Electrolytic lesions within central complex neuropils of the cockroach brain affect negotiation of barriers

Animals must negotiate obstacles in their path in order to successfully function within natural environments. These actions require transitions from walking to other behaviors, many of which are more involved than simple reflexes. For these behaviors to be successful, insects must evaluate objects in their path and then use that information to change posture or re-direct leg movements. Some of this control may occur within a region of the brain known as the central complex (CC). We used discrete electrolytic lesions to examine the role of certain sub-regions of the CC in various obstacle negotiation behaviors. We found that cockroaches with lesions to the protocerebral bridge (PB) and ellipsoid body (EB) exhibit abnormalities in turning and dealing with shelf-like objects; whereas, individuals with lesions to the fan-shaped body (FB) and lateral accessory lobe (LAL), exhibit abnormalities of those behaviors as well as climbing over blocks and up walls to a horizontal plane. Abnormalities in block climbing include decreased success rate, changes in climbing strategy, and delayed response to the block. Increases in these abnormal behaviors were significant in individuals with lesions to the FB and LAL. Although turning abnormalities are present in individuals with lesions to the LAL, EB and the lateral region of the FB, there are some differences in how these deficits present. For instance, the turning deficits seen in individuals with lateral FB lesions only occurred when turning in the direction opposite to the side of the brain on which the lesion occurred. By contrast, individuals with lesions to the EB and LAL exhibited turning abnormalities in both directions. Lesions in the medial region of the FB did not result in directional turning deficits, but in abnormalities in block climbing

Tomographic reconstruction of neopterous Carboniferous insect nymphs

Two new polyneopteran insect nymphs from the Montceau-les-Mines Lagerstätte of France are presented. Both are preserved in three dimensions, and are imaged with the aid of X-ray micro-tomography, allowing their morphology to be recovered in unprecedented detail. One–Anebos phrixos gen. et sp. nov.–is of uncertain affinities, and preserves portions of the antennae and eyes, coupled with a heavily spined habitus. The other is a roachoid with long antennae and chewing mouthparts very similar in form to the most generalized mandibulate mouthparts of extant orthopteroid insects. Computer reconstructions reveal limbs in both specimens, allowing identification of the segments and annulation in the tarsus, while poorly developed thoracic wing pads suggest both are young instars. This work describes the morphologically best-known Palaeozoic insect nymphs, allowing a better understanding of the juveniles’ palaeobiology and palaeoecology. We also consider the validity of evidence from Palaeozoic juvenile insects in wing origin theories. The study of juvenile Palaeozoic insects is currently a neglected field, yet these fossils provide direct evidence on the evolution of insect development. It is hoped this study will stimulate a renewed interest in such work

Feedback Control as a Framework for Understanding Tradeoffs in Biology

Control theory arose from a need to control synthetic systems. From regulating steam engines to tuning radios to devices capable of autonomous movement, it provided a formal mathematical basis for understanding the role of feedback in the stability (or change) of dynamical systems. It provides a framework for understanding any system with feedback regulation, including biological ones such as regulatory gene networks, cellular metabolic systems, sensorimotor dynamics of moving animals, and even ecological or evolutionary dynamics of organisms and populations. Here we focus on four case studies of the sensorimotor dynamics of animals, each of which involves the application of principles from control theory to probe stability and feedback in an organism's response to perturbations. We use examples from aquatic (electric fish station keeping and jamming avoidance), terrestrial (cockroach wall following) and aerial environments (flight control in moths) to highlight how one can use control theory to understand how feedback mechanisms interact with the physical dynamics of animals to determine their stability and response to sensory inputs and perturbations. Each case study is cast as a control problem with sensory input, neural processing, and motor dynamics, the output of which feeds back to the sensory inputs. Collectively, the interaction of these systems in a closed loop determines the behavior of the entire system.Comment: Submitted to Integr Comp Bio

The Effect of Deantennation on the Dominant-Subordinate Relationship in the American Cockroach (Periplaneta americana)

Author Institution: Department of Educational Studies, The Ohio State UniversityThe American cockroach has been observed to exhibit complex social behavior. In this study the effect of deantennation on the dominant-subordinate relationship in the American cockroach, Periplaneta americana, was investigated. Ablation of the antennae of a dominant individual caused a reversal in status to occur with a previously subordinate male assuming the dominant position

Cricket antennae shorten when bending (Acheta domesticus L.).

