bluuebunny/crossref_metadata_2025 huggingface dataset:
Parasitoid vibrations as potential releasing stimulus of evasive behaviour in a leafminer
Authors: BACHER SVEN , CASAS JÉRÔME , DORN SILVIA
Published: March 2008

Abstract. The aim of this study was to characterize the vibratory signals produced by the parasitoid Sympiesis sericeicornis Nees (Hymenoptera: Eulophidae) while foraging on apple leaves infested by one of its hosts, the spotted tentiform leafminer Phyllonorycter malella (Ger.) (Lepidoptera: Gracillariidae).This leafminer changes its behaviour as a function of the parasitoid's behaviour to escape parasitization.We propose that the leafminer uses vibrations triggered by the parasitoid to detect the presence of its enemy.We measured vibrations produced by a foraging parasitoid on a mine with a laser vibrometer.By recording concurrently the behaviour of the parasitoid on video, vibrations could be assigned to particular behaviours.Subsequently, vibrations were characterized by their dominant frequencies and intensities.The behaviours Landing and Take‐off both produced strong impact‐like vibrations characterized by an initial irregular phase during which frequencies up to 25 kHz occurred followed by a slow decaying regular phase.Vibrations elicited by Moving, Standing and Probing showed no clear temporal pattern.During Probing, dominant frequencies of up to 5.6 kHz were observed frequently at intensities well above the background noise (>10 dB).During Moving and Standing, vibrations were more scarce and of lower frequencies and intensities.Due to their impact‐like nature, vibrations produced by Landing and Take‐off are probably not specific to the parasitoid.Vibrations produced by Moving and Standing are difficult to detect and not reliable because of their non‐specificity.Therefore, only Probing provides a reliable and detectable source of information for the host.The vibrations elicited during Probing could account for the evasive behaviour that is observed in this and other leafminers.
Effects of food quality on growth and body composition of the collembolan Orchesella cincta
Authors: LAVY D. , VERHOEF H.A.
Published: March 2008

Abstract.The effects of food quality on growth and body composition of the collembolanOrchesella cincta(L.) (Entomobryidae) were investigated to determine optimal values for dietary nitrogen.Hyphae ofCladosporium cladosporioidescontaining 2.2%, 2.7%, 4.0% and 6.2% nitrogen were used as food sources.These different nitrogen contents were obtained by adjusting the medium on which the fungi were grown.Collembola were fed on one of these four food sources for 8 weeks.

O.cincta grew faster and reached a higher asymptotic body mass when fed on fungi with 4% or 6.2% nitrogen content: this effect decreased with higher nitrogen content.The lipid concentration in the animals was negatively correlated with dietary nitrogen content, whereas protein concentration was positively correlated.Glycogen concentration was not found to correlate with the composition of the food.

A mechanism is proposed by whichO.cincta compensates for low dietary nitrogen by consuming more to maintain a relatively constant amount of protein in its body and, as a result, accumulates more fat than animals fed on fungi with a higher nitrogen content.
The effects of temperature and season on the O2 consumption of third‐instar larvae of the goldenrod gall fly (Eurosta solidaginis)
Authors: LAYNE JACK R. , EYCK CHRIS TEN
Published: March 2008

Abstract. Third‐instar larvae of the goldenrod gall fly (Eurosta solidaginis Fitch) live inside ball galls on goldenrod plants from summer to the following spring.Because galls are highly exposed to the weather, larvae experience substantial variations in body temperature.This study documents the oxygen consumption of gall fly larvae with regard to the effects of ambient temperature, seasonal conditioning, and prior exposure to subzero temperature.The body mass of larvae doubles between the late summer and the autumn; it subsequently undergoes a modest decline by early winter.The O2, consumption of field‐acclimatized larvae increases with ambient temperature, especially between 0 and 10°C (Q10= 2.6‐3.4).The thermal sensitivity of metabolism declines at higher ambient temperatures, most notably during the autumn/early winter.After exposure to 15°C for 1 week, autumn and early winter larvae maintain much lower rates of O2 consumption than do late summer specimens.Prior exposure to ‐5°C for 24 h did not influence the O2 consumption of larvae.Low thermal sensitivity of O2 consumption, especially at higher ambient temperatures, is an energy‐sparing mechanism during seasonal inactivity.Indeed, the persistence of this metabolic pattern in larvae exposed to 15°C suggests that they have entered a state of diapause.
Separating food and water deprivation in locusts: effects on the patterns of consumption, locomotion and growth
Authors: RAUBENHEIMER DAVID , GÄDE GERD
Published: March 2008

