bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal influence on the incidence and duration of larval diapause in Calliphora vicina
Authors: SAUNDERS D. S.
Published: March 2008

ABSTRACT. The photoperiodic mechanism governing larval diapause in the blowfly Calliphora vicina R.‐D. (Diptera: Calliphoridac) is largely maternal. The critical daylength for adult flies at 20d̀C, and larvae derived from day 12 eggs and maintained in darkness at 11d̀C, is about 14.5 h/24. At short daylength (LD 12:12 h) and a range of temperatures, eggs laid on or before day 9 gave rise to a low incidence of diapause, whereas those laid on day 10 and later gave rise to a high incidence; the photoperiodic ‘counter’ therefore shows a temperature‐compensated mechanism for ‘accumulating’ successive short days. The rate of switching from non‐diapause to diapause progeny is hardly affected by the timing of protein meals, although an early supply of meat accelerates egg development and leads to an increasing proportion of early, non‐diapausing progeny. There is no evidence for a maternal effect preventing diapause induction in the first post‐diapause (‘spring’) generation of flies. Diapausing larvae terminate diapause spontaneously in darkness at 11d̀C after a variable period which is positively correlated with the incidence of diapause in the group. Diapause incidence and duration therefore are both determined maternally.
Sexual transfer of prostaglandin precursor in the field cricket, Teleogryllus commodus
Authors: STANLEY‐SAMUELSON DAVID W. , JURENKA RUSSELL A. , BLOMQUIST GARY J. , LOHER WERNER
Published: March 2008

ABSTRACT. When injected into the haemolymph of newly emerged adult males of the field cricket, Teleogryllus commodus (Walker), [3H]arachidonic acid is incorporated into tissue phospholipids. Two reproductive tissues, testes and accessory glands, incorporate and preserve the labelled arachidonic acid for at least 49 days. With onset of circadian rhythm‐controlled spermatophore production, radioactive arachidonic acid is incorporated into spermatophore phospholipids. After mating with untreated females, radioactivity was detected in spermathecae and in haemolymph from females. Some of the transferred radioactive arachidonic acid is subsequently converted into prostaglandins. Hence, males of T. commodus transfer prostaglandin synthetase activity and substrate by way of spermatophores during mating
Monitoring the effects of juvenile hormones and 20‐hydroxyecdysone on yolk polypeptide production of Drosophila melanogaster with enzyme immunossay
Authors: WU SHUENN‐JUE , ZHANG JIAN‐ZHONG , MA MICHAEL
Published: March 2008

ABSTRACT. A double antibody sandwich enzyme‐linked immunosorbent assay (ELISA) was developed for detecting and quantifying small amounts of yolk polypeptides (YP) in studies on the hormonal control of vitellogenesis in Drosophila melanogaster Meigen. Monoclonal antibodies were incorporated as primary antibodies in the ELISA procedure to ensure selectivity in YP detection. The fact that YP concentration increases immediately after adult eclosion presents some difficulties in designing hormonal regulation experiments. Female adults decapitated immediately after eclosion remain alive for several days and virtually no YP is detected in the haemolymph 24 h after decapitation. The surgical procedure does not interfere with the competence of the fat bodies to respond to exogenous source of hormones. The effect of juvenile hormone (JH) on vitellogenesis can be studied by topical application of test material to these decapitated adults. A juvenile hormone analogue. Methoprene applied at 0.2 μg/fly or greater, restores YP production. The relative potencies of JH I2 II3 III and ZR 515 are compared at the same dose of 0.25 μg/fly. Their ranking in terms of re‐initiating vitellogenesis is ZR‐515 < JH II<JH III=JH I.

Fat bodies which are left attached to the body wall, are successfully maintained in culture. With this in vitro system, synthetic hormone can be administered precisely to the organ culture. After a short incubation period, aliquots of medium are removed for the quantification of YP. Incubation of fat bodies with a physiological dose of the 20‐hydroxyecdysone (20‐HE) stimulates the production and release of YP into the medium. This represents the first direct experimental evidence for 20‐HE stimulation of Drosophila fat bodies for YP production in the absence of other endogenous factors that might either promote or interfere with vitellogenesis
The sunset activity of tsetse flies: a light threshold study on Glossina morsitans
Authors: BRADY JOHN
Published: March 2008

ABSTRACT. At dusk, tsetses fly from their day‐time resting sites on tree trunks to spend the night on leaves and twigs. At the end of the day in the laboratory, they show a few minutes of heightened activity which apparently represents this behaviour. This occurs immediately after lights‐out in a square‐wave LD cycle, but just before the end of a 30‐min artificial ‘dusk’ which mimics the natural change in light intensity at sunset. The activity is triggered when the declining light falls to a mean value of c. 350 mW m‐2. Accurate, 24‐h light measurements made in Zimbabwe show that in tsetse ‘bush’ this intensity occurs close to sunset. Neither the initial photophase light intensity (900 and 2500 mW m‐2 were tested) nor the rate of dimming affect the critical value, which is also the same whether arrived at within c. 10 min in a ‘logarithmic dusk’ or within c. 20 min in a ‘linear dusk’. In newly‐emerged or recently fed flies, however, it is lower (c. 50–100 mW m‐2); and when a similar activity burst is induced by a ‘dusk’ at midday (i.e. at the flies' phase of minimum activity), the threshold is c. 200 m W m‐2. It is concluded that this short behavioural programme is primarily a direct response to a specific, low light intensity, but that the threshold is modified by circadian and other physiological inputs.
Light measurement for entomology in the field and laboratory
Authors: YOUNG S. , DAVID C. T. , GIBSON G.
Published: March 2008

