Repellent activity of Abroma augusta extracts against Tribolium castaneum (Herbst) adults

Context: Repellency test can play an important role in special environmental conditions. Objectives: The main objective of this study was to make a standard protocol to control the pest by screening the test materials using adult beetles by repellency test to see whether or not the extracts contain any potential to repel the stored grain pest. Materials and Methods: The experiment was conducted in choice chamber, which was divided by half filter paper discs (Whatman No. 40, diameter 9 cm). One half of the filter paper was loaded with untreated (control) and the other half was loaded with the extract of A. augusta. All the CHCl3 extracts were separately applied onto each of the half-discs and allowed to dry out in the air for 10 mins. Each treated half-disc was then attached lengthwise, edge-to-edge, to a control half-disc with adhesive tape and placed in petri dishes. The orientation of the same was changed in the replicates to avoid the effects of any external directional stimulus affecting the distribution of the test insects Tribolium castaneum (Herbst). Ten adult insects were released in the middle of each of the filter-paper circles and each test was replicated five times. Results: All the test extracts of seed, leaves, root wood, stem bark and stem wood of A. augusta collected in chloroform showed repellent activity against adult beetles of T. castaneum at dose levels of 314.540, 157.270, 78.635, 39.318, 19.659 and, 9.831 ?g/cm2 on filter paper. According to the intensity of repellency the results could be arranged in the order: stem bark >seed> root wood > leaf > stem wood and in all the cases significant differences were obtained. Conclusion: The present results revealed that A. augusta extracts can be used as a reduced risk repellent compound in the grain and cereal stores to manage the population of T. castaneum. The results also seen to be encouraging when there is a greater need for environment-friendly pesticides then ever before. DOI: http://dx.doi.org/10.3329/jbs.v20i0.17655 J. bio-sci. 20: 49-55, 2012

HUMAN AUDIO/VESTIBULAR SYSTEM: DATA INPUT CHANNELS FOR ROBOTIC FORCE AND MOMENT SENSOR MEASUREMENTS

The design goal was development of an intuitive human machine interface for force and moment data from space robotic operations. This paper defines overall requirements and goals. It describes experimental approaches used to evaluate our ‘nature’ inspired solution. The final portion of the paper discusses the design and prototyping of the segment of the problem which has lead to our first product. One of nature’s ways of presenting multiple degree of freedom (dof), vector data is through our audio and vestibular systems. This directional capability is being applied as a human machine interface (HMI) for robotic force sensing. Human audio direction ability is accurate except for sounds generated above and behind our heads. This inaccuracy has lead us to the development of the vestibulator. The vestibulator is a wireless device which applies low levels of current, to the human subject mastoid bones through surface mounted electrodes. These induce perceptions of tilt. The polarity of the signals provide directional stimulus.

Photo-gyrotactic bioconvection

Many microorganisms exhibit taxes, biased swimming motion relative to a directional stimulus. Aggregations of cells with densities dissimilar to the medium in which they swim can induce hydrodynamic instabilities and bioconvection patterns. Here, three novel and mechanistically distinct models of the interaction of the two dominant taxes in suspensions of swimming phototrophic algae are presented: phototaxis, swimming towards or away from light, and gyrotaxis, a balance between viscous and gravitational torques. The descriptions are accordant with, and extend, recent rational models of bioconvection. In particular, the first model is for photokinesis–gyrotaxis, the second varies the cells' centre-of-mass offset, and the third introduces a reactive phototactic torque associated with the propulsive flagellar apparatus. Equilibria and linear-stability analysis in a layer of finite depth are analysed in detail using analytical and numerical methods. Results indicate that the first two models, despite their different roots, remarkably are in agreement. Penetrative and oscillatory modes are found and explained. Dramatically different behaviour is obtained for the model with phototactic torques: instabilities arise even in the absence of fluid motion due to induced gradients of light intensity. Typically, the response of microorganisms to light is multifaceted and thus some combination of the three models is appropriate. Encouragingly, qualitative agreement is found with recent experimental measurements on the effects of illumination on dominant pattern wavelength in bioconvection experiments. The theory may be of some interest in the emergent field of bioreactor design.

The alignment of the axis of asymmetry in regenerating protoplasts of the moss, Ceratodon purpureus, is determined independently of axis polarity