Abstract. In a factorial experiment, fifth‐instar Locusta migratoria (L.) (Orthoptera: Acrididae) were given either dry food (lyophilized grass) and drinking water, food only, water only, or neither food nor water.Food consumption and insect weight were measured daily, and the behaviour of each locust was recorded for 5 h on each of four consecutive days and for 2.5 h on the fifth.Consumption declined progressively in locusts given food only, and those given water only were not observed to drink after the first day of food deprivation.The decline in food consumption on the first day was accounted for by a decrease in the average duration of feeds, which remained constant thereafter.The further decline in consumption over subsequent days was due to a progressive decline in the number of feeds.Although food availability did not slow weight loss relative to locusts given neither food nor water, the availability of water without food did.The proportion of time locomoting increased in all deprivation treatments, but the pattern of change across the five observation days differed markedly between treatments.Locusts given food but no water increased locomotion from 20% of the time budget (the value for controls) to 30% on the first day of deprivation, and by the second day had reached a plateau of approximately 65%.which was maintained until the experiment was terminated on day 5.In contrast, locusts given water but no food approached the 65% level of locomotion on the first day, which was stutistically greater than the 55% observed in those deprived of both food and water.This increase was due both to an increase in the number of locomotion bouts initiated and an increase in the average duration of locomotion bouts.On the second and third days, all deprivation treatments maintained locomotion at around 65%.By day 4, locomotion had decreased to approximately 15% in locusts deprived of both food and water, but not in those deprived of food only or water only.Unlike those given only food, locusts given only water showed a reduction in locomotion of c. 15% on the fifth day.
Flying to feed or flying to mate: gender differences in the flight activity of tsetse (Glossina palpalis)
Authors: ADLINGTON DAVID , RANDOLPH SARAH E. , ROGERS DAVID J.
Published: March 2008

Abstract. To test the prediction that female and male tsetse should differ in their behaviour and the partitioning of their energy budgets to maximize their respective reproductive outputs, we investigated experimentally the relationship between blood intake, fat content and flight activity in virgin and mated female flies, following the same procedure as in a previous study on males.Those flies whose fat content was raised to higher levels by being fed more frequently performed more flight activity, but all females showed very little activity until day 4 after their last blood meal, thereby using only a small fraction of their fat reserves.This contrasted markedly with the large amount of flight performed by males on day 3, resulting in the depletion of their fat reserves.The difference is interpreted with respect to females flying only to find food approximately once every 3 days (and larviposition sites approximately once every 9 days), compared with males flying to find as many mates as possible during the earlier part of the feeding cycle when their energy reserves are high and feeding is a low priority.
The influence of the host plant of diamond‐back moth (Plutella xylostella) on the plant preferences of its parasitoid Cotesia plufellae in Sri Lanka
Authors: BOGAHAWATTE C.N.L. , EMDEN H.F.VAN
Published: March 2008

Abstract. In Y‐tube olfactometer tests, female Cotesia plutellae Kurdjmov (Hymenoptera: Braconidae), a major parasitoid of Plutella xylostella (L.) in southeast Asia, preferred the odour of the brassica type (Blue Lake cabbage) on which they had developed.Such plants were even preferred to the odour of caterpillar‐infested and damaged leaves of another brassica (Early Phenomenal cauliflower).However, within one brassica type, the odour of caterpillar‐infested leaves was preferred to that of uninfested and undamaged leaves.Odours of both Blue Lake and Early Phenomenal were preferred to the control odour (water).However, following the transfer of the parasitoid from Blue Lake to another cabbage (Brunswick) for one generation, females no longer distinguished between Blue Lake and Early Phenomenal.
Phase‐independent responses to phase‐specific aggregation pheromone in adult desert locusts, Schistocerca gregaria (Orthoptera: Acrididae)
Authors: NJAGI PETER G.N. , TORTO B. , OBENG‐OFORI D. , HASSANALI A.
Published: March 2008

Abstract. Volatiles from solitary‐reared (solitarious) and crowd‐reared (gregarious) adult male desert locusts, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae), were quantitatively and qualitatively different.In particular, solitarious males did not emit phenylacetonitrile, a key component of the aggregation pheromone produced by gregarious adult males.In laboratory bioassays, solitarious and gregarious adults of both sexes responded similarly to the natural aggregation pheromone blend, the major pheromone component phenylacetonitrile, and a synthetic pheromone blend comprising benzaldehyde, guaiacol, phenylacetonitrile and phenol.EAG measurements showed significant differences in the responsiveness of adults of the two phases to the four synthetic components at high doses; however, the general response patterns were similar.These results suggest that the gregarious adult male aggregation pheromone may play a role in the arrestment and subsequent recruitment of solitarious individuals into gregarious or gregarizing groups during the early stages of a locust outbreak.
Upwind flight of tsetse (Glossina spp.) in response to natural and synthetic host odour in the field
Authors: TORR S.J. , MANGWIRO T.N.C.
Published: March 2008

Abstract.In Zimbabwe, studies were made of the flight responses of tsetse (Glossinaspp.) to synthetic and natural ox odour using arrangements of electric nets.Tsetse flying away from a target showed a significant upwind bias when a blend of carbon dioxide (2/1 min), acetone (500 mg/h), octenol (0.4 mg/h), 4‐methylphenol (0.8 mg/h) and 3‐n‐propylphenol (0.1 ma) was dispensed 15 m upwind, withc.35% flying upwind.Without carbon dioxide this percentage was significantly reduced to 15% which was not significantly different from that with no odour (8%).This pattern was not altered by reducing the doses of acetone, octenol and phenols by 10–100 times, to levels comparable to those produced by an ox.With natural ox odour or a synthetic equivalent of ox odour dispensed from a ventilated pit 8 m upwind of the target,c.28% flew upwind.This was reduced significantly to 15% if carbon dioxide was removed.In studies using a 17 m line of nets arranged orthogonally across the prevailing wind line,c.50% of the catch was caught on the downwind side in the absence of odour.This increased significantly to c.60% when acetone, octenol and phenols were dispensed 15 m upwind, with or without carbon dioxide.With a shorter line (9 m) or an incomplete one (16.5 m long with 5 times 1.5 m wide gaps along its length) there was no change in the proportion caught downwind.For all three lines, dispensing odour upwind increased the catch 2–5 times on both the up‐and downwind sides of the nets.It is concluded that a stronger upwind response to host odour is elicited when carbon dioxide is present.It is suggested that in nature upwind flight is very imprecisely orientated, with tsetse making flights up and down an odour plume ‘searching’ for a host.
Circadian activity pattern in the stable fly, Stomoxys calcitrans
Authors: SCHOFIELD STEVEN , BRADY JOHN
Published: March 2008

