bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dispersion and spatial orientation ofGerris remigisin response to water current: a comparison of pre‐ and post‐diapause adults
Authors: FAIRBAIRN D. J. , BRASSARD J. 
Published: March 2008

ABSTRACT.The movements and orientation of adultGerris remigisSay (Hemiptera; Gerridae) were examined in an artificial stream to determine the mechanisms by which these stream‐dwelling waterstriders compensate for and/or avoid downstream drift, and to compare the movement tendency of pre‐ and post‐diapause adults.G. remigisrespond to current by turning to face directly into the current (rotational orientation), intermittently rowing against the current (translational orientation), and moving onto land to avoid the current. These rotational and translational responses enableG. remigisto maintain their positions in currents =S10 cm s‐1. However, avoidance increases with current speed, and few animals are found where currents exceed 10 cm s‐1. These observations correlate well with the observed distribution of adultG. remigisin a natural stream.Comparisons between life stages reveal that post‐diapause adults move more, and are more susceptible to drift than pre‐diapause adults. Post‐diapause adults also avoid even slight currents (<5 cm s_1) by seeking land, while pre‐diapause adults do not show a significant preference for land until currents exceed 10 cm s‐1. These data suggest that previously reported differences in the movement tendency of pre‐ and post‐diapause adults in the field may reflect physiologically‐based behavioural differences between these two life stages rather than merely direct responses to environmental cues.
‘Bistability’ experiments and photoperiodic morph determination in the aphid Aphis fabae
Authors: NUNES MARLIES VAZ , HARDIE JIM 
Published: March 2008

Abstract. Newly born larvae (presumptive gynoparae) of the aphid Aphis fabae were exposed to ‘symmetrical skeleton’ photoperiods, consisting of two equal pulses of light per 24 h. The general form of the photoperiods tested was LDLD 1:10:1:12 h. This regime is open to two ‘interpretations’, LDLD 1:10:1:12 h (PPs12) and LDLD 1:12:1:10 h (PPs14). As both light pulses are close to 12 h apart, it is expected that the interpretations result in two distinct steady state phase relationships, i.e. this regime would show bistability. If this is true and both interpretations could be adopted, PPs12 is expected to result in a low and PPs14 in a high percentage of ‘apterized’ insects.Experiments undertaken with the aphid showed that bistability did not occur either at 15d̀C or 20d̀C, and the results could be entirely explained on the basis of an ‘instantly’ damping circadian oscillator clock.
Chemoreception of amino acids in larvae of two species of Pieris
Authors: VANLOON J.J.A. , VAN EEUWIJK F.A. 
Published: March 2008

ABSTRACT. Specificity and sensitivity of gustatory neurones in response to twenty‐two amino acids were studied in larvae of Pieris brassicae L. and Pieris rapae L. (Lepidoptera: Pieridae) using electrophysiological methods. Twelve amino acids stimulated a specific amino acid receptor cell in the lateral styloconic sensillum on the maxillary galea of both species, and a further two evoked single unit responses in the same sensillum of P.brassicae only. Histidine, phenylalanine and tryptophane were the weakest stimulants for P.brassicae, but were among the four best stimulants for P.rapae. In both species, eight amino acids were ineffective. Significant differences in stimulatory effectiveness were found between amino acids. Nutritionally essential amino acids were more effective in both species, as in five other lepidopterous species. Similarities with postulated sites for amino acid recognition in the dipteran Boettcherisca peregrina were found.Concentration‐response (C/R) relations were studied for five amino acids. Significant differences were found in saturated response levels. Parameters characterizing C/R relations were estimated using a logistic model. Comparing C/R parameters with phytochemical data on concentrations of free amino acids in a common host plant, Brassica oleracea L., shows that amino acids are effective stimuli at their natural concentrations. The amino acid chemoreceptor seems able to transmit information about concentration differences of amino acids in the plant tissue.
Differential responses of galeal gustatory sensilla of the adult Colorado potato beetle, Leptinotarsa decemlineata (Say), to leaf saps from host and non‐host plants
Authors: MITCHELL B. K. , ROLSETH B. M. , McCASHIN B. G. 
Published: March 2008

