bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Azadirachtin on reproduction in the African armyworm (Spodoptera exempta)
Authors: Tanzubil Paul B. , McCaffery Alan R.
Published: April 2011

Azadirachtin, applied topically to final instar larvae of the African armyworm (Spodoptera exempta, Walker) (Lepidoptera: Noctuidae), adversely affected oogenesis and reproductive maturation in subsequent female moths. Moths obtained from such treated larvae failed to mature their oocytes, probably as a result of interference of azadirachtin with vitellogenin synthesis and/or its uptake by developing oocytes. Such larval treatment also caused substantial decreases in fecundity and although fertility in affected females was not decreased significantly, emerging larvae were less viable, less than 40% reaching the fourth instar.

Closer examination revealed that protein levels as well as fat body development in female moths were suppressed by azadirachtin. Prospects for field control of this pest with neem are discussed in the light of these findings.

Effets de l'azadirachtine sur la reproduction de Spodoptera exempta

L'application locale d'azadirachtine sur des chenilles de dernier stade de S. exempta Walker nuit à l'ovogenèse et à la maturation des ovaires des futures femelles. Les papillons provenant des chenilles traitées ne produisent pas d'ovocytes mûrs, probablement par suite de l'interférence de l'azadirachtine avec la synthèse de la vitellogénine et/ou son incorporation dans les ovocytes en développement. De tels traitements larvaires provoquent aussi une diminution importante de la fécondité et bien que la fertilité des femelles touchées ne diminue pas significativement, les chenilles néonates sont moins viables, moins de 40% atteignant le 4e stade. Un examen plus précis a révélé que la teneur en protéines et le développement du corps gras des papillons femelles étaient altérés par l'azadirachtine. Des perspectives d'utilisation du NEEM dans la lutte contre cet insecte ont été discutées à la lumière de ces résultats.
Host population density influence on host acceptance in Trichogramma
Authors: Reznik S. Ya. , Umarova T. Ya.
Published: April 2011

In 7 Trichogramma species (Hymenoptera, Trichogrammatidae) the percentage of females, parasitizing at least one host, directly depends on the number of host eggs. Trichogramma females that refused Sitotroga eggs will still oviposit in natural hosts. These refusing females were yet active, moved in test tubes and sometimes contacted the host. It seems that the sequence of behavioural reactions resulting in parasitization is interrupted at the stage of arrestment and host recognition. Host density within a habitat proved to be an important factor in host acceptance. Possible mechanisms that formed the basis of the observed effect (behavioural response to host kairomones, the learning ability, endocrine processes) are discussed.

La densité de population de l'hôte influence l'acceptation de l'hôte chez Trichogramma

En utilisant l'hôte de laboratoire (Sitotroga cerealella Oliv.) nous avons démontré qu'une partie des femelles refuse la parasitation. L'analyse de la succession des actes constitutifs de la parasitation montre que celle‐ci est interrompue au moment de l'acceptation. Le pourcentage des femelles parasitante est en dépendance directe du nombre des œufs de l'hôte. Les résultats de cette étude suggèrent que l'acceptation de l'hôte par le parasitoid est finction de la densité de population de celui‐là. Les mécanismes possibles de cette dépendance (la réaction aux kairomones, l'apprentissage, les modification endocrines) sont discutés.
Does immunization of cucumber against anthracnose by Colletotrichum lagenarium affect host suitability for arthropods?
Authors: Ajlan A. M. , Potter D. A.
Published: April 2011

Restricted infection of a lower leaf of cucumber, Cucumis sativus L., with the anthracnose fungus Colletotrichum lagenarium has been previously shown by others to induce persistent, systemic resistance to the same fungus and to at least 12 other diverse plant pathogens. The non‐specificity of pathogen‐induced resistance has fueled speculation that it might also affect arthropod herbivores. However, we found that immunization of cucumber with C. lagenarium had no effect on population growth of twospotted spider mites, Tetranychus urticae Koch, reared on foliage for which induced resistance to the same pathogen was confirmed. Similarly, immunization with C. lagenarium had no systemic effect on weight gain, duration of development, or pupal weight of fall armyworms, or on progeny production by melon aphids. In reciprocal tests, previous feeding injury from spider mites or fall armyworms did not induce systemic resistance to C. lagenarium. These results indicate that, at least for cucumber, pathogen‐activated induced resistance is specific to plant pathogens, suggesting separate mechanisms of induced resistance to pathogens or herbivores.

