bluuebunny/crossref_metadata_2025 huggingface dataset:
How Trichogramma parasitoids use moth sex pheromones as kairomones: orientation behaviour in a wind tunnel
Authors: NOLDUS L. P. J. J. , LENTEREN J. C. VAN , LEWIS W. J.
Published: March 2008

Abstract The orientation behaviour of Trichogramma egg parasitoids (T.evanescens Westwood and T.pretiosum Riley) in response to the sex pheromone of their noctuid hosts {Mamestra brassicae L. and Heliothis tea (Boddie)) was investigated in a wind tunnel. Wasps were released on platforms which served as models of leaves, and were exposed to overhead light and an air stream that was either clean or loaded with host sex pheromone. The wasps exhibited: upwind anemotaxis, which was not affected by odour; odour‐modulated positive phototaxis; and odour‐induced inverse orthokinesis. Compared with clean air, residence times, walking times and path lengths on a platform were higher in pheromone‐loaded air than in clean air. In pheromone‐loaded air, walking velocity was reduced. During locomotion on a horizontal platform, net movement was upwind, regardless of the presence or absence of pheromone in the air. On a platform inclined at 45o, anemotaxis appeared offset by positive phototaxis. If wasps were released on top of a glass rod above a platform, host sex pheromone caused wasps to land shortly after take‐off. These results are used to explain higher rates of parasitism of moth eggs in pheromone‐treated plots in earlier field experiments.
Moth sex pheromone adsorption to leaf surface: bridge in time for chemical spies
Authors: NOLDUS L. P. J. J. , POTTING R. P. J. , BARENDREGT H. E.
Published: March 2008

Abstract When brussels sprouts leaves were exposed to air passed over a single calling Mamestra brassicae moth, sex pheromone was adsorbed onto the leaf surface to such an extent that it subsequently elicited behavioural responses in conspecific male moths, as well as in female Trichogramma evanescens, egg parasitoids of M. brassicae. Male moths responded to odour‐treated leaves over a short distance (c. 5 cm) in a wind tunnel, but were not attracted at a distance of 1 m. In contrast, sex pheromone adsorbed to and re‐released from the glass wall of a wind tunnel compartment attracted male moths from 1 m. Trichogramma's locomotory behaviour on leaves is described. On leaves previously exposed to air passed over a calling female moth, Trichogramma wasps stayed significantly longer on leaves treated with clean air or air passed over a non‐calling female moth. In addition, wasps spent relatively more time along the margin and on the leaf underside on treated leaves compared with control leaves. All effects persisted for at least 4 h, and after 24 h treated leaves still increased wasp residence times. These results are the first example of responses of male moths to adsorbed airborne sex pheromone originating from a single female moth. They further suggest how sex pheromone released by nocturnal moths may function as a kairomone for diurnally foraging parasitoids.
The effect of temperature on progeny allocation and short interval timing in a parasitoid wasp
Authors: SCHMIDT J. M. , PAK G. A.
Published: March 2008

Abstract The parasitoid wasp Trichogramma dendrolimi Matsumura sets the number of progeny allocated to its insect egg hosts according to the duration of its initial transit walk across the host surface. Although cooling the wasp reduces its walking speed, reduced temperature does not affect progeny allocation. By locally heating and cooling the wasps, the initial transit can be thermally uncoupled from the subsequent oviposition. Using this technique we show that the timing of initial transit duration is temperature‐dependent. These findings suggest that short interval timing by Trichogramma differs physiologically from the temperature compensated clocks that have been described for other insects.
Celestial orientation in Gryllotalpa gryllotalpa
Authors: UGOLINI A. , FELICIONI S.
Published: March 2008

Abstract This study examines the capacity in Gryllotalpa gryllotalpa L. to assume a correct direction towards the bank it originally came from when released in water, by using only celestial orienting cues. These cues can be identified as the sun and, probably, polarized skylight. The orienting mechanism is time‐compensated.
Compensatory responses of the fall armyworm (Spodoptera frugiperda) when fed water‐ and cellulose‐diluted diets
Authors: WHEELER G. S. , SLANSKY F.
Published: March 2008

Abstract Caterpillars of the noctuid moth, Spodoptera frugiperda (J. E. Smith), reared on artificial diets diluted with cellulose and water, increased fresh weight (fw) consumption 2.2–2.5‐fold over those on the undiluted diet. At moderate levels of water‐ or cellulose‐dilution, the increased consumption, combined with increased digestion and absorption of nutrients (ADNU), sufficiently compensated for the reduced nutrient intake to achieve pupal biomass equivalent to that of pupae from the undiluted diet. At higher levels of water‐ and cellulose‐dilution, fw consumption and ADNU increased further but pupal dry weight declined on the water‐diluted diets. At each level of dilution fw consumption and ADNU increased similarly on the water‐ and cellulose‐diluted diets, but biomass gain was reduced on the water‐ compared with the cellulose‐diluted diets. This was due in part to lowered food conversion efficiency on the water‐diluted diets, possibly caused by increased costs of metabolizing the wetter diets. Our data support the hypothesis that consumption rates are regulated by a nutrient feedback mechanism. Our data also suggest that digestive enzyme activity is correlated with consumption. Furthermore, the cost of increased consumption rates on diets of reduced energetic value may constitute a substantially greater energy expenditure than previously believed. However, this cost was insufficient to reduce relative growth rates but was apparently manifested in lowered lipid accumulation.
Some mechanical properties of the flagellar‐pedicellar suspension in Aedes aegypti (L.)
Authors: McVEAN ALISTAIR
Published: March 2008