Abstract. Activity rhythms of Stomoxys calcitrans (L.) were assessed under constant conditions using actographs.In LD 12:12 h, activity was almost completely diurnal, had a 24 h period, and peaked 4 h after lights‐on.In constant darkness, activity peaked in the early afternoon and the period of the rhythm was c. 26 h, indicating a circadian pacemaker.A delay in feeding shortened the free‐running period in constant dark to c. 24 h.In constant light, flies were arrhythmic.Starvation also affected activity, with 24‐ and 48‐h starved flies being as much as 20 times more active than recently fed flies.
Adipokinetic hormone content of the corpora cardiaca in gregarious and solitary migratory locusts
Authors: AYALI A. , PENER M.P. , SOWA S.M. , KEELEY L.L.
Published: March 2008

Abstract. The adipokinetic hormone (AKH‐I and AKH‐II) content of the corpora cardiaca from adult males of crowded (gregarious) and isolated (solitary) Locusta migratoria migratorioides (Reiche & Fairmaire) was quantified by reverse‐phase high‐performance liquid chromatography.Significantly less total hormone was found in the corpora cardiaca of crowded locusts than in those glands of isolated locusts at the age of 12–19 days after fledging.The ratio of AKH‐I/AKH‐II was higher in crowded than in isolated locusts at this age.From the age of 12–19 days to that of 25–30 days, AKH content increased significantly in the corpora cardiaca of crowded locusts, but no such increase was found in the glands of isolated locusts, and at 25–30 days there were no significant differences in the AKH content of the glands from crowded and isolated locusts.
Pyrgomorphid grasshoppers of the genus Phymateus contain species‐specific decapeptides of the AKH/RPCH family regulating lipid‐mobilization during flight
Authors: GÄDE GERD , KELLNER ROLAND , RINEHART KENNETH L.
Published: March 2008

Abstract. Using heterologous and conspecific bioassays, two peptides have been isolated from methanolic extracts of corpora cardiaca from the pyrgomorphid grasshopper Phymateus morbillosus L.The structures of both peptides were elucidated by a combination of Edman degradation, after deblocking the N‐terminal pyroglutamic acid residue, and mass spectrometric techniques.One peptide is an octapeptide (pGlu‐Leu‐Asn‐Phe‐Ser‐Thr‐Gly‐TrpNH2) which also occurs in other insects and is code‐named Scg‐AKH‐II.The second peptide is a novel decapeptide member of the AKH/RPCH family (pGlu‐Leu‐Asn‐Phe‐Thr‐Pro‐Asn‐Trp‐Gly‐SerNH2 code‐named here Phm‐AKH.It is the first example of a different peptide in the same genus.The analysis of changes of metabolites in the haemolymph, fat body and flight muscles of male P.morbillosus during a 30 min flight and rest after flight reveal an overall picture of flight metabolism similar to that of Locusta migratoria. Carbohydrate‐fuelled metabolism is pronounced during the first 15 min of flight, whereas lipid‐based metabolism is mainly used thereafter.By analogy with work on L.migratoria, it is concluded that the endogenous peptides of P.morbillosus regulate these metabolic events.
The allometry of metabolism in southern African millipedes (Myriapoda: Diplopoda)
Authors: FREARS SARA L. , WEBB PETER I. , TELFORD STEVEN R.
Published: March 2008

Abstract.We determined standard metabolic rate at 25°C in forty‐eight species of millipede from southern Africa and compared these data with confident measures of standard metabolic rate previously published for other arthropod groups.Metabolic rate in millipedes was not significantly different from that in beetles, ants or spiders once body mass effects had been accounted for, but was significantly higher than that in ticks.The exponent for the mass scaling of metabolic rate did not vary significantly between the five arthropod orders.Our best estimate for the relationship between standard metabolic rate (μl O2h‐1) and body mass (mg) in non‐tick arthropods was 0.86 mass0.73.
Resource partitioning and tolerance of monoterpenes in four species of spruce aphid
Authors: JACKSON DEBORAH L. , JAROSIK VOYTECH , DIXON ANTHONY F.G.
Published: March 2008

Abstract. The tolerance of four species of aphids to myrcene was assessed by measuring the mortality of aphids exposed to different amounts of this monoterpene.Each species was found to exhibit significantly different levels of tolerance to myrcene.which is explicable in terms of the likely concentration of myrcene at the feeding site of each species.

