bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of sperm removal and sperm transfer in Orthetrum coerulescens (Fabricius) (Odonata: Libellulidae)
Authors: MILLER P. L.
Published: March 2008

ABSTRACT An account of the structure of the secondary genitalia of male Orthetrum coerulescens (Fabricius) is given together with an outline of the internal genitalia of the female. Observations on the experimental inflation of the penis are described. No sperm was released during fast inflations and deflations of the penis, but sustained inflation of the penis led to the release of a clear fluid followed by the slow discharge of sperm. Examination of natural copulations in the field has shown that rapid rhythmic movements at up to 5 Hz take place in the male's third abdominal segment throughout most of copulation, but towards the end they cease though inflation is maintained. It is suggested that the rapid movements coincide with the removal of rival sperm from the female and that sperm is transferred to the female only during the maintained inflation. Possible mechanisms of sperm translocation, sperm removal and sperm transfer are discussed with reference to male and female genital structures and the action of relevant muscles.
The cocoon and humidity in the development of Acrolepiopsis assectella (Lep.) pupae: consequences in adults
Authors: NOWBAHARI B. , THIBOUT E.
Published: March 2008

Abstract In a saturated atmosphere, the cocpon of the leek moth can absorb up to two‐thirds of its weight in water. It is shown that this phenomenon enables the pupae to lose less water in the course of their development, particularly during pupal moulting. Although quantitatively minor, this protection is qualitatively important: it has no effect on mortality or the duration of pupal development, but does affect vitellogenesis and fertility in females. It thus clearly has an adaptive role towards the environment.
Deposition and longevity of oviposition‐deterring pheromone in the cabbage seed weevil
Authors: FERGUSON ANDREW W. , WILLIAMS INGRID H.
Published: March 2008

Abstract The cabbage seed weevil (Ceutorhynchus assimilis Payk.) lays eggs singly into pods of oilseed rape (Brassica napus L.) through punctures bored with the mouthparts, preferring pods not recently used for oviposition. A simple new choice test has been used to test individual components of egg‐laying behaviour for their effect on oviposition site selection. It is confirmed that an oviposition‐deterring pheromone (ODP) is deposited during abdomen brushing of the pod which follows egg‐laying. Neither pin punctures, weevil feeding punctures, oviposition punctures nor eggs had any deterrent effect. Pods walked on by female weevils were not avoided by those laying eggs. Observations suggest that the ODP is sensed by contact chemoreceptors on the antennae. The deterrent effect lasted only 1–2 h. The implications of these findings on the adaptive significance of the pheromone and its possible use in pest control are 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.
Flying mate detection and chasing by tsetse flies (Glossina)
Authors: BRADY JOHN
Published: March 2008

Abstract Male tsetse flies, probably Glossina morsitans morsitans Westw., were video‐recorded in the field as they took off and chased other tsetse flies. Chasers responded (took off) to a target fly at a maximum distance of c. 55 cm, when it subtended c. 1.6o to their eye (–1 foveal ommatidial subtense). Chased targets were always within this range (mean subtense at take‐off = 3.2o) and approaching the chaser. The most significant difference between chased and non‐chased targets was in the rate of approach of the target fly in terms of the increase in its image size immediately before the chaser took off (x̄ 21o s−1), especially as its relative increase (x̄690% s‐1P<0.005). No feature of the target's translational velocity, nor any relationship between that and the image size approached this level of significance. Chasers seemed to ‘slipstream’ their target at c. 20 cm directly behind it, perhaps suggesting target identification by speed matching. Chases were apparently abandoned when the target image shrank from covering at least two of the chaser's foveal ommatidia to covering only one. Parallax‐free measurements of flight speeds indicated a preferred, stable mean groundspeed of 4.8±0.1 m s_1 (SE), at a mean wing‐beat frequency of 209±3 Hz.
Wingstroke frequency of foraging and hovering bumblebees in relation to morphology and temperature
Authors: JOOS B. , YOUNG P. A. , CASEY T. M.
Published: March 2008