ABSTRACT Responses of galeal sensilla of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), to leaf sap from Solanum tuberosum and a number of other solanaceous and non‐solanaceous plants are described. A single cell responds vigorously to expressed sap from S.tuberosum, ‐and even to ten‐fold dilutions of expressed sap. The response is characterized by a high spike frequency, low phasic activity and a tonic phase which can last for tens of seconds. At 8 s following stimulus application the primary response is typically 50% of its original activity, indicating slow adaptation to the sap stimulus. The primary response varies little among multiple stimulations of single sensilla and among sensilla on the same animal. There is a secondary response to potato leaf sap from one or more cells which have low spike amplitudes. This is usually of much lower frequency than the response from the primary cell, and it is highly variable.The prominent and reproducible single cell response to potato sap may be an important component in signalling the presence of a host plant. This hypothesis is tested using saps from two other species of Solanum which are hosts, and several solanaceous and non‐solanaceous non‐hosts. Responses of galeal sensilla to the three host‐plants tested were qualitatively similar and reproducible while responses to the non‐hosts were highly variable and qualitatively different from responses to host saps. These results are interpreted and discussed in the context of a possible mechanism for chemosensory coding of complex stimuli in the insect/plant relationship.Analysis of the raw electrophysiological data required extensive use of a microcomputer and several programs were developed during the course of this study. The computer analyses are briefly described in the paper and additional information and copies of the programs are available from the authors.
Tarsal chemoreception in the polyphagous grasshopper Schistocerca americana: behavioural assays, sensilla distributions and electrophysiology
Authors: WHITE PETER R. , CHAPMAN REGINALD F. 
Published: March 2008

ABSTRACT Behavioural and electrophysiological responses of Schistocerca americana (Drury) (Orthoptera: Acrididae) to chemical stimulation of the tarsi were investigated. Using restrained insects, differences in leg‐waving behaviour were observed following stimulation by sucrose and nicotine hydrogen tartrate (NHT), compared to control stimulations by water. Furthermore, free‐walking insects were able to detect NHT on leaf surfaces, resulting in leg‐raising to avoid tarsal contact.SEM studies showed the presence of numerous peg chemoreceptor sensilla on the ventral surface of the tarsus. Tip recordings from such pegs showed activity from up to three chemosensitive neurones, plus a mechanoreceptor neurone. Stimulation by NaCl and KC1 elicited similar responses from two or three neurones in all sensilla tested, with increased firing rates at higher concentrations. Sucrose caused an increase in firing rate in few sensilla. In such cases several neurones were stimulated, and there was no evidence of a specific neurone sensitive to sucrose. In contrast, NHT elicited rapid firing in a single neurone, which was not sensitive to NaCl. Stimulation by NHT also inhibited the activity of the NaCl‐sensitive neurones.Possible mechanisms for chemical discrimination in S. americana tarsi are compared with those previously proposed for grasshopper mouthpart sensilla, and the significance of a NHT‐sensitive neurone in tarsal sensilla is discussed.
High sensitivity to sodium in the sugar chemoreceptor of the cherry fruit fly after emergence
Authors: STÄDLER ERICH , SCHÖNI RETO 
Published: March 2008