Tolerance to monoterpenes maybe specific only to those encountered in high concentrations at the feeding site.whereas others are found to be toxic.This suggests that each species has become physiologically adapted to tolerate different levels of the specific monoterpenes that occur in the microhabitats they occupy.
Effects of social conditions on Juvenile Hormone mediated reproductive development in Bombus terrestris workers
Authors: BLOCH GUY , BORST DAVID W. , HUANG Z.‐Y. , ROBINSON GENE E. , HEFETZ ABRAHAM
Published: March 2008

Abstract. During the annual life cycle of the bumble bee Bombus terrestris (L.) colony, there is a stage characterized by worker reproduction in the presence of the queen. It has been proposed that this is a result of a decrease in queen inhibition. This hypothesis was examined by studying the effects of queens taken from colonies at different stages of development on several aspects of worker physiology and behaviour: rates of Juvenile Hormone (JH) release in vitro, ovary development, and behaviour associated with reproduction. After optimizing and validating the radiochemical assay for JH release for bumble bee workers, we found that queenless workers had significantly more developed ovaries and higher rates of release of JH than did queenright workers, confirming and extending previous findings that suggest that bumblebee ovarian development is under JH control. Mated queens, separated from their colony and brood, can have the same inhibitory effect on the reproductive development of callow workers. In contrast, workers confined with virgin queens or in queenless groups demonstrated a significantly higher rate of release of JH, overt aggression and threatening behaviours. However, there were no differences in rates of release of JH between workers confined in groups in the laboratory with queens taken from colonies either before or after the onset of worker reproduction. Furthermore, overt aggression and threatening behaviours were similar and low in both types of groups. These results gave no support to the hypothesis that a decrease in queen inhibition is associated with the onset of worker reproduction. We also show that young workers reared in colonies either before or after worker reproduction occurs, or in queenless colonies, all demonstrated similar, low rates of release of JH. These results suggest that older workers may inhibit the corpora allata of younger workers in queenless colonies.
No inhibitory effect on receptor neurone activity by sulphur analogues of the sex pheromone component (Z)‐5‐decenyl acetate in the turnip moth, Agrofis segetum (Lepidoptera: Noctuidae)
Authors: HANSSON BILL S. , OCHIENG‘ SAMUEL A. , WELLMAR ULF , JÖNSSON STIG , LILJEFORS TOMMY
Published: March 2008

Abstract. Olfactory responses from the entire antenna and from single antennal sensilla of the male turnip moth, Agrotis segetum (Lepidoptea: Noctuidae Schiff.), were recorded after stimulation of the antenna with the sex pheromone component, (Z)‐5‐decenyl acetate (Z5‐10:OAc), and three sulphur analogues of this compound. Adaptation of olfactory receptor neurones tuned to Z5‐10:OAc was investigated after pre‐exposure of these receptor neurones to the key stimulus and to the three sulphur analogues. Both electro‐antennographic and single sensillum recordings revealed that the sulphur analogues had a significantly decreased effect compared to the natural stimulus. The pre‐exposure experiments demonstrated that no further inhibition of neural activity was observed than could be expected from receptor neurone adaptation. Earlier reports, describing sulphur analogues as possible hyperagonists acting on moth pheromone receptor neurones, are not supported by the present study.
Morphology of reproductive and trophic eggs and their controlled release by workers in Trigona (Tetragonisca) angustula llliger (Apidae, Meliponinae)
Authors: KOEDAM D. , VELTHAUSZ P. H. , KRIFT T. v. d. , DOHMEN M. R. , SOMMEIJER M. J.
Published: March 2008

Abstract.To study the reproductive potential of workers in the stingless beeTrigona (Tetragonisca) angustulaIlliger (Apidae, Meliponinae), we examined the morphological quality of their eggs. Worker‐eggs were all placed on the inside of the upper wall of brood cells. Normally, such eggs are consumed by the queen and are therefore referred to as trophic. The provisioning and oviposition processes in queenright colonies are characterized by the occurrence of circular aggregations of workers, ‘rosettes’, around the broodcell opening immediately after the release of a worker‐egg. The ovaries of 35% of these rosette workers contained mature, chorionated eggs. In a single worker ovary, always only one mature egg was found. Some of the eggs, dissected from the ovarioles, showed a reticulate chorion pattern. Worker‐eggs which lacked this pattern were significantly bigger than patterned eggs. Scanning electron micrographs revealed that the patterned worker‐eggs are similar in appearance to queen‐eggs.

After a worker‐egg had been removed experimentally from a broodcell, the same cell could be oviposited by a worker again. Light microscopic analysis revealed that all these worker‐eggs lacked the reticulate chorion pattern and were very similar in their morphology. In a colony without a laying queen workers laid eggs which had a reticulate pattern on the chorion. Since these eggs developed into males, we assume that the pattern on the chorion is characteristic for reproductive eggs. We also assume that the queen prevents the release of reproductive eggs by the workers. However, she does not inhibit the development of this type of egg.
The effect of wind speed on the flight responses of tsetse flies to CO2: a wind‐tunnel study
Authors: PAYNTER QUENTIN , BRADY JOHN
Published: March 2008

Abstract. Female Glossina morsitans morsitans Westwood were video‐recorded in a wind‐tunnel as they entered, in cross‐wind flight, a broad plume of CO2 (a component of host odour). At a wind speed that corresponds with peak catches in the field (c. 0.6 ms‐1) odour produced both significant upwind turning responses (in‐flight anemotaxis) and kinetic responses (reduced flight speed and increased sinuosity (d̀m‐1). At a wind speed of c. 0.2 ms‐1 flies displayed anemotactic, but not kinetic, responses to odour. At very low wind speeds (0.1ms‐1) neither upwind turning responses nor kinetic responses to odour were detected. The results are discussed with regard to current theory of host‐location by tsetse.
Short‐and long‐term sperm precedence in the beetle Tenebrio molitor: a test of the ‘adaptive sperm removal’ hypothesis
Authors: SIVA‐JOTHY MICHAEL T. , BLAKE DAVID EARLE , THOMPSON JILL , RYDER JONATHAN J.
Published: March 2008

Abstract. Sperm removal in Tenebrio molitor L. (Coleoptera: Tenebrionidae) has been proposed as an adaptation to sperm competition and has been documented when the remating interval between successive copulations is short, but not when it is long (Gage, 1992). If sperm removal is adaptive, it follows that there should be different fertilization outcomes from double matings with different remating intervals.