Abstract Wingstroke frequency, morphometries and thoracic temperatures of freely foraging bumblebees were examined in the field at ambient temperatures varying from 10 to 29oC. Frequency was strongly correlated with morphometric parameters, particularly wing length, but was not correlated with either ambient or thoracic temperature. Magnitudes and scaling of frequency of foraging bees were comparable to values obtained for bees hovering in a closed chamber. These data indicate that frequency is primarily determined by morphometric characteristics which determine lift requirements and do not support the hypothesis that frequency is varied in response to environmental conditions as a means of in‐flight thermoregulation.
The effects of different blend ratios and temperature on the active space of the Oriental fruit moth sex pheromone
Authors: LINN CHARLES , ROELOFS WENDELL
Published: March 2008

Abstract The wing‐fanning activation response of male Oriental fruit moths (OFM), Grapholita molesta (Busck), in the field to the three‐component pheromone containing the female‐produced ratio of components (Z8‐12:OAc + 6% E8‐12:OAc + 3% Z8‐12:OH) was compared with the response to blends containing 2,10 and 20% E with 3% OH, and the 6% E blend containing 30 and 100% OH. Comparisons were made over three temperature ranges: 15–17, 20–21 and 26–28oC. Both the maximum response distance and male response specificity were significantly altered by changes in odour quality as well as temperature. For blends containing different Z/E ratios the maximum response distance increased significantly with temperature. Response specificity was most pronounced at the 20–21oC range, with males displaying a lower threshold for the natural 6% E ratio, evidenced by the fact that fewer males responded and at closer distances to the source with off‐ratios. At 26–28oC response specificity for the Z/E ratios was much reduced, primarily due to more males activating to off‐ratios. With blends containing different proportions of Z8‐12:OH in the 6% E blend, increasing temperature increased the maximum response distance for all treatments, but in addition increasing the proportion of OH alone from 3% to 30% significantly increased the maximum response distance over the three temperature ranges tested. This increase occurred without affecting the proportion of responders or the distribution of response distances around the mean value. However, with 100% OH added to the blend, whereas male response was high at 20–21oC, the distribution of response distances was significantly more variable than with 3% or 30%, and male response was eliminated or very low at 15–17oC and 26–28oC. Our results support previous studies showing that peak response levels in this species are dependent on male perception of the natural blend of components, and that males have a high degree of specificity for the qualitative properties of the pheromone. However, the present results also extend those of previous flight tunnel tests in which response specificity was most pronounced in the upwind flight phase of the sequence, by showing that male OFM also display a
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.
Developmental manipulation of the circadian pacemaker in the cockroach: relationship between pacemaker period and response to light
Authors: PAGE TERRY L.
Published: March 2008

Abstract Previous research has shown that fundamental properties of the circadian pacemaker that drives the rhythm of locomotor activity in the cockroach Leucophaea maderae L. are permanently altered by exposure of animals to 22 or 26 h light cycles during post‐embryonic development (Barrett & Page, 1989; Page & Barrett, 1989). The present results document differences between animals exposed to either constant darkness (DD) or constant light (LL) during postembryonic development in the free‐running period, the phase shifting response to light pulses, and the response to an LL to DD transition of the adult pacemaker. In addition, the changes in pacemaker period and in the phase shifting response that result from raising animals in several different lighting conditions are shown to be strongly correlated. The data suggest there is a developmentally labile interdependence between the period of the pacemaker and its sensitivity to light.
The optics of tsetse fly eyes in relation to their behaviour and ecology
Authors: GIBSON GABRIELLA , YOUNG STEPHEN
Published: March 2008

