bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
The mating behaviour of tsetse flies (Glossina): a review
Authors: WALL R. , LANGLEY P. A.
Published: March 2008

Abstract. The mode of reproduction of tsetse flies, by adenotrophic viviparity, is unusual among the Diptera and is associated with many unique aspects of the tsetse's mating system. Tsetse exist at relatively low densities in the environment but a combination of olfactory and visual stimuli brings males and virgin females together on or around host animals. The behavioural repertoire associated with mate location and identification, courtship and copulation is regulated by external physical and chemical stimuli as well as by internal physiological mechanisms. With a view to identifying stimuli that could be used to manipulate tsetse behaviour and exploited for control purposes, much progress has been made in recent years in elucidating the mating behaviour of tsetse and its regulatory mechanisms. This progress and the current state of understanding of tsetse mating behaviour is reviewed.
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.
Biological differences between strains of Tribolium castaneum selected for resistance to hypoxia and hypercarbia, and the unselected strain
Authors: DONAHAYE E.
Published: March 2008

Abstract. A strain of the red flour beetle Tribolium castaneum (Herbst) was selected separately for resistance to hypoxia and hypercarbia. At the 21st generation, adults and pupae of the line selected for resistance to hypoxia were significantly heavier than those selected for resistance to hypercarbia and the unselected line. It also exhibited a more prolonged developmental range than the unselected line. The line selected for resistance to hypercarbia was also significantly heavier than the unselected line. When the selected and unselected lines were subjected to starvation at the 26th generation, metabolism in both selected lines proceeded at a lower rate than in the unselected line and consequently the selected lines survived for much longer periods.
Variability in Juvenile Hormone production by locust corpora allata kept in vitro for long periods
Authors: GADOT M. , PENER M. P. , SCHAL C.
Published: March 2008

Abstract. Juvenile Hormone III (JH‐III) production by corpora allata (CA) of sexually mature female locusts (Locusta migratoria migratorioides (R. & F.)) was maintained in vitro for up to 30 days in an agar‐solidified medium. Hormone production was measured periodically with a short‐term radiochemical assay. Low‐activity CA increased their activity significantly after 24–48 h incubation in the long‐term medium, but high‐activity glands did not. Variations in activity were considerable among glands tested on the same day and among measurements from the same gland on different days. Farnesoic acid‐stimulated rates of JH‐III production were always higher than the basal rates, suggesting that the CA were not maximally activated. However, freshly excised low‐activity CA, whose hormone production increased in the long‐term conditions, showed similar farnesoic acid‐stimulated rates of JH‐III production to those of freshly excised high‐activity glands, suggesting that at the time of excision of the corpora allata rate‐limiting step(s) preceding farnesoic acid biosynthesis were inhibited or refractory to stimulation in vivo.
Fine structure of aphid stylet routes in plant tissues in correlation with EPG signals
Authors: TJALLINGII W. F. , ESCH TH. HOGEN
Published: March 2008

Abstract. Plant penetration by Aphis fabae (Scopoli) was recorded by the electrical penetration graph (EPG) technique and followed by stylectomy during wave‐forms that were suspected of indicating sieve element punctures. The severed stylets in the plant tissue were subsequently processed for transmission electron microscopy (TEM) and sectioned either transverse or longitudinal to the stylets. Two completely serially sectioned probes from the epidermis to the phloem were reconstructed.

In one probe the stylet pathway went to a sieve element and showed many empty branches of salivary sheath material. Breaks in cell walls filled with sheath material demonstrated that the majority of cells bordering the track had been punctured, which supports earlier evidence from EPGs. All types of cells showed punctures and the highest number was found inside the vascular bundle. Very few cells died, which would appear to be important for virus transmission, and in others cellular reactions remained limited to some callose formation. The route of the stylets was intercellular and passed through the secondary wall material. The role of pectinase in intercellular penetration, and previous evidence for intracellular tracks are discussed. Most sieve elements had been punctured but only one was eventually accepted. Thus, reaching a sieve element in a host plant does not automatically imply its acceptance though the reason remains unclear. Gelation of phloem proteins was shown in the stylet canal.

In a second probe, plant cytological and morphological correlations with the EPG were emphasized. Probes by other aphid‐plant combinations showed great similarity.
Vibrational alarm communication in the damp‐wood termite Zootermopsis nevadensis
Authors: KIRCHNER WOLFGANG H. , BROECKER INGRID , TAUTZ JÜRGEN
Published: March 2008

Abstract. Vibrational alarm communication was studied in the New World, damp‐wood termite Zootermopsis nevadensis (Isoptera: Termopsidae). Workers and soldiers react to disturbance such as sudden bright light or air currents by drumming their heads against the substratum. This drumming has been described as alarm signalling; its functional significance and perception by the nest mates, however, remained unclear. In the present study we analysed spectral and temporal properties and absolute amplitudes of the vibrational signals and used behavioural responses of the termites to determine the thresholds of the sense of vibration and to find out if and how the termites discriminate the conspecific alarm signals from the background noise.

