of the male caudal appendages is the basis for understanding the evolution of these structures in Odonata and respective organs in other insects. However, it is still not exactly known how the zygopteran claspers work. In this study, we applied micro-computed tomography and a variety of microscopy techniques to examine the morphology, surface microstructure, cuticle material composition and muscle topography of the male caudal appendages of Ischnura elegans. The results indicate that the closing of the paraproctal claspers is mainly passive. This indirect closing mechanism is very likely supported by high proportions of the elastic protein resilin present in the cuticle of the paraproctal bases. In addition, the prothoracic morphology of the female plays an important role in the indirect closing of the male claspers. Our data indicate that both structures - the male claspers and the female prothoracic hump - function together like a snap-fastener.

Studying temporal properties of stimulus-evoked responses in the ventral nerve cord of insects.

Students in undergraduate laboratory settings learn many of the foundational principles of sensory processing in the comparatively simple, easy to study invertebrate nervous system. In this example preparation, the American cockroach, students record action potentials from the fibers in the ventral nerve cord (VNC) that participate in a well explained escape behavior in response to stimulation of its cerci, a pair of mechanosensitive abdominal appendages. A system that allows good control over the time and amplitude of the air pulse delivered to the cerci is described. This experimental setup enables students to extract and display temporal information from recordings to learn how to interpret those responses in the context of the properties of the stimulus. I offer examples of specific investigations and analyses that work well for this purpose in an undergraduate laboratory.

Using crickets to introduce neurophysiology to early undergraduate students.

Anatomy and physiology instructors often face the daunting task of teaching the principles of neurophysiology as part of a laboratory course with very limited resources. Teaching neurophysiology can be a difficult undertaking as sophisticated electrophysiology and data acquisition equipment is often financially out-of-reach for two-year institutions, and for many preparations, instructors need to be highly skilled in electrophysiology techniques when teaching hands-on laboratories. In the absence of appropriate laboratory tools, many undergraduate students have difficulty understanding concepts related to neurophysiology. The cricket can serve as a reliable invertebrate model to teach the basic concepts of neurophysiology in the educational laboratory. In this manuscript, we describe a series of hands-on, demonstrative, technologically simple, and affordable laboratory activities that will help undergraduate students gain an understanding of the principles of neurophysiology. By using the cerci ganglion and leg preparation, students can quantify extracellular neural activity in response to sensory stimulation, understand the principles of rate coding and somatotopy, perform electrical microstimulation to understand the threshold of sensory stimulation, and do pharmacological manipulation of neuronal activity. We describe the utility of these laboratory activities, provide a convenient protocol for quantifying extracellular recordings, and discuss feedback provided by undergraduate students with regards to the quality of the educational experience after performing the lab activities.

The function of the cercal sensory system in escape behavior of the cave cricket Troglophilus neglectus Krauss.

Long cerci of cave crickets Troglophilus neglectus Krauss (Rhaphidophoridae, Orthoptera) are, in contrast to other investigated species, oriented perpendicularly to the ground. Behavioural experiments indicated that cave crickets detect wind direction and respond to stimulation by jumping away from the stimulus. Directed wind puffs deflect filiform sensory hairs on the cerci, trigger physiological responses of their sensory neurons and change activity of interneurons that control the escape direction. Two local interneuron pairs, one non-spiking and one spiking, were identified using intracellular recording and subsequent dye injection techniques. The non-spiking interneuron responds to the puffs from sides with a large depolarization and to the puffs from the front and back of the animal with a small depolarization. After stimulation from the ipsilateral side the spiking interneuron responds with a burst of spikes at the onset of stimulation and, after stimulation from the contralateral side, it responds with a burst of spikes at the onset and at the end of the stimulation.

Embryonic development of an insect sensory system, the abdominal cerci ofAcheta domesticus.

1. The embryonic development of the abdominal cerci of the house cricketAcheta domesticus is described from scanning and transmission electron microscope data. 2. A staged description of externally visible events in embryogenesis is tabulated as a context for describing the chronology of embryonic development of the abdominal cerci. 3. Three phases of cercal development are distinguished: differentiation of the cercal anlagen and secretion of the first embryonic cuticle; elongation of the cercus culminating in the secretion of the second embryonic cuticle after completion of a continuous epidermis at the time of dorsal closure; and differentiation of functional sensilla on the third embryonic (first instar) cuticle. 4. The first axon profiles appear in the cercus immediately before elongation of the cercus. These axons have dendrites with ciliary configuration in the lumen of the cercus. Glial cells associated with the pioneer axons may precede the axons in occupying dorsal and ventral luminal midlines of the cerci. 5. Trichoid sensilla appear in the integumet following apolysis of the second embryonic cuticle. 6. Axons are added to the dorsal and ventral pioneer fibre bundles shortly before sensilla become apparent. 7. The majority of sensory axons traverse the cercus during the final 15% of embryonic development. 8. The sensilla of the first instar cercus do not achieve their final orientation until the cercal cuticle is expanded following eclosion from the second embryonic cuticle that encloses the hatchling until it reaches a free surface. 9. The role of the pioneer fibres in establishing a pathway for the functional sensillar neurons is discussed in relation to other studies of sensillar development in insects.