Abstract The visual acuity of two species of tsetse flies, Glossina morsitans morsitans Westw. and Glossina pallidipes Aust., was investigated. Male G. morsitans eyes have an acute zone in the forward region, with large hexagonal lenses (mean minimum diameter, D=33, SE±0.7 μm), relatively small interommatidial angle (Δ(φ=1.08o) and angular receptive field of individual ommatidia (Δp) of not less than 1.14o. A narrow band of square lenses, with intermediate diameter and Δφ, merges with smaller hexagonal lenses in the periphery (24±0.7 μm), with relatively large interommatidial angle (Δφ=3.7o) and small angular receptive field (Δp =c. 1.6o). G.pallidipes eyes are similar, except that the lenses in the acute zone are larger than those of G.morsitans, in proportion to their larger body size. Female eyes are not significantly different from male eyes, except that they have a narrower region of binocular overlap (maximum for males = 24o, for females = 18o). The eye parameter (p=DΔφ) in the acute zone of male G.morsitans= 0.62, and in the peripheral zone = 1.56. These relatively high values are consistent with fast flight, visual detection of drift due to low wind speeds, mating chases and discrimination of cryptic host animals at high light intensities. The extended region of binocular overlap in males may serve as an early warning system of the approach of potential females. From our estimates, tsetse flies ought to be able to detect small objects against the sky c. 30 min before sunrise and after sunset, and to use their peripheral vision perhaps 15 min earlier and later than this.
Influence of thermoperiod and photoperiod on reproductive diapause in Bruchidius atrolineatus (Pic) (Coleoptera, Bruchidae)
Authors: LENGA ARSENE , THIBEAUDEAU CHRISTIAN , HUIGNARD JACQUES
Published: March 2008

Abstract Bruchidius atrolineatus (Pic) is a common pest infesting cowpea seeds (Vigna unguiculata Walp) in Africa. In the Sahelian zone, the adults are in reproductive diapause during the dry season. Diapause induction depends on the climatic conditions during embryonic and post‐embryonic development. A strain of B. atrolineatus originating from the Niamey (13oN) was reared in different thermoperiodic and photoperiodic conditions. In the thermoperiodic regime 40:25oC, in continuous darkness, induction of diapause was dependent on the duration of the thermophase. Photoperiod could also influence diapause induction but the response depended on the temperature. When the beetles were reared in conditions of LD 12:12 h, 40:25oC, for seven generations, the proportion of diapausing adults decreased and their sensitivity to photoperiod increased. In LD 14:10 h, 40:25CC, the proportion of diapausing adults remained high regardless of the photoperiod. In these conditions, the first emerging adults were sexually active and were used for selection of a strain with a low incidence of diapause. After twelve generations, the proportion of diapausing beetles was lower than 5%. The responses of this selected strain to photo‐ and thermoperiods were reduced. The sensitivity of B. atrolineatus to photoperiod and thermoperiod could be controlled by genetic systems as observed in other insect species.
A comparison of the water balance characteristics of temperate and tropical fly pupae
Authors: YODER JAY A. , DENLINGER DAVID L.
Published: March 2008

Abstract Water balance characteristics of temperate zone fly pupae are compared with the characteristics of flies inhabiting the tropics. The flies, all of which were reared without diapause, had very similar equilibrium weights that were quite high (av 0.90‐0.92), thus implying a limited capacity to absorb water from a subsaturated atmosphere. Likewise, the critical transition temperatures (CTT) were nearly the same for all the flies. Net transpiration rates at 20oC are a function of size, but the rate is less size dependent as temperature increases. When water loss is examined across a broad temperature range, as described by activation energies, it is apparent that the tropical flies lose water at a greater rate than their temperate zone counterparts. Activation energy may be a good parameter to use in evaluating habitat preference and suitability for a species because it describes water loss as a function of temperature, and thus is likely to be a good indicator of the insect's response to the fluctuating temperatures that occur naturally.
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.
The use of eryopreservation for convenient bioassay of insect organs in vitro
Authors: RAFAELI A. , KAMENSKY B. , SOROKER V.
Published: March 2008

Abstract Pheromone glands of the female moth Helicoverpa (Heliothis) armigera and Malpighian tubules of the locust Locusta migratoria migratorioides (R&F) retained partial biological activity after eryopreservation. Pheromone glands were frozen to ‐70oC in a tissue culture medium (TC‐199) containing 10% of the cryoprotectant dimethylsulfoxide. Malpighian tubules, however, required initial preincubation for 24 h in a medium of high osmolarity before being frozen to ‐70oC in the presence of 10% of the cryoprotectant glycerol. After rapid thawing of both organs, biological activity was compared with the respective fresh organs. Using a radiochemical assay, it was shown that previously frozen pheromone glands were stimulated by pheromone biosynthesis activating neuropeptide to the same degree as fresh pheromone glands. In addition, previously frozen Malpighian tubules were stimulated by an extract of corpora cardiaca to produce c‐AMP to the same extent as fresh Malpighian tubules.
Body temperatures of Namib Desert tenebrionid beetles: their relationship in laboratory and field
Authors: ROBERTS C. S. , SEELY M. K. , WARD D. , MITCHELL D. , CAMPBELL J. D.
Published: March 2008

