Walking and take-off in Aphis fabae.

ABSTRACT. A walking aphid ready to emigrate is directed by light, gravity and mechanical stimuli to the upper and outer parts of the plant. There, the new conditions enhance the probability of take-off, as a kinetic response, but the precise moment at which the aphid stops walking and takes flight does not depend on any new external ('releasing') stimulus. The probability of take-off, then, appears to depend partly on substrate stimuli received during walking. Aphids were tested either when suspended by the thorax (and carrying and walking on spheres or paper bands) or when walking on a treadmill with a variable surface structure and aspect relative to gravity. A variety of situations that stimulated faster walking (e.g. a 'cat-walk'), also delayed take-off. Other situations that retarded walking (e.g. being upside-down), similarly delayed taking off, and tended as well to induce probing of the surface. A common feature of these latter situations appeared to be that they elicited traction movements of the legs on the surface: a flexor reflex opposed to the leg extension that regularly precedes a take-off.     

Ensemble activity of neurons in the visual, frontal, and sensorimotor cortices and dorsal striatum during actualization of behavioral program under conditions of strategy choice

Unit and network activity of neurons in the visual, sensorimotor, and frontal cortical areas and dorsal striatum was investigated in cats under conditions of choice of the reinforcement value depending on its delay. The animals did not differ from each other in behavior. After immediate or delayed responses cats got low- or highly-valuable reinforcement, respectively. Single-unit activity in the visual and sensorimotor cortical areas and dorsal striatum was similar during performance of immediate and delayed responses. However, significant inhibition was observed in the frontal neurons during the delay period. The network activity of visual and frontal cortex displayed smaller number of interneuronal interactions during delayed responses as compared to immediate reactions. The network activity of neurons in the brain structures under study pointed to the interstructural interaction, but only during delayed reactions, steady interneuronal communication was observed between the frontal cortex and dorsal striatum. Thus, both types of estimation of cellular activity revealed differences in the ensemble organization during different types of behavior and showed specific reactions of neuronal ensembles.     

Take-off and the 'tarsal reflex' in Aphis fabae

ABSTRACT. In the transition from walking to flight in free and tethered aphids, forward progression was more or less abruptly checked and the walking pattern of leg movements gave way to a stationary, treading phase. This was followed by leg extension and wing-spreading, kicking of the mesothoracic legs, wing-beating and final lift-off. Removal of the wings, but not of the middle legs, inhibited this pre-take-off behaviour. Jumping appeared to play no part in takeoff, nor did loss of tarsal contact stimulate flight in tethered aphids but resulted only in wing-raising. However, restoration of tarsal contact often resulted in immediate take-off, as well as stimulating post-flight wing-folding, Wing-beating, but not wing-raising, was apparently inhibited during walking.     

Behaviour of coconut mites preceding take-off to passive aerial dispersal

For more than three decades the coconut mite Aceria guerreronis Keifer is one of the most important pests of coconut palms and has recently spread to many coconut production areas worldwide. Colonization of coconut palms is thought to arise from mites dispersing aerially after take-off from other plants within the same plantation or other plantations. The underlying dispersal behaviour of the mite at take-off, in the airborne state and after landing is largely unknown and this is essential to understand how they spread from tree to tree. In this article we studied whether take-off to aerial dispersal of coconut mites is preceded by characteristic behaviour, whether there is a correlation between the body position preceding aerial dispersal and the direction of the wind, and whether the substrate (outer surface of coconut bracts or epidermis) and the wind speed matter to the decision to take-off. We found that take-off can sometimes be preceded by a raised body stance, but more frequently take-off occurs while the mite is walking or resting on its substrate. Coconut mites that become airborne assumed a body stance that had no relation to the wind direction. Take-off was suppressed on a substrate providing food to coconut mites, but occurred significantly more frequently on the outer surface of coconut bracts than on the surface of the fruit. For both substrates, take-off frequency increased with wind speed. We conclude that coconut mites have at least some degree of control over take-off for aerial dispersal and that there is as yet no reason to infer that a raised body stance is necessary to become airborne.     

