bluuebunny/crossref_metadata_2025_split huggingface dataset:
Timing of diapause induction outside the natural distribution range of a species: an outdoor experiment with the bean bug Riptortus clavatus
Authors: Musolin Dmitry L. , Numata Hideharu , Saulich Aida H. 
Published: October 2003

AbstractThe phytophagous bug Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) produces two or three generations per year in Central Japan and overwinters in the adult stage. In bugs from the Kyoto population (35°00′ N, 135°45′ E), we studied (1) the effects of day‐length on the nymphal and preoviposition periods under constant photoperiod at 20.5 °C, and (2) photoperiodic induction of adult diapause at 20.5 °C and under a combination of constant photoperiod and natural daily rhythm of temperature in the forest‐steppe zone of Russia (50°38′ N, 35°58′ E). Then, we examined (3) the timing of diapause induction under quasi‐natural conditions in the same region, far outside the species' natural geographical range. At 20.5 °C, the nymphal period in both males and females was significantly longer under regimes with shorter photophases than under those with longer photophases. The preoviposition period in females was significantly longer under the near‐critical long‐day regime L14:D10 than under typical long‐day regimes (L15:D9, L16:D8, and L17:D7). The critical day‐length for diapause induction was shorter under conditions of natural daily rhythm of temperature than those reported at constant 20, 25, and 30 °C. Under quasi‐natural conditions in the forest‐steppe zone, R. clavatus entered diapause in September, much later than the local populations of true bugs studied to date. This experiment showed that R. clavatus was maladapted to new environmental conditions: diapause was induced too late with the result that all or most nymphs hatched in late August or early September will die.
Irreversible thelytokous reproduction in Muscidifurax uniraptor
Authors: Gottlieb Yuval , Zchori‐Fein Einat 
Published: October 2003

AbstractVertically transmitted bacteria of the genus Wolbachia are obligatory endosymbionts known to cause thelytokous (asexual) reproduction in many species of parasitic Hymenoptera. In these species production of males can be induced, but attempts to establish sexual lines have failed in all but one genus. We have found three reproductive barriers between antibiotic‐induced males and conspecific females of Muscidifurax uniraptor Kogan and Legner (Hymenoptera: Pteromalidae): males do not produce mature sperm, females are reluctant to mate, and a major muscle is absent from the spermatheca. These findings suggest that Wolbachia‐induced thelytokous reproduction in M. uniraptor is irreversible, and are consistent with the idea that since sexual reproduction has ceased, selection on sexual traits has been removed leading to the disappearance or reduction in these traits. Because under these circumstances asexual reproduction is irreversible, the host has become totally dependent on the symbiont for reproduction.
Encapsulation and hemocyte numbers in three lepidopteran stemborers parasitized by Cotesia flavipes‐complex endoparasitoids
Authors: Alleyne Marianne , Wiedenmann Robert N. 
Published: October 2003

AbstractDetermination of the potential and actual host range of a natural enemy is crucial before its importation and release for biological control. We studied some of the factors that are important in determining the physiological host range of insect parasitoids attacking lepidopteran hosts. Our experimental system consisted of novel host‐parasitoid associations, with two New World pyralid stalk borers, Diatraea saccharalis and D. grandiosella; one Old World crambid borer, Ostrinia nubilalis as hosts; and three Old World microgastrine braconids, Cotesia chilonis, C. sesamiae, and C. flavipes as parasitoids. Experiments on the chronology of encapsulation of the parasitoid progeny by host hemocytes indicated that lepidopteran stemborers that are taxonomically, behaviorally and ecologically very similar differ in their ability to encapsulate a parasitoid species. D. saccharalis encapsulated C. flavipes sometimes, whereas D. grandiosella consistently encapsulated C. sesamiae and C. flavipes. C. chilonis was not encapsulated by either Diatraea host. If encapsulation occurred it did not start until four days after parasitization and continued during the following days. O. nubilalis was an unsuitable host for all three parasitoid species; parasitoid eggs were killed within 24 hours of parasitization. O. nubilalis had nearly twice as many hemocytes present in the hemolymph compared to the Diatraea species. In many of the host‐parasitoid combinations, there was an initial increase of hemocyte number soon after parasitization, which was not due to mechanical damage at oviposition. There was no correlation between total numbers of hemocytes present in the host hemolymph and the observed encapsulation levels. By understanding the encapsulation response we may be able to make better predictions about the host range of a parasitoid species before its release as a biological control agent.
Does host‐feeding on GNA‐intoxicated aphids by Aphelinus abdominalis affect their longevity and/or fecundity?
Authors: Couty Aude , Poppy Guy M. 
Published: October 2003