Abstract The body temperatures of six apterous species of Namib Desert tenebrionid beetles were measured continuously with indwelling thermocouples under laboratory conditions and in the field. The range of body temperatures selected was within the upper half of their ‘tolerated range’, which we defined as the temperatures lying between measured critical thermal maximum and critical thermal minimum. In the field, individuals also maintained their body temperatures within the upper half of the ‘tolerated range’. These beetles maintained higher body temperatures than those recorded for any other ectothermic insect. Three of the six species maintained lower body temperatures in the field than they selected in the laboratory. The other three species showed no significant difference between field and laboratory body temperatures. We conclude that these beetles are not forced by biotic or abiotic factors to adopt thermal niches which present them with physiological difficulties.
Pheromone‐mediated upwind flight of male gypsy moths, Lymantria dispar, in a forest
Authors: WILLIS MARK A. , MURLIS JOHN , CARDÉ RING T.
Published: March 2008

Abstract Lymantria dispar L. males flying upwind in a pheromone plume in a forest were video‐recorded at 2.5, 10 and 20 m from the source of pheromone. Males flew slower and steered more across the wind as they approached the source. In concert, their ground speed decreased and track angles increased. In contrast to these changes, their drift angles were fairly constant and the transverse component of image flow, above and/or below the moths eyes, showed almost no change. The inter‐turn duration (time between sequential turns), a temporal aspect of the male flight manoeuvres, showed a consistent but relatively small increase as the distance from the source increased. The flight tracks narrowed as the males approached close (2.5 m) to the source. Because of unpredicted correlations between physical variables (i.e. temperature, wind velocity) and the distance from the source, we used principal components analysis to generate a set of completely independent variables. Greater than 90% of the variability in the data could be explained by four principal factors which corresponded well with known relationships in the flight manoeuvres. All four of these factors showed a significant regression against distance to the source. Although uncontrolled factors such as temperature and wind velocity may have contributed to changes in flight behaviour, recent data indicate that, in addition to concentration, certain temporal and spatial characteristics (i.e. burst period, burst return period) of plumes in wind vary systematically with distance from the source. We propose that L.dispar males might adjust their flight manoeuvres in response to these changes.
Physiological mechanisms underlying the control of meal size in Manduca sexta larvae
Authors: TIMMINS W. A. , REYNOLDS S. E.
Published: March 2008

Abstract. Fifth stadium larvae of the tobacco hornworm, Manduca sexta (L.), ate larger meals than usual when they had been deprived of food for periods of time longer than the usual intermeal interval (c. 45 min). Meal size increased with time since the last meal until 180 min, when it was about 3 times normal. There was no evidence of a role for volumetric feedback from the gut in controlling meal size. Injections of a paraffin oil/wax mixture, or of petroleum jelly (Vaseline) into the foregut, midgut or rectum failed to decrease meal size. Cutting the recurrent nerve failed to alter meal size compared to sham‐operated controls (although both groups took smaller meals than unoperated controls). By contrast, injections of an extract of soluble nutrients from the diet into the midgut inhibited feeding in some insects and reduced subsequent meal size in others. Appropriate controls showed that these effects were not due to the volumetric or osmotic effects of the injections. These results imply that nutrient feedback plays an important role in controlling meal size in Manduca caterpillars, while volumetric feedback is probably unimportant.
Water vapour uptake by diapausing eggs of a tropical walking stick
Authors: YODER JAY A. , DENLINGER DAVID L.
Published: March 2008