The drumming signals are trains of pulses of vibrations of the substratum with a pulse repetition rate of about 20 Hz. The carrier frequency depends on the substratum; in the nests studied it was in the range 1–3 kHz. The highest vibrational amplitudes measured close to the signal emitters are usually about 10m/s2 (acceleration, RMS). The threshold of the behavioural response is about 1m/s2 over a wide range of frequencies (10 Hz to 5 kHz), indicating that the termites can detect these signals as vibrations of the substratum. The animals respond preferentially to temporal patterns similar those of the natural signals; temporal rather than spectral cues seem to be used for signal discrimination.
Mechanisms regulating salt intake in fifth‐instar nymphs of Locusta migratoria
Authors: TRUMPER S. , SIMPSON S. J.
Published: March 2008

Abstract. Investigations were undertaken into the mechanisms controlling regulation of salt intake in fifth‐instar nymphs of Locusta migratoria L. Initially, the pattern of feeding was recorded for 24 h in locusts fed a chemically‐defined food either with or without salt. Differences were apparent from the first meal, with smaller meals being eaten more frequently on the salt‐free food over the next 8h. As a result, total food intake over the first 8h was similar on the two foods. By 24 h, however, intake of the salt‐free food was considerably reduced and the rate of prefeeding rejections was high. Next, following a period of pretreatment (24 or 48 h) on one of these two foods, responses were recorded to glass‐fibre discs impregnated with salts, artificial foods differing in salt content, and wheat germ. Haemolymph amino acid titres were also recorded in locusts feeding ad libitum on salt‐free or salt‐containing food to test the ‘metabolic bottleneck’ hypothesis for explaining rejection of a salt‐free food after a period of feeding on it. Finally, the role of learning was investigated in experiments in which distinctive plant odours and flavours were paired with foods lacking or containing salt. Results across all the experiments indicate that regulation of mineral intake in locust nymphs involves a number of mechanisms, including modulation of locomotory behaviour, innate taste responses and learning. Additionally, there was evidence of a sex difference in salt appetite.
Reproductive behaviour of the South American fruit fly Anastrepha fraterculus (Diptera: Tephritidae): laboratory and field studies
Authors: LIMA I. S. DE , HOWSE P. E. , SALLES L. A. B.
Published: March 2008

Abstract. The mate choice, courtship and oviposition behaviour of laboratory‐reared and field‐collected Anastrepha fraterculus (Wied.) were compared. In laboratory cultures in Southampton the duration of male calling activity in small leks increased gradually from 1‐2h at 5 days old to up to 7 h at 10 days. This finding correlates with previous reports on the time at which male salivary glands, which are believed to produce sex pheromone, are fully developed. Wild flies which emerged from infested fruits in Brazil began to oviposit on the day they mated, whereas in laboratory flies oviposition began 1 day following the first mating. Both types of fly usually defended their position on a particular fruit throughout the day, and re‐mated with either virgin or mated males. There was no significant difference in mating duration. Females did not copulate before the mean age (±SE) of 16.8±0.9 days. For both types of flies mating initiation occurred in the first 2h of photophase, with virgin females choosing mainly mated males. The average number of matings in the laboratory was three for females and four for males, and the interval between matings in females was significantly increased after the second mating. It is suggested that the tendency of virgin females to mate with mated males will lead to increased fitness, as males are on average 48 days old at their second mating. The potential life span of around 200 days for both sexes would allow adults to bridge the gap between seasonally available fruits in warm‐temperate and sub‐tropical South America.
The dynamics of collective exploration and trail‐formation in Monomorium pharaonis: experiments and model
Authors: FOURCASSIÉ V. , DENEUBOURG J. L.
Published: March 2008

Abstract. When exploring a chemically unmarked area devoid of food sources, workers of the pest ant Monomorium pharaonis L. (Formicidae, Myrmicinae) leave scent marks on the ground and after 30–60min a network of diverging exploratory trails begins to emerge.

Exploratory activity is affected by the nutritional state of the colony and a period of food deprivation induces a dramatic increase in the number of workers leaving the nest. A mathematical model based on a logistic growth equation is proposed to describe the exploratory recruitment observed. When travelling along exploratory trails the proportion of ants displaying trail‐laying behaviour is higher for outbound than for nestbound workers. Outbound ants also show a greater propensity than nestbound ants to follow the scent marks of their nestmates. The chemical used to mark a novel area does not appear to be colony‐specific and thus does not have a territorial function sensu stricto. The adaptive value of the collective exploratory behaviour observed in this study is discussed in relation to the common features of other pest ant species described in the literature.
Is bigger better? Water balance in the polymorphic desert harvester ant Messor pergandei
Authors: LIGHTON JOHN R. B. , QUINLAN MICHAEL C. , JR DONALD H. FEENER
Published: March 2008

