bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA sequences and cross‐breeding experiments in the hawthorn spider mite Amphitetranychus viennensis reveal high genetic differentiation between Japanese and French populations
Authors: Navajas Maria , Gutierrez Jean , Lagnel Jacques , Fauvel Guy , Gotoh Tetsuo 
Published: October 2003

AbstractSequence variation of the complete second internal transcribed spacer (ITS2, 445 bp) of nuclear ribosomal DNA and part of the mitochondrial cytochrome oxidase I gene (COI, 350 bp) was examined in Amphitetranychus viennensis (Zacher) mites (Acari:Tetranychidae) from four French and four Japanese locations. Sequence analysis consistently revealed the separation of the samples in two major groups: French mites differed from Japanese by 3.8–4.1% of the nucleotide divergence in COI sequences. These two groups also displayed distinct ITS2 consensus sequences (2.1% nucleotide divergence). A few variations, not affecting the diagnostic sites around the consensus sequence, were revealed among cloned copies of the same individual. Reciprocal crosses and backcrosses between one French and two Japanese populations disclosed strong reproductive incompatibility. However, fertile hybrid females were obtained, indicating the conspecificity of the tested mites. Despite the presence of Wolbachia in the French strain, but not in the Japanese ones, our crosses did not display the unidirectional incompatibility typically produced by this microorganism, but rather a bidirectional – although asymmetrical – incompatibility pattern. The post‐zygotic incompatibilities in A. viennensis cannot be explained by the presence of Wolbachia but to some extent by mite genome divergence resulting from limited gene exchange between allopatric populations. Experiments of Wolbachia elimination by antibiotic treatment and subsequent crosses with cured strains are still needed to fully understand the reproductive incompatibility patterns in this mite species.
Larval predation by Chrysomya albiceps on Cochliomyia macellaria, Chrysomya megacephala and Chrysomya putoria
Authors: Faria Lucas Del Bianco , Orsi Letícia , Trinca Luzia Aparecida , Godoy Wesley Augusto Conde 
Published: October 2003

Abstract Chrysomya albiceps, the larvae of which are facultative predators of larvae of other dipteran species, has been introduced to the Americas over recent years along with other Old World species of blowflies, including Chrysomya megacephala, Chrysomya putoria and Chrysomya rufifacies. An apparent correlate of this biological invasion has been a sudden decline in the population numbers of Cochliomyia macellaria, a native species of the Americas. In this study, we investigated predation rates on third instar larvae of C. macellaria, C. putoria and C. megacephala by third instar larvae of C. albiceps in no‐choice, two‐choice and three‐choice situations. Most attacks by C. albiceps larvae occurred within the first hour of observation and the highest predation rate occurred on C. macellaria larvae, suggesting that C. albiceps was more dangerous to C. macellaria than to C. megacephala and C. putoria under these experimental conditions. The rates of larvae killed as a result of the predation, as well as its implications to population dynamics of introduced and native species are discussed.
Pre‐exposure affects the olfactory response of Drosophila melanogaster to menthol
Authors: Barron Andrew B. , Corbet Sarah A. 
Published: October 2003

AbstractA modification of the trap assay (Woodard et al., 1989) was used to evaluate the response of Drosophila melanogaster (Meigen) to food media containing menthol. Dose‐response curves for flies to mentholic foods were produced for flies that had been pre‐exposed to menthol, during development and adult life, and flies that had not been exposed to menthol before the assay. Mentholic food media were less attractive to Drosophila than plain food medium. Rearing flies on a medium containing menthol reduced their aversion to some concentrations of menthol. The rearing effect was not simply due to lowered general activity levels resulting from developing in a medium containing menthol. There was a threshold concentration of menthol in the rearing medium below which we found no induced behavioural change.
Alfalfa physiological response to potato leafhopper injury depends on leafhopper and alfalfa developmental stage
Authors: Nielsen Gary R. , Fuentes Clara , Quebedeaux Bruno , Wang Z. , Lamp William O. 
Published: October 2003