Abstract The rotation of the flagellum of male and female Aedes aegypti (L.) was measured in a wind tunnel at wind speeds between 0 and 116cms‐1. Although the surface area of the female flagellum is only 10% of the male, it rotates through double the angle of the male flagellum for the same increase in wind speed. The larger rotation of the female flagellum could result from: a reduced resistive torque in the flagellar‐pedicellar suspension; a larger antennal‐positioning reflex; a smaller initial angle of attack. The resistive torque in the flagellar‐pedicellar suspension was measured in both male and female Aedes aegypti. In ten adult females the average torque at 8o rotation was 2.70 ± 1.33 times 10‐10Nm and in ten males it was 6.46 ± 3.46 times 10‐10Nm. The significance of these results is discussed with reference to the sexual dimorphism in the sensory tasks required of Johnston's organ in the two sexes.
Reproductive and developmental consequences of a diapause maternal effect in the flesh fly, Sarcophaga bullata
Authors: ROCKEY SARAH J. , YODER JAY A. , DENLINGER DAVID L.
Published: March 2008

Abstract Progeny of Sarcophaga bullata produced from mothers with a history of short day will not enter pupal diapause even if they are reared in a strong diapause‐inducing environment (LD 12:12 h at 20oC). Short‐day exposure and diapause commitment are normally inseparable, but this maternal effect provides a tool for examining separately the effect of photoperiod and diapause commitment. Duration of the wandering period of the third instar is longer in diapause‐destined larvae than in non‐diapause‐destined larvae, and fecundity of flies that have experienced pupal diapause is lower than in long‐day flies that have not been through diapause. The puparia of diapausing pupae contain more hydrocarbons than puparia of nondiapausing pupae, and this contributes to higher rates of net transpiration for the nondiapausing flies. Flies showing the maternal effect (short‐day experience but no diapause) show an intermediate response: length of wandering, fecundity rate and quantities of puparial hydrocarbon are between the extremes observed in the other two groups of flies. Thus, the maternal effect switches the developmental programme to nondiapause, but the progeny retain some characteristics of diapause. Evidence from reciprocal crosses indicates that the photoperiodic history of the female, rather than the male, is responsible for the influence on fecundity.
The effects of unilateral antennectomy on the flight behaviour of male Heliothis virescens in a pheromone plume
Authors: VICKERS NEIL J. , BAKER THOMAS C.
Published: March 2008

Abstract .Unilaterally antennectomized Heliothis virescens (F.) males flying close to the central axis of a plume of sex pheromone display no significant differences in behaviour compared to sham‐operated males in course angles, track angles, airspeed and groundspeed. This demonstrates that right/left antennal information is not necessary for normal orientation movements in response to pheromone, but rather that it is ‘blended’ within the moth's central nervous system before pheromone‐mediated manoeuvres are made. However, some unilaterally antennectomized moths (36%) make repetitive, asymmetrical, saw‐tooth‐shaped tracks during pheromone‐mediated upwind progress, whereas control moths never make such tracks. Unilaterally antennectomized moths made such tracks on the side of the plume contralateral to the missing antenna. We hypothesize that these occasional asymmetrical tracks in unilaterally ablated males are the result of reiterative asymmetrical pheromone stimulation of a higher probability on track legs going toward rather than away from the long axis of the plume on males with a single antenna remaining on the ‘away from axis’ side. Combined with a greater propensity for treated moths to lock onto the plume away from the central axis on one side rather than the other, repetitive successive asymmetrical track legs (resulting in a saw‐tooth‐shaped track) are commonly observed in these moths. Control moths do also make asymmetric successive track legs but they rarely are repeated and thus are not readily observed.
Volume of Protein meals taken by females of the blowfly, Lucilia cuprina: ovarian development‐related and direct effects of protein ingestion
Authors: BROWNE L. BARTON , GERWEN A. C. M. VAN
Published: March 2008

Abstract. The effect of the stage of ovarian development on the volumes of meals of the protein‐rich material, liver exudate, taken by females of the blowfly, L. cuprina (Wiedemann), was examined using an experimental regime which was designed to isolate the effects of ovarian development from any other more direct effects of protein feeding or deprivation. It was found that volumes of meals taken by females with developing ovaries were little, if any, smaller than the volumes taken by protein‐deprived females until quite late in vitellogenesis, at which stage meal size fell abruptly to that of meals taken by gravid females. A direct effect of protein‐feeding was also demonstrated, with females that had consumed exudate during the previous few hours taking substantially smaller meals than those that had not done so. This effect was, however, shown to be non‐specific in that the recent consumption of an equal volume of concentrated sucrose solution caused a similar reduction in the volume of exudate taken.
Response properties of CO2‐sensitive receptors in tsetse flies (Diptera: Glossina Palpalis)
Authors: BOGNER FRANZ
Published: March 2008

Abstract. Extracellular single cell recordings of CO2‐sensitive receptors in tsetse flies revealed a steep dose response over a range of stimuli of two to three orders of magnitude and a maximum response of approximately 70 impulses/s after exposure to a high, but naturally feasible, C02 concentration of 5%. These receptor neurones are slightly sensitive to C02 levels occurring in air (‐0.03%); the sensitivity to CO2 above that level may be used to locate potential hosts. The C02‐sensitive neurones did not respond to some other biologically relevant odours such as octenol, butanone or p‐cresol; however, other receptor cells, some in the same sensillum, are sensitive to some of these odours.