Behavioural evidence for detection of the repellent polygodial by aphid antennal tip sensilla

Abstract. Close-up video was used to record responses of the aphid Myzus persicae (Sulzer) (Homoptera: Aphididae) to the plant-derived repellent polygodial. When 0.1% (±)-polygodial was painted onto one half of a Chinese cabbage leaf disc, and the other half treated with the ethanol solvent, apterous adult aphids avoided walking onto the polygodial-treated area during 15 min access periods. Similarly, when the rim of a small plastic Petri dish was treated with polygodial, aphids took significantly longer to walk off the base of the dish and onto the rim, compared with insects in solvent-treated control dishes. Analysis of video-recordings indicated that aphids were repelled following contact of antennal tips with the polygodial-treated areas of leaf or plastic. In contrast, aphids with both antennal tips surgically removed showed no apparent response to polygodial treatment of leaf or plastic surfaces. Aphids were placed between polygodial- and solvent-treated angled glass cover slips to enable unilateral presentation of polygodial on either the left or right side of the insects. Most aphids with antennae intact moved away from the polygodial-treated side, but removal of both antennal tips again negated the response. When the tip was removed from only one antenna, and the other remained intact, unilateral presentation caused a repellent response only if polygodial occurred on the same side as the intact antenna. Presentation of polygodial on both sides of aphids (bilaterally) caused no response if both antennal tips were intact or removed, but aphids with only one antennal tip removed were repelled from the side where the antenna remained intact. The results indicate that aphids detect polygodial upon contact with sensilla located on the antennal tips, and that the repellent response occurs as a negative chemotropotaxis following unilateral stimulation of these sensilla. Contact between the antennal tips and glass substrates was demonstrated using a fluorescent pigment.     

Neural Basis of Stimulus-Angle-Dependent Motor Control of Wind-Elicited Walking Behavior in the Cricket Gryllus bimaculatus

Crickets exhibit oriented walking behavior in response to air-current stimuli. Because crickets move in the opposite direction from the stimulus source, this behavior is considered to represent ‘escape behavior’ from an approaching predator. However, details of the stimulus-angle-dependent control of locomotion during the immediate phase, and the neural basis underlying the directional motor control of this behavior remain unclear. In this study, we used a spherical-treadmill system to measure locomotory parameters including trajectory, turn angle and velocity during the immediate phase of responses to air-puff stimuli applied from various angles. Both walking direction and turn angle were correlated with stimulus angle, but their relationships followed different rules. A shorter stimulus also induced directionally-controlled walking, but reduced the yaw rotation in stimulus-angle-dependent turning. These results suggest that neural control of the turn angle requires different sensory information than that required for oriented walking. Hemi-severance of the ventral nerve cords containing descending axons from the cephalic to the prothoracic ganglion abolished stimulus-angle-dependent control, indicating that this control required descending signals from the brain. Furthermore, we selectively ablated identified ascending giant interneurons (GIs) in vivo to examine their functional roles in wind-elicited walking. Ablation of GI8-1 diminished control of the turn angle and decreased walking distance in the initial response. Meanwhile, GI9-1b ablation had no discernible effect on stimulus-angle-dependent control or walking distance, but delayed the reaction time. These results suggest that the ascending signals conveyed by GI8-1 are required for turn-angle control and maintenance of walking behavior, and that GI9-1b is responsible for rapid initiation of walking. It is possible that individual types of GIs separately supply the sensory signals required to control wind-elicited walking.     

Take-off activity in caged desert locusts,Schistocerca gregaria (Forsk.) (Orthoptera,Acrididae) in relation to meteorological disturbances

Take-off activity of the desert locust,Schistocerca gregaria (Forsk.), phasegregaria, was studied in a temperature-controlled laboratory environment and possible relationships with certain meteorological factors were analysed. A statistically significant relationship between the passage of cold fronts and an increased take-off rate was found. The reaction of the locusts could not be correlated to changes in VLF electromagnetic radiation or to the atmospheric pressure.     