AbstractWe examined the effects of potato leafhopper (Empoasca fabae) developmental stage and alfalfa (Medicago sativa) developmental stage on the physiological response of the plant to injury. We used radioactive carbon dioxide to label the photoassimilate stream and evaluate the phloem health of alfalfa. In one experiment, six first instar, four fourth instar, and three adult leafhoppers were caged by stage on single alfalfa stems for approximately one day. Only fourth instar nymphs significantly reduced the amount of label transported to injured tissues above the source of the labeled assimilate. First instar nymphs had no effect and adults reduced assimilate transport to stem tips, but this trend was not significant possibly because of confounding variables. However, injury by both first instar nymphs and adults resulted in greater concentration of labeled assimilate in portions of the stem below the feeding site. In another experiment, the developmental stage of alfalfa stems was central to the physiological response of alfalfa to leafhopper injury. A 20 h exposure to three adult leafhoppers significantly reduced the amount of label translocated to the tip and crown tissues of early vegetative plants, and to the crown tissue only of late vegetative plants. In reproductive plants, assimilate translocation was not affected by leafhopper injury. In a final experiment, we found no evidence of an effect on the photosynthesis of leaves of similar age and position to those used as source leaves in our translocation studies. Our findings contribute to our understanding of the physiological response of plants to injury by sap‐feeding insects, and suggest the need for greater refinement of economic injury levels based on leafhopper and plant developmental stage.
Do functional responses of predatory arthropods reach a plateau? A case study of Orius insidiosus with western flower thrips as prey
Authors: van, Den Meiracker R.A.F. , Sabelis M.W. 
Published: October 2003

AbstractParameters determining the functional and numerical response of Orius insidiosus to the density of second instar larvae of the western flower thrips (WFT), Frankliniella occidentalis, were estimated with the aim to be used in models calculating adequate release ratios of predators vs prey. Especially when the prey population must decrease immediately after predator release and the time to suppression must be short, it is of crucial importance to know whether the functional response reaches a plateau or keeps on increasing with prey density within the range of densities that are realistic for the prey. Such plateaus may arise from constraints on the time budget or from constraints on gut‐fullness‐associated motivation to attack the prey. Estimates of the plateau for O. insidiosus based on prey handling times by far exceed realistic values. In addition, motivation constraints did not apply, because the level of gut fullness above which attack ceases coincides with gut capacity. This implies that the predation rate keeps on increasing linearly with the square root of the density of WFT‐larvae and does not reach a plateau within the realistic range of thrips densities (0–20 WFT per cm2). Such plateaus are likely to occur for smaller‐sized predators and smaller‐sized stages of the same predator and they may also occur when the prey stage offered has better capacities to escape or resist attack. We argue that the presence and level of plateaus in functional responses are of importance for determining initial predator‐to‐prey ratios.
Dynamic representation of odours by oscillating neural assemblies
Authors: Laurent Gilles , MacLeod Katrina , Stopfer Mark , Wehr Michael 
Published: October 2003

AbstractStimulus evoked oscillatory synchronization of neural assemblies has been most clearly documented in the olfactory and visual systems. Recent results with the olfactory system of locusts show that information about odour identity is contained in spatial and temporal aspects of an oscillatory population response. This suggests that brain oscillations may reflect a common reference for messages encoded in time. Although stimulus‐evoked oscillatory phenomena are reliable, their roles in perception, memory and pattern recognition remain to be demonstrated. Using honey bees, we demonstrated that odour encoding involves, as in locusts, the oscillatory synchronization of assemblies of neurons, and that this synchronization is, here also, selectively abolished by the GABA receptor antagonist picrotoxin. In collaboration with Dr Brian Smith's laboratory, we showed, using a behavioural learning paradigm, that picrotoxin‐induced desynchronization impairs the discrimination of molecularly similar odourants, but not that of dissimilar odours. It appears, therefore, that oscillatory synchronization of neuronal assemblies is relevant, and essential for fine odour discrimination. Finally, experiments with locust mushroom body neurons, two synapses downstream from the antennal lobe, indicate that their responses to odours become less specific when antennal lobe neurons are desynchronized by picrotoxin injection. These results suggest that oscillatory synchronization and the kind of temporal encoding it affords provide an additional dimension by which the brain can segment spatially overlapping stimulus representations.
Olfactory responses and sensilla morphology of the blackcurrant leaf midge Dasineura tetensi
Authors: Crook D.J. , Mordue (Luntz) A.J. 
Published: October 2003