AbstractTransgenic potatoes have been transformed with a gene coding the snowdrop lectin Galanthus nivalis agglutinin (GNA) and they have been shown to be partially resistant to aphids. GNA binds to insect gut cells, including those of aphids, consequently inducing disruption of nutrient assimilation. Aphid parasitoids are important natural biocontrol agents of aphids and some species such as Aphelinus abdominalis are commercially available. Aphid parasitoids are endoparasitoids during their larval stages and free‐living insects as adults. They could be directly or indirectly affected by GNA during both these stages. In this work, we present data on the potential direct and indirect effects of GNA on adult A. abdominalis. Aphelinus abdominalis is a synovigenic species (eggs are matured throughout the adult life) which needs a diet relatively rich in proteins and amino‐acids to produce anhydropic eggs (large, yolk‐rich eggs that do not expand in the host during embryonic stages). Adult A. abdominalis females feed on aphid haemolymph and they may be directly exposed to the entomotoxin or indirectly affected by a change in aphid haemolymph quality due to intoxication by GNA. We conducted a first tier experiment to investigate this potential risk. A. abdominalis females were offered either aphids reared on control diet or aphids reared on GNA 0.1% diet as hosts (i.e., as food and oviposition sites). No trace of GNA was found in females fed with GNA‐aphids but no GNA could be detected in the haemolymph of aphids fed a 0.1% GNA diet. Longevity and fecundity were not affected suggesting that the quality of the haemolymph necessary for A. abdominalis egg maturation and production was not significantly altered.
Stylet penetration and survival of three psyllid species on adult leaves and ‘waxy’ and ‘de‐waxed’ juvenile leaves of Eucalyptus globulus
Authors: Brennan Eric B. , Weinbaum Steven A. 
Published: October 2003

AbstractThe stylet probing behavior and survival of Ctenarytaina eucalypti Maskell, C. spatulata Taylor and Glycaspis brimblecombei Moore (Homoptera, Psyllidae) on adult leaves and ‘waxy’ (untreated) and ‘de‐waxed’ (rubbed) juvenile leaves of the heteroblastic plant Eucalyptus globulus Labillardiere were compared. Psyllids were confined within clip‐on cages and after 15 days the leaf tissue under each cage was sectioned and stained to characterize and quantify stylet tracks. Across all leaf treatments and psyllid species 1438 stylet tracks were observed in 7239 leaf sections and 571 of these stylet tracks reached the vascular tissue. Survival and the number of stylet tracks of C. eucalypti on the different leaf types did not differ. In contrast, C. spatulata survived significantly longer and produced significantly more stylet tracks on adult leaves and ‘de‐waxed’ juvenile leaves than on ‘waxy’ juvenile leaves. Although G. brimblecombei survived equally on all treatments, it produced more stylet tracks on adult leaves and ‘de‐waxed’ juvenile leaves than on ‘waxy’ juvenile leaves. For all three psyllid species, there was a positive correlation between survival and number of stylet tracks reaching the vascular tissue. Stylet tracks of all species were generally intercellular from the leaf epidermis to the vascular tissue. Oil glands were avoided by all species, as indicated by the repeated branching and formation of stylet tracks at the periphery of the glands. In ‘de‐waxed’ juvenile leaves, C. spatulata and G. brimblecombei produced stylet tracks that entered the leaf at the adaxial surface and exited at the abaxial surface. This pattern was rarely observed on adult leaves, and never occurred with C. eucalypti in any leaf type. We conclude that (1) the epicuticular wax on juvenile leaves reduced stylet probing by C. spatulata and G. brimblecombei, (2) there were apparently no internal physical barriers in either juvenile or adult leaves to prevent the stylets of any of the psyllid species from reaching the vascular tissue, (3) the psyllids avoided oil glands in both leaf types, and (4) C. spatulata and G. brimblecombei may lack cues to orient their stylets towards the vascular tissue in the juvenile leaves.
Potential for habituation to a neem‐based feeding deterrent in Japanese beetles, Popillia japonica
Authors: Held D.W. , Eaton T. , Potter D.A. 
Published: October 2003