Abstract. Foraging activity of ants in xeric areas may be limited by desiccation stresses. To assess the extent of such stresses on a polymorphic ant species [Messor pergandei (Mayr), body mass range 1‐12mg], we measured body water reserves, absolute rates of water loss, and cuticular permeability over the species' foraging temperature range (15–45d̀C). Cuticular permeability of M. pergandei was typical of xeric arthropods (17μgcm‐2h‐1mmHg‐1). However, the effect of polymorphism on both absolute and relative rates of water loss was unexpected. Large workers lost water more slowly than small workers, even after adjusting for cuticular surface area. In addition, the body water reserves of large workers were larger, even after adjusting for body mass. Small workers of this ant species are therefore disproportionately prone to dehydration, yet, in spite of this, constitute a large and important component of the foraging force. To assess the practical relevance of desiccation to polymorphic ants, we developed a ‘worst‐case’ model of desiccation‐limited foraging parameters (time to complete loss of locomotor coordination in 5% of the foraging force). In this model, average actual foraging duration was substantially less than would be required to incapacitate the ants by dehydration. We discuss direct and indirect evidence suggesting that desiccation may, nevertheless, impose limitations on the foraging activity of ants.
Juvenile Hormone inhibition in corpora allata from ovariectomized Blattella germanica
Authors: MAESTRO JOSÉ‐LUIS , DANÉS MARIA‐DOLORS , PIULACHS MARIA‐DOLORS , CASSIER PIERRE , BELLÉS XAVIER
Published: March 2008

Abstract. Ovariectomy has been used to study the role of the ovary in endocrine homeostasis. Our studies on young virgin adults of the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae) show that the cytological development of the corpora allata (CA) in ovariectomized females proceeds as in intact specimens, whereas the rates of Juvenile Hormone (JH) synthesis are lower. Stimulation of the CA from ovariectomized females in vitro by mevalonolactone suggests that enzymatic mechanisms which follow mevalonate formation in the biosynthetic pathway are functional. The synthetic capabilities of these CA are also illustrated by the kinetics of JH production in vitro, because hormonal release increases with time to reach ‘normal’ levels after 8h of incubation. Our data suggest that the absence of ovaries leads to effective inhibition of JH biosynthesis rather than to an impairment of the developmental process in the CA cells.
Geographical variation in resistance of the parasitoid Asobara tabids against encapsulation by Drosophila melanoqaster larvae: the mechanism explored
Authors: KRAAIJEVELD ALEX R. , ALPHEN JACQUES J. M. VAN
Published: March 2008

Abstract. The braconid parasitoid Asobara tabida Nees attacks larvae of several Drosophila species in fermenting substrates. Northwestern and central European populations of the parasitoid attack mainly D.subobscura Collin. Southern European parasitoids attack mainly D.melanogaster Meigen. Larvae of this last species can defend themselves against parasitoids by encapsulating the parasitoid egg. Parasitoids from southern European populations are better able to resist encapsulation of their eggs than their northwestern and central European conspecifics. The eggs of southern European parasitoids appear to have a ‘sticky’ egg chorion. As a result of this ‘stickiness’ the eggs become embedded in host tissue where they are not completely covered by the host's blood cells. This leads to, at most, partial encapsulation of the egg. Parasitoid larvae can escape from partially closed capsules.
Mating effects on the feeding and locomotion of the German cockroach, Blattella germanica
Authors: LEE HOW‐JING , WU YEN‐LI
Published: March 2008

Abstract. Feeding cycles and daily locomotory patterns of the German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae), were correlated with the ovarian development cycle. To meet the nutrient requirement for ovarian development, females increased feeding before forming oothecae. Locomotory activity also increased when females became sexually receptive. All these activities reached a peak just before the formation of oothecae. Ovarian development ceased and locomotion and food consumption decreased during pregnancy. Both mated and virgin females showed similar reproductive cycles, but those of mated females were more precisely timed (intervals between successive oothecae, and pregnancy duration, were 5 ± 0.6 and 17 ± 0.6 days, respectively). However, the intervals between successive oothecae of virgin females were longer and less synchronized. During this longer interval, feeding took place immediately following the discharge of the ootheca, but locomotory activity increased 5 days later when females became sexually receptive. Mated females increased locomotory activities 1 or 2 days before the end of pregnancy, presumably searching for deposition sites for oothecae. Female adults were found to exhibit a daily nocturnal locomotory pattern. However, under the physiological demands of reproduction, the pattern could be changed, for example by increasing activity during photophase when females were sexually receptive. The physiological effects of reproduction override the control of the daily locomotory pattern by its diel clock.
Variable egg development among Anopheles (Nyssorhynchus): control by mating?
Authors: LOUNIBOS L. P.
Published: March 2008