ABSTRACT. Light units weighted for human vision (e.g. lux) are unsuitable for work on insects which have good sensitivity in the blue and UV. We have built and calibrated two light meters ‐ a portable field unit and a mains operated laboratory device‐which measure illumination in physical units over a wavelength range suitable for insect vision. Both meters share a single photocell, so field and laboratory measurements are strictly comparable. The field meter covers a range from starlight to tropical sunlight on a single scale, and can be used in conditions when the operator has no effective vision. The laboratory meter is linear over five decade ranges, of which the most sensitive has a full‐scale deflection of 1 mW m‐2.
Differentiation of roles of chemosensory organs in food discrimination among host and non‐host plants by larvae of the tobacco hornworm, Manduca sexta
Authors: BOER GERRIT DE , HANSON FRANK E.
Published: March 2008

ABSTRACT. The contributions of olfactory and gustatory organs in food plant discrimination were examined in larvae of Manduca sexta (Johan.) (Lepidoptera, Sphingidae). Larvae, from which various chemosensory organs had been removed surgically, were tested for feeding preferences for a host, tomato (Lycopersicon esculentum); a weakly acceptable non‐host, rape (Brassica napus); and an unacceptable non‐host canna (Canna generalis), using a two‐choice disc bioassay.

Removal of all known chemosensory organs resulted in failure to show discriminatory behaviour in a strictly chemosensory bioassay, indicating that all external chemosensory organs have been accounted for. The involvement of non‐chemosensory organs results in residual discrimination for leaves by individuals with total chemosensory ablations.

Larvae possessing either olfactory or gustatory organs still exhibit normal preferences for tomato over rape. Gustatory (but not olfactory) organs are required for larvae to show normal preferences for tomato over canna; in fact, olfactory organs do not appear to participate in this decision.

To examine which if any of the plant species is being selected in two‐choice tests, larvae were given a choice between each leaf species and a ‘neutral’ substance (wet filter paper). Both olfactory and gustatory organs are required for normal preferences for tomato, but either alone will suffice for rape. Only gustation is needed to select canna, and participation of either the epipharyngeal sensilla or a single medial sensillum styloconicum is sufficient to elicit complete rejection behaviour.

We conclude that, in larvae of M. sexta, the complement of chemosensory organs needed for food plant discrimination varies with the plant species sampled. Evidence is presented exposing a potential artefact of ablation experiments; extirpation of one sensory organ may affect the functioning of others nearby, even though they may appear normal by visual inspection.
Pheromone puff trajectory and upwind flight of male gypsy moths in a forest
Authors: ELKINTON J. S. , SCHAL C. , ONOT T. , CARDÉ R. T.
Published: March 2008

ABSTRACT. Pheromone released from a point source beneath a forest canopy usually follows a non‐linear trajectory as demonstrated by the paths of small, neutrally‐buoyant, helium‐filled balloons or puffs of smoke. Mark‐recapture experiments show that few male gypsy moths (Lymantria dispar L.) follow a pheromone plume over distances greater than 80 m even though they can easily detect pheromone at that distance as indicated by wingfanning assay. The directional consistency of successive puffs of pheromone appears more important than the linearity of their trajectories in enabling males to locate a pheromone source.
Host‐plant discrimination and evolution of feeding preference in the Colorado potato beetleLeptinotarsa decemlineata
Authors: HARRISON GLENN D.
Published: March 2008

ABSTRACT.The behaviour of newly emerged adult Colorado potato beetles on preferred hosts follows a stereotyped pattern of sampling, feeding, grooming and rest. Reduced meal sizes on less‐preferred hosts is accompanied by increased sampling and frequent interruptions in feeding. A systematic increase in pre‐ingestive sampling on less‐preferred foodplants indicates that beetles discriminate among closely related species within the Solanaceae. This ability may depend primarily on stimuli perceived at, and near, the leaf surface. Three geographic populations of beetles have adapted to different local host plants, but have not lost their preference for feeding on an ancestral host species. Host shifts by oligophagous insects to related plant species may evolve through selection for feeding generalists in isolated populations, and may not require genetic changes affecting the perception of a particular novel host.
Sex pheromone perception by males of the tsetse fly, Glossina morsitans morsitans
Authors: LANGLEY P. A. , HUYTON P. M. , CARLSON D. A.
Published: March 2008

ABSTRACT. Inanimate decoys elicit copulatory responses from intact males of Glossina morsitans morsitans when dosed with the sex pheromone of that species. In a series of ablation or masking experiments it was shown that chemoreceptors on the tarsi and tibiae of the legs are stimulated by the pheromone on contact or at ultra‐short range. Removal of the antennae from males does not diminish responses to decoys consisting of dead females, nor does it affect the dose‐related responses to decoys consisting of dead males previously washed clean of their cuticular hydrocarbons and dosed with synthetic pheromone. Antennectomized males are as capable of copulatory behaviour and insemination of virgin females as are intact control males. More setae corresponding to the description of chemoreceptors are found on the legs of males than of females. It is concluded that whatever the role of the antennae may be in the identification of a female by a male it is the chemoreceptors on the legs of the male which are necessary to elicit copulatory behaviour.
A quantitative analysis of underwater oviposition by the mosquito Mansonia titillans
Authors: LOUNIBOS L. P. , LINLEY J. R.
Published: March 2008