Sperm precedence patterns were assessed using reciprocal double matings of normal and γ‐irradiated (sterile) virgin males of controlled size and age with virgin females of controlled size and age.

Immediate last male sperm precedence was high whether the remating interval was short (<10 min) (P2,= 0.89) or long (24h) (P2= 0.92).

Sperm precedence in eggs laid in a 16‐day period after the last copulation showed no difference in the pattern of change between females with short and long remating intervals.

By examining the aedeagus of males we show that sperm are removed at the end of copulation by the first and the second male to mate with a virgin female regardless of whether the remating interval is short or long.

We conclude that sperm removal is unlikely to be the primary mechanism by which males gain such high levels of last male sperm precedence.
Calling behaviour in M.convecta females under different temperature and photoperiodic conditions
Authors: SOCORRO A. P. DEL , GREGG P. C.
Published: March 2008

Abstract. . The effects of temperature and photoperiod on calling behaviour in females of the Australian common armyworm, Mythimna corwecta (Walker) (Lepidoptera: Noctuidae), were studied in the laboratory. Age at first calling was greater at 15 and 20oC compared with 25oC, but there were no significant differences between 25 and 30oC. Females kept at 10oC did not call, but if transferred at 10 days to 20oC they called after a period similar to the pre‐calling period at constant 20oC. Onset time of calling was earlier at 15 and 20oC compared with 25 and 30oC, but there were no significant differences in calling duration. At 20oC, age at first calling was increased by shorter day length (12h and 14h, compared with 16h), and there was an interaction between daylength and moth age affecting the duration of calling. Onset times advanced with longer daylength, but peak calling was later in relation to the lengtii of the scotophase. These results are discussed in connection with migration in M.convecta. Evidence for a circadian rhythm of calling was found in females entrained for 3 and 8 days after emergence under reverse‐cycle conditions and then transferred to constant darkness. However, after 56 h and 80 h respectively of darkness, calling became de‐synchronized. Subsequently, it appeared to re‐synchronize to a different clock, which approximately correlated with the normal photoperiods the moths had experienced during larval development.
Polyphenic wax production in Abacarus hystrix(Acari: Eriophyidae), and implications for migratory fitness
Authors: FROST W. E.
Published: March 2008

Abstract. . Wax production in the grass‐feeding eriophyid Abacarus hystrix (Nalepa) is seasonally variable; enlarged lateral and dorsal bands of wax filaments develop in adults of summer generations. Wax filaments increase the total surface area of summer‐generation mites, without a concomitant increase in cuticular surface‐to‐volume ratio. Genetic and environmental interactions in changes in the rate of wax production were examined. High temperatures, but not changes in photoperiod, were found to stimulate increased rates of wax production. The degree of wax filamentation was independent of the genetic origin of mites, hence filaments are polyphenic, rather than polymorphic, in origin. The role of wax filaments in the regulation of water‐loss and in drag maximization were experimentally investigated. The relative survival of waxed and unwaxed mites was compared at various temperature and humidity combinations, and the influence of wax filaments on surface drag was assessed by comparing the slopes of regression lines of cuticular surface area relative to terminal velocity of waxed and unwaxed mites. Significantly greater survival times in waxed compared to unwaxed mites at low relative humidities suggest mat wax filaments have a function in the regulation of water‐loss. Significantly lower mean terminal velocities in waxed mites indicated that total drag relative to cuticular surface area was greater in waxed than unwaxed mites, probably as a result of increased skin friction generated by wax filaments. The increased non‐cuticular surface area created by wax filaments may be advantageous during summer‐migrations of A.hystrix by increasing wind shear stress on the mites at the leaf margin, enhancing buoyancy while air‐borne and reducing the rate of desiccation‐induced mortality.
Variation in temperature and dietary nitrogen affect performance of the gypsy moth (Lymantria dispar L.)
Authors: LINDROTH RICHARD L. , KLEIN KARI A. , HEMMING JOCELyN D. C. , FEUKER ANITA M.
Published: March 2008

Abstract. . The independent and interactive effects of temperature and dietary nitrogen content on performance of the gypsy moth (Lymantria dispar L.) were examined. In long‐term feeding trials, larvae were reared from egg hatch to pupation on low (1.5%) and high (3.7% dry weight) nitrogen diets, under three temperature regimes. Short‐term feeding trials with fourth instars and the same treatments were conducted in order to calculate nutritional indices.