Abstract. This study is the first to demonstrate the capacity of an arthropod egg, that of a tropical walking stick Extatosoma tiaratum (Macleuy), to absorb water vapour from the air. This species diapauses both as an early embryo and then again as a pharate first instar larva, and both stages are capable of absorbing water vapour. Water vapour absorption occurs at lower humidities and at a lower rate for an egg in early embryonic diapause (c. av 0.30, 0.516 mg h‐1δv‐1) than in the diapausing pharate first instar (c. av 0.60, 0.725 mgh‐1δav‐1) at 25d̀C. In addition to having the capacity to gain water at very low vapour activities, water is efficiently conserved as indicated by the low rate of water loss (0.015% h‐1 in the early embryo and 0.046% h‐1 in the pharate larva at 25d̀C). Eggs that have been killed lose water when held at a hydrating vapour activity, thus implying that active uptake contributes to net absorption. Wax block experiments suggest that water is absorbed over the entire chorionic surface. Eggs of five other insect species that were examined [Lymantria dispar (L.), Bombyx mori (L.), Antheraea polyphemus (Cram.), Oncopeltus fasciatus (Dallas) and Diaferomera femorata (Say)] lacked the ability to absorb atmospheric water.
A dynamic model of water gain and loss in larval Mexican bean beetle
Authors: CHU PING‐CHU , GIROUX K. J. , STINNER R. E.
Published: March 2008

Abstract. Quantitative effects of temperature, vapour pressure deficit, host, and larval body size were experimentally determined. A simulation model for dynamic water balance in the Mexican bean beetle, Epilachna varivestis Mulsant, is presented and parameters are estimated from laboratory data for water gain/loss equations. The model is based on water loss through the cuticle, spiracles and frass, and water gain through ingestion.
A dynamic model of larval Mexican bean beetle survival as a function of body water balance
Authors: CHU PING‐CHU , STINNER R. E. , GIROUX K. J.
Published: March 2008

Abstract. This paper presents evidence of the relationship between survival and body water content in the Mexican bean beetle, Epilachna varivestis Mulsant (Coleoptera: Coccinellidae). Results of a simulation model for dynamically describing water balance and survival are compared with experimental data for the Mexican bean beetle feeding on both lima bean and soybean under different variable temperature and moisture regimes.
The two groups of sensilla in the ventral coxal hairplate of Carausius morosus have different roles during walking
Authors: DEAN J. , SCHMITZ J.
Published: March 2008

Abstract. The ventral coxal hairplate (cxHPv) of the stick insect Carausius morosus Br. (Phasmida: Bacteriidae) contains two morphologically distinct groups of sensilla designated as group 1 and 2 (Gl, G2). The function of these sensilla during walking was tested by selectively ablating one or both groups on one middle leg in thirty‐four animals. It has previously been shown that ablation of the entire hairplate leads to two kinds of errors: the operated leg swings farther forward and the adjacent caudal leg ends its swing more to the rear relative to the operated leg. Following selective ablation of cxHPv Gl on the middle leg, the first kind of error is more pronounced, indicating that this group contributes more to limiting forward protraction during the swing. Following ablation of cxHPv G2, the second kind of error is more evident, indicating that during stance this group contributes more to the target information influencing the swing end‐point of the adjacent caudal leg. These results are interpreted to reflect the phasic and phasic‐tonic response characteristics of Gl and G2 hairs, respectively.
Feeding electrogram studies on the African cattle brown ear tick Rhipicephalus appendiculatus: evidence for an antifeeding effect of tick resistant serum
Authors: LOSEL P. M. , GUERIN P. M. , DIEHL P. A.
Published: March 2008

Abstract. Feeding behaviour of partially engorged Rhipicephalus appendiculatus(Neumann) (Acari: Ixodidae) on rabbit serum held in capillary tubes and placed over the tick mouthparts was studied using the feeding electrogram technique with simultaneous macro video photography. Correlation of electrical events with fluid movement in the vicinity of the tick's mouthparts and the capillary meniscus, permitted the characterization of an orderly sequence of signals, termed the ‘Feeding Complex’, associated with highest weight gains. This complex consisted of a 3–8 Hz fast‐sucking waveform typically lasting 4–5 min, a sharp drop in potential at salivation, and rest lasting 1 or 2 min where no waveform or fluid movements occur. Very high impedence recordings from within the tick capitulum indicate that the fast‐sucking waveform coincides with bursts of potentials corresponding to contraction of the pharyngeal dilator muscles, whereas during rest a tonic series of spikes signifies that the floor of the salivarium is actively lowered. Feeding electrograms of ticks fed on serum from tick‐resistant rabbits showed significantly fewer feeding complexes. The weight gains achieved by these ticks were reduced correspondingly. This suggests that some of the humoral effectors of immunity have an antifeedant effect on this unusual parasite of rabbits.
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
Circadian oscillatory patterns of oxygen uptake in individual workers of the ant Camponotus rufipes
Authors: TAKAHASHI‐DEL‐BIANCO M. , BENEDITO‐SILVA A. A. , HEBLING M. J. A. , MARQUES N. , MARQUES M. D.
Published: March 2008