ABSTRACT. Formation of the rosette‐like egg mass of the neotropical mosquito Mansonia titillans Walker is described from video recordings of thirteen females ovipositing on the undersurfaces of water lettuce (Pistia stratiotes) leaves in the laboratory. The female abdomen executes symmetrical stroking behaviour to the right and left of centre line. Outstrokes consist solely of scratching, in which spines on the eighth tergite abrade the leaf surface preparatory to oviposition. A row of eggs is glued to the leaf only on instrokes, which are of longer duration than outstrokes, and may be interrupted by scratches and pauses. Scratching precedes oviposition of each of the first four eggs, which are laid without stroking behaviour. The egg mass is enveloped in an air bubble which is transported underwater on the hydrofuge female abdomen. The deposition of eggs on instrokes is homologous to the behaviour used by Culex and Culiseta mosquitoes in the construction of free‐floating egg rafts.
Odour‐conditioned anemotaxis of apterous aphids (Cryptomyzus korschelti) in response to host plants
Authors: VISSER J. H. , TAANMAN J. W.
Published: March 2008

ABSTRACT. Orientation responses of adult apterous virginoparae of Cryptomyzus korschelti Börner were recorded using a locomotion‐compensator in front of a wind tunnel. Individual aphids were tested under four consecutive treatments: without wind; clean wind; and wind carrying odour of the host plant Stachys sylvatica or odour of a non‐host plant Solanum tuberosum. The walking tracks were tortuous in all treatments except when the odour of host plants was used. Host plant odour induced upwind orientation of aphids (odour‐conditioned positive anemotaxis). Track variables such as vector length, straightness, upwind time and upwind length, increased when the aphids moved upwind. Walking speeds were not affected. The simultaneous stimulation by wind and host plant odour caused aphids to walk upwind for more than 1 m in 10 min. These findings suggest that olfactory attraction of aphids is involved in host plant selection.
Physiology of a sucrose‐sensitive cell on the galea of the eastern spruce budworm larva, Choristoneura fumiferana
Authors: ALBERT P. J. , PARISELLA S.
Published: March 2008

ABSTRACT The lateral styloconic sensillum on the galea of the eastern spruce budworm larva Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae) contains a cell which responds to sucrose. The electro‐physiologial threshold for response is below 0.5 mM sucrose. The Kb for the response is 1.5 mM, and the Vmax is 200 impulses/s. The physiological data are interpreted with respect to the sucrose‐stimulated feeding behaviour of the larva.
The inhibition of lipid synthesis in vitro in the locust, Schistocerca gregaria, by factors from the corpora cardiaca
Authors: GOKULDAS M. , HUNT P. A. , CANDY D. J.
Published: March 2008

ABSTRACT. The rate of lipid synthesis from [14C]acetate in fat body from Schistocerca americana gregaria has been studied in vitro. Maximum incorporation is found on days 6–10 in adults and day 4 of the fifth stadium. The label appeared in the fatty acid components of triacyl‐glycerol, diacylglycerol and phospholipid.

Lipid synthesis in vitro was inhibited by extracts of corpora cardiaca, and such inhibition was most marked (up to 85%) in fat bodies from insects at stages where fatty acid synthesis was greatest. HPLC separation of corpora cardiaca extracts gave several active fractions of which the most active was adipokinetic hormone 1 (AKH‐1).
Analysis of the mating activity of male tsetse flies Glossina m. morsitans and G. pallidipes in the laboratory
Authors: WALL RICHARD
Published: March 2008

ABSTRACT. The responses of male Glossina morsitans morsitans West‐wood and Glossina pallidipes Austen to freeze‐killed females were examined in the laboratory. Analyses were performed using a specially designed, automated, computer‐based, recording system. G. pallidipes were more active than G. m. morsitans, interacting with the female decoys twice as often. Interactions with the decoys divided broadly into short‐stay (<60 s) and long‐stay, full copulatory attempts. For G. m. morsitans 90% of interactions resulted in full copulatory attempts, the mean duration of which was >1 h. For G. pallidipes only 40% of interactions resulted in full copulatory attempts, the mean duration of which was 35 min. The initiation of interactions showed a clear V‐shaped activity pattern in G. m. morsitans but in G. pallidipes only a morning peak was observed. In neither species was there a tendency for full copulatory responses to be initiated in any specific period of the diurnal activity pattern. The results indicate that the two species have very different mating systems, and represent an initial step in the quantification of these differences.
Food aversion learning in the polyphagous grasshopper Schistocerca americana
Authors: BERNAYS ELIZABETH A. , LEE JEREMY C.
Published: March 2008

ABSTRACT. The ability of the acridid Schistocerca americana (Drury) (Orthoptera: Acrididae) to learn to avoid a food when it is associated with an artificial aversive stimulus was examined. The aversive stimulus used was an injection of nicotine hydrogen tartrate at a concentration which usually did not cause knockdown. Insects learned to avoid a food which already had limited sustained acceptability. The learning was not found when the aversive stimulus followed a meal on a fully acceptable food.
Discharge patterns of locust visual interneurones
Authors: CATTON W. T.
Published: March 2008