A striking feature of the C02 receptors is that they appear not to adapt in their response frequencies. The spike numbers of the phasic‐tonic response remain constant in the tonic portion during continuous (or repetitively pulsed) long‐term stimulation (1 min). This unusual physiological ability would allow continuous monitoring of C02 values as well as detecting potential hosts that exhale CO2. These electrophysiological results are compared to the behavioural findings in tsetse flies and to the physiological data on C02 receptors of other, non‐bloodsucking insects.
Azadirachtin‐induced effects on larval‐pupal transformation of Spodoptera mauritia
Authors: JAGANNADH V. , NAIR V. S. K.
Published: March 2008

Abstract. Penultimate (fifth) and last (sixth) stadium larvae of Spodoptera mauritia Boisd. (Lepidoptera: Noctuidae) of various ages were injected with 0.5 μg, 1 μg or 2 μg azadirachtin and the effects on moulting and larval‐pupal transformation were analysed. Higher doses (1 μg and 2 μg) of azadirachtin induced a prolongation of the fifth stadium in larvae treated on day 0 and day 1. The resulting sixth stadium larvae failed to pupate. Sixth stadium larvae injected with 0.5 μg, 1 μg or 2 μg azadirachtin showed prolongation of sixth larval period. Azadirachtin treatments completely prevented normal pupation in ‘day 0’ and ‘day 1’ larvae even though the percentage of pupation increased in treated larvae of other age groups. Injection of 2 fig azadirachtin prevented normal pupation in larvae of all age groups. Injection of 4 μg ecdysterone to sixth stadium larvae pre‐treated with 1 fig azadirachtin (on day 0) promoted normal pupation in the majority of animals.
The effect of oxygen lack on egg hatching in an Indian dragonfly, Potamarcha congener
Authors: MILLER P. L.
Published: March 2008

Abstract.During oviposition, femalePotamarcha congener(Rambur) (Libel‐lulidae: Odonata) hover over water and face towards the margins of temporary pools. They repeatedly scoop up drops of water with the posterior end of the abdomen and flick them together with eggs towards the bank. Embryonic development is complete in 7–8 days at 28d̀C but hatching can be delayed for up to 80 days if the eggs are kept in air at 100% r.h. Hatching is triggered by oxygen lack. In the laboratory, perfusion with gases containing oxygen at partial pressures below 5.3kPa causes hatching without submergence in water. Eggs exhibit considerable variability of hatching threshold: this is partly due to age but it also occurs regardless of age among the eggs of a single clutch and probably has adaptive value. The eggs of two other species tested,Pantala flavescensandOrthetrum pruinosum, show no hatching response to oxygen lack.
The effect of sugar meals and body size on fecundity and longevity of female Aedes communis(Diptera: Culicidae)
Authors: ANDERSSON I. HELENA
Published: March 2008

Abstract. Starved females of Aedes communis(DeGeer) had significantly shorter mean lifespans than females with access to one blood meal and/or sugar meals. For the starving females, lifespan was significantly correlated with wing length. This correlation was not found in sugar‐ and/or blood‐fed females. Fructose and sucrose had similar effects on mosquito lifespan. The 25% and 50% (w/w) solutions of each, increased mean lifespans to 37.8 ± 7.2 and 34.9 ± 9.1 days, respectively. A 10% solution, of either sugar, was significantly inferior, mean lifespan 23.2 ± 10.2 days. The initial sugar meal was very important for female longevity. Subsequent meals aided in ovarian development. One sugar meal, one blood meal, and several sugar meals during oogenesis was found to be the optimal diet for the female mosquitoes in this study.
A comparative study on insemination dependency of circadian activity pattern in mosquitoes
Authors: CHIBA YOSHIHIKO , SHINKAWA YASUHIRO , YOSHII MAKOTO , MATSUMOTO AKIRA , TOMIOKA KENJI , TAKAHASHI SUSUMU Y.
Published: March 2008

Abstract. Two forms of mosquitoes in the Culex pipiens complex, C.p.pallens and C.p.molestus, were compared for the insemination‐dependency of entrained female circadian activity in LD 16:8h. When virgin, Pallens is nocturnal and molestus is, in addition, diurnal. Insemination and injection of extracts of the male accessory gland affects virgin activity in that nocturnality is strengthened in both mosquitoes, and the diurnal activity of molestus is depressed. This was so whether the treatments were intra‐ or interspecific. These findings are compared with those already published for other mosquitoes. A coherent view is proposed that the mosquito, nocturnal/crepuscular, nocturnal and diurnal, or diurnal, has potentially a similar entrained waveform which is affected by insemination in a common way, and by lighting conditions in species specific ways.
Physiological differences between strains of Tribolium castaneum selected for resistance to hypoxia and hypercarbia, and the unselected strain
Authors: DONAHAYE E.
Published: March 2008