Abstract. Respiratory rates of individual workers of Camponotus rufipes Fabricius (Hymenoptera: Formicidae) were measured at 25d̀C and LD 12:12 h (lights on 06.00 hours), DL 12:12h (lights on 18.00 hours), LL (850 lux) and DD (red light, 20–30 lux), using the micro‐Warburg technique. Worker ants were collected from natural nest during the winter of 1987 in a woodland park in the region of Rio Claro, Sāo Paulo, Brazil. The respiration of ants showed a circadian rhythm with acrophase ranging from 20 h 41 min to O1 h 18 min and from 10 h 32 min to 12 h 22 min at LD and DD, respectively. In constant darkness the rhythmometric variables were similar to those presented by ants kept at LD 12:12 h. Under constant light no circadian rhythm in the respiration rates was found. A reduction in the amplitude was observed, indicating an inhibitory effect of this light regime on the respiration process.
A comparison of queen oviposition rates from monogyne and polygyne fire ant, Solenopsis invicta, colonies
Authors: MEER ROBERT K. VANDER , MOREL LAURENCE , LOFGREN CLIFFORD S.
Published: March 2008

Abstract. The oviposition rate of individual queens of Solenopsis invicta Buren (Hymenoptera: Formicidae) in relation to their weight and number of queens present in the colony was investigated by direct 2 h observations. There is a strong positive correlation between the weight of a queen and its oviposition rate in both monogyne and polygyne colonies. However, the number of eggs laid per mg queen is higher for moonogyne queens than for polygyne queens. This difference is more evident when the total weight of queens present in a colony is considered. The individual queen oviposition rate is negatively correlated with the number of queens in the colony. In addition, the weight loss per egg laid is significantly greater for polygyne than for monogyne queens, probably due to differences in egg size. These data suggest that oviposition is more efficient in monogyne than in polygyne queens at the individual level; however, at the colony level, polygyne colonies produce significantly more eggs. Comparison of colony level efficiency predicts that polygyne colonies must have at least nine queens to compete reproductively with a mature monogyne queen. Therefore, oligogyny does not appear to be a viable strategy for S.invicata.
Responses of individual antennal olfactory cells of tsetse flies (Glossina m. morsitans) to phenols from cattle urine
Authors: OTTER C. J. DEN , NATERS W. M. VAN DER GOES VAN
Published: March 2008

Abstract. Action potentials from olfactory cells in antennae (funiculi) of living tsetse flies, Glossina morsitans morsitans Westwood, were recorded using a surface‐contact technique. Stimuli were the vapours of the seven alkylphenols identified in cattle urine: phenol, 3‐methyl‐, 3‐ethyl‐, 3‐n‐propyl‐, 4‐methyl‐, 4‐ethyl‐, and 4‐n‐propylphenol. In addition, responses to the vapours of 1‐octen‐3‐ol, acetone and dichloromethane were recorded. The phenol‐sensitive cells could be grouped into four subclasses. Subclass, 1, 2 and 3 cells responded to the phenols only, cells of subclass 1 and 2 being activated by these substances, those of subclass 3 inhibited. Cells of subclass 4 were activated to a similar degree by all phenols and by one or more of the other chemicals tested. Subclass 1 cells were strongly activated by the 3‐alkylphenols, whereas subclass 2 cells were most sensitive to 4‐methylphenol. Subclass 3 cells were most strongly inhibited by phenol, and 3‐ and 4‐methylphenol. The results suggest that though individual phenols may be attractive to G. m. morsitans, preference for certain blends of phenols may exist; for example, blends composed of moderate doses of 4‐methylphenol and 3‐methyl‐, 3‐ethyl‐ or 3‐n‐propylphenol.
The effect of mating on phonotactic behaviour in Gryllus bimaculatus (De Geer)
Authors: LOHER WERNER , WEBER THEO , HUBER FRANZ
Published: March 2008