The spike discharges of the descending contralateral movement detector (DCMD) neurone, and of some smaller visual interneurones (S‐units), were recorded in the ventral nerve cord of adult Schistocerca gregaria Forsk., in response to a stationary disc (25o) or a small spot (0.2o) stimulus. The discharge rate of each neurone was plotted over a period of 5 s exposure; the total number of spikes in this period was also noted. The DCMD response to the 25o disc was a high‐frequency burst falling off quickly to a low rate; the 0.2o spot evoked a prolonged discharge with an early peak in rate. In S‐units the discharge was prolonged with both targets; the rate rose to an early peak in each case, with a much higher rate for the larger disc. For the DCMD the total number of spikes per stimulus (5 s) was greater for the 0.2o spot; for S‐units it was greater for the 25o disc. Thus an increase of about 30‐fold in the number of ommatidia stimulated resulted in a fall in the total DCMD response to about one‐quarter; a similar increase evoked a rise of about 6‐fold in the S‐unit response. When the 25o disc was presented at progressively reduced intensities the total spike response of the DCMD rose steadily to a maximum at about 2.9 μW m‐2; using the same procedure the spike output of S‐units, initially high, declined monotonically. The role of inhibition in these results is discussed.
The importance of seasonal variation in hair coloration for thermoregulation of Ctenucha virginica larvae (Lepidoptera: Arctiidae)
Authors: FIELDS PAUL G. , McNEIL JEREMY N.
Published: March 2008

ABSTRACT. . A marked seasonal variation in the hair colour of Ctenucha virginica (Esp.) larvae is observed under field conditions. During the autumn and spring larvae are black and yellow, while during the summer they are predominantly yellow. Under sunny conditions in the field, or when exposed to a radiation heat source in the laboratory, black and yellow larvae have significantly higher body temperatures than yellow ones. As larvae feed over a limited range of temperatures, it is proposed that seasonal changes in hair colour may help larvae to thermoregulate, thereby maintaining body temperatures within the range where feeding is possible.
Effects of azadirachtin on oogenesis in Aedes aegypti
Authors: LUDLUM CAROLE T. , SIEBER KLAUS‐PETER
Published: March 2008

ABSTRACT. . Azadirachtin in blood fed to adult female Aedes aegypti through an artificial membrane does not cause feeding inhibition over a wide dose range (0–200 ng/female), and high doses of ingested azadirachtin fail to inhibit or delay oviposition. However, significant, transient retardation of oocyte growth is observed for up to 72 h after feeding. Immature oocytes are observed in 86% of azadirachtin‐fed females decapitated 10 h after a blood meal, whereas 96% of decapitated control females contain maturing oocytes. This suggests that azadirachtin delays the release of one or more factors from the head that regulate oogenesis. We propose that adult females overcome the effect of azadirachtin by rapid metabolism rather than by excretion of the compound, since by 2 h after a blood meal, only 0.1% of ingested azadirachtin was recovered from excreta and 5% recovered from the body.
A female sex pheromone in Bruchidius atrolineatus (Pic) (Coleoptera, Bruchidae): analysis of the factors affecting production or emission of this pheromone
Authors: NAMMOUR D. , HUIGNARD J. , POUZAT J.
Published: March 2008

ABSTRACT. . The females of the tropical Bruchid Bruchidius atrolineatus (Pic) (Coleoptera) produce a sex pheromone that influences male behaviour. This pheromone, tested on males in an olfactometer, triggers characteristic antennal movements followed by a distinct chemo‐anemotaxis. Sex pheromone production depends on the age of the females and is partly correlated with their ovarian activity. Females 0–24 h old are not attractive, but they begin to attract males on the second day of adult life. Vitellogenesis seems to correlate with the emission or the production of the pheromone but there is no precise synchrony between the two phenomena which are probably induced by the same endocrine factors. Within 1 h after mating there is a decrease in the females' attractiveness, which lasts at least 48 h. Under our experimental conditions no particular rhythm of production or emission of the sex pheromone in B. atrolineatus could be observed.
Group size affects the metabolic rate of a tropical beetle
Authors: TANAKA SEIJI , WOLDA HENK , DENLINGER DAVID L.
Published: March 2008

ABSTRACT. . Dormancy is metabolically very costly for insects and other poikilotherms of the tropics because energy reserves are rapidly utilized at high temperature. Yet, the beetle Stenotarsus rotundus Arrow spends up to 10 months each year in a tropical lowland forest as a non‐feeding adult, dependent upon its fat reserve as an energy source. While in this dormant state, the beetles aggregate in huge numbers and the size of the group greatly influences the metabolic rate. As group size increases, the metabolic rate decreases, and the minimum rate observed in the field (22μl O2 g‐1 h‐1) is estimated to occur when group size reaches about 300 individuals. A decrease in metabolic rate can also be achieved by elevating relative humidity, thus suggesting that one function of the aggregation is to increase humidity within the group and thereby decrease metabolic rate.
Female phonotaxis and frequency discrimination in the bushcricket Requena verticalis
Authors: BAILEY WINSTON J. , YEOH PAUL B.
Published: March 2008