Abstract. Among ten species of neotropical malaria vectors the frequency of egg development by virgin females fed both sugar and blood varied from 23% to 100% and was positively correlated with their mean fecundity. The mean volume of male accessory glands of these same species varied more than 10‐fold and was negatively correlated with population‐ or species‐specific incidence of egg development by virgin females. The accessory glands of Anopheles nuneztovari Gabaldon and Anopheles rangeli Gabaldon, Cova Garcia & Lopez are much greater in size than those of the other eight species and are believed to contain secretory materials that stimulate egg production following mating. Insemination did not stimulate egg development in Anopheles albimanus Wiedemann whose males possess comparatively small accessory glands.
Anoxia blocks thermotolerance and the induction of rapid cold hardening in the flesh fly, Sarcophaga crassipalpis
Authors: YOCUM GEORGE D. , DENLINGER DAVID L.
Published: March 2008

Abstract. Anoxia induced by nitrogen or carbon dioxide, or hypoxic/hypobaric conditions generated by a partial vacuum sensitizes red‐eye pharate adults of Sarcophaga crassipalpis Macquart to a high temperature exposure that is normally nonlethal (40d̀C for 2–3 h). Thermotolerance induced by a2h exposure to 40d̀C (under aerobic conditions) doubles the pharate adults' tolerance to 45d̀C but provides no protection against a combined exposure to 45d̀C and anoxia, and only modest protection against a combined exposure to 40d̀C and anoxia. Under aerobic conditions, exposing pharate adults to 0d̀C for 2 h increases their tolerance to ‐10d̀C (rapid cold hardening). Rapid cold hardening at 0d̀C is not induced under anoxia. These results imply that tolerance to high temperatures and rapid cold hardening are dependent on aerobic processes and suggest that certain forms of temperature stress can be further exacerbated with anoxia.
Regulation of pheromone production by female pink bollworm moths Pectinophora gossypiella (Sanders) (Lepidoptera: Gelechiidae)
Authors: RAFAELI A. , KLEIN Z.
Published: March 2008

Abstract. We present in this study data which indicate that there is a diel periodicity in the pheromone production of the pink bollworm moth Pectinophora gossypiella (Sanders) (Lepidoptera: Gelechiidae) but that it is not well defined. Moreover the control mechanism of pheromone production differs somewhat from that reported for other moths. No pheromonotropic response was obtained when photophase females were injected with synthetic Helicoverpa zea pheromone biosynthesis activating neuropeptide (Hez‐PBAN). After decapitation for 24 h, Hez‐PBAN did not induce pheromonotropic activity above control levels, which themselves remained relatively high. No effect on pheromone production was observed after treatment with the non‐steroidal ecdysone agonist (RH5999). Decapitation for 72 h resulted in a significant drop in the control levels of pheromone titres. After decapitation for 72 h, stimulation by injections of Hez‐PBAN and pink bollworm head extracts was observed. In addition, an enhancement of the PBAN stimulation was observed when combined with severance of the ventral nerve cord before injection. On the other hand, pink bollworm head extracts did not cross‐react with Hez‐PBAN antiserum in a radioimmunoassay, indicating that the pheromonotropic factor present is sufficiently different from Hez‐PBAN and does not recognize the antigenic binding sites. In studies using isolated abdomen and pheromone gland cultures in vitro, no stimulation of de novo pheromone biosynthesis was observed but a 3‐fold increase in the de novo fatty acid biosynthesis was detected in pheromone gland cultures.
Do protein‐limited female Lucilia cuprina (Diptera: Calliphoridae) obtain a nutritional benefit from mating?
Authors: COOK DAVID F.
Published: March 2008

Abstract. Cohorts of adult female Lucilia cuprina Wiedemann (Diptera: Calliphoridae) were fed a single 5 μl droplet of liver exudate after which half the females were allowed to mate and the other half left as virgins. Females were housed individually with water and sucrose for between 4 and 7 days after mating. Females were dissected to record the level of ovarian development and the size of their primary oocytes. Mating did not give protein‐limited females any significant nutritional benefit in terms of either increased oocyte development, yolk deposition or oocyte size. Hence, it is concluded that male L.cuprina do not provide females at mating with any obvious material benefits beyond their sperm.
The influence of eclosion timing on winter survival and triacylglycerol accumulation in four temperate species of Drosophila
Authors: OHTSU T. , KIMURA M. T. , HORI S. H.
Published: March 2008