AbstractWe tested the potential for the Japanese beetle, Popillia japonica Newman, to habituate to a neem‐based feeding deterrent applied to foliage of linden, Tilia cordata L., a preferred host for the adults. Female beetles' consumption of control foliage versus foliage treated with either a low or high rate of neem insecticide, corresponding to 9 or 39 pm azadirachtin, respectively, was tested in a series of 4‐h choice or no‐choice tests over four successive days. In another experiment, females were conditioned for 22 h with either control foliage, leaves treated with the low rate, or a mixture of both treated and untreated leaves. Deterrence of either the low or high rate of neem to these beetles was then evaluated in choice tests with control foliage, as before. In choice tests, mean consumption of control foliage was always greater than for treated foliage, regardless of rate. There was, however, proportionately more feeding on foliage treated with the high rate upon successive exposures. In no‐choice tests, beetles initially deterred by the low rate were not significantly deterred by that rate by the third and fourth days of the experiment. Finally, beetles conditioned by exposure to leaves treated with the low rate were not deterred by that rate in a subsequent choice test, although they were deterred by the higher rate. Despite these trends, we suggest that Japanese beetles' polyphagy and mobility probably would reduce the likelihood for habituation to neem‐based feeding deterrents in the field.
Mechanisms for tolerance to diatomaceous earth between strains of Tribolium castaneum
Authors: Rigaux Marilyn , Haubruge Eric , Fields Paul G. 
Published: October 2003

AbstractFourteen strains of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) had mortalities ranging from 5 to 100% when exposed to diatomaceous earth at 600 ppm for seven days. The most tolerant strain had a lethal dose for 50% of the population (LD50) of 413 ppm and the most susceptible strain had a LD50 of 238 ppm. Adults of the tolerant strain were lighter (2.0 mg) than the susceptible strain (2.6 mg). Tolerant adults lost water at lower rate (6 μg h−1 than susceptible adults (12 μg h−1), when held in wheat treated with 600 ppm diatomaceous earth for 24 h, than held at 5% r.h. with no food. Tolerant adults that were not exposed to diatomaceous earth lost water at a lower rate (3 μg h−1) than susceptible adults (5 μg h−1). Both strains, exposed and not exposed to diatomaceous earth died when their water content was between 33 and 37% of their total weight. Insects taken directly from the cultures had 52% (tolerant) and 53% (susceptible) of their total weight as water. Tolerant adults moved slower through grain and across filter paper than susceptible adults. Tolerant adults avoided wheat treated with diatomaceous earth at concentrations as low as 75 ppm, whereas the adults from the susceptible strain did not avoid diatomaceous earth, even at 600 ppm. The consequences of a strain tolerant to diatomaceous earth is discussed with respect to the use of diatomaceous earth to control stored‐product insect infestations.
Lack of specificity in the interaction between two maize stunting pathogens and field collected Dalbulus leafhoppers
Authors: Ebbert Mercedes A. , Jeffers Daniel P. , Harrison Nigel A. , Nault Lowell R. 
Published: October 2003