Est‐ce que l'immunization du concombre contre l'anthracnose par Colletotrichum lagenarium affecte ses propriétés d'hôte vis‐à‐vis des arthropodes?

Dans une étude de résistance induite, l'infection basale des feuilles du concombre, Cucumis sativus L., avec Colletotrichum lagenarium, le champignon de l'anthracnose, a généré une induction systémique et persistante, non seulement au même champignon, mais aussi et surtout à l'égard de douze autres. La nature non‐spécifique de cette résistance a dès lors engendré une hypothèse, celle de savoir si cette non‐spécificité pourrait s'entendre au niveau d'arthropodes phytophages. Cependant, nos travaux ont démontré que l'immunité vis‐à‐vis de C. lagenarium n'affecte ni la population de tétraniques, Tetranychus urticae Koch, élevée sur des feuilles résistantes de concombre; ni le gain pondéral, ni la durée de développement, ni le poids nymphal de Spodoptera frugiperda, ou la fertilité des aphides de melon. De ces résultats, il peut‐être déduit que, au moins chez le concombre, l'induction de résistance due à C. lagenarium démeure spécifique aux champignons saprophytes, c'est à dire qu'il existe des mécanismes séparés pour la résistance, soit aux champignons, soit aux arthropodes phytophages.
Effect of temperature on glandular trichome exudate composition and pest resistance in geraniums
Authors: Walters D. S. , Harman J. , Craig R. , Mumma R. O.
Published: April 2011

One inbred geranium line (71‐18‐6) which exhibits host plant resistance to the twospotted spider mite and foxglove aphid, becomes susceptible to these pests under some temperature conditions, while another resistant line (71‐17‐7) maintains its resistance. Resistance to these pests is conferred by the presence of glandular trichomes and the exudate they produce. The tall glandular trichome exudate of resistant geraniums has been identified as chiefly C22 and C24 unsaturated anacardic acids. Plants of a resistant line, a susceptible line and the temperature sensitive resistant line were exposed to three different temperature regimes and were analyzed chemically and for resistance using a foxglove aphid bioassay. Results indicate that the loss of resistance in the temperature sensitive line is not due to reduced production of the anacardic acids which comprise the exudate. Similarly, analysis of the exudate present on the leaf exterior indicate the loss of resistance in line 18‐6 with increasing temperature is not the result of reduced translocation of the exudate to the trichome tip. Evidence is presented to support the hypothesis that loss of resistance in line 18‐6 with increasing temperature is the result of an increased proportion of the shorter chain (C22) anacardic acid in the trichome exudate, which reduces the viscosity of the material and causes it to flow from the trichome tips as the temperature increases. Presentation of the material as an exudate droplet at the trichome tip is apparently required for resistance.
Variation between strains of the flour beetle Tribolium castaneum in relative performance on five flours
Authors: Via S.
Published: April 2011

When populations are exposed to different environments, evolutionary processes can lead either to genetically differentiated strains or to the appearance of increased generalism at the individual level. For evolution to occur, genetic variability in performance in different environments is required. Here, intra‐specific genetic variation across environments was estimated in the flour beetle Tribolium castaneum (Herbst) by comparing the responses of two strains of T. castaneum to different flour types. Replicated groups from each strain were allowed to develop on either the standard whole wheat medium or on one of four novel flours (wheat, rice, corn and oat). In several of the novel flours, clear differences in mean development time or population size of one or both strains were seen relative to performance in the standard medium. Moreover, the strains differed significantly in their phenotypic responses to the flours. One strain did particularly poorly on oat flour. Reduced oviposition, reduced larval survivorship and increased larval cannibalism were examined as possible causes of the low productivity on oat flour. These three factors accounted for about 70% of the reduction in population size when this strain oviposited and developed in oat flour. The difference between these two outbred strains in response to these five flours suggests that genetic variation in resource use is present within T. castaneum and may also be present within strains and natural populations in grain storage facilities. Such variation would permit an evolutionary response to selection in multiple environments (flours). This process has agricultural implications when several types of grain are stored in a single location because it could eventually lead to the evolution of highly generalized populations of T. castaneum, an important pest of stored products.
Artificial injury experiments on the damaging effect of Leucoptera malifoliella on apple trees
Authors: Baufeld P. , Freier B.
Published: April 2011