Relationship Between the Reaction Time and EEG Parameters During Judgments on the Correspondence of Delayed or Simultaneously Presented Images of Two Models

This study examined how judging whether the poses of two figures are the same in tasks with delayed and simultaneous image presentation affects the participants’ reaction times and electroencephalograms (EEGs). Eighteen university students performed a delayed task, in which an image of a doll was first presented for 3 sec followed by a second image of the doll, and a simultaneous task, in which images of two dolls were presented on the left and right sides of the monitor at the same time. The dolls were shown from the front and rear angles. The participants were instructed to judge whether the images were the same as accurately and quickly as possible, and the reaction times were recorded. EEG signals were recorded from Fp1, Fp2, F3, F4, C3, C4, P3, and P4. The reaction times in the delayed task were found to be shorter then those in the simultaneous task, and that these times for the 0° condition were shorter than for the 180° condition. The amplitudes of EEG responses at Fp1 and Fp2 were larger than those at other electrodes, and the responses in the right hemisphere during the 180° condition and the delayed task within the α1 frequency band were smaller than the responses at other electrodes. These results indicate that cerebral activity in the frontal region of the right hemisphere is associated with the judgment of correspondence or non-correspondence in spatial compatibility tasks.     

Odour-conditioned anemotaxis of apterous aphids (Cryptomyzus korschelti) in response to host plants

ABSTRACT. Orientation responses of adult apterous virginoparae of Cryptomyzus korschelti Börner were recorded using a locomotion-compensator in front of a wind tunnel. Individual aphids were tested under four consecutive treatments: without wind; clean wind; and wind carrying odour of the host plant Stachys sylvatica or odour of a non-host plant Solanum tuberosum. The walking tracks were tortuous in all treatments except when the odour of host plants was used. Host plant odour induced upwind orientation of aphids (odour-conditioned positive anemotaxis). Track variables such as vector length, straightness, upwind time and upwind length, increased when the aphids moved upwind. Walking speeds were not affected. The simultaneous stimulation by wind and host plant odour caused aphids to walk upwind for more than 1 m in 10 min. These findings suggest that olfactory attraction of aphids is involved in host plant selection.     

Morphometric relationships of take-off speed in anuran amphibians

Locomotory speed correlates with muscle mass (determining force and stride rate), limb length (stride rate and distance), and laterally compressed body trunk (force and stride distance). To delineate generalization of the locomotory-morphometric relationships specifically in anuran amphibians, we investigated take-off speed and the three morphological variables from seven species, Rana nigromaculata, R. rugosa, and Bombina orientalis, Eleuthrodectilus fitzingeri, E. diastema, Bufo typhonius, Colostethus flotator and Physalaemus pustulosus. The fastest jumper E. fitzingeri (3.41 m s(-1)) showed 2.49-fold greater speed than the slowest B. typhonius. Take-off speed correlated well with both thigh muscle mass relative to body mass and hindlimb length relative to snout-vent length (HL/SVL), but poorly correlated with the inter-ilial width relative to SVL. The best morphological predictor was HL/SVL (speed=-3.28+3.916 HL/SVL, r=0.968, P<0.0001), suggesting that anuran take-off speed is portrayed well with high gear and acceleration distance characterized by hindlimbs.     

紫外辐射对两种体色型麦长管蚜生物学特征的影响

紫外辐射对蚜虫产生了强烈的选择压力,可导致蚜虫种下遗传分化,而紫外辐射对蚜虫种下体色分化的影响尚不清楚.本研究选定两种不同体色型的麦长管蚜初生若蚜经过30 W紫外线（UVB波）照射5 d,每天30 min,在不同温度（15 ℃、20 ℃和25 ℃）和不同小麦品种（小偃-22、Astron）条件下,通过在人工智能控制温室内单头饲养,分别测定了各处理麦长管蚜的发育历期、体质量差及相对日均体质量增长率等生物学参数.结果表明：在品种小偃-22上,温度较低时,紫外辐射显著延缓了绿色型麦长管蚜生长,而温度较高时,紫外辐射显著延缓了红色型麦长管蚜生长;在品种Astron上,温度较低时,紫外辐射显著延缓了绿色型麦长管蚜生长,而温度较高时,紫外辐射对两种体色型麦长管蚜生长均无显著影响.说明两种体色型蚜虫对紫外胁迫的反应不同,且紫外胁迫对麦长管蚜的影响与温度和小麦品种有关.     