Abstract. The metabolic rates, as expressed by oxygen (O2) consumption, carbon dioxide (CO2) production, and losses in wet and dry weights, were examined for adults of three strains of the red flour beetle Tribolium castaneum (Herbst), during exposure to two modified atmospheres (MAs). Exposure of a strain selected for resistance over twenty‐one generations to an atmosphere of 65% CO2, 20% O2 and the balance nitrogen (N2), termed a high carbon dioxide concentration atmosphere (HCC) and exposure of an unselected strain to HCC, showed considerable levels of aerobic metabolism during exposure. For the unselected strain water loss and mobilization of energy reserves were rapid and mortality was followed by rapid desiccation. For the HCC‐resistant strain water balance was maintained and energy reserves were utilized more slowly over a prolonged period. Exposure of a strain selected for resistance over twenty‐one generations to a low oxygen concentration atmosphere (LOC) of 0.5% O2 in N2, and an unselected strain to LOC, revealed that even at 0.5% O2, metabolism was largely aerobic in both strains. Maintenance of water balance was not a major factor causing mortality of either strain during exposure to LOC. In air, metabolic rates of both the resistant strains were lower than that of the unselected strain.
Influence of host deprivation on egg load and oviposition behaviour of Brachymeria intermedia, a parasitoid of gypsy moth
Authors: DROST Y. C. , CARDÉ R. T.
Published: March 2008

Abstract. Mated female Brachymeria intermedia (Hymenoptera: Chalcididae) deprived, since emergence, from pupae of their host Lymantria dispar (Lepidoptera: Lymantriidae), accumulated eggs but had a very low rate of hostacceptance. Parasitoids that were host‐deprived after encountering pupae early in life also accumulated eggs, but maintained a high acceptance rate. Thus early exposure to hosts promoted active reproductive behaviour. Total egg production depended on the total number of pupae encountered, indicating that B.intermedia adjust their egg production to host availability. Hence, in B. intermedia both the physiological state of the parasitoid (age and egg load) and the informational state (in this case host‐availability and experience) interact to shape oviposition behaviour.
Spacing behaviour in resting Culex pipiens (Diptera, Culicidae): a computer modelling approach
Authors: KRAUSE JENS , BROWN DAVID , CORBET SARAH A.
Published: March 2008

Abstract. We compared two models based on Monte Carlo simulations with the spacing patterns of resting adults of the mosquito Cx pipiens L. (form molestus) (Diptera, Culicidae). The comparison with the first model which assumed a distribution of complete spatial randomness showed that there was a tendency for mosquitoes to repel other mosquitoes which were too close, resulting in high local regularity. The second model took this repulsion into account. A final test of global patchiness using Model 2 indicated that the spacing behaviour of Cx pipiens was not sufficiently described by local regularity only, but also required a gregarious element. This supports the hypothesis that the molestus form of Cx pipiens shows spaced‐out gregariousness in the sense of Kennedy & Crawley (1967).
Glutamine synthetase activity during embryonic and larval development of the silkworm Bombyx mori L. and role of a JH analogue
Authors: SESHACHALAM R. V. , SUBRAMANYAM M. V. V. , KRISHNAMOORTHY R. V.
Published: March 2008

Abstract. Silkworm eggs of diapause nature were chilled or treated with hydrochloric acid. Glutamine synthetase activity in such treated eggs was present soon after the treatment, whereas in non‐diapause eggs it was not detectable until 24 h after the start of development. During larval life, the glutamine synthetase was found to be absent in midgut tissue. Topical application of a JH analogue resulted in extened larval duration and it reduced glutamine synthetase activity initially, but in the latter part of development the activity was higher.
New pathway of utilization of ammonia nitrogen for the synthesis of amino acids through NADH dependent transaminases in Bombyx mori L.
Authors: SESHACHALAM R.V. , SUBRAMANYAM M. V. V. , KRISHNAMOORTHY R. V.
Published: March 2008

Abstract. NADH dependent transamination was recorded for the first time in silkworm Bombyx mori(L.) eggs and in larval tissues. L‐Glutamine:2–oxoglutarate amino transferase (GOGAT) and L‐asparagine:2–oxoglutarate amino transferase (AOGAT) were determined in embryonic and also in larval tissues of multi‐and bivoltine races. The presence of these two enzymes coupled to glutamine synthetase indicated efficient utilization of metabolic ammonia hitherto unknown in higher organisms. It is proposed that these transfer enzymes help in building the free amino acid pool seen during the diapause and also in the fibroin synthesis in the last larval stadium.
Reactions of adult female parasitoids, particularly Aphidius rhopalosiphi, to volatile chemical cues from the host plants of their aphid prey
Authors: WICKREMASINGHE M. G. V. , EMDEN H. F. VAN
Published: March 2008

Abstract. In Y‐tube olfactometer tests, Aphidius ervi Hal., Trioxyssp., Praon sp., Aphelinus flavus (Nees), Lysiphlebus fabarum (Marsh.) and Aphidius rophalosiphi De Stef. responded positively to the odour of the plant on which aphid mummies containing them had been collected. The response to host plant odour was greater than the response to the odour of host aphids, their honeydew or a combination of the two. The strongest response was to a combination of plant and host aphids. A. rhopalosiphi showed a strong positive response to three wheat volatiles (cis‐3‐hexenyl acetate, cis‐3‐hexen‐1‐ol and trans‐2‐hexenal) as well as to indole‐3‐acetaldehyde (a breakdown product of tryptophan in aphid honeydew). In both olfactometer tests with odours and choice trials with whole plants, newly emerged A. rhopalosiphidistinguished and preferred the variety of wheat on which their development had occurred to other wheat varieties.
Effects of alkaloids on feeding by Phormia reginaconfirm the critical role of sensory inhibition
Authors: DETHIER V. G. , BOWDAN E.
Published: March 2008