Higher temperatures did not influence larval survival and marginally increased final pupal weights, but strongly decreased long‐term development rates. They also accelerated short‐term growth and consumption rates, and tended to improve food processing efficiencies. High concentrations of dietary nitrogen increased survival rates and final pupal weights markedly, but decreased long‐term development rates only marginally. A high content of dietary nitrogen also accelerated short‐term development and growth rates, reduced consumption rates, and improved food digestibility. Insects responded to low nitrogen‐content diets primarily by eating faster, rather than by altering efficiency of nitrogen use. In the short‐term feeding trials, thermal regime and dietary nitrogen interacted to influence growth rates, overall food processing efficiencies and nitrogen consumption rates. No interactive effects were observed in long‐term studies.

This research demonstrates that small changes in thermal regime and ecologically relevant variation in dietary nitrogen content can strongly affect gypsy moth performance. Moreover, various performance parameters are differentially sensitive to the direct and interactive effects of temperature and diet.
Temporal occurrence of the pupal melanization reducing factor during development of the butterfly, Inachis io
Authors: STARNECKER G. , BÜCKMANN D.
Published: March 2008

Abstract. . In prepupae of Inachis io L. (Lepidoptera: Nymphalidae), a pupal melanization reducing factor (PMRF) which controls morphological colour adaptation (Bückmann & Maisch, 1987) is located in the brain, suboesophageal ganglion, thoracic ganglia, and all abdominal ganglia and their closely associated neurohaemal organs (Stamecker et al, 1994)

In animals adapted to a yellow background, PMRF content decreased in all these ganglia complexes during the prepupal stage which may be due to a release of the hormone at the critical period of the melanization reducing effect. The release of PMRF apparently occurs in a slow, but continuous, manner and may be superimposed by an incessant PMRF production at the same time recognizable by reincreasing melanization scores towards the end of prepupal and beginning of pupal stage. Therefore PMRF content in ganglia were not completely exhausted. When animals were kept on a black background, such a decline of PMRF content did not occur in both posterior ganglia complexes, whereas values from brain‐suboesophageal ganglion complexes were too variable.

The target cells seem to be sensitive to PMRF treatment over a wide time range of nearly 20 h from the early stage of spinning a silk mat to 13‐h‐old prepupae for the melanization reducing effect.

PMRF activity was also detected in first‐instar larvae and in the nervous system of third‐instar larvae as well as in pupae which had completed their pigmentation. Furthermore, all three parts of the adult body still contained PMRF. Possibly PMRF may have functions in larval and adult stages in addition to its effect on morphological colour adaptation.
Geographical and species variation in circadian rhythm parameters in nemobiine crickets
Authors: SHIMIZU TORU , MASAKI SINZO
Published: March 2008

Abstract. . Locomotor activity rhythms were studied in eight species of nemobiine crickets with different habitat preferences. They showed similar patterns with a major peak of activity around dusk and a minor one around dawn. These patterns did not change within the natural range of daylengm (12–16 h). The acrophase time of the rhythm varied between ‐3.2 and +3.5 h as measured from dusk, and the free‐running period (T) varied between 22.8 and 24.5 h. In the Dianemobius fascipes species complex these circadian parameters varied among nine local strains (8oS to 43oN) but did not show any latitudinal trend. In a temperate strain of this species complex (Dianemobius nigrofasciatus from Teshikaga, 43oN), two lines which differed from each other in mean T by 1.4h were selected, and a high heritability of T, 0.78 + 0.20 (mean±SE) was obtained. On the other hand, in a subtropical strain (Dianemobius fascipes from Ishigaki Island, 24oN), low heritabilities, 0.35 ± 0.15 for acrophase and 0.17 ± 0.21 for T, were obtained from the full‐sib correlations. The variation in i seemed to be random and not related to fitness.
Passive aerodynamic stabilization by beetle elytra (wing covers)
Authors: SOUZA MICHELLE M. DE , ALEXANDER DAVID E.
Published: March 2008

Summary. Most beetles extend their elytra laterally during flight, where they can act as fixed airfoils; typically, such elytra are held at a pronounced dihedral angle. We fixed extended elytra of June beetles (Scarabaeidae: Melolonthinae) and tiger beetles (Cicindelidae) over a range of dihedral angles (‐10° to 45°) and towed them in a water tunnel. We also towed them with flexed elytra (i.e. in the resting position). (Reynolds number was used to maintain dynamic similarity with air.) We measured the maximum rolling angle and the lateral oscillation rate as two indices of stability. There was no relationship between oscillation rate and dihedral angle, or between maximum roll angle and dihedral angle. At all dihedral angles tested, however, beetles were much more stable than when they were towed with the elytra flexed. We also included a third beetle type, flower beetle (Scarabaeidae: Cetoniine), which normally flies with flexed elytra. We measured stability indices for these beetles with elytra only in the flexed position. When all beetles were tested with flexed elytra, flower beetles showed no difference in maximum roll angle, but more stability in oscillation rate than the other two beetle types.
Tarsal chemoreceptors and oviposition behaviour of the cabbage root fly (Delia radicum) sensitive to fractions and new compounds of host‐leaf surface extracts
Authors: ROESSINGH PETER , STÄDLER ERICH , BAUR ROBERT , HURTER JAKOB , RAMP THOMAS
Published: March 2008

Abstract. Contact chemoreception plays a decisive role in host selection and oviposition behaviour of the cabbage root fly, Delia radicum L. (Diptera, Anthomyiidae). Glucosinolates (mustard oil glucosides) are known to be perceived by the flies, and when sprayed on paper leaf‐models induce oviposition. Recently it has become clear that other non‐volatile types of compounds must also be involved in host selection.