In 1986 and 1987 defoliation experiments on the apple cultivar Herma were performed to simulate the occurrence of Leucoptera malifoliella Costa. Those model experiments were based on investigations on the mine size of Leucoptera malifoliella and yield loss on infested and tagged trees. Defoliation carried out by hand showed that heavy leaf loss reduced fruit number. Insufficient nutrient supply due to reduced leaf area and a consequently smaller leaf‐fruit ratio led to a decrease in mean fruit size and total yield. Heavy leaf loss had also an adverse effect on fruit quality components (dry matter substance, viscosity, total sugar and acid content of fruit juice). This was finally reflected in sensory evaluation criteria. Heavy leaf losses also influenced blossom bud differentiation in the blossom set of the following year. Both number of inflorescences and number of blossoms per inflorescence were reduced. The evaluation of the extent of damage of L. malifoliella was based on previous investigations on reduced leaf area. For L. malifoliella a mean mine size of 0.96 cm2 was found. This corresponds to a 4.2% loss of leaf area.

The leaf‐fruit ratio is of special importance for the evaluation of the extent of damage of leaf‐damaging pests and was used to derive injury threshold ranges for L. malifoliella. Previous investigations on L. malifoliella infestations and the results from the artificial defoliation experiments enabled the determination of preliminary flexible injury thresholds. Depending on leaf‐fruit ratio, yield level, and leaf miner generation, the thresholds vary between 0.1–2.5 eggs and mines per leaf.
Flight propensity and diapause incidence in five populations of the bark beetle Ips typographus in Scandinavia
Authors: Forsse E.
Published: April 2011

Emergence from brood logs, take‐off activity and the duration of tethered flight was recorded in the first laboratory generation of the bark beetle Ips typographus L. (Coleoptera: Scolytidae) from five locations (ca 300 km apart) in Sweden and Denmark. Beetles of northerly origin emerged later from brood logs. This pattern was associated with an increasing proportion on non‐fliers towards the north. After overwintering, both the rate of development of flight activity and the proportion of non‐fliers were the same among populations. Flight duration of fliers was similar among populations and appeared unaffected by outbreak conditions.
Effects of mating status and age on dispersal behavior in the twospotted spider mite, Tetranychus urticae in response to fenvalerate‐treated leaf surfaces
Authors: Suiter K. A. , Gould F.
Published: April 2011

Effects of variation in age and mating status on dispersal of the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), from fenvalerate‐treated leaf surfaces were investigated. Unmated and mated female mites, 1 to 6 days in age, were scored for walkoff and spindown dispersal response on bean leaves treated with a sub‐lethal, residual dose of fenvalerate. Variation in mite age did not have a pronounced effect on dispersal response. Significant differences in dispersal response due to mating type were observed, yet the mean differences in dispersal response between unmated and mated females was generally small. Our data suggest that the current practice of using mated female mites of unknown age when testing for among‐population differences in dispersal response, in most cases, provides an adequate estimate of population response when differences among treatments in dispersal response are large. However, when testing for within‐population differences in dispersal response, small treatment effects may be more easily measured using a single age class of mites, because this could decrease within‐treatment variance.
The combination of electronic monitoring and video‐assisted observations of plant penetration by aphids and behavioural effects of polygodial
Authors: Hardie J. , Holyoak M. , Taylor N. J. , Griffiths D. C.
Published: April 2011