Abstract. Inhibition of peripheral chemoreceptors by micromolar concentrations of alkaloids may account for feeding deterrence. Earlier work showed a reduction in both the proboscis extension response and sensory activity recorded from sugar‐sensitive cells in tarsal D and labellar ‘largest’ hairs when the stimulating solution was sucrose mixed with alkaloids. In the present work a similar behavioural effect was also seen when alkaloids were mixed with pyranose and furanose sugars as well as with water and deuterium oxide. Behavioural deterrence continued after the stimulus was removed. Complete recovery occurred after 120 s. To check against the possibility of a central inhibitory state (CIS) having been established two sets of experiments were run in which quinine was applied to a single tarsus followed by a sucrose post‐test to the contralateral tarsus. In one half of the tests sugar was applied first (S1Q2), and in the other half quinine first (Q1S2). Comparable tests were run with contralateral labellar hairs. No CIS was set up by Q1; however, a central excitatory state (CES) was set up by S1. In order to test (a) whether quinine had different effects on other known or unknown receptors and (b) post‐ingestive effects, volumes imbibed in single drinks of sucrose with and without quinine were compared. Volumes of the mixture imbibed were not significantly different from what was predicted based on the known reduction in sensory acitivty.
Mechanoresponsive neurones in the suboesophageal ganglion of the locust
Authors: SIMPSON S. J.
Published: March 2008

Abstract. A preparation is described for intracellular recording from the neur‐opile of the sub‐oesophageal ganglion (SOG) of the locust, while stimulating the labial and maxillary palps with plant material in such a way as to mimic the palpation behaviour which precedes and continues throughout feeding. Twelve neurones responding to simulated palpation were recorded from and stained in the SOG. Axons of three neurones ascended to the brain, six had descending axons and three had all of their processes confined to the suboesophageal ganglion. The major regions of arborization were in the ventrolateral and mediolateral neuropiles of the maxillary and labial neuromeres. All twelve neurones were solely mechanoresponsive. In addition to responding to palpation of one or more of the four palps, five also responded to stimulation of the labrum, one to touching each antenna, and one to mechanical stimulation of each of the six tarsi. In the context of what is known about the role of mechano‐stimulation in the control of feeding, and given their particular patterns of input and arborizations, it is suggested that the neurones may be active during food selection and ingestion.
Protein, lipid and carbohydrate use during metamophosis in the fire ant, Solenopsis xyloni
Authors: WHEELER DIANA E. , BUCK NORMAN A.
Published: March 2008

Abstract. Concentrations of total sugars, lipids and soluble proteins were measured in prepupae and pupae of a native fire ant, Solenopsis xyloni W. M. wheeler (Hymenoptera: Formicidae). Changes in the concentratons of these reserves were examined over the course of metamorphosis, in response to starvation, and in relation to body size. During metamorphosis, only lipid concentrations changed during the prepuapal period, dropping slightly. During the pupal state, however, approximately 75% of total sugars, 45% of lipids and 40% of soluble proteins were used. Starvation immediately prior to metamorphosis greatly decreased the quantity of carbohydrate detected at the beginning of the prepupal stage. Soluble protein levels were also slightly reduced. In contrast, lipid concentrations in prepupae increased in individuals that had been starved for 2–4 days immediately before metamorphosis. The relationship between body size and amount depended on the type of reserve. Lipid concetrations decreased with increasing size, while carbohydrate levels tended to increase slightly. Overall, soluble protein concentration did not change with size. Gel electrophoresis showed that two major polypeptides account for most of the soluble protein and one on these decreased sharply over the pupal period.
The reproduction‐flight syndrome and the inheritance of tethered‐flight activity in the cotton‐bollworm moth, Heliothis armigera
Authors: COLVIN JOHN , GATEHOUSE A. GAVIN
Published: March 2008

Abstract. To test the hypothesis that the flight activity of Heliothis armigera (Hiibner) (Lepidoptera: Noctuidae) conforms to the ‘oogenesis‐fiight syndrome’, female moths from India and Malawi were flight tested on nights 2, 4 and 6 after eclosion, using a tethered‐flight technique. Maximum flight activity in the Indian strain occurred on night 2, that of the Malawian strain was not significantly different on the three nights of flight. This difference is explained by the Indian females reaching reproductive maturity c. 48 h before the Malawian females. The existence of a ‘reproduction‐flight syndrome’ was confirmed by flight testing males and females of different maturity status on the fourth night after eclosion. Immature moths flew significantly more than did either mature‐virgin or mature‐mated moths. The inheritance of tethered‐flight activity in a late‐maturing line of Malawian H. armigera was investigated. Significant estimates of heritability, by offspring on mid‐parent regressions, were obtained for both the total flight time (0.39 æ 0.083) and the longest flight (0.15 ± 0.058). The significance of such tethered‐flight data to noctuid migration in the field is discussed, and the conclusion drawn that the current experimental design does not index migratory flight satisfactorily.
Geographic variation of diapause intensity in the spider mite Tetranychus urticae
Authors: KOVEOS D. S. , KROON A. , VEERMAN A.
Published: March 2008

Abstract. Eight strains of the spider mite Tetranychus urticae, originating from different localities in western and central Europe, with latitudes ranging from 40.5 to 60oN, displayed marked differences in the period of chilling at 4oC required for diapause termination under a diapause‐maintaining short‐day photoperiodic regime at 19oC, to which the mites were transferred after the cold period. The higher the latitude from which the strains originated the longer was the period of chilling required for diapause termination, suggesting the presence of a gradient in diapause intensity, diapause being deeper the more northern the origin of the strains.