A pair of ventro‐medial C sensilla on die fifth tarsomere respond strongly to a novel compound called tentatively ‘cabbage identification factor’ (CIF), but not to sucrose, glucose, fructose and proline. CDF is a new non‐glucosinolate oviposition stimulant. A single neurone in each sensillum is activated by this compound and the same is true for glucosinolates. In some flies a mixture of bom types of stimuli evoked an apparent mononeural spike train, whereas in odiers spikes of two separate cells were activated. The significance of this variability is not yet clear.

The new stimulant, CIF, does not evoke responses in glucosinolate receptors in the D sensilla. The involvement of the C3 sensilla in the detection of host‐specific compounds constitutes the first known function for C sensilla in D. radicum. CIF appears to be present in leaf surface extracts from the host‐plant Brassica oleracea in quantities as low as 1 ng per gram leaf. In spite of this low level, it stimulates oviposition significantly better than glucobrassicin at higher concentrations, which up till now was known as the most powerful stimulant for D.radicum.
Long flights in Cydia pomonella L. (Lepidoptera: Tortricidae) measured by a flight mill: influence of sex, mated status and age
Authors: SCHUMACHER PETER , WEyENETH ALBERT , WEBER DONALD C. , DORN SILVIA
Published: March 2008

Abstract. The flight capacity of Cydia pomonella L. (Lepidoptera: Tortricidae) was measured in the laboratory by using computer‐linked flight mills. Codling moths showed a large variation in flight capacity between individuals. We defined arbitrarily a longest single flight (LSF) of more than 5 km as an index for long‐flyers. About 16.7% of virgin and 10.0% of mated males and 20.0% of virgin and 7.4% of mated females undertook such flights. Based on the LSF and the total distance flown (TDF^we concluded that males and females have little or no difference in flight capacity and that both the within‐and between‐habitat flights are similar in number and magnitude for both sexes. In the field, females are therefore potentially able to undertake flights of up to 11 km, as reported for males by other authors. This ability was highest at ages of 2–7 days after emergence, i.e. the first third of their lifetime, for virgin and mated male moths and for virgin female moths. Mated females showed peak flight capacity between 1 and 3 days after eclosion, which corresponded with the major egg‐laying period. Few long flights were undertaken before oviposition. These findings do not agree with the oogenesis flight syndrome described by other authors, and this theory is believed not to apply to C.pomonella. Our laboratory results are discussed in relation to field experiments in general and hypotheses are developed about the significance of long‐flyers for this species.
Sex pheromone blend discrimination in two races and hybrids of the European corn borer moth, Ostrinia nubilalis
Authors: JR CHARLES E. LINN , YOUNG MARIA S. , GENDLE MATTHEW , GLOVER THOMAS J. , ROELOFS WENDELL L.
Published: March 2008

Abstract. The response specificity of males of two races, and hybrids, of the European corn borer moth, to a large series of doses/ratios of E‐ and Z11‐14:OAc, was determined in a sustained‐flight tunnel. For both races an area of peak response was determined, which included the natural ratio eliciting peak levels of source contact, and other treatments eliciting response profiles over the behavioural sequence not significantly different from the peak. Consistent with studies on other moth species response specificity was controlled by two threshold effects, one affecting locking‐on to odour plumes of lower doses and off‐ratios containing lower proportions of the E or Z isomer than the natural blend, and the other resulting in arrestment of upwind flight to higher doses and off‐ratios containing higher proportions of the E or Z isomer man the natural blend. A comparison of the size of the areas of peak response showed that males of the univoltine Z race (UZ) using a 3:97 E:Z mix displayed greater specificity and sensitivity than did males of the bivoltine E race (BE) responding to a 99:1 E:Z pheromone mix. At doses higher than those eliciting peak response (<100 μg) response specificity was lower for both races, but especially for the BE race, with increased levels of upwind flight and source contact occurring to off‐ratios. Finally, consistent with a previous behaviour/genetic study on this species, F1 hybrid males displayed peak levels of source contact not only to their natural isomer ratio (65:35 E:Z), but also to an expanded range of doses of ratios ranging from 2% to 98% E.
Olfactory responses recorded from sensilla coeloconica of the silkmoth Bombyx mori
Authors: POPHOF BLANKA
Published: March 2008

Abstract. Extracellular single sensillum recordings were made from the double‐walled multiporous sensilla coeloconica on the antennae of males and females of Bombyx mori L. (Lepidoptera: Bombycidae). The receptor neurones responded to olfactory stimuli; no thermo‐ or hygroreceptors were found. Many neurones responded with a decrease of the transepithelial potential and increased rates of nerve impulses to aliphatic hydrocarbons with chain lengths between three and ten carbon atoms. Most abundant were neurones responding best to acids and aldehydes. Receptor neurones responding with a low threshold to only one acid of a certain chain length were considered as specialists. In some sensilla an increase of the transepithelial potential combined with nerve impulse inhibition was observed in response to monoterpene alcohols. Neurones responding with excitation to aliphatic acids and with inhibition to terpenes were found in the same sensilla. Some neurones excited by aliphatic acids were inhibited by terpenes. Responses to headspace volatiles of mulberry leaves, the larval food, were also obtained. Therefore the coeloconic sensilla may be involved in the selection of oviposition sites.
Rates of Juvenile Hormone biosynthesis and degradation during reproductive development and diapause in the boll weevil, Anthonomus grandis
Authors: TAUB‐MONTEMAyOR TINA E. , DAHM KARL H. , BHASKARAN GOVINDAN , RANKIN MARy ANN
Published: March 2008