Abstract. Diapause incidence, winter survival and triacylglycerol content were studied in temperate species of Drosophila by outdoor rearing in Sapporo (a cool‐temperate region), northern Japan. In strains of D.subauraria and D.triauraria (cool‐temperate species) from northern Japan, diapause was induced in adults having eclosed after early September, but in those having eclosed after mid October in strains of D.rufa and D.lutescens (warm‐temperate species) from southern Japan. A subtropical strain of D.triauraria did not enter diapause. In the strains of cool‐temperate species from northern Japan, about 70% survived until spring when eclosed in mid autumn, whereas when eclosed earlier and later flies had a lower ability to overwinter. The warm‐temperate species and a subtropical strain of D.triauraria also survived longer when eclosed in mid autumn than when eclosed later, but they were unable to survive until spring. The triacylglycerol content was higher in the cool‐temperate species from northern Japan than in the warm‐temperate species and a subtropical strain of D.trauraria. In each species the triacylglycerol content of adults was higher when they eclosed in early and mid than in late autumn. It is assumed that triacylglycerol plays an important role in overwintering of these Drosophila species and the low triacylglycerol level is the primary cause of the low overwintering capacity of individuals eclosing in late autumn.
Relationships between parasitoid host range and host defence: a comparative study of egg encapsulation in two related parasitoid species
Authors: BRODEUR JACQUES , VET LOUISE E. M.
Published: March 2008

Abstract. Parasitoid host range may proceed from traits affecting host suitability, traits affecting parasitoid foraging behaviour, or both. We tested the hypothesis that encapsulation can be used as a reliable indicator of parasitoid host range in two closely related larval endoparasitoids of Lepidoptera. Cotesia glomerata (L.) (Hymenoptera: Braconidae) is gregarious and a generalist on several species of Pieridae, whereas C. rubecula (Marshall) is solitary and specific to Pieris rapae (L.). We determined the effects of host species (Pieris brassicae (L.), P. napi (L.) and P. rapae) (Lepidoptera: Pieridae) and host developmental stage (early first, second and third instar) on encapsulation of parasitoid eggs. Host species and parasitoid species, as well as the resulting interaction between these two factors had significant effects on encapsulation of Cotesia eggs. Encapsulation in Pieris hosts was much lower for C. glomerata (<34%, except for second and third instar of P. rapae) than for C. rubecula (>32%), even when the latter was parasitizing P. rapae. Encapsulation increased with the age of the larvae, although the only significant difference was for C. glomerata. Overall, P. rapae showed a stronger encapsulation reaction than P. brassicae and P. napi. Encapsulation levels of C. glomerata corresponded well to patterns of female host species and host age preference for oviposition and parasitoid larval performance. In contrast, percentages of encapsulation of C. rubecula were not consistent with host preference and host suitability. We argue that encapsulation alone is unlikely to provide a sufficient explanation for C. glomerata and C. rubecula host range.
Differential nutrient extraction in the funnel web spider Agelena labyrinthica
Authors: FURRER SAMUEL , WARD PAUL I.
Published: March 2008

Abstract. Agelena labyrinthica Clerck spiders were raised in the laboratory at three diet levels. Growth, reproduction and the pattern of nutrient extraction of each spider were monitored. The extraction of proteins, carbohydrates and lipids by each spider was analysed on three occasions, covering the immature and mature stages. More nutrients were extracted the less well‐fed the spider, and females extracted more nutrients than did males. Nutrients were extracted most completely during early growth and, especially protein, by females in the reproductive phase. Protein was extracted more completely than lipids or carbohydrates. The relative amounts of the three nutrients extracted changed significantly with time, indicating that spiders are able to adjust their detailed feeding behaviour to their immediate needs. Field collections over the season showed that most spiders in the field grew approximately as those on the medium laboratory ration for most of the time.
Patterns of haemolymph vitellogenin and ovarian vitellin in the German cockroach, and the role of Juvenile Hormone
Authors: MARTÍN DAVID , PIULACHS MARIA‐DOLORS , BELLÉS XAVIER
Published: March 2008

Abstract. The concentrations of fat body and haemolymph vitellogenin and ovarian vitellin during the first gonadotropic cycle of the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae) have been studied. For these purposes, a polyclonal antibody against B. germanica vitellogenin and vitellin has been obtained, and an ELISA to quantify these proteins has been developed. Ovarian vitellin levels follow a pattern which parallels those of basal oocyte growth and Juvenile Hormone production by the corpora allata. This suggests that Juvenile Hormone regulates vitellogenin uptake into oocytes. Fat body and haemolymph vitellogenin levels give cyclic and parallel patterns. However, the cycle of Juvenile Hormone appears delayed with respect to that of vitellogenin. We suggest that the production of Juvenile Hormone, although cyclic in profile, does not modulate alone the cycle of vitellogenin. At least a supplementary mechanism, apparently independent of Juvenile Hormone, may be involved in the decline of vitellogenin production at the end of the vitellogenic cycle.
Effects of ingested ivermectin on body mass
Authors: GOVER JANE , STRONG LES
Published: March 2008