Two strains originating from higher altitudes appeared to have a much deeper diapause than expected from their latitudinal origin. In addition, these two mountain strains showed mutual differences in diapause intensity, notwithstanding the fact that they originated from similar latitudes and altitudes; local climatic conditions probably act as strong selective forces with regard to diapause depth.

All strains appeared to be sensitive to photoperiod during the period of diapause development. Diapause was quickly completed by a long‐day photoperiod (LD 17:7 h), but was maintained by a short‐day photoperiod (LD 10:14h). However, even under the latter regime sensitivity to photoperiod gradually diminished and eventually disappeared, thus leading to ‘spontaneous’ termination of diapause. The length of the period of diapause development, as measured by the sensitivity to photoperiod of diapausing mites, varied between strains; it was shorter in the southern strains and longer in the northern strains. The results indicate great variation in diapause intensity between strains, which is probably genetically determined and may have adaptive significance for this widespread species.

When young females which had just entered diapause were kept for ever longer periods of time under the diapause inducing short‐day regime at which they had been reared, before being transferred to the cold room, the duration of the period of chilling required for diapause termination was found to decrease proportionally in all three strains tested. These results suggest that intensification of diapause does not occur in T. urticae; diapause intensity seems to be highest at the beginning of diapause and to diminish gradually during diapause development.
Haemolymph ecdysteroid titres at metamorphosis in the fruit fly Ceratitis capitata: multiple peaks not apparent in whole body extracts
Authors: VAFOPOULOU X. , STEEL C. G. H. , ALEPOROU‐MARINOU V. , PATARYAS T.
Published: March 2008

Abstract. The titre profile of haemolymph ecdysteroids in the fruit fly Ceratitis capitata was constructed from determinations of haemolymph taken from single animals and compared with ecdysteroid levels in whole body extracts. Larvae were sampled throughout the period from the late third instar larva until eclosion and were synchronized using a conspicuous behavioural marker (‘leaping’) that occurs at the end of the wandering period. Extracts of the whole body exhibit two peaks of ecdysteroids, one associated with pupariation (‘pupariation peak’ of other authors) and the other with pharate adult development. However, the ‘pupariation peak’ corresponded with three temporally distinct peaks in the titre of haemolymph ecdysteroids. The first peak occurs at the time of head retraction (lh before formation of the white puparium) and may represent the initial response to release of prothoracicotropic hormone. The second peak occurs 2–3 h later at the onset of tanning and may be responsible for induction of dopa‐decarboxylase. These peaks are brief (c. 2h each), whereas the third is much longer (16 h) and occupies most of the ‘pupariation peak’. The first two peaks have not been reported previously in any dipteran. Their existence illustrates that extremely brief pulses of ecdysteroids occur in vivo, apparently with profound developmental consequences. The fact that brief pulses in the haemolymph titre are not apparent in whole body extracts emphasizes that results obtained using the latter method must be interpreted with caution.
An improved method for detecting substrate preferences shown by mosquitoes that exhibit ‘skip oviposition’
Authors: CORBET PHILIP S. , CHADEE DAVE D.
Published: March 2008

Abstract. A new method is described for detecting and characterizing ovi‐position‐substrate preferences among insects (e.g. Aedes aegypti) that customarily disperse the eggs of a single batch among several sites (i.e. that exhibit ‘skip oviposition’). The method entails recording the distribution of eggs by individual females provided initially with an array of identical sites, thus eliminating possible effects of position preference and female density, and then placing one test site into the array. A preferred substrate can be identified promptly in this way without having to count eggs.
Transient uptake of hypericin by chrysomelids is regulated by feeding behaviour
Authors: DUFFEY S. S. , PASTEELS J. M.
Published: March 2008

Abstract. The uptake of hypericin from the foliage of Hypericum perforatum by four species of adult chrysomelid beetles, Chrysolina brunsvicensis, C. geminata, C. hyperici and C. varians, was investigated under laboratory conditions. In no species were detectable levels of hypericin passed from the larval to the pupal or adult stages. The total amount of hypericin found in the adult beetles was positively related to the rate of ingestion of foliage. When feeding activity lessened or ceased, body levels of hypericin declined. In adults of C. brunsvicensis, C. hyperici and C. varians maximal body levels of hypericin occurred after 1–10 days of feeding. In C. brunsvicensis a maximal average level of c. 0.96 μg/beetle was obtained. After 20 days body levels in C. brunsvicensis declined to nearly zero. Adults of C. brunsvicensis contained more hypericin than the other species of beetles, but in no case was enough hypericin sequestered to match the original values (c. 13.3 μg/beetle) published by Rees (1969). Our results caste doubt on the role of hypericin as a sequestered defence against predators.

Analysis of body distribution of hypericin indicated the majority was in the gut lumen (80%). An input‐output analysis of hypericin ingested by adults of C. brunsvicensis showed that the greatest majority of hypericin was eliminated in the faeces (up to 85%). Between 15% and 35% of the ingested hypericin was unaccounted for. This loss is the result of a post‐defecational degradation of hypericin (perhaps bacterial).
The migration syndrome in the African armyworm moth, Spodoptera exempts: allocation of resources to flight and reproduction
Authors: GUNN A. , GATEHOUSE A. G.
Published: March 2008

Abstract. Selection for the capacity for prolonged tethered flight in Spodoptera exempta resulted in heavier moths, with significantly larger abdominal glyceride glycerol contents in females of two flight‐selected strains (87% and 49% higher than in the comparable non‐selected strain) and in males of one of them (80% higher). All flight‐selected strains contained individuals of both sexes with very high abdominal glyceride levels. There was no significant relationship between abdominal total glyceride glycerol after flight and flight duration for non‐selected moths, but an inverse linear relationship was evident in both sexes from a flight‐selected strain. Oxygen consumption during tethered flights by flight‐selected moths ranged from 28.2 to 56.6 ml O2g‐1h‐1.