Abstract Recordings from the tarsal contact chemoreceptor D‐sensilla of the cherry fruit fly (Rhagoletis cerasi, Dipt., Tephritidae) revealed the presence of a cell which had a variable sensitivity spectrum. In about 60% of the sensilla of freshly emerged flies this cell was found to be very sensitive to sodium and to a lesser degree to lithium cations. Potassium and other alkali cations were non‐stimulatory. The anions tested, Cl‐, F‐, Br, NO3‐, and CO3‐, had no effect on the response to sodium.The same Na+‐sensitive receptor cells fired in response to stimulation with sucrose plus NaCl or sucrose plus KCI mixtures and were therefore considered to be sugar cells. This was confirmed by cross‐adaptation experiments using NaCl, and sucrose dissolved in dilute NaCl or KCI. However, the two adaptive stimuli were not acting symmetrically: NaCl did inhibit the following stimulation with sucrose, whereas sucrose had no effect on the subsequent NaCl stimulation. The response to sucrose and NaCl were not additive, sucrose being apparently, in some sensilla, inhibitory to the stimulation by NaCl. This observation, the lack of symmetry in adaptation, as well as the fact that only a proportion of the sensilla were sensitive to NaCl, seems to indicate that sodium had a different stimulating mechanism than sucrose.In most sensilla of flies older than 24 h, the Na+ sensitivity of the sugar cell was either reduced or completely lost. Behavioural observations of cherry fruit flies during the first 3 ½ days of adult life revealed that the flies fed little or not at all in the first 12 h. Thus the pronounced sodium sensitivity of the sugar cell early in adult life seems not to be correlated with a specific need for sodium intake but may have some role in the functioning of the sugar cell.
Effects of the corpora allata on sexual receptivity and completion of oocyte development in females of the cricket, Gryllus bimaculatus
Authors: ORSHAN L. , PENER M. P. 
Published: March 2008

Abstract Allatectomy of young penultimate nymphs of Gryllus bimaculatus De Geer (Gryllidae) resulted in prothetelic creatures which exhibited reproductive competence. The same operation performed on young last instar nymphs resulted in moulting to morphologically normal adults. Allatectomized morphologically normal adult females, as well as prothetelic ones, showed the same level of sexual receptivity as untreated control females. Allatectomized morphologically normal and prothetelic females laid viable eggs, but rate of egg laying and number of eggs produced by these females were much reduced in comparison with the controls. Administration of methoprene (a Juvenile Hormone analogue) to allatectomized females restored egg production to a more or less normal rate. Removal of the spermatophore within 10 min of copulation had no effect on subsequent sexual receptivity of the females, nor on the reduced rate of egg laying by the allatectomized females, but did affect the rate of egg laying by control females.It is suggested that the corpora allata (CA) and the Juvenile Hormone (JH) play no major role in controlling basic sexual receptivity of G.bimaculatus females, and do not have an all‐encompassing control on egg production, though they do exert a marked quantitative effect on the rate of egg production.
Olfactory responses of tsetse flies to phenols from buffalo urine
Authors: OTTER C. J. DEN 
Published: March 2008

Abstract A comparison was made of the EAG responses of males and females of Glossina morsitans morsitans Westwood, G.austeni Newstead and G.tachinoides, Westwood to various doses of compounds known to be components of ox and buffalo urine fractions which are attractive to tsetse in the field (phenol, 3‐ and 4‐methylphenol, 3‐ and 4‐ethylphenol, 4‐n‐propylphenol, dimethylsulfone). All three species did not respond to dimethylsulfone. The overall responses to the phenolic substances were higher in females than in males in G.m.morsitans and higher in males than in females in G.austeni and G.tachinoides. Response spectra of the species for the phenolic substances suggested that G.m.morsitans and G. austeni were most responsive to 3‐ and 4‐methylphenol and 3‐ethylphenol, whereas G. tachinoides was most sensitive to 3‐ethylphenol and 3‐methylphenol, and only moderately sensitive to 4‐methylphenol.Cross‐adaptation experiments, in which l‐octen‐3‐ol, acetone, 4‐heptanone and 3‐nonanone were also included, revealed that all phenolic compounds stimulated one and the same class of receptors, which differed from the class of receptors activated by l‐octen‐3‐ol. The ketones also had their own receptors. Hence, the flies can obtain information about the presence of attractants by at least three different receptor classes. It was concluded that phenol and any individual alkylphenol found in ox and buffalo urine should be attractive to tsetse flies, provided that stimulus intensity is above threshold and not beyond optimum. One class of receptors may respond more strongly in males than in females, whereas another class is more responsive in females than in males. This may result in a change in sex ratios in catches depending on the odour bait used.
Physiological aspects of diapause and cold tolerance during overwintering in Pieris brassicae
Authors: PULLIN A. S. , BALE J. S. , FONTAINE X. L. R. 
Published: March 2008