AbstractOlfactory responses of Dasineura tetensi (Rubs) (Diptera; Cecidomyiidae) to leaf volatiles of blackcurrant (Ribes nigrum) were tested in a 4‐way olfactometer. Newly emerged virgin females showed no response to the leaf volatiles emitted from a blackcurrant shoot. Newly emerged males (which are known to respond to a pheromone released by the female) also showed no response to the leaf volatiles. Two hours after mating females responded positively, indicating that leaf volatiles may play a role in host plant finding. Scanning (SEM) and transmission (TEM) electron microscopy of the antennae of D. tetensi showed that males and females share five sensillum types; sensilla chaetica (mechanoreceptors), sensilla trichodea, sensilla basiconica, uniporous peg sensilla and circumfila (chemoreceptors). The sensilla chaetica and sensilla trichodea resemble those found on other insects. Sensilla basiconica were found on all antennal subsegments except the tip. These are multiporous receptors with five unbranched dendrites filling the lumen. Small peg sensilla located on the tips of both male and female antennae may function as contact‐chemoreceptors. The circumfila, which are a unique type of sensilla found only on cecidomyiid antennae, form loops around each of the antennal subsegments, being attached to the surface by a series of stalks. TEM revealed that each stalk consisted of one sensillum containing a single highly branched dendrite. The distal regions of the walls of each sensillum are fused together to form the circumfila. Circumfila have multiporous walls and a lumen filled with multiple branches of dendrites. Their structure suggests that they are important olfactory receptors in both the male and female.
Experience‐based food consumption by larvae of Pieris rapae: addiction to glucosinolates?
Authors: Renwick J. A. A. , Lopez Kimberly 
Published: October 2003

AbstractWhen newly hatched larvae of P. rapae were transferred to cowpea foliage, they readily accepted this non‐host as food, whereas later instars that had fed on cabbage rejected cowpea. However, when cowpea leaf discs were treated with aqueous extracts of cabbage foliage, they were accepted by cabbage‐reared larvae. Experiments were conducted to determine whether larvae reared on one host plant would be stimulated to feed by extracts of other hosts. Larvae reared on Brassica juncea, Cleome spinosa, Tropaeolum majus, Sinapis alba, Alliaria petiolata, Barbarea vulgaris and cabbage (Brassica oleracea) were offered extracts of each of the other host plants on cowpea discs in choice assays. Larvae were generally stimulated to feed by extracts of all the alternate hosts, but quantitative differences in consumption occurred. In most cases, levels of discrimination between treatment and control cowpea discs showed no significant preference for extracts of the previously experienced plant. Since the test plants (and their extracts) contain glucosinolates of widely different structures, a general addiction to glucosinolates was suggested. A single glucosinolate, sinigrin, was sufficient to elicit feeding by cabbage‐reared larvae. The time required for individual neonates to become addicted to glucosinolates as they fed on cabbage, as measured by refusal of cowpea, varied from 6 to 30 hours. Bioassays of cowpea extracts failed to show any deterrent activity and, therefore, supported the conclusion that addiction to glucosinolates is responsible for the fixation of P. rapae larvae on their host plants.
Role of visual cues and interaction with host odour during the host‐finding behaviour of the cabbage moth
Authors: Rojas Julio C. , Wyatt Tristram D. 
Published: October 2003

AbstractThe approach and landing responses of female Mamestra brassicae (L.) (Lepidoptera: Noctuidae) to visual cues from artificial plant leaves of different shapes and presence/absence of cabbage plant odour were investigated in a laboratory wind tunnel. The leaves were painted with cadmium yellow colour and observed under dim red light. Females showed oriented flight towards plant odours but landed significantly more often when the odour was presented with an artificial leaf. In three‐choice tests, the shape of the leaf targets (circle, square or triangle) did not influence the female response. However, the size of the target did influence the insect response: the females preferred landing on square targets with sides of 5 or 10 cm rather than on the largest target, with sides of 15 cm. The orientation of the target influenced the insects' response: females landed significantly more often on the target positioned vertically than horizontally.
Salivation into sieve elements in relation to plant chemistry: the case of the aphid Sitobion fragariae and the wheat, Triticum aestivum
Authors: Ramírez Claudio C. , Niemeyer Hermann M. 
Published: October 2003