Using these and previous data, notional energy budgets were calculated to account for flight, reproduction and resting metabolism for non‐selected and flight‐selected S. exempta flown on the flight balances and provided thereafter with distilled water. The results confirm the trade‐off between flight and reproduction reported by Gunn et al. (1989). A similar approach using data for two non‐selected strains from the field in Kenya indicated genetic variation in migratory potential, reflected both in pre‐reproductive period and resources available for flight. We conclude that elevated glyceride levels are a component of the migratory syndrome in S. exempta and that this is the major factor underlying the curvilinear relationship between flight duration and fecundity obtained by Gunn et al. (1989).
Methoprene accelerates age polyethism in workers of a social wasp (Polybia occidentalis)
Authors: O'DONNELL SEAN , JEANNE ROBERT L.
Published: March 2008

Abstract. Topical applications of the Juvenile Hormone (JH) analogue methoprene to 1‐day‐old adult workers of the highly eusocial wasp Polybia occidentalis (Olivier) (Hymenoptera: Vespidae) accelerate the rate of age polyethism. Longevity of laboratory‐reared wasps is negatively correlated with dose of topically applied methoprene. Doses of 25 μg methoprene or greater are lethal. Untreated wasps show marked age polyethism in the field. Age of first performance of acts in seven behavioural categories (in‐nest, transition to outside, non‐task on nest envelope, nest maintenance, foraged material handling, defence, and foraging) is negatively correlated with methoprene dose. Topical applications of methoprene accelerate age polyethism of highly eusocial bee and wasp workers, but do not have this effect on primitively eusocial bees and wasps, suggesting that JH control of age polyethism evolved independently in advanced species of Apidae and Vespidae.
Turbulence, trees and semiochemicals: wind‐tunnel orientation of the predator, Rhizophagus grandis, to its barkbeetle prey, Dendroctonus micans
Authors: WYATT TRISTRAM D. , PHILLIPS ALUN D. G. , GRÉGOIRE JEAN‐CLAUDE
Published: March 2008

Abstract. Insects apparently responding to the visual stimulus offered by a tree or other object may also be responding to the variety of physical effects caused by the obstruction, including turbulence, a reduction in wind velocity and eddies. The relative importance of prey odour associated with the bark beetle Dendroctonus micans (Kugelann) (Scolytidae), prey‐host‐tree odour, silhouette, and physical barrier to the wind, in the orientation and landing behaviour of a predatory beetle, Rhizophagus grandis Gyllenhall (Rhizophagidae), were investigated. R. grandis responded very positively to the frass of its prey when presented on a ‘tree’ but not to the same quantity of frass presented alone. Frass on black plastic uPVC pipes was significantly more attractive than frass on real host tree logs, suggesting that host‐tree volatiles do not enhance the attractiveness of prey frass.

The beetles responded to ‘transparent’ Mylar three‐dimensional cylinders in the same way as they did to the black plastic pipes. Beetles were also tested with frass and two‐dimensional stimuli offering a visual stimulus or physical barrier alone or in combination. Frass with a two‐dimensional visual stimulus was no better than frass alone: few insects landed. Significantly more insects were attracted to the same two‐dimensional visual stimulus with a hidden upwind barrier producing turbulence, but a similar number were attracted to the frass in front of a hidden barrier alone. As many plants are similar in size to the logs used in these experiments, comparable effects might influence the behaviour of other phytophagous insects, their predators and parasitoids.
Factors affecting female sexual receptivity in the planthopper, Prokelisia dolus
Authors: HEADY S. E.
Published: March 2008

Abstract. The mating system of Prokelisia dolus Wilson (Homoptera: Delphacidae) was characterized by determining: if males and females multiply mate; when transitions occur in female sexual receptivity, what triggers sexual refractoriness; and what behaviours characterize unreceptive virgins, receptive virgins, and unreceptive mated females. Males copulated with up to six females in less than 1 h, but completely inseminate, on average, only the first four females. Females rarely mated more than once, unless males were depleted of sperm due to previous copulations or if copulation was interrupted (if duration was<2 min). Male and female calling was associated (100% and 91%, respectively) with sexual receptivity and resultant matings. The transition from unreceptive virgin to receptive (calling) mature virgin occurred 48 h posteclosion, and all were mated by day 4. Females that were sexually immature and those completely inseminated did not call. Rejection of males by females included walking away from approaching males (65%), female kicking (7%), and abdominal lifting (5%). Rejection of males was observed by immature, mature and calling, and mated females. Sexual refractoriness was not triggered by acoustic and visual stimuli or mechanical stimulation of genitalia. Refractoriness was also not triggered by reception of small quantities of sperm because some females laid a few viable eggs yet calling was not terminated. Sexual refractoriness was activated by a substance in the ejaculate as demonstrated by injection into the haemocoel of male accessory glands or testes and homogenates of seminal vesicles. This is the first study that documents the role of male ejaculate in inhibiting female sexual receptivity in Hemiptera (Homoptera).
Temporal dynamics of host‐marking in the tropical tephritid fly, Anastrepha ludens
Authors: PAPAJ D. R. , A M. ALUJA
Published: March 2008