Abstract. Phonotaxis of G. bimaculatus females is expressed by a course‐consistent, directional approach to a conspecific model calling song emitted alternatingly at sound intensities of 50–90 dB SPL and appears at the age of 6–7 days, the onset of maturation. Mating abolishes phonotaxis after about 1 h. By that time, the content of the attached spermatophore has migrated into the female's sper‐matheca. Removal or emptying of the spermatheca, or severing the ventral nerve cord, fully reinstates phonotaxis, whereas ovariectomy has no effect. We suggest that mechanoreceptors record the expansion of the filled spermatheca and that the inhibitory message is communicated via the ventral nerve cord anteriorly to an unknown control centre in the brain. The loss of phonotaxis is combined with reduced locomotor activity and results in the female no longer being attracted to another calling male.
Effects on the feeding behaviour of Nilaparvata lugens (Stål) of sublethal concentrations of the foliarly applied nitromethylene heterocycle 2‐nitromethylene‐1, 3‐thiazinan‐3‐yl‐carbamaldehyde
Authors: EL P. M. LÖS , GOODMAN L. J.
Published: March 2008

Abstract. An electrical recording technique, combined with simultaneous videofilming, was used to investigate the detailed feeding behaviour of Nilaparvata lugens (Stål) (Homoptera: Delphacidae) on rice. Phases of brief probing, of non‐feeding activities, such as walking and of sustained feeding were observed. Monitoring of electrical signals recorded during long, uninterrupted periods of contact between the insect and its host plant, revealed three pattern classes. Two clearly distinguishable wave‐like patterns represent the hopper sucking from xylem and phloem tissues. The third represents a ‘complex’ of signals believed to be associated with stylet penetration, salivation and sucking activities in non‐vascular tissues of the host plant. This recording method and simple counts of honeydew excretion activity were used to assess the effect on the feeding behaviour of N. lugens of a sublethal concentration of the nitromethylene heterocycle insecticide 2‐nitromethylene‐l, 3‐thiazinan‐3‐yl‐carbamaldehyde applied to rice. The treatment caused a general reduction in feeding activity. Analysis of the electrical trace revealed that phloem feeding was strongly inhibited. Since these effects were largely reversed on transferring hoppers from treated to untreated hosts, the test compound was considered to have an antifeedant rather than a conventional poisoning effect on the hoppers when applied at sublethal doses.
Glycerol and glucose accumulation during diapause in a tropical beetle
Authors: PULLIN A. S. , WOLD A H.
Published: March 2008

Abstract. Carbohydrate changes were measured during the 10‐month adult diapause in the neotropical beetle, Stenotarsus rotundus Arrow (Endomychidae, Coleoptera) to test the hypothesis that metabolic suppression causes the accumulation of polyols in the absence of the need for cold tolerance. Glycerol and glucose both accumulate during the first 3 months from June to September, but decline in October, accumulate again in December‐January and finally decline after January and stay low until the adults leave their diapause site in April. Any adaptive significance for this pattern is unknown but its coincidence with previously measured metabolic suppression suggests that glycerol and glucose accumulate as a result of metabolic adjustments during diapause. The relevance of these results to the evolution of polyol accumulation for cryoprotection in temperate insects in discussed.
Interactions between male moths of the lightbrown apple moth, Epiphyas postvittana (Walker) (Lep.: Tort.), landing on synthetic sex pheromone sources in a wind‐tunnel
Authors: RUMBO E. R.
Published: March 2008