AbstractWe tested hypotheses concerning the specificity of interactions between insect vectors and mollicute plant pathogens in a 22‐month study of leafhoppers collected at three agricultural field sites in Mexico. The common species collected, Dalbulus maidis, D. elimatus, D. gelbus, and D. guevari were equally likely to test positive for corn stunt spiroplasma (CSS) in ELISA, and to transmit maize bushy stunt phytoplasma (MBSP) to test maize seedlings. We documented intraspecific variation in the ability of D. maidis to transmit confirmed CSS infections. Dalbulus guevari and D. gelbus were less successful in transmitting CSS than D. maidis from the same population. Our results suggest this vector‐plant pathogen interaction is not specific to a single Dalbulus‐mollicute combination, and that both the range of potential vectors in agricultural fields, and intraspecific variation across populations of these vectors, should be the focus of future work.
Electrical penetration graphs from Cicadulina mbila on maize, the fine structure of its stylet pathways and consequences for virus transmission efficiency
Authors: Lett Jean‐Michel , Granier Martine , Grondin Martial , Turpin Patrick , Molinaro Franck , Chiroleu Frédéric , Peterschmitt Michel , Reynaud Bernard 
Published: October 2003

AbstractFive distinct electrical penetration graph waveforms characterising the feeding behaviour of the leafhopper Cicadulina mbila Naudé (Homoptera: Cicadellidae) on maize (Zea mays L.) were obtained using a DC based system. The waveforms were distinguished by spectral features and by statistical analysis of their median voltages, durations and time to first waveform recording. By changing the polarity of the system voltage and the level of the input resistor it was shown that the waveforms are mainly determined by the electromotive force (emf) component. Based on the correlation between waveforms and the fine structure of the stylet pathways observed by transmission electron microscopy, insect's activities have been associated with five waveforms: stylet pathway formation (waveform 1), active ingestion (waveform 2), putative stylet work (waveform 3), salivation (waveform 4) and passive ingestion (waveform 5). Like waveform E1 and E2 of aphids, waveforms 4 and 5 of C. mbila correspond to feeding activities in sieve tubes. However, unlike aphids which probe briefly in non‐vascular cells, waveform 2 corresponds to active ingestion in cells, where the cell content is partially ingested and hence the organelles' integrity severely affected. These observations suggest that this specific feeding feature, typical of leafhoppers, determines their ability to acquire geminivirus virions located in the plant cell nucleus.
Oviposition in Culicoides impunctatus under laboratory conditions
Authors: Carpenter S. , Mordue (Luntz) A.J. , Mordue W. 
Published: October 2003

AbstractWe present a laboratory‐based examination of oviposition preference in the Scottish biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae). A variety of oviposition substrates were screened in no‐choice and choice bioassays for efficacy in eliciting an egg‐laying response. Both upper‐layer photosynthetic Sphagnum spp. moss and Juncus articulatus infusions were identified as producing increased oviposition under no‐choice conditions. During choice trials against a control of damp cottonwool, upper‐layer Sphagnum spp. moss produced a significantly greater egg‐laying response. These conclusions are interpreted in terms of possible cues involved in oviposition site selection and assessed for future use in colonisation of this troublesome species.
In vitro enzymatic chlorophyll catabolism in wheat elicited by cereal aphid feeding
Authors: Ni Xinzhi , Quisenberry Sharron S. , Markwell John , Heng‐Moss Tiffany , Higley Leon , Baxendale Frederick , Sarath Gautam , Klucas Robert 
Published: October 2003

AbstractChlorophyll degradation is a complex phenomenon that often accompanies insect feeding damage to plants. Loss of chlorophyll can be initiated by several reactions, including oxidative bleaching, chlorophyllase activity, and Mg‐dechelatase activity. Extracts from the Russian wheat aphid [Diuraphis noxia (Mordvilko)], the bird cherry‐oat aphid [Rhopalosiphum padi (L.)], and aphid‐infested and uninfested wheat plants were assayed in vitro for activities involved in chlorophyll degradation. Although the initial infestation was the same (10 apterous adults) for both aphid species, D. noxia weight was significantly higher than R. padi after feeding for 12 days. Consequently, D. noxia feeding caused greater fresh leaf weight reduction than R. padi feeding. Chlorophyll degradation assays showed no activity from either D. noxia or R. padi extracts. Plant extract assays showed a significant difference in Mg‐dechelatase activity, while no difference was detected in either the chlorophyllase or oxidative bleaching pathways among the aphid‐infested or uninfested plant extracts. Diuraphis noxia‐infested leaf extracts showed a greater increase of Mg‐dechelatase activity than either R. padi‐infested or the uninfested plants. The findings suggest that leaf chlorosis elicited by D. noxia feeding is different from the chlorophyll degradation that occurs in natural plant senescence. Aphid‐elicited chlorosis might be the result of a Mg‐dechelatase‐driven catabolism of chlorophyll in challenged wheat seedlings, however, the factor(s) from D. noxia that elicited the increase of Mg‐dechelatase activity still remain to be determined.
Entomophily of the cloudberry (Rubus chamaemorus)
Authors: Pelletier Luc , Brown Adam , Otrysko Barbara , McNeil Jeremy N. 
Published: October 2003