ABSTRACT. The male bushcricket, Requena verticalis, calls with a signal containing two predominant frequencies, 16 kHz and 28 kHz. A synthesized call, made from a template of the natural call, was played to females under conditions of a two‐speaker trial on a flat arena. Orientation pathways to a speaker emitting only a 16 kHz signal were more circuitous than the pathways made by females orientating to a speaker emitting only a 28 kHz signal. Females preferred a signal with both carrier frequency peaks present within the song to a signal with only a 16 kHz or 28 kHz carrier frequency, when the signal containing a double peak was kept at equivalent absolute intensity to that with a single peak. Females chose signals containing a more powerful high frequency peak over a signal in which both peaks were balanced. For the higher peak, they were able to differentiate between frequencies with a separation of 8 kHz but not of 4 kHz. They were unable to differentiate between frequencies with a separation up to 8 kHz in the lower peak when one frequency was held at 16 kHz; however, when this frequency was held at 18 kHz, females were able to distinguish between frequencies with a difference of 4 kHz. (N.B. 18 kHz is 2 kHz above the mean value for this frequency within the natural population.) We conclude that females are choosing males on the amount of power in the higher frequency range of their song and that this may be equivalent to a close calling male in the field.
Analysis of searching movements of a leafminer parasitoid in a structured environment
Authors: CASAS J.
Published: March 2008

ABSTRACT. Pnigalio soemius (Hymenoptera, Eulophidae) is a polyphagous ectoparasitoid of the apple leafminer Phyllonorycter cydo‐niella (Lepidoptera, Gracillaridae). The tracks of females searching on the unmined leaf lamina and on the mine were segmented into 2 mm steps and analysed for angle distributions and correlations between successive steps. The movements on the mine are characterized by a higher mean and higher variance of turn angles compared to the turn angles on the leaf (kinesis‐reaction family). Both klinokinesis and schemakinesis, for which a more precise definition is proposed, are present. Varying the step length has a great influence on the result and can be used to identify different orientation reactions within one track. The insect turns sharply once the mine border has been reached, a behaviour shown to be a crude taxis. An ecologically related species, Sympiesis sericeicornis (Hymenoptera, Eulophidae), moves in the same way. For this species a taxis towards the host could also be observed. A complex mixture of these orientation behaviours allows the parasitoid to remain on the mine and to localise the host.
Fluid secretion by single isolated Malpighian tubules of the house cricket, Acheta domesticus, and their response to diuretic hormone
Authors: COAST G. M.
Published: March 2008

ABSTRACT. A simple modification of the Ramsay method is described for the isolation in vitro of Malpighian tubules from Acheta domesticus. Isolated tubules continue to secrete for many hours in a simple Ringer solution. The rate of secretion is linearly related to the length of tubule within the bathing fluid.

Secretion rates during the immediate post‐equilibration period relate to the physiological state of the donor insect. Highest rates are recorded in tubules removed from animals during the scotophase when the crickets are most actively feeding. Starvation reduces the rate of secretion and when previously starved insects are given access to food the rate increases. These results are consistent with variations in the haemolymph titre of DH that are induced by feeding.

Tubule fluid secretion is stimulated by either CC extract (1 gland pair/50 μ1) or dibutyryl cAMP (10‐3M). CC extracts increase the rate of fluid secretion by c. 200 pl/mm/min for up to 6 h after the tubules have been isolated. The response varies little with the age or physiological state of the donor insect. However, tubules from newly moulted insects secrete at very low rates and respond poorly to CC extract, although they are stimulated by cAMP. The significance of these results is discussed with particular reference to the use of Acheta tubules as a bioassay preparation for DH.
Host acceptance behaviour of Colorado potato beetle larvae influenced by potato glandular trichomes
Authors: DIMOCK MICHAEL B. , TINGEY WARD M.
Published: March 2008

ABSTRACT. In no‐choice tests, larvae of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), avoided contact with, and were less frequently observed feeding on, excised foliage of the resistant wild potato Solanum berthaultii Hawkes than on leaves of the cultivated potato, S.tuberosum L. For older larvae, reduced feeding was a consequence of less frequent contact with S.berthaultii leaves. However, first instars appeared unable to penetrate the adhesive barrier presented by glandular trichomes of S. berthaultii, and those that remained on the leaflets fed less often than did first instars on S. tuberosum. Removal of the trichome barrier by wiping leaflets with tissue paper did not attenuate the apparent repellent effect of S. berthaulti foliage, but led to increased incidence of feeding by first instars. Inhibition of larval feeding may therefore rely on a mechanical barrier provided by the glandular trichomes of S.berthaultii.
Effects of egg availability and egg maturity on the ovipositional activity of the parasitic wasp, Coccophagus atratus
Authors: DONALDSON J. S. , WALTER G. H.
Published: March 2008

ABSTRACT. Effects of egg availability on daily ovipositional activity were determined for Coccophagus atratus Compere (Hymenoptera: Aphelinidae). Females were observed for 6 h per day for their entire adult lives. Observed ovipositional activity was analysed in relation to egg maturation before and after emergence, egg depletion during oviposition and egg replenishment after oviposition. Ovipositional activity, including oviposition, inconsequential probes and searching for hosts, occurred predominantly in the first 30 min of exposure to hosts on the 2nd, 4th, 7th, 10th and 13th days after emergence. The remaining time was spent on non‐ovipositional activities (preening, drinking honeydew and sitting on the glass of the experimental arena). Peaks of ovipositional activity were associated with high numbers of mature eggs in the ovaries. Eggs that remained in the ovaries after a bout of oviposition were apparently not mature even though they had attained their maximum size. Non‐ovipositional activity continued until females had built up a reserve of about eighteen mature eggs. After each successive bout of oviposition, the rate of oogenesis slowed down. Consequently females took longer to accumulate a supply of eggs and periods of non‐ovipositional activity increased.