Abstract. Adults of Neomyia cornicina (F.) given continuous access to cow dung containing ivermectin at concentrations of 0.5.0.25 and 0.125 μg g‐1, the range found in the dung of injected cattle (Sommer et al., 1992), were monitored every 12 h for changes in mass and excretory rates over a period of 3–5 days. Compared with the control insects, adult females that had ingested ivermectin showed disrupted patterns of daily mass change, an increase in dawn mass, and greatly reduced rates of excretion. Flies fed continuously with dung containing ivermectin at 0.25 μg g‐1 and 0.125 μg g‐1 in a regime identical to the above showed significantly increased abdominal mass compared with the controls. The observations are discussed in relation to other known effects of ivermectin on insect physiology.
Rates of progress up odour plumes by tsetse flies: a mark‐release video study of the timing of odour source location by Glossina pallidipes
Authors: GRIFFITHS NIGEL , PAYNTER QUENTIN , BRADY JOHN
Published: March 2008

Abstract. The arrival of individually marked Glossina pallidipes Austen at a host odour source after their video‐timed release from 30–75 m downwind was measured in the field in Zimbabwe. In the absence of odour, the proportion recaptured was <2% (= ‐ random expectation); when synthetic ox odour was released, the probability of recapture at the source increased with proximity of release, from 6% at 75 m to 21% at 30 m (about twice this number arrived within ∼2 m of the source). There were two distinct distributions of recaptures: a ‘fast’ cohort which found the source within 40 s, and a ‘slow’ cohort which took from one to >20 min, with ∼50% of the flies in each cohort. The fastest flies probably reached the source in a single, mainly straight flight from take‐off, at an overall average (straight line) displacement speed of 2.8‐4.5 ms‐1 (i.e. close to the preferred flight speed of ∼5 m s‐1). The flies apparently maintained their ground speed largely independent of the wind speed they headed into. The ‘slow’ cohort had a constant probability of arrival at the source, presumably after losing and re‐contacting the plume, and after having stopped at least once on the way. There were no marked correlations with wind parameters, although the probability of recapture increased slightly with the directness of the wind from the source, and the probability of ‘slow’ flight increased slightly with wind speed. It is inferred that a repeated sequence of anemotactic ‘aim‐then‐shoot’ orientation at take‐off plus optomotor‐steered in‐flight correction of direction is used as a form of biassed random walk to bring the flies close to the odour source, rather than the use of moth‐type anemotactic zigzagging.
Wind speed effects on odour source location by tsetse flies (Glossina)
Authors: BRADY JOHN , GRIFFITHS NIGEL , PAYNTER QUENTIN
Published: March 2008

Abstract. Tsetse flies (mainly Glossina pallidipes Aust.) were captured by various means at sources of artificial host odour in Zimbabwe and Kenya. Their rates of arrival and flight directions were compared with simultaneous data on the wind's speed and direction, on time‐scales ranging from 1 s to 30 min. It was predicted that because increasing wind speed up to 1 m s‐1 straightens out the airflow (Brady et al., 1989) it will straighten out odour plumes, make them easier to navigate, and should therefore increase the rate of arrival of flies at an odour source. In the event, the relationship proved to be more complex, with both positive and negative correlations of arrival rate on wind speed. It seems there is a bimodal relationship: odour source finding is positively related to increasing wind speed in weak winds up to ∼0.5 m s‐1 (presumably as the odour plume straightens out), but is negatively related to increasing wind speed in strong winds above ∼1.0 m s‐1 (presumably due to increasing turbulence breaking up the odour plume).
Influence of environmental factors on the wandering phase and pupariation in stable fly, Stomoxys calcitrans, larvae
Authors: McPHERON LINDA J. , BROCE ALBERTO B.
Published: March 2008

Abstract. Components of the wandering phase of mature stable fly (Stomoxys calcitrans L. (Diptera: Muscidae)) larvae were examined. The mean length of the wandering phase was estimated to be 10.6 ± 3.5 h. In a factorial experiment in which wandering larvae were allowed to pupate in media with three levels each of moisture, temperature and light, the mean time to 50% pupariation was delayed and the rate of pupariation was lowest at high moisture levels, but this latter effect was seen only at the moderate light level. Pupae in media with higher moisture contents had significantly higher fresh weights. However, none of the three factors affected dry weight of pupae. A significant interaction was observed between the effects of moisture and temperature on survival; only at highest moisture content and at the highest temperature did a significant decrease in survival occur. In a separate experiment, density was found to have no effect on mean time to 50% pupariation or the rate of pupariation. Puparium formation appeared to be random under a LD 169 h photocycle, showing no apparent circadian rhythm.
Functional organization of the macroglomerular complex related to behaviourally expressed olfactory redundancy in male cabbage looper moths
Authors: TODD J. L. , ANTON S. , HANSSON B. S. , BAKER T. C.
Published: March 2008