Insect antennae are important mechanosensory and chemosensory organs. Insect appendages, such as antennae, are encased in a cuticular exoskeleton and are thought to bend only between segments or subsegments where the cuticle is thinner, more flexible, or bent into a fold. There is a growing appreciation of the dominating influence of folds in the mechanical behavior of a structure, and the bending of cricket antennae was considered in this context. Antennae will bend or deflect in response to forces, and the resulting bending behavior will affect the sensory input of the antennae. In some cricket antennae, such as in those of Acheta domesticus, there are a large number (>100) of subsegments (flagellomeres) that vary in their length. We evaluated whether these antennae bend only at the joints between flagellomeres, which has always been assumed but not tested. In addition we questioned whether an antenna undergoes a length change as it bends, which would result from some patterns of joint deformation. Measurements using light microscopy and SEM were conducted on both male and female adult crickets (Acheta domesticus) with bending in four different directions: dorsal, ventral, medial, and lateral. Bending occurred only at the joints between flagellomeres, and antennae shortened a comparable amount during bending, regardless of sex or bending direction. The cuticular folds separating antennal flagellomeres are not very deep, and therefore as an antenna bends, the convex side (in tension) does not have a lot of slack cuticle to "unfold" and does not lengthen during bending. Simultaneously on the other side of the antenna, on the concave side in compression, there is an increasing overlap in the folded cuticle of the joints during bending. Antennal shortening during bending would prevent stretching of antennal nerves and may promote hemolymph exchange between the antenna and head

Characterization of the 2-Phase Turning Response of Madagascar Hissing Cockroach Biobots to Antennal Stimulation

Biobots are living insects that are controlled via neurostimulation applied through implanted electrodes and have a variety of potential applications such as search and rescue operations. Madagascar Hissing Cockroaches (MHCs) are commonly used as biobots; however, their use remains under investigation due to lack of a comprehensive motion profile in response to neurostimulation, which makes consistent control a challenge. MHC biobots often exhibit a 2-phase turning response to antennal stimulation, with an initial turn (primary) in the desired direction followed by a “corrective” turn (secondary) in the undesired direction. The purpose of this research is to characterize the 2-phase turning response of MHC biobots to antennal stimulation. Electrodes were implanted into the antennae of MHC biobots (n=20), and antennae of each subject were stimulated 40 times using a duty cycle of 50%, frequency of 125 Hz, and four sets of stimulus voltages and durations: 1 V and 0.5 s, 3 V and 0.5 s, 1 V and 1.5 s, and 3 V and 1.5 s. Modulation of stimulation voltage and duration did not significantly affect the responsiveness, direction of, or magnitude of turn angles. The direction of primary turns were found to be controlled in 88% of subjects, while the direction of secondary turns were able to be controlled in only 53% of subjects, which demonstrates that MHC biobots are able to be consistently controlled during the primary turn but not during the secondary turn. A histogram of the magnitude of secondary turns is centered approximately at 0°, which demonstrates that the secondary turn is likely when the cockroach regains control of its motion rather than a “corrective” turn as noted in previous studies. To improve MHC biobot technology, researchers could limit the amount of time between stimuli or introduce a feedback system where actual turn angle is measured, and stimuli are applied when the MHC biobot begins turning in the undesired direction

The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta . I. Sexual dimorphism in the distribution of antennal sense organs in five species