We conclude that (1) the availability of eggs and the tendency of females to store mature eggs influences ovipositional activity, (2) full‐sized eggs are not necessarily mature, (3) future experiments with C.atratus could be restricted to days of high ovipositional activity, and (4) the terms syn‐ and pro‐ovigenic formulated by Flanders (1950) to describe apparent differences in oogenesis between various parasitic Hymenoptera do not apply to C. atratus and are therefore not universally applicable.
Gorging response of Glossina palpalis palpalis to ATP analogues
Authors: GALUN R. , KABAYO J. P.
Published: March 2008

ABSTRACT. The potencies of seventeen analogues of ATP as gorging inducers for Glossina palpalis palpalis were evaluated. The ranking for effective dose that induced half the flies to gorge (ED50) was: A tetra P 5 ATP=2'd ATP ADP=2'd ADP > AMP‐PNP > 3'd ATP 2'3′dd ATP > AMP‐PCP > adenosine 5′ triphosphate 2′,3'dialdehyde AMP‐CPP » AMP. Females detect ATP and its analogues better than males. The ED50 of ATP was 5 × 10‐7 M for teneral females and 1.5 × 10‐6 M for males. According to the potency order of the ATP analogues, the G.p.palpalis gustatory receptors recognizing ATP can be classified as P2y purinoceptors.
Modulation of juvenile hormone release and oocyte growth following (RS)‐hydroprene treatment in virgin female Diploptera punctata
Authors: KIKUKAWA S. , TOBE S. S. , STAY B.
Published: March 2008

ABSTRACT. The effect of (flS)‐hydroprene treatment (2, 20, 200 μg) on JH release was assessed in virgin females of D. punctata (Eschscholtz) during the first 10 days of adult life as was basal oocyte length and number of cells in the CA. At a dose of 2 μg hydroprene, JH release was stimulated slightly and, on days 4 and 6, oocyte growth was significantly greater than that of acetone‐treated controls. A similar but more striking enhancement of JH release and basal oocyte growth was observed at a dose of 20 μg and a significant inhibition of JH release, in concert with a rapid growth of basal oocytes, was observed at a dose of 200 μg. During the observation period, the mean number of cells in the CA decreased in a dose‐dependent fashion, with a highly significant reduction in numbers in 20 and 200 μg‐treated animals. Reimplantation of vitellogenic ovarioles (three or six) into ovariectomized virgin females also resulted in an enhancement of JH release; this indicates that virgin female CA can respond to the stimulatory action of the ovary and is consistent with a model for (RS)‐hydroprene action in which the ‘positive feedback’ effect (stimulation of JH release) observed with low doses of the analogue occurs as a consequence of the action of the analogue on the ovary. (RS)‐hydroprene treatment stimulates basal oocyte growth to the point at which the previously unstimulatory virgin oocytes are able to enhance JH release by a feedback loop involving the CA and probably the brain.
Acoustic response to a pheromonal cue in the arctiid moth Pyrrharctia Isabella
Authors: KRASNOFF STUART B. , YAGER DAVID D.
Published: March 2008

ABSTRACT. The acoustic properties of the clicks emitted in response to male courtship pheromone by female Pyrrharctia Isabella (J. E. Smith) (Lepidoptera: Arctiidae) have been investigated. Extracts of male scent organs or synthetic male pheromones can be applied to a glass rod and used to stimulate females to produce these sounds. Power spectra, sound pressure readings, and oscillographic analyses show that the acoustic signals elicited by male extracts or synthetic male pheromones are not distinguishable from those produced in response to disturbance (handling). This is the first reported example of a sound produced by a female moth in a sexual context, and is the first reported example in moths of an acoustic response to a pheromonal stimulus.
A mutant strain of Chymomyza costata (Diptera: Drosophilidae) insensitive to diapause‐inducing action of photoperiod
Authors: RIIHIMAA ARI J. , KIMURA MASAHITO T.
Published: March 2008

ABSTRACT. From a Japanese population of Chymomyza costata which has been known to have a photoperiodic larval diapause, we selected a mutant strain which did not respond to photoperiod. However, about 70% of the individuals of this strain entered diapause at 11oC irrespective of photoperiod, and about the same percentage of those of the photoperiod‐sensitive strain also did so in continuous illumination at 11oC. This indicates that low temperature induces diapause independently of photoperiod. On the other hand, a temperature drop from 18 or 25oC to 15oC and chilling at 4oC did not induce diapause.
Field and laboratory electroantennographic measurements of pheromone plume structure correlated with oriental fruit moth behaviour
Authors: BAKER T. C. , HAYNES K. F.
Published: March 2008