Abstract. The temporal dynamics of host‐marking behaviour in the tropical tephritid fly, Anastrepha ludens (Loew), is described and used to formulate a model of control of marking behaviour. The following temporal patterns in host‐marking behaviour were observed. Time spent marking increased as Aludens females deposited clutches in a given fruit previously marked zero, one, two or three times. This trend was paralleled by an increase in the number of pauses in marking behaviour within the host‐marking bout (and hence an increase in the number of sub‐bouts separated by such pauses). Finally, within any given marking bout, the length of a sub‐bout diminished progressively. The length of a pause, by contrast, showed no significant trend. Based on these results, we propose that host‐marking pheromone, or HMP, while deterrent to females prior to egg‐laying, actually stimulates continued host‐marking behaviour after egg‐laying. We argue that host‐marking is regulated by sensory adaptation or habituation to HMP in conjunction with a dosage‐dependent restoration of inhibition of the motor pattern. Functional aspects of this pattern of motor control are discussed.
Deterrence coding by a larval Manduca chemosensory neurone mediating rejection of a non‐host plant, Canna generalis L.
Authors: PETERSON STEVEN C. , HANSON FRANK E. , WARTHEN J. DAVID
Published: March 2008

Abstract. The physiological basis of phagodeterrence was studied electrophy‐siologically and behaviourally in the phytophagous caterpillars Manduca sexta and Manduca quinquemaculata. The model unacceptable non‐host plant was the canna lily, Canna generalis.

A strongly deterrent extract was obtained from fresh leaves of canna by extraction with hot ethanol or ethyl acetate in a blender. Behavioural rejection of these extracts was similar to that of fresh leaves, although less intense. In contrast, blender extracts using other solvents, as well as leaf surface rinses, were phagostimulant or neutral. Chromatographic fractionation of the deterrent ethanolic extract showed the active principles to be moderately polar and separable into two fractions.

Previous ablation experiments had shown that the medial maxillary styloconica and epipharyngeal sensilla are the two most important chemosensory organs in mediating behavioural rejection of canna leaves; if only one of these organs is spared, the animal completely rejects canna. We investigated the neural responses of the medial styloconica and their contribution to the sensory coding responsible for this phagodeterrence.

The active fractions of the deterrent ethanolic extract elicited a vigorous response from one chemosensory neurone in the medial styloconica. This neurone is distinguishable from others in the medial styloconica by its unique temporal response parameters and the characteristic shape changes of its action potentials. The response frequency of this neurone correlates with the degree of phagodeterrence in a dose‐dependent manner. Threshold deterrence occurs at a concentration of extract (1%) that elicits firing in this neurone at a rate of c. 50 spikes/s peak instantaneous frequency and 30 total spikes in the first Is.

We conclude that this is a ’deterrent neurone’ in the sense that vigorous response from this neurone is a sufficient sensory code for behavioural rejection of canna. Thus input from a single sensory neurone is capable of blocking feeding, since only one (unilateral) medial styloconicum is needed to mediate this rejection.
Induction of winged sexuparae in root‐inhabiting colonies of the aphid Pemphigus betae
Authors: MORAN NANCY , SEMINOFF JEFFREY , JOHNSTONE LAUREL
Published: March 2008

Abstract. Growth chamber experiments were conducted to determine what environmental factors induce the development of sexuparae in root‐feeding colonies of the aphid Pemphigus betae Doane (Aphididae: Pemphiginae). Experimental colonies were derived from clones that had been reproducing for at least 15 months under constant laboratory conditions. At constant 20–23oC, sexuparae were almost never produced regardless of the level of crowding or photoperiod. In contrast, every culture of several clones produced sexuparae when subjected to temperatures alternating between 20 and 15oC during the light and dark phases respectively. This fluctuating temperature regime resulted in sexupara production regardless of photoperiod. All cultures also produced some sexuparae when cultures were kept in constant darkness at temperatures that were either alternated between 20 and 15oC or kept constant at 15oC. Constant 17oC resulted in sexupara production in most cultures. At 17oC, experimental manipulation of densities within cultures showed that crowding promotes sexupara production. Thus, within the range of conditions occurring at the time of sexupara induction in the field, photoperiod has no effect on sexupara production, temperature below a threshold between 17 and 20–23oC triggers sexupara production, and crowding promotes sexupara production but only if temperature is low enough.
The time‐course of behavioural phase change in nymphs of the desert locust, Schistocerca gregaria
Authors: ROESSINGH P. , SIMPSON S. J.
Published: March 2008

Abstract. The time‐course of behavioural phase change was investigated in nymphs of Schistocerca gregaria, using logistic regression analysis of behaviour recorded in a standard assay. Gregarization occurred very rapidly. Solitary‐reared nymphs became markedly gregarious in behaviour within 1‐4h of being placed in a crowd. These insects re‐solitarized equally quickly if removed from the crowd. Crowd‐reared locusts also solitarized within l‐4h, but this effect was not complete. Results indicate that, while behavioural gregarization is maximal within a few hours of crowding, solitarization is a two‐stage process, changing rapidly at first, then more slowly as a function of the period of previous crowding.