Abstract The relationship between diapause‐associated metabolic suppression and carbohydrate metabolism linked with cold tolerance was investigated in pupae of Pieris brassicae L. Cold tolerance was assessed by measuring the crystallization temperature (Tc) and by estimates of pre‐freeze mortality. Metabolic suppression was measured using 31P nmr and carbohydrates by GLC.Sorbitol (a possible cryoprotectant) accumulated from the onset of diapause in October until December reaching a concentration of c. 40 mMolal in both years of the study, but then declined from January until adult eclosion in May. The Tc remained between ‐23 and ‐25oC throughout the winter except for a slight rise before eclosion in May. The absence of a significant Tc suppression is as predicted from the low concentration of sorbitol accumulated. The pre‐freeze mortality experiments indicate that pupae are most cold tolerant in the period December‐February when sorbitol concentration is high, suggesting an alternative cryoprotective role for sorbitol. Glycogen declined at the beginning of diapause until February after which there was some recovery suggesting that it may be the source of carbon for sorbitol synthesis.Diapause‐associated metabolic suppression is evident in the low 31P nmr resonances of ATP during November‐February compared with non‐diapause pupae and diapause pupae soon after pupation. The suppression of metabolism at this time may have a direct role in cryoprotection and by itself (rather than sorbitol) account for the increased pre‐freeze cold tolerance. ATP appears to increase slowly from February until a sharp increase occurs shortly before eclosion. Arginine phosphate remains high during diapause until late February‐March when it begins a decline which continues until eclosion. A period of change in energy and carbohydrate metabolism is apparent at the same time which may indicate diapause termination and related changes in cold tolerance mechanisms.It is argued that in P.brassicae sorbitol accumulates as a result of metabolic suppression and may have no cryoprotective role. However, for species living in, or colonizing, low temperature environments it is a short evolutionary step to exploit this pathway and accumulate high concentrations of polyols as a specialized cold tolerance strategy.
Voltinism and seasonal changes in haemolymph protein pattern of Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae) in relation to diapause
Authors: SOCHA RADOMÍR , ŜULA JAN 
Published: March 2008

Abstract. The red firebug, Pyrrhocoris apterus (L.), was shown not to be strictly a monovoltine species in Czechoslovakia. A second generation arises from eggs laid by females emerging between June and the beginning of August. Oviposition takes place before diapause is induced in the females by shortening of photophase. Adults that moult later, enter diapause without having laid eggs.Electrophoretic patterns of haemolymph proteins of adults collected in the field throughout a year showed a characteristic temporal pattern of changes correlated not only with the stages of ovarian development, but also with the progression of diapause and post‐diapause quiescence. The changes mainly concerned vitellogenin and polypeptides of molecular weight 78 and 80 kDa.Vitellogenin was present only in the haemolymph of reproductive females. The polypeptides of 78 and 80 kDa, belonging to the group of storage proteins, accumulated conspicuously in the haemolymph of adults undergoing diapause and post‐diapause quiescence. However, the occurrence of these polypeptides seems not to be connected exclusively with cold, because their titres increased with the length of diapause development, even in diapausing adults reared in the laboratory at a constant 26d̀.C
Reproductive under‐performance of tsetse flies in the laboratory, related to feeding frequency
Authors: GASTON KIRSTY A. , RANDOLPH SARAH E. 
Published: March 2008