Abstract. Peak‐to‐trough electroantennogram amplitudes (bursts), caused by the individual filaments of a plume of female pheromone, diminish as high‐emission‐rate sources are approached by male Grapholita molesta, and this reduction is correlated with in‐flight arrestment (ceasing to advance upwind). These findings are consistent with the hypothesis that one cause of in‐flight arrestment in response to high‐concentration point sources is the attenuation of the peak‐to‐ trough amplitudes close to the source. High burst frequency, high pheromone flux, or low levels of continuous neuronal activity all are less well correlated with arrestment. Rather, arrestment appears due to a reduction of chemosensory input to the CNS during flight up the plume, even though the actual molecular concentration continues to increase. In a laboratory wind tunnel, upwind flight initiation by more than 20% of males was elicited only by pheromone source concentrations evoking significant fluctuations in EAG amplitudes at downwind release points. The burst frequencies that evoked high levels of upwind flight initiation ranged from a mean of 0.4‐2.2 bursts/s. Because a previous study revealed that flying male G. molestachange their course angle within 0.15 s of losing or contacting pheromone, these EAG burst frequencies indicate that during flight in a pheromone plume, many manoeuvres are probably made in response to contact with individual plume filaments. Thus, upwind flight tracks may be shaped by hundreds of steering reactions in response to encounters with individual pheromone filaments and pockets of clean air. Field‐recorded EAGs reveal that burst amplitudes diminish from 3 to 30 m downwind of the source, whereas burst frequencies do not, averaging c.1/s at 3, 10 and 30 m downwind.
Effects of artificial and natural diets on success in tip recording and on galeal chemosensillum morphology of European Corn Borer larvae
Authors: CANNEY PETER J. , GARDNER DAVID R.
Published: March 2008

Abstract. Larvae of Ostrinia nubilalis(Hübner) (Lepidoptera: Pyralidae) were reared on artificial diet, fresh cut corn, or switched from diet to corn for 5 days prior to tip recording. Electrophysiological responses to a standard mixed chemical stimulus were obtained from the galeal uniporous chemosensilla of the early fifth‐stadium larvae. Mouthparts of some larvae were briefly treated with protease, then recorded again. Larvae were then processed for scanning electron microscopy (SEM) of chemosensilla terminal pores. Spike:noise ratios were significantly higher for corn‐reared, switched‐to‐corn, and protease‐ treated larvae, relative to diet‐reared larvae. Morphology of the chemo‐ sensilla terminal pores, as assessed by SEM, reveals that apparent occlusion of the pore tip is significantly greater for diet‐reared larvae relative to the other groups. The data suggest an association between quality of the electrophysiological recordings and physical blockage of the terminal sensillum pore. These data should serve as a caveat for those engaged in chemosensory studies of insect herbivores.
Factors affecting egg maturation in the bean weevil Callosobruchus maculatus
Authors: WILSON KENNETH , HILL LEONARD
Published: March 2008

Abstract. This paper concerns the effects of mate and seed availability on the rate of egg maturation in the bean weevil Callosobruchus maculatus (F.). Egg maturation starts before emergence from the seed and, provided that both oviposition sites and mates are available, eggs are laid at a rate determined by the number of oviposition sites, and mature at a similar rate. If seeds or mates are absent then a small number of eggs are laid, but oocytes continue to mature until the oviduct‐capacity is approached. The number of eggs that a female can store is dependent on her body weight and does not correlate with the number of ovarioles. If, after a period in which oocyte development has been halted, conditions for egg‐laying become suitable, then egg maturation can be re‐started, but only after the oviducts have been emptied of eggs. The rate of egg maturation is then similar to that for females of the same age which have been maturing eggs since emergence.
The effect of alkaloids on sugar receptors and the feeding behaviour of the blowfly
Authors: DETHIER V.G. , BOWDAN E.
Published: March 2008

ABSTRACT. The deterrent effect of alkaloids on feeding by the black blowfly Phormia regina Meigen (Diptera: Calliphoridae) was tested by determining tarsal thresholds for mixtures of sucrose and alkaloids. The following alkaloids were used: atropine sulphate, berberine sulphate, quinine mono‐hydrochloride, caffeine, yohimbine sulphonic ester, pilocarpine hydrochloride, coniine hydrochloride and codeine. The same alkaloids were tested electrophysiologically on tarsal chemoreceptors (D hairs). Both behaviourally and electrophysiologically alkaloids reduced response to sucrose. Deterrence and peripheral inhibition could be blocked by increasing the concentration of sucrose. Application of kinetic analyses to the electrophysiological data ruled out competitive, non‐competitive, and uncompetitive inhibition at receptor sites. There is no correlation of thresholds with available data on lipid solubility or octanol/water partition coefficients. The diverse pharmacological properties of alkaloids suggest that there is no uniform limiting mechanism for this multiform array of compounds.
Morphogenetic and gonadotrophic effects of a juvenile hormone analogue ((7S)‐hydroprene) in last instar female larvae of Diploptera punctata
Authors: KIKUKAWA S. , SMITH C.L. , TOBE S.S.
Published: March 2008

ABSTRACT. The effect of treatment of last instar female larvae of Diploptera punctata with a Juvenile Hormone (JH) analogue, (7S)‐hydroprene, has been determined with respect to the ability of the analogue to alter the duration of the stadium and the nature of the ensuing ecdysis. We have also investigated the effects of the analogue on JH release, the growth of the basal oocytes, as well as ecdysteroid titres during the fourth stadium. Analogue treatment prior to day 10 of the stadium results in prolongation of the stadium and desynchronization of ecdysteroid release. Thereafter, treatment with the analogue has little effect. Analogue treatment results also in the formation of supernumerary larvae and intermediates, in a dose‐dependent fashion, provided that animals are treated on day 10 or earlier. Thus, the ‘critical’ period for metamorphosis in last instar D. punctata is between days 0 and 10.