Abstract. This study was designed to determine whether landings of males of Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) on synthetic sex pheromone sources are influenced by other males which have preceded them in flying to and landing on the sources. The investigation comprised two separate experiments. In one, using a single pheromone source, insects released singly were compared with insects released in groups of three, and in the other, insects released in groups of five were presented with a choice between two identical sources. The resolution for changes in attractancy was higher in the choice experiment which demonstrated an increase in attraction for a source on which males had already landed and remained whilst the new male flew towards it. A single resident insect increased the source attractancy by a factor of 1.40 and a pair of insects by 1.77 compared with an empty source. With the single sources the data exhibited the same trend but the result was rendered not significant by an insufficient amount of data, although approximately equal times were allocated to each experiment. To achieve a significant result with the single sources at least 6 times as much data would need to be collected.
Flight responses of tsetse flies (Glossina) to octenol and acetone vapour in a wind‐tunnel
Authors: PAYNTER QUENTIN , BRADY JOHN
Published: March 2008

Abstract. Female Glossina morsitans morsitans Westwood were video‐recorded in a wind‐tunnel as they entered, in crosswind flight, a broad plume of either octenol or acetone (two components of ox odour). Both odours produced upwind turning responses (in‐flight anemotaxis) to a range of concentrations, with thresholds at around 10‐8mg1‐l for octenol and 10‐6mg1‐1 for acetone. Kinetic responses were unaffected by octenol at low concentrations, but flight speed was significantly reduced and sinuosity (om‐1) and angular velocity (os‐1) significantly increased by concentrations at or above those in ox breath; for acetone, these effects were apparent but inconsistently related to concentration. It is concluded that octenol and acetone vapour are used by tsetse flies to locate hosts by upwind anemotaxis, probably combined with kinetic responses. The behavioural basis for the ‘repellency’ of high octenol concentrations in the field is discussed in the context of the virtual loss of upwind anemotaxis to octenol at the highest concentration tested in the tunnel (30 × ox breath).
Migration and the effect of three environmental factors on the pre‐reproductive period of the cotton‐boliworm moth, Helicoverpa armigera
Authors: COLVIN JOHN , GATEHOUSE A. GAVIN
Published: March 2008

ABSTRACT. Migration by noctuid moths generally occurs while the adults are sexually immature, and so the pre‐reproductive period provides an indication of the time available for migratory flight. Helicoverpa armigera (Hb.) (Lepidoptera: Noctuidae) is considered to be a facultative migrant, emigrating in response to a deterioration in local environmental conditions for adult survival and larval development; hence the effects of temperature, vapour‐pressure deficit and the availability of sugar solution on the duration of the pre‐reproductive period are investigated. Temperatures below 28oC lengthened female pre‐reproductive periods but, contrary to the findings of Isley (1935) for Helicoverpa zea (Boddie), temperatures above 28oC shortened them. Females maintained at a vapour‐pressure deficit of 23.7 ± 0.5 mmHg (c. 12% r.h.) and 6.45 ±0.15mmHg (c. 76% r.h.) did not have significantly different pre‐reproductive period distributions. The availability of 10% w/v sugar solution (provided ad libitum) had a marked effect on both the survival and the pre‐reproductive period of both sexes. Moths given water for four nights followed by sugar solution thereafter, took significantly longer to reach reproductive maturity than those given sugar solution from emergence. Survival to reproductive maturity of moths given water only throughout their lives was poor (c. 20%). The significance of these findings to the migratory behaviour of H. armigera is discussed.
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.
Microorganisms are involved in the production of volatile kairomones affecting the host seeking behaviour of Diadromus pulchellus, a parasitoid of Acrolepiopsis assectella
Authors: THIBOUT E. , GUILLOT J. F. , AUGER J.
Published: March 2008

Abstract. Experiments were carried out to determine the origin of dialkyl disulphides found in the larval frass of Acrolepiopsis assectella Zell. which enable the specialist parasitoid Diadromus pulchellus Wsm. to find its host. These kairomones are not specific: they are also found in the frass of the generalist Cacoecimorpha pronubana Hb. fed a leek‐based diet. They are emitted only after the frass emerges from the gut. Bacteria are present in the gut of larvae and in their frass. The addition of antibiotics to the larval diet prevents bacterial development and suppresses disulphide emission. When grown in the presence of sulphur amino acids, precursors of sulphur volatiles, some bacteria metabolize kairomones. The production of volatile kairomones, responsible for host– parasitoid relationships, depends on the presence of additional organisms, i.e. bacteria, and not on enzymes arising from the plant or the phytophage.