AbstractCloudberry (Rubus chamaemorus L.), a dioecious perennial plant of boreal circumpolar distribution, is greatly prized for its berries. We crossed two treatments, pollinator exclusion and supplementary hand‐pollination, to determine i) the relative importance of insects as pollinators, ii) if pollinator activity was a limiting factor for the sexual reproduction of the plant, and iii) the relative contribution of diurnal vs. nocturnal visitors to pollination. The activity of natural pollinators resulted in 97.5 and 88.5% fruit set, along with 76.7 and 62.5% seed set in 1998 and 1999, respectively. When insects were excluded, fruit‐set dropped significantly to 18.4 (1998) and 12.8% (1999) and seed‐set to 5.4 (1998) and 5.0% (1999) showing the importance of mid‐ and large‐sized insects as pollinators. Natural levels of insect activity were sufficient to ensure complete pollination in both years as supplementary hand‐pollination did not significantly increase either parameter in plots where pollinators had free access. Nocturnal insects may serve as pollinators (fruit‐set = 41%), although they were less effective than diurnal pollinators (fruit‐set = 93%).
Attraction of the predatory mites Typhlodromalus manihoti and Typhlodromalus aripo to cassava plants infested by cassava green mite
Authors: Gnanvossou Désiré , Hanna Rachid , Dicke Marcel , Yaninek Steve J. 
Published: October 2003

AbstractThe attraction of the predatory mites, Typhlodromalus manihoti and Typhlodromalus aripo, to the host plant‐spider mite complex, Manihot esculenta–Mononychellus tanajoa, was investigated with a Y‐tube olfactometer. Factors examined included predator starvation period, several combinations of cassava leaf biomass and initial M. tanajoa infestations, M. tanajoa‐damaged leaves with mites and/or their residues removed, M. tanajoa alone, and mechanically damaged cassava leaves. We found that females of T. manihoti and T. aripo were significantly attracted to M. tanajoa‐infested cassava leaves when the predators were starved for 2, 6, or 10 h. Satiated T. aripo was significantly attracted to infested cassava leaves whereas satiated T. manihoti did not discriminate between infested and non‐infested leaves. When a choice was given between either two or four leaves infested with 200 female M. tanajoa and an equivalent number of non‐infested leaves, 2 h‐starved T. manihoti and T. aripo were significantly attracted to each of the infested groups of cassava leaves. At a density of 12 female M. tanajoa per leaf on four leaves, 2 h‐starved T. manihoti was still attracted to M. tanajoa‐infested leaves whereas 2 h‐starved T. aripo was not attracted. When a choice was given between non‐infested cassava leaves and either infested leaves from which only M. tanajoa females had been removed, or infested leaves from which all M. tanajoa and their visible products (web, feces) had been wiped off, T. aripo preferred odors from both types of previously infested leaves. Typhlodromalus manihoti was only attracted to infested leaves from which the M. tanajoa females only had been removed. Finally, the two predators were not attracted to 400 female M. tanajoa on clean cotton wool or to mechanically wounded leaves. This supports the hypothesis that M. tanajoa damage induces volatile cues in cassava leaves that attract T. manihoti and T. aripo to M. tanajoa‐infested leaves.