Treatment with (7S)‐hydroprene produces profound effects also on both JH release, and basal oocyte growth. At a dose of 500μg administered on day 1, JH release is stimulated significantly at a time when JH release is normally undetectable. Significant growth of basal oocytes is observed in such treated animals, and appears to precede the peak in JH release. We suggest that the growth of the basal oocytes, as a result of analogue treatment, stimulates the production of JH by CA in these last instar larvae.
The energetics of mimicry: the cost of pedestrian transport in a formicine ant and its mimic, a clubionid spider
Authors: LIGHTON JOHN R.B. , GILLESPIE ROSEMARY G.
Published: March 2008

ABSTRACT. Little information exists on the energetics of locomotion in small insects, and none in small spiders. We examined standard rate of oxygen consumption (SV̊O2) and net cost of transport (NCOT) in Camponotus sericeiventris (Guerin), a formicine ant, Myrmecotypus rettenmeyeri(Unzicker), its clubionid spider mimic (mean masses 43 and 24 mg, respectively), and an unrelated clubionid, Clubiona barroana (Chickering), mean mass 37mg. All species are from Barro Colorado Island, Panama. NCOT in the species studied was 12, 21 and 27 ml O2g‐1 km‐1, respectively; NCOT in the two spiders was significantly higher than in the ant. The minimum cost of transport of M. rettenmeyeri (8.6ml O2g‐1 km‐1), though low, did not differ significantly from the value predicted for an insect of its body mass, while its Y intercept elevation (estimated V̊O2 at zero running speed/SV̊O2) was extremely high. Y intercept elevation may be high in spiders as a group, leading to high NCOT at low running speeds, and hence to a tendency to adopt ambush predation. It is also predicted that, to minimize locomotion cost per unit distance, spiders will travel faster than insects of equivalent body mass.
Removal and subsequent ingestion of rivals' semen during copulation in a tree cricket
Authors: ONO TOMOHIRO , SIVA‐JOTHY MICHAEL T. , KATO AKI
Published: March 2008

ABSTRACT. A novel combination of adaptations resulting from sperm competition is demonstrated for the tree cricket Truljalia hibinonis (Matsumura) (Podoscirtinae: Gryllidae: Orthoptera). 87.5% of the semen of previous males is displaced onto the penis of the copulating male and is removed at the end of copulation. Semen thus removed is ingested during post‐copulatory oro‐genital grooming. No overt morphological adaptations for sperm removal were observed and, on the basis of anatomical evidence, it is suggested that rivals' semen is flushed out of the female?s sperm storage organ by the semen of the last male.
Respiration during the metamorphosis of sexuals in Lasius flavus (Hymenoptera, Formicidae)
Authors: PEAKIN GREG , NIELSEN MOGENS GISSEL , SKYBERG NILS
Published: March 2008

ABSTRACT. The respiration of metamorphosing gyne Lasiusflavus Fab. has been measured in field and laboratory populations. Twelve morphological stages are identified and their respiratory rate investigated. Only five physiological phases are distinguished. The specific respiratory rate varies between these phases, to produce the U‐shape characteristic of insects. There is good agreement between the data from English field and Danish laboratory populations. The minimum rate is only 40% of the maximum. Except at the beginning and end of metamorphosis, the Q10 is significantly different in the two temperature intervals 10–20 and 20–30d̀C. Metamorphosis was completed in approximately 33 days at 20d̀C. The total oxygen consumption by the gynes during metamorphosis was 2.4 ml. Their weight loss amounted to 2.2 mg, or 36% of the dry weight and, of this, 0.67mg was accounted for by fat. Assuming the rest was carbohydrate, consumption of these reserves would release 62.9 J, which, for this combination of fat and carbohydrate, can be calculated to be equivalent to 3.1 ml oxygen which is in reasonable agreement with the figure calculated from the measurement of oxygen consumption. The specific respiratory rate in English field populations of male pupae varies in the same way as the gyne‐pupae, but it is about 50% higher.
On the relationship between queen number and fecundity in polygyne colonies of the fire ant Solenopsis invicta
Authors: VARGO EDWARD L. , FLETCHER DAVID J. C.
Published: March 2008

ABSTRACT. The reproductive status of individual queens in relation to the number of queens in polygyne colonies of Solenopsis invicta Buren was investigated under both field and laboratory conditions. In field colonies, the weight of individual queens is inversely related to the number of resident queens present. The weight of a queen is positively correlated with fecundity, as measured by the number of eggs laid in 5 h in isolation. Thus increasing queen number has a strong negative effect on the fecundity of individual queens in these colonies. A similar relationship was established in standardized laboratory colonies using queens from a single experimental population. Colony size by itself had no significant effect on queen weight in either the field or laboratory colonies, suggesting that the inverse relationship between queen number and fecundity results from mutual inhibition among queens, possibly involving pheromones, rather than reduced nutrition through lower worker/queen ratios. While uninseminated queens can comprise up to 50% of the functional (i.e. egglaying) queens in polygyne colonies of this ant, they tend to be less fecund than their inseminated nestmates; uninseminated queens within a given colony generally weigh 5–25% less.