Abstract. The neurophysiological bases for behaviourally expressed olfactory redundancy in the sex pheromone communication system of the cabbage looper moth, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), were examined by coupling the cut‐sensillum extracellular recording technique with a highly specific neuronal marking method for moth peripheral receptors. In seventy‐two antennal sensilla, axonal pathways of cobalt‐stained neurones could be traced into the male‐specific macroglomerular complex in the antennal lobe. In T. ni males this comprises five glomeruli, two of which are subdivided into morphologically, and in some instances functionally identifiable, regions. Axonal arborizations of forty‐eight neurones (single stainings) showed high fidelity (98%) for containment within a specific glomerulus or glomerular subdivision, and the neuropil targeted seemed to be related to the specificity of a neurone to a particular female‐emitted sex pheromone component (27‐12:Ac, Z7‐14:Ac, Z9‐14:Ac, 12:Ac, 11–12:Ac, Z5‐12:Ac), or to a behavioural antagonist (Z7‐12:OH). Double (twenty‐one) and multiple stainings (three) showed axons projecting into two or more glomeruli, respectively, with 100% fidelity for the component‐specific glomerulus or glomerular subdivision to be targeted. We suggest that the potential for a single minor component to cross‐stimulate two or more neurones within a sensillum may enable partial blends to continue to provide sensory input into all of the pheromone‐processing glomeruli of the complex. Our interpretation is that redundancy occurs at the receptor level on neighbouring dendrites, and thus allows various four‐component partial blends to evoke full pheromone‐mediated behaviour.
The role of direct chilling injury and inoculative freezing in cold tolerance of Amblyomma americanum, Dermacentor variabilis and Ixodes scapularis
Authors: BURKS CHARLES S. , STEWART RICHARD L. , NEEDHAM GLEN R. , LEE RICHARD E.
Published: March 2008

Abstract. Supercooling points and chill tolerance were compared among nymphs and adults of the ixodid ticks Dermacentor variabilis, Amblyomma americanum and Ixodes scapularis (Acari: Ixodidae).Supercooling points in the range of <‐22 to ‐18°C were observed for nymphs, and ‐22 to ‐8°C for adults.The lower lethal temperatures observed under dry conditions, ‐14 to ‐10°C, were warmer than the supercooling points, but still much colder than ‐4.8°C, the lowest temperature recorded from a likely tick habitat in southwestern Ohio.Based on our experiments, spontaneous freezing and direct chilling injury are not significant mortality factors in these species in the field.Mortality was observed between ‐5 and ‐3°C for A.americanum and D.variabilis nymphs chilled for 2 h while in direct contact with ice.This mortality is probably due to inoculative freezing.Given the requirement for a rather humid microhabitat for off‐host survival, these findings suggest that inoculative freezing is an important cause of overwintering mortality in these medically important species.
Oviposition behaviour of the cowpea seed beetle, Callosobruchus maculatus
Authors: PARR MARTIN J. , TRAN BRUNO M.D. , SIMMONDS MONIQUE S.J. , CREDLAND PETER F.
Published: March 2008

Abstract. The activity of female Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), the cowpea seed beetle, between making contact with a potential host seed and egg deposition is analysed in detail on cowpeas, mung beans and mung beans bearing conspecific eggs.The data differ from previous accounts in that descriptors do not ascribe function (inspection, patrolling, etc.) to the activities but are restricted to observable postures and movements.From the twenty‐four discrete patterns of behaviour, kinetograms are constructed following analysis of a three‐dimensional contingency table in which expected values have been calculated in eight models assuming various considerations of independence, from complete independence of each behavioural element to alternative two‐way interactions among the three variables, viz preceding behaviour, following behaviour, and host.Core transitions were determined by calculation of standardized residuals, by their high conditional probabilities and transitional frequencies.There is a very clear sequence of oviposition behaviour, parts of which are the same on all three hosts.The simplest behavioural sequence was observed on mung beans which was shown to be the most acceptable of the three hosts.The presence of an egg resulted in a diversification of behaviour.The method provides a quantitative method of describing and comparing behavioural sequences and hence a means of determining one aspect of the acceptability of different hosts.Using this method the occurrence of a behavioural sequence has been determined with an objective statistical basis applicable to numerous multitrophic relationships.
A circadian rhythm of thermal preference in the ant Camponotus mus: masking and entrainment by temperature cycles
Authors: ROCES FLAVIO , NÚÑEZ JOSUÉ A.
Published: March 2008