Take-off flight performance in the butterfly Pararge aegeria relative to sex and morphology: a quantitative genetic assessment

Adult fitness components may strongly depend on variation in locomotory performance such as flight; this variation can be sex specific. Fast take-off to intercept females and competing males is an essential behavioral component of the territorial perching behavior in male speckled wood butterflies (Pararge aegeria L.). Females on the other hand avoid frequent take-offs particularly under suboptimal temperatures, typically showing fewer but longer flights than males. We estimated the heritability of take-off acceleration performance under suboptimal body temperatures by a restricted maximum-likelihood model. We calculated genetic correlations between this performance and a selection of morphological traits: size (body mass), flight muscle investment (relative thorax mass), and wing shape (forewing aspect ratio). Our results show significant additive genetic variation for mean acceleration performance and a similar but nonsignificant trend (P= 0.08) for maximal acceleration performance during take-off in males (h(2)= 0.15). In females, heritability was not significantly different from zero for either of the acceleration performance measures. Morphological traits and take-off performance were genetically linked in a sex-specific way. In males, relative thorax mass and forewing aspect ratio were positively genetically correlated with acceleration performance. In females, there was a negative genetic correlation between acceleration performance and abdomen mass, but not with residual abdomen mass (i.e., regressed on total body mass). To fully understand the evolution of sexual differences in flight performances and morphology, several other flight performances will have to be included. This multifunctional nature of flight and its consequences for the evolutionary study of flight has not yet been fully appreciated in the literature.     

Alarm pheromone eliciting attack and escape responses in the sugar cane woolly aphid,Ceratovacuna lanigera (Homoptera,Pemphigidae)

All nymphal stages and apterous adults ofCeratovacuna lanigera secreted droplets containing an alarm pheromone from their abdominal cornicles when stimulated with a pin. When fresh droplets on piece of filter paper were put near the aphids, 1st-instar nymphs originating from apterous adults attacked it, but the advanced instar nymphs and adults escaped from the spot. Nymphs and adults originating from alate adults showed escaping behavior only. These different responses strongly correlated with morphological differences, such as relative lengths of the frontal horns and legs. When a syrphid larva,Allograpta javana, was placed on a colony of aphids, many 1st-instar nymphs attacked it using their frontal horns. During the attack, these nymphs spontaneously secreted droplets and adhered them to the syrphid body. When these droplets were placed on the body, the syrphid larva was agressively attacked by additional 1st-instar nymphs.     

Thermoregulatory behavior, heat gain and thermal tolerance in the periwinkle Echinolittorina peruviana in central Chile

The amount of solar radiation absorbed by an organism is a function of the intensity of the radiation and the area of the organism exposed to the source of the radiation. Since the prosobranch gastropod Echinolittorina peruviana is longer than it is wide, its areas of the lateral sides are approximately twice as large as the areas of the frontal and dorsal faces. We quantified the orientation of the intertidal prosobranch E. peruviana with respect to the position of the sun and solar heat gain in the different orientations. In the field, 80.9% of the E. peruviana monitored on sunny summer days tended to face the sun frontally or dorsally while only 19.1% faced the sun with the larger lateral sides. On overcast summer or on winter days, this trend was not observed. We then show that the body temperature of individuals increases more rapidly and reaches higher equilibriums when the lateral sides are facing the sun than when they face the sun with either of the smaller frontal or dorsal sides. These results therefore show that the orientation behavior of E. peruviana is thermoregulatory and that it permits the organisms to maintain lower temperatures on hot summer days.     