Abstract. The rates of development of the eggs and larvae in utero and the next two developing ovarioles were measured by ovarian dissection on each day of the pregnancy cycle in tsetse, Glossina morsitans, subject to different feeding regimes. Compared with flies fed four times per pregnancy cycle, flies fed three times per cycle showed a lower pupal production rate (70%), the same (zero) adult mortality, a slightly slower growth rate of the larva and second ovariole only from day 8 onwards, but the same growth rate of the first ovariole. Flies fed only twice per pregnancy cycle produced no pupae, suffered 18% adult mortality and showed a significantly slower growth rate of the larva and second ovariole from days 6 and 7 respectively, but still the growth rate of the first ovariole was barely affected.Flies offered food three times or twice per pregnancy cycle engorged fully at every opportunity, but 16.5% of the flies offered food four times per cycle did not feed on every occasion, while 12–22% did not engorge fully on days 3, 5 or 7.In assessing the applicability of these laboratory results to the field situation the following points must be borne in mind: in the laboratory flies take smaller mean blood meals than in the field; during protein production associated with larval growth the proportion of the blood meal lost to transformation and excretory costs is less than during normal lipid metabolism; the balance between the tsetse's known fertility rate and adult and pupal mortality rates reveals that the abortion rate in the field must be extremely low. The high abortion rates usually observed in laboratory colonies, even when flies are offered food dailyl would be quite untenable in the field and indicate that laboratory conditions impose physiological stresses on the flies that are quite different from those in the field. These facts indicate that three field‐sized meals may be sufficient to meet the energy demands of normal larval development in the field.
Control of flight by means of lateral visual stimuli in gregarious desert locusts, Schistocerca gregaria
Authors: SPORK P. , PREISS R. 
Published: March 2008

Abstract. Tethered flying locusts were stimulated either by a periodic grating or by a spotted ‘swarm‐simulating’ pattern moving horizontally, parallel to their longitudinal body axis within their lateral visual fields. The direction of movement of the pattern was changed periodically from progressive to regressive and vice versa.Both kinds of patterns induced a correlated modulation of yaw‐torque and thrust. The two measured flight parameters were modulated independently of each other. Each parameter either increased with progressive and decreased with regressive pattern motion or vice versa. The characteristic curves of thrust and yaw‐torque responses ‐ i.e. response amplitude versus contrast frequency resp. angular velocity – measured upon stimulation with the periodic grating between 2 and 70 Hz were at a maximum at 10 Hz and decreased at higher and lower contrast frequencies. The shape of the curves was nearly identical. The characteristic curves measured upon stimulation with the ‘swarm‐simulating’ pattern between 60 and 1500o s‐1 could be simulated using the spatial wavelength content of the pattern and the characteristic curves for periodic gratings.Therefore, we suggest that the speed and direction of locusts' flight result from the optomotor effectiveness of the pattern image formed by the neighbouring individuals under free flight. The measured responses would thus contribute to the common orientation of groups of locusts within a migrating swarm and thus to swarm cohesion.
Flight behaviour of Bemisia tabaci in a vertical flight chamber: effect of time of day, sex, age and host quality
Authors: BLACKMER J. L. , BYRNE D. N. 
Published: March 2008

Abstract. The free‐flight behaviour of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), the sweet potato whitefly, was investigated in a vertical flight chamber. A mercury‐vapour lamp presented from above induced a phototactic flight response. Although flight propensity was comparable from 06.00 to 19.00 hours, flight duration was maximum between 06.00 and 10.00 hours. Males flew longer than females and their mean flight duration remained constant throughout the day. Females flew longer from 06.00 to 13.00 hours than from 13.00 to 19.00 hours. Both sexes were capable of sustaining flight for more than 2h, although less than 5% of those tested did so.Flight activity also was influenced by age and by host quality. The propensity to take off, proportion exhibiting phototactic orientation and flight duration varied with the age of the whitefly. Host quality influenced the timing of flight behaviour. Whiteflies reared on senescing plants exhibited greater take‐off rates and initiated longer phototactic flights up to 4 days following adult eclosion when compared to individuals reared on vegetative plants. Thereafter, individuals reared on vegetative plants exhibited greater response levels. Whiteflies reared on vegetative plants weighed more and survived longer than did individuals reared on senescing plants.Whiteflies that responded to the overhead light initially exhibited a strong photokinetic and phototactic response. Over the course of the flight, these responses declined and flight instability increased, as indicated by an overall decrease in the mean rate of climb, accompanied by an increase in the variability of this parameter and an increase in horizontal displacement. Although males and females displayed similar flight characteristics, females exhibited a greater rate of climb than did males, and for both sexes, individuals that flew longer than 25 min had a greater rate of climb than did individuals that flew for less than 25 min.