Abstract. Along a stable temperature gradient and under a LD 12:12 h cycle, nurse workers of the ant Camponotus mus Roger 1863 (Hymenoptera: Formicidae) select for the brood two different temperatures daily: 30.8°C at the middle of the light period (circadian phase = 90°), and 27.5°C 8 h later, during the dark period (circadian phase = 210°), this rhythm being of endogenous nature.When a 24 h temperature cycle was superimposed along the thermal gradient, so that the immobile brood experienced a temperature transition as they receive when translocated by nurses (8 h at 30.8°C and 16 h at 27.5°C), no brood translocations occurred.The thermal cycle masked the rhythm of brood translocation when temperature fitted the daily pattern expected by nurses.When the same temperature cycle was presented with a phase‐advance, nurses did not tolerate the early thermal increase and removed the brood as temperature rose.However, when workers experienced this new phase relationship between light and temperature cycles for more than 10 days, brood translocations were suppressed.Records under constant conditions of light and temperature indicated that the overt rhythm was locked‐on to the expected early increase in temperature, so that the temperature cycle dominated over the LD cycle in resetting brood‐carrying activity.
Effects of diet and activity on lipid levels of adult Mediterranean fruit flies
Authors: WARBURG MEIRAV S. , YUVAL BOAZ
Published: March 2008

Abstract. The objectives of this study were to determine whether adult Mediterranean fruit flies, Ceratitis capitata Wiedeman (Diptera: Tephritidae), are capable of synthesizing lipids, and whether adult diet affects this ability.Lipid levels in females fed protein and carbohydrate or carbohydrate alone declined significantly from emergence to the fourth day of life and then rose back to teneral levels on the fifth day, before oviposition took place on the sixth day.In males fed protein and carbohydrate, lipid levels initially declined as males aged and then stabilized.In carbohydrate‐fed males lipid levels declined following emergence and recovered somewhat by the sixth day.Lipid levels declined significantly when flies underwent post‐emergence starvation, but after substantial feeding on the above‐mentioned diets they eventually (within 6–7 days) reached teneral levels in all experimental groups.Multivariate analysis of variance revealed that differences in lipid contents are primarily related to the flies' age, which corresponds to the various sex‐specific activities these flies exhibit.Average lipid investment in eggs was found to equal teneral lipid levels in females.Without lipogenic abilities, oviposition would completely deplete female lipid reserves.We conclude that adult medflies are capaple of lipid synthesis, and that this capability is modulated by individual and sex‐specific activity patterns.
Abdominal ventilatory pattern in crickets depends on the stridulatory motor pattern
Authors: PARIPOVIC I. , HENNIG R.M. , OTTO D.
Published: March 2008

Abstract. Ventilatory motor patterns were recorded from abdominal muscles in crickets, Gryllus campestris L.and Teleogryllus commodus (Walker), at rest and during three types of stridulatory motor activity; calling, courtship and aggressive song.

Increases in ventilatory period were almost exclusively due to an increase of the pause between expiratory bursts, whereas abdominal ventilatory bursts remained constant at 200 ms.Ventilatory patterns depended on the stridulatory motor pattern and indicated that the same basic respiratory oscillator exists in both cricket species.

In G.campestris there was a strict 1:1 coupling between chirps and ventilatory bursts.In T.commodus such a relationship was also observed for the chirp part of the songs, but less strictly for the trill part of the calling song and not for the courtship song.In both species the onset of the ventilatory burst was within ± 100 ms of a stridulatory chirp.Ventilatory burst lasted longer the earlier they began before a stridulatory chirp.This suggests strongly that the stridulatory motor pattern terminates the expiratory burst, and thus influences the ventilatory motor pattern.
Laboratory‐simulated naturally‐decreasing day lengths, twilight and aphid photoperiodism
Authors: NUNES MARLIES VAZ , YOUNG STEPHEN , HARDIE JIM
Published: March 2008

Abstract. Day‐length changes, as well as periods of twilight, that occur in the course of each natural day‐night cycle, were recreated for two chosen latitudes in a computer‐controlled ‘natural‐day‐length simulator’.The photoperiodic responses of two aphid species, Aphis fabae and Megoura viciae, were examined in conditions which mimicked late summer to autumn at two simulated latidudes, 51.5d̀N (e.g.Ascot, Southern Britain) and 60°N (e.g.southern tip of Shetland Islands, Northern Britain), with temperatures between 16°C (‘night’) and 18°C (‘day’).The responses under simulated natural photoperiodic conditions were similar to those observed under conventional experimental conditions of squarewave light‐dark cycles (with abrupt lights‐on and lights‐off and constant light intensities during the light phase): both aphid species responded to civil twilight as light, and the critical day lengths (including civil twilight) for the induction of sexual morphs by the two aphid species observed in the simulator were the same as those found in squarewave light‐dark cycles.

Autumn field experiments (51.5°N) with the same clones of A.fabae and M.viciae revealed much longer critical day lengths for gynopara and male induction in A.fabae compared with those in the laboratory, but the same critical day length for ovipara induction in M.viciue. Minimal night temperatures in the field were on average 6°C, whereas maximal day temperatures declined from around 30°C in early September to 12°C at the end of October; it seems that the critical day lengths in A.fabae are temperature dependent, whereas the findings for M.viciae confirm that the critical day length is temperature compensated.