Ceratodon protoplasts regenerate by polar outgrowth to form cell filaments. The kinetics of regeneration show that some cellular event has to be completed before regeneration can be initiated. The development of the regeneration axis is strongly influenced by light, with axis alignment and axis polarity being fixed independently. We define axis alignment as the relationship of the regeneration axis to the incident light, independent of polarity. Thus protoplasts regenerating directly towards, or directly away from the light source are defined as being similarly aligned but with opposite polarity. Protoplasts that regenerate in unidirectional red light form axes that are aligned parallel to the light direction, with about 70% being polarised towards the light and about 30% away. In unidirectional blue or white light, almost all protoplasts regenerate towards the light but axis alignment is determined less stringently. Re-orientation of protoplasts regenerating in unidirectional light shows that axis alignment is fixed between 8 and 9 hours before protoplasts regenerate and that axis polarity is fixed later. When protoplasts are removed from directional light to either non-directional light or to darkness, regeneration axes continue to be aligned by the earlier directional stimulus for at least 24 hours. Thus although axis alignment is fixed only about 8 hours before regeneration, in the absence of contradictory information about directionality in the light environment, protoplasts retain a memory of light direction for much longer. However, both reorientation and removal from a directional light field have profound effects on axis polarity; the pattern observed in undisturbed protoplasts being lost. To account for these observations, we propose that separate gradients are established independently to determine the alignment and polarity of the regeneration axis respectively. The alignment gradient is established rapidly and is steeper in red than in blue or white light, the polarity gradient is established slowly and is steeper in white or blue light than in red. These studies will now allow a genetic dissection of these processes in moss.

Monkey hippocampal neurons related to spatial and nonspatial functions

1. Neural activity in the monkey hippocampal formation (HF) was analyzed during a spatial moving task in which the monkey was guided by auditory and visual cues and when stimuli were presented from various directions. The monkey could control a motorized, movable device (cab) and its route to a target location by pressing the proper one of five available bars in an appropriate sequence (spatial moving task). In any of several locations in the field, neural responses were evident in relation to the presentation of various objects or human movement in some relative direction (left, anterior, right) as a directional stimulus test. 2. Of 238 hippocampal neurons analyzed, 172 (72.3%, 238-66) responded in either the spatial moving task, or to the direction from which stimulation was presented, or to the location of the monkey in the field, or to some combination of these. 3. The activity of 79 (33.2%) neurons was higher when the monkey was in some specific location in the field during the spatial moving task, regardless of the approach route or other task parameters (place related neurons). 4. Responses to the task cues in the spatial moving task were evident in 110 (46.3%) neurons (task related neurons). Of these, 77 (32.4%) neurons were not place related. The remaining 33 (13.9%) neurons were both task related and place related. These neurons responded to task cues in only that part of the field in which place related responses occurred. The neural response to the task cues disappeared when the monkey moved out of the place response region. The place related and task related neural responses disappeared when the room light was switched off. Thus information from the environment outside of the cab contributed to the place related and task related responses. 5. Stimuli presented from certain specific directions induced responses, selectively, in 41 (17.2%) of the neurons (direction related neurons). The dependence of the preferred direction was described in one of three ways--egocentric, allocentric, or place-direction specific. Nineteen egocentric neurons responded to a stimulus only when it was presented from a certain direction relative to the orientation of the monkey, regardless of the location of the monkey. Eleven allocentric neurons responded to a stimulus only when it was presented at a particular position in the room, regardless of the location or orientation of the monkey.(ABSTRACT TRUNCATED AT 400 WORDS)

THE EFFECTS OF PHYSICAL STIMULI ON THE LARVAL STAGE OF TERRANOVA DECIPIENS: III. ELECTROMAGNETIC SPECTRUM AND GALVANOTAXIS

Various frequencies in the range of 25.9 kc to approximately 100 mmmc were used as a source of stimuli to the larval stage of the nematode Terranova decipiens. Larvae exposed to 650 kc ultrasound were killed in 4 minutes, while those exposed to 25.9 and 1000 kc were killed in 30 and 270 minutes respectively. The larvae were not affected by radiation produced either in the radio- or the micro-wave frequencies. Light radiation of less than 280 mμ had no effect on the nematode, while fish muscle insulated the larvae from the limited effects of radiations between 253.7 to 900 mμ. The larvae showed no photo tactic response. When exposed to 4 million roentgen equivalent physical, the larvae died immediately (LD50); however, after a latent period of 288 hours a much lower dose (400,000 rep) will bring about death. The larvae were stimulated by low-level direct current applied intermittently, but exhibited no directional response to any level of alternating or direct current. The low resistance offered by the fish muscle habitat of the nematode excludes any application of directional stimulus.

The Orientation of Ants

1. Von Frisch has shown that in the honey-bee orientation established in relation to one directional stimulus (light) can be transferred to another directional stimulus (gravity or polarized light). In the present work the orientation of ants has been studied in experiments in which one type of directional stimulus has been replaced by another. Light, gravity and polarized light have been used as stimuli. 2. When light and gravity are interchanged, the ant's successive orientations to the two stimuli are correlated. The angle between the track and the stimulus is the same for both orientations. 3. When light and polarized light are interchanged, the ant's successive orientations are again correlated. The actual relationship depends on the experimental conditions. 4. When polarized light and gravity are interchanged there is no significant correlation between successive orientations. 5. It is suggested that in bees and ants there is a single taxis mechanism for orientation to light, polarized light and gravity, and that the ‘setting’ of this mechanism during an orientation to one stimulus persists and partially determines the subsequent orientation to another stimulus.