Locomotory activity in the extensor and flexor tibiae of the cockroach, Periplaneta americana

Electromyograms (EMGs) were recorded from the metathoracic extensor and flexor tibiae of cockroaches when the animals were: walking on a level surface, walking on a ball, or producing rhythmic leg movements while being restrained ventral surface upward. In the rapidly walking (> 2 steps/s) and restrained animals, there was reciprocity between EMGs from the extensor and flexor tibiae. In slowly walking (<-2 steps/s) animals there was a conspicuous overlap in the flexor and extensor EMGs. The overlap was due to an increase in duration in the activity of the flexor. In experiments in which distal portions of a limb were amputated, the overlap observed in slow walking was either reduced greatly or lost entirely. These results are in agreement with recent locomotory models which state that the motor output is produced by a central pattern generator but can be modified by peripheral sensory inputs.     

Locomotory behaviour of the seven-spotted ladybird, Coccinella septempunctata, in response to five commonly used insecticides

Coccinella septempunctata is known to actively avoid substrates treated with an insecticide containing the organophosphate dimethoate. This study examines the responses of C.   septempunctata to a range of different insecticide products from three chemical classes, carbamates, organophosphates and pyrethroids. Five formulated product insecticides were compared with the active ingredients (AIs) at two different application rates and using two different spray patterns (conferring choice or no-choice designs) in a randomised block design. Coccinellids' responses differed between insecticide classes. Pyrethoid treatments significantly reduced locomotion. Organophosphates effected mixed locomotory responses, as found in previous studies. Carbamate treatments effected very few changes in locomotory activity. Similar results were found at both application rates tested and under different test designs. The results of the AI tests indicated that different components of the products were responsible for the different reactions, with the AIs being responsible for some responses but the carriers being responsible for others. Results are discussed in relation to the insecticides' modes of action and to their potential to increase the efficiency of integrated aphid control.     

Light Environments Differently Affect Parasitoid Wasps and their Hosts’ Locomotor Activity

In natural environments, organisms must adapt to changing light conditions. Significant research has been done on diurnal pollinating insects’ vision. However, little is known on parasitoid insects. Here, we studied how locomotor activity of the parasitoid wasp Aphidius ervi and its main host, the pea aphid Acyrthosiphon pisum, is affected under controlled artificial illumination. Using LEDs of 5 different wavelengths (361, 450, 500-600, 626 and 660 nm), we created different artificial light spectra that parasitoids and host aphids can encounter in natural environment including leaf-shade and direct sunlight. We found that pea aphid probability of walking depended on interactions between illumination, developmental stage and genotype as expressed in clonal variation. Artificial light intensity did not affect the parasitoid’s probability of walking as opposed to wavelength, and activity depended on the sex of individuals. Males were more active than females under all monochromatic wavelength spectra tested. Virgin females were much less active under the artificial leaf-shade illumination and artificial sunlight, as compared to males and mated females. Delay before flight for females was favored by sunlight illumination whereas the light environment did not affect flight delay for males. We demonstrated that locomotor activity of A. pisum (walking) and of A. ervi (walking and flight) vary according to the light environment. This study should help develop better understanding of the effects of illumination on host-parasitoid interactions, which in turn may help control insect pest populations.     