AbstractExtended sieve element salivation (E1 waveform in the electrical penetration graph) is a characteristic activity during early sieve element punctures, particularly in resistant plants. In order to explore a chemically‐mediated mechanism of resistance associated with sieve element salivation, we compared the pattern of feeding behaviour of the aphid, Sitobion fragariae (Walker), on two cultivars of the wheat Triticum aestivum L., with different concentrations of hydroxamic acids (Hx). During 24 h of electronic monitoring, aphids dedicated over 50% of the total time to phloem ingestion from the sieve elements. Total time allocated to E1 in the experiment, time to first E1 within the experiment, time allocated to E1 before a sustained phloem ingestion (E2) and the contribution of sieve element salivation to the phloem phase (E1/[E1+E2]) were significantly higher in the high‐Hx cultivar. The increased salivation in plants with higher contents of Hx suggests the existence, at least in this system, of a chemically‐mediated sieve element constraint.
Aphid responses to non‐host epicuticular lipids
Authors: Powell Glen , Maniar Sangita P. , Pickett John A. , Hardie Jim 
Published: October 2003

AbstractInitiation of stylet penetration by aphids depends on the sensory assessment of a number of plant surface features including colour, texture and phytochemicals (volatile and non‐volatile). Video recording behaviour of the black bean aphid, Aphis fabae, showed that these insects rapidly inserted their stylets following contact with host plants (beans), but were reluctant to penetrate non‐hosts (oats). However, when epicuticular waxes were stripped from oats, using cellulose acetate, aphids penetrated the plant surface significantly earlier than on oats with the wax layer intact. Chloroform extraction of epicuticular lipids, followed by coupled gas chromatography‐mass spectrometry, revealed a complex blend of wax components on beans, whereas one compound (1‐hexacosanol) predominated on oats. Epicuticular lipids were applied to artificial (glass) substrates in order to investigate their behavioural activity. Initiation of a stylet penetration attempt by A. fabae was delayed when the oat extract or pure 1‐hexacosanol were applied, but the bean extract had no behavioural effect. The results suggest that epicuticular lipids play an important role in the early stages of host‐plant selection by A. fabae.
Are herbivore‐induced plant volatiles reliable indicators of herbivore identity to foraging carnivorous arthropods?
Authors: Dicke Marcel 
Published: October 2003

AbstractPlants that are damaged by herbivorous arthropods provide carnivorous enemies of the herbivores with important information. They emit an induced volatile blend that is highly detectable to the carnivores from a distance. Such detectable signals that indicate herbivore presence are important for the carnivores because herbivores themselves are under strong selection not to expose themselves. In addition, carnivores would benefit from a specificity of the induced plant volatiles. Whether herbivore‐induced plant volatiles are reliable indicators of herbivore identity, however, has not been resolved unambiguously. Some studies support the reliability of herbivore‐induced plant volatiles, while others do not. Different approaches have been used such as chemical analysis, behavioural analysis or a combination of the two. Based on the total of chemical studies one might conclude that in most cases herbivore‐induced plant volatiles are not very specific for the herbivore that damages the plant. However, arthropod chemosensors are much more sensitive than the detectors of analytical instruments. Therefore, chemical analyses are not suitable to demonstrate whether or not herbivore‐induced plant volatiles are reliable indicators of herbivore identity to carnivores. Behavioural studies should provide this information. In analysing carnivore behaviour it should be realised, however, that arthropod behaviour can be highly variable. Arthropod foraging decisions are affected by external and internal factors such as (a) abiotic environmental factors, (b) presence of competitors or enemies, (c) deprivation of food or oviposition sites, (d) specific deprivation of certain nutrients or (e) learning. In this paper their effect on discrimination of carnivores between volatile blends emitted by plants infested by different herbivores is reviewed. This provides testable hypotheses of why discrimination was not found in some studies. The ability of carnivores to discriminate is likely to be more common than is clear to date, which should invoke functional studies of the conditions that influence the occurrence of this discrimination.
Induction of cotton extrafloral nectar production in response to herbivory does not require a herbivore‐specific elicitor
Authors: Wäckers F.L. , Wunderlin R. 
Published: October 2003