Sexual dimorphism in the distribution of antennal sense organs is common among adults of the genus Periplaneta. In three out of the four strains of Periplaneta americana examined, adult males had more contact chemoreceptors than females. In the fourth strain of P. americana and in P. australasiae, P. brunnea, P. fuliginosa , and P. japonica , no statistically supportable sexual dimorphism of contact chemoreceptors was found. However, in all strains and species of Periplaneta examined, sexual dimorphism was found in the total number and/or density of olfactory sensilla. Male adults had nearly twice as many olfactory sensilla as female adults. These observations are consistent with the behavioral observation that males within the genus Periplaneta rely on the reception of an airborne pheromone for the initiation of courtship behavior. In P. americana , where sexual dimorphism was found in the contact chemoreceptors, contact stimuli release the full wing raising display and presentation in males during courtship.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50261/1/1051490202_ftp.pd

Antennal Depression as a Consummatory Response in the Madagascar Hissing Cockroach

Sign-tracking is a counterintuitive response that occurs when a signal stimulus is paired with reinforcement. Sign- and goal-tracking studies have been replicated across several species including pigeons, rats, quail, and cuttlefish. To date, no sign-tracking studies with the Madagascar Hissing Cockroach (MHC) are in the literature. Replicating sign-tracking studies with this new species is essential to an understanding how this counter-intuitive behavior occurs, particularly in invertebrate species like the MHC. To establish research on MHC sign- and goal-tracking, however, will first require ethological studies to identify potential dependent variables that indicate MHC responses to meaningful versus neutral stimuli. This study identifies the response topography of consummatory behavior in the MHC, for use with future studies

Auto-spermatophore extrusion in male crickets

The reproductive cycle of the male cricket consists of the mating stage and the sexually refractory stage. The latter is further divided into the first refractory stage (RS1) from spermatophore extrusion in copulation to spermatophore preparation after copulation, and the second refractory stage (RS2) from spermatophore preparation to recommencement of a calling song. RS2 is time-fixed and unaffected by the female or by stress, hence RS2 is assumed to be controlled by the reproductive timer. Previously, we suggested that the timer is located in the terminal abdominal ganglion (TAG), because functional inactivation of the TAG by local cooling lengthened RS2 in proportion to cooling time. To obtain further evidence of timer localization and to examine the operation of the timer in dissected animals, we investigated the characteristics of auto-spermatophore extrusion, a phenomenon in which males eject the mature spermatophore themselves without any prior courtship. The occurrence of auto-spermatophore extrusion was 100% in dissected males with the TAG separated, compared to 1.7% in intact males. The time interval (SPaSE) between spermatophore preparation and autospermatophore extrusion was comparable to RS2 measured by the calling song. Spike recording from a genital motor neurone in the separated TAG indicated that burst discharge associated with auto-spermatophore extrusion occurred with a SPaSE comparable to RS2. Other efferent neurones, some of which were identified as dorsal unpaired median (DUM) neurones, showed a timedependent spike frequency increase during SPaSE. These results strengthen our previous conclusion that the reproductive timer is located within the TAG, and demonstrate that the timer functions normally even when the TAG is separated from the central nervous system.</p

Analysis of the direction of escape response of crickets to looming-object stimulation

Arthropods such as cockroaches, locusts, and crickets exhibit various escape strategies in response to wind, tactile, and looming stimulation. Cockroaches typically run from aversive stimuli, while locusts execute large jumps away from stimulation, and crickets display a combination of both walking and jumping techniques in response to stimulation. Looming object stimulation is perhaps the best type of stimulation to obtain information about how arthropods would respond to aversive stimuli in a natural setting, as it most accurately represents the complexity of multimodal inputs received by arthropods from external sources of stimulation while being preyed upon in the wild. Previous studies regarding looming object stimulation have centered mainly upon the response direction of locusts to the aversive stimuli, while not much research has been done with crickets. Further, the few studies regarding the response of crickets to looming stimulation focused on the type of escape strategy executed by crickets as well as whether or not their escape was successful, while the escape direction of the cricket in response to looming stimulation has not been as widely studied. As a result, the specific aim of this study was to determine whether the escape direction of the cricket was dependent upon the angle of approach of the looming stimulus. In response to looming stimulation, crickets displayed a combination of turning and either walking or jumping away from the incoming stimulus (a black ball). The degree of turn of the cricket’s body was significantly dependent upon the angle of the incoming stimulus, and crickets almost always moved away from the direction of the looming object