Abstract. The role of Juvenile Hormone (JH) during reproductive development and diapause was investigated in the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae). JH sythesized by corpora allata (CA) in vitro of A.grandis was identified as JH‐UJ by high‐performance liquid chromatography and by conversion to the methoxyhydrin. Optimal conditions for the use of a short‐term assay in vitro were established to examine profiles of CA activity. In addition, rates of JH degradation by JH‐specific esterase were determined. Patterns of CA and JH‐esterase activity during reproductive development and the diapause state were established with laboratory‐reared reproductive weevils and diapausing weevils collected as larvae and pupae in the field after the cotton‐growing season. The results indicate that JH production is elevated in reproductive females whereas males and winter field‐collected females show no CA activity. Vitellogenin concentrations in haemolymph and rates of oviposition were studied in relation to CA activity and JH degradation. An attempt to induce diapause in the laboratory failed.
Components of tomato leaf homogenate suppress responses from galeal chemoreceptors of the adult Colorado potato beetle
Authors: ZHANG TOM Z. , MITCHELL B. K.
Published: March 2008

Abstract. Effects of both potato and tomato residues (obtained following vacuum distillation of leaf homogenate) on responses to galeal chemosensilla of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), to trans‐2‐hexenol, one of the leaf alcohols that stimulate a highly uniform gustatory response in this system, are described. Tomato residue suppressed the response to hexenol in a dose‐dependent manner whereas potato residue had no effect. Suppression was detectable 0.3 s after the first application began and the normal response to hexenol recovered within 2 min. Alkaloids from potato (solanine) and tomato (tomarine) also suppressed the response to hexenol but the characteristic actions of these compounds could not fully explain the activity of the tomato residue. Constituents of tomato residue, in addition to tomatine, are probably responsible for its significant effect on galeal chemosensory responses and these probably comprise a complex set of active compounds that allow the Colorado potato beetle to distinguish potato and tomato leaves.
Variation in rates of nitrogen fixation in termites: response to dietary nitrogen in the field and laboratory
Authors: CURTIS ANTHONy D. , WALLER DEBORAH A.
Published: March 2008

Abstract. Termites contribute nitrogen to their habitat through the nitrogenase activity of their bacterial symbionts. Previous studies indicate that high levels of dietary nitrogen suppress nitrogen fixation in termites. We examined the effects of dietary nitrogen on fixation rates in termites in both field and laboratory experiments. Ten field cplonies of Reticulitermes were collected and assayed for nitrogenase activity in July 1993, October 1993, January 1994, and April 1994. The nitrogen content of the wood collected with each colony was determined. There was no correlation between termite nitrogen fixation rates and the amount of nitrogen in their food for any of the four collection periods. In laboratory experiments, nitrogen fixation rates decreased when termites were fed filter paper treated with 2% and 5% ammonium nitrate or a 5% mixture of the amino acids proline, tryptophan and leucine, compared to water‐treated controls. By contrast, the nitrogenase activity of termites fed filter paper treated with 2% and 5% ammonium phosphate, a mixture of the amino acids histidine, serine and aspartic acid, or 2% and 5% urea did not differ from the controls. However, nitrogenase activity increased when termites were fed with 2% uric acid. No clear association exists between termite nitrogen fixation and the nitrogen content of their food.
Helicoverpa zea males (Lepidoptera: Noctuidae) respond to the intermittent fine structure of their sex pheromone plume and an antagonist in a flight tunnel
Authors: FADAMIRO HENRy y. , BAKER THOMAS C.
Published: March 2008

Abstract. We investigated the behavioural response of male Helicoverpa zea (Boddie) to the fine‐scale structure of an odour plume experimentally modified in a wind tunnel by using an air‐pulsing device. Male H. zea flew upwind to pulsed filaments of a binary pheromone blend of (Z)‐11‐hexadecanal (Z11‐16:Ald) and (Z)‐9‐hexadecanal (Z9‐16:Ald) in the ratio of 20:1. Sustained upwind flight in experimentally altered intermittent plumes was dependent on concentration, as well as the frequency of generation of odour filaments. At a loading of 10μg of the major pheromone component, Zll‐16:Ald, which gave an emission rate of approximately that released by a female H. zea, sustained upwind flight and source contact correlated positively with filament delivery rate, becoming significant at a minimum filament delivery rate of 2/s. Decreases in upwind progress and source location were recorded at a loading of 1 μg of Z11‐16:Ald. At this suboptimal dosage, a high filament generation rate of 10/s was necessary for significant upwind progress and source contact. When an interspecific compound: (Z)‐11‐hexadecenyl acetate (Z11‐16:OAc), was added to the attractive pheromone binary aldehyde blend of H. zea at a proportion of 10% of the major pheromone component, and pulsed from the same source, there was a significant reduction in sustained upwind progress and source location by males, indicating that Z11‐16:OAc is antagonistic to the upwind progress of H. zea. However, Z11‐16:OAc was less antagonistic when its filaments were isolated and alternated with pheromone filaments, indicating a strong effect of the synchronous arrival of odour filaments on the antenna needed for antagonism of upwind flight.