In vivo strain in the humerus of pigeons (Columba livia) during flight

Longitudinal and principal strain recordings were made in vivo at three sites (dorsal, anterior, and ventral) on the humeral midshaft of pigeons executing five modes of free flight: Take-off, level flight, landing, vertical ascent, and near-vertical descent. Strains were also recorded while the birds flew carrying weights that were 33%, 50%, or 100% of their body weight. The relative distribution of strain measured at the three surface midshaft sites and across the bone's cortex was found to be similar for all flight modes. Principal strains recorded in the dorsal and ventral humerus indicated considerable torsion produced by aerodynamic loading of the wing surface posterior to the bone. Measured torsional shear strains (maximum: 2,700–4,150 μ ε during level flight) were 1.5 times greater than longitudinal strains. In addition to torsion, the humerus is also subjected to significant dorsoventral bending owing to lift forces acting on the wing during the downstroke. Analysis of the cross-sectional distribution of longitudinal strains at the humeral midshaft cortex shows that the orientation of bending shifts in a regular manner during the downstroke, indicating that the wing generates progressively more thurst (vs. lift) later in the downstroke. This shift is less during take-off and vertical ascent when greater lift is required. Peak principal and longitudinal strains increased by an average of only 50% from landing to vertical ascending flight and take-off (e.g., dorsal humerus: ?1,503 to ?2,329 μ ε) and did not exceed ?2,600 μ epsiv; at any site, even when the birds flew carrying twice their body weight. Strains recorded when birds flew at two times their body weight (100% BW load) were similar in magnitude to those recorded during vertical ascent and take-off and likely represent those developed during maximal performance. Strains developed within the midshaft were maximal in the anterodorsal and posteroventral cortices, not at the dorsal, ventral, and anterior sites at which strain was recorded. Consequently, maximum strains experienced by the bone are probably 20–25% greater than those recorded (ca. 3,200 μ ε), indicating a safety factor of about 3.5 for compressive strain failure. The much higher shear strains, however, indicate a lower safety factor (1.9), in which the bone's torsional strength is its most critical design feature. Finally, the magnitude and distribution of strains developed in the humerus of pigeons are generally similar to those recorded in the humerus of large fruit-eating bats during flight. © 1995 Wiley-Liss, Inc.     

Alarm pheromone mediates production of winged dispersal morphs in aphids

The aphid alarm pheromone ( E )- β -farnesene (EBF) is the major example of defence communication in the insect world. Released when aphids are attacked by predators such as ladybirds or lacewing larvae, aphid alarm pheromone causes behavioural reactions such as walking or dropping off the host plant. In this paper, we show that the exposure to alarm pheromone also induces aphids to give birth to winged dispersal morphs that leave their host plants. We first demonstrate that the alarm pheromone is the only volatile compound emitted from aphid colonies under predator attack and that emission is proportional to predator activity. We then show that artificial alarm pheromone induces groups of aphids but not single individuals to produce a higher proportion of winged morphs among their offspring. Furthermore, aphids react more strongly to the frequency of pheromone release than the amount of pheromone delivered. We suggest that EBF leads to a 'pseudo crowding' effect whereby alarm pheromone perception causes increased walking behaviour in aphids resulting in an increase in the number of physical contacts between individuals, similar to what happens when aphids are crowded. As many plants also produce EBF, our finding suggests that aphids could be manipulated by plants into leaving their hosts, but they also show that the context-dependence of EBF-induced wing formation may hinder such an exploitation of intraspecific signalling by plants.     

Different kinetics of membrane potential formation in dark-adapted and preilluminated chloroplasts

The effects of varying dark interval on the kinetics of light-induced formation of the membrane potential were studied on individual chloroplasts of Anthoceros with the use of capillary microelectrodes. Illumination of the chloroplast with 1 s light pulse after 3 min dark period induced the photoelectrical response with two peaks of the potential that were located at 20 and 500 ms after the onset of illumination. The position of the second peak was shifted along the time-scale depending on the preceding dark interval. The repeated illumination of the chloroplast with 1 s light pulse after 30 s dark interval induced the electrical response with only one maximum and a monotonous decay of the potential in the light. Distinctions in the electrical responses induced by the first and the second light pulses were eliminated by the addition of 50 μM dicyclohexylcarbodiimide (DCCD). The results show that the photoinduction kinetics of the membrane potential in chloroplasts is affected by functioning of H⁺-ATPase. The delayed peak of the membrane potential in the photoinduction kinetics is interpreted as a consequence of the photoactivated electron transport supported by Photosystem I.