AbstractThe production of extrafloral nectar is thought to represent an indirect plant defense, as it allows plants to recruit natural enemies which can protect the plant against herbivore attacks. In previous work we demonstrated that plants may show a strong increase in extrafloral nectar secretion in response to herbivory. Here we address the question of whether this induction is herbivory‐specific, or simply a general response to tissue damage. We compared the level of induction in Gossypium herbaceum (L.) (Malvaceae) following either herbivory by Spodoptera littoralis (Boisduval) (Lepidoptera; Noctuidae) or mechanical damage with and without the addition of S. littoralis regurgitate. Both herbivore feeding and mechanical damage significantly raised nectar production. No difference in volume or pattern of nectar secretion was found between natural and mechanical damage, nor between artificially damaged plants treated with regurgitate or water. Our findings indicate that the induction of extrafloral nectar secretion constitutes a general response by the plant to tissue damage, rather than representing a herbivory‐specific mechanism. The costs and benefits of such a non‐specific strategy for the plant are discussed.
Wound‐induced increases in the glucosinolate content of oilseed rape and their effect on subsequent herbivory by a crucifer specialist
Authors: Bartlet Elspeth , Kiddle Guy , Williams Ingrid , Wallsgrove Roger 
Published: October 2003

AbstractDamage to the oilseed rape plant (Brassica napus L.) by the cabbage stem flea beetle, Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae) induces systemic changes to the glucosinolate profile, most noticeably an increase in the concentration of indole glucosinolates. When jasmonic acid was applied to the cotyledons of the plant, a similar effect was observed. Feeding tests with artificial substrates compared a glucosinolate fraction from jasmonic acid‐treated plants with a similar fraction from untreated plants. In these tests, alterations to the glucosinolate profile increased the feeding of a crucifer‐specialist feeder (P. chrysocephala). However, in whole plant tests, P. chrysocephala did not feed more on the jasmonic acid treated plants than on the controls. This implies that other aspects of the damage response are being induced by the jasmonic acid treatment and having a negative effect on subsequent herbivory.
Pyrrolizidine alkaloid distribution in Senecio jacobaea rosettes minimises losses to generalist feeding
Authors: de Boer Nico J. 
Published: October 2003

AbstractThe within‐plant distribution of pyrrolizidine alkaloids (PAs) was determined in the shoots of vegetative Senecio jacobaea L. Asteraceae plants. Also the distributions of feeding stimulants, soluble sugars and total nitrogen, were determined. PAs were found to decrease with leaf age, sugars were constant, and nitrogen decreased with leaf age. These results were compared with the within‐plant distribution of feeding damage by the generalist herbivores Spodoptera exigua Hübner and Mamestra brassicae L. Both generalists showed a strong preference for older leaves. It was concluded, that the herbivores were forced to feed on sub‐optimal parts of the plant.
A galling aphid furnishes its home with a built‐in pipeline to the host food supply
Authors: Wool David , Aloni Roni , Ben‐Zvi Ofra , Wollberg Miriam 
Published: October 2003

AbstractGalling insects modify the developmental pathways of their host plants and create a protected and favourable microhabitat for their offspring. Galling aphids reproduce in their galls and the resulting clones often comprise hundreds of individuals. We followed the histological changes in the host Pistacia palaestina (Anacardiaceae) induced by the galling aphid Geoica wertheimae (Aphidoidea, Pemphigidae: Fordinae). We showed that the leaf tissues are altered in the gall in a way that gives the aphids easy access to the vascular system from which they obtain their nourishment. Specifically, the cuticle that lines the normal leaf epidermal cells is absent on the surface of the inner gall cavity, and the normal palisade cells are replaced by parenchymatous tissue with numerous wide latex ducts. Associated with these ducts, many new sieve tubes (phloem elements) are formed just a few cell layers below the inner gall surface. This arrangement enables the hundreds of aphids to feed simultaneously and continuously in the gall throughout the summer.