Simultaneous electronic and close‐up video recordings were made of behaviour during the initial 15 min of plant contact by adult, apterous Aphis fabae Scopoli on tick bean seedlings (Vicia faba Moench). Electronic techniques accurately determined stylet penetration of plant tissue and there was a close correlation between penetration and periods during which the insect antennae and body were immobile (r = 0.994, n = 60). Video techniques were then used alone to infer stylet penetration and the behaviour of aphids after various treatments was monitored. In particular, the time to first penetration, the number of penetrations, the mean duration of penetrations and the total time of penetration were observed. Behavioural differences were recorded between tethered (as required for electronic recording) and freely‐moving insects as well as between fed and starved insects. The behaviour of starved aphids placed on beans treated with the plant‐derived antifeedant, polygodial could not be distinguished from aphids on solvent‐treated control beans. However, there were significant differences in behaviour of aphids which had previously been exposed to polygodial on plant or green/yellow paper surfaces for 24 h when compared with insects exposed to solvent alone. The possible modes of action of polygodial are discussed.
Intensification de la diapause embryonnaire d‘Archanara sparganii par la température: Incidences écologiques
Authors: Galichet P. F. , Girard R. , Cousin M.
Published: April 2011

L'incubation des oeufs d'Archanara sparganii, Esper (Lepidoptera: Noctuidae) s'étend sur 8 à 9 mois dans les conditions naturelles. Elle est temporairement interrompue par une diapause qui intervient à un stade précoce de l'embryogénèse et se prolonge de l'été à la fin de l'hiver. Au laboratoire, l'incubation est néanmoins possible à température constante entre 8 et 21 °C. Une étude expérimentale a montré que l'intensité de la diapause s'accroft lorsque la température en début d'incubation est portée pendant 15 jours de 11 °C à 15 °C et 21 °C. Aucun des modèles expérimentaux faisant intervenir la température n'a permis d'éviter totalement la diapause. La durée de celle‐ci a néanmoins été réduite des trois quarts dans certaines circonstances, rendant possible l'éclosion des larves avant l'hiver. Ces résultats servent à interpréter les altérations du cycle biologique du nord au sud de la distribution d'A. sparganii. La perte rapide de réceptivité de Typha spp. à l'égard des larves jeunes justifie par ailleurs une entrée en diapause précoce de l'espèce sous climat méditerranéen.

Archanara sparganii. Diapause intensification induced by temperature in the eggs of Archanara sparganii. Ecological implications

Egg incubation of A. sparganii Esper (Lepidoptera: Noctuidae) requires 8 to 9 months under natural conditions extending from the early summer to the early spring of the next year. The egg development is interrupted by an obligatory diapause at an early stage of embryogenesis. The whole of the egg's incubation can be concluded at a constant temperature within the range 8 °C–21 °C. The intensity of diapause has been found to be directly correlated with rising temperatures from 11 °C to 21 °C, applied for 15 days immediately after egg laying. None of the experimental temperature regimes tested prevented the occurrence of diapause, the incubation period could however be reduced to a quarter of its natural duration thus allowing larvae to hatch before winter. These results afford a better understanding of the life cycle modifications observed throughout the geographical range. A rapid loss in the receptivity of the main host plant towards young larvae makes of an early diapause a necessity under the mediterranean climate.
Spatial distribution and sequential sampling of adults of Gonocephalum macleayi and Pterohelaeus darlingensis in different cropping regimes
Authors: Allsopp P. G. , Forrester N. W.
Published: April 2011

Counts of adults of the false wireworms Gonocephalum macleayi (Blackburn) and Pterohelaeus darlingensis Carter in pitfall traps in burnt, mulched and sorghum treatments conformed to Taylor's power law. Within a species there were no significant differences in distributions of counts of either sex in any habitat but G. macleayi were more aggregated than P. darlingensis (Taylor's b 1.35 and 1.26, respectively). Relationships to determine sample sizes for fixed levels of precision and fixed‐precision‐level stop lines for sequential sampling are developed for each species using Taylor's parameters for combined data over all habitats.
Effect of shape, size and color on selection of oviposition sites by Chaetorellia australis
Authors: Pittara I. S. , Katsoyannos B. I.
Published: April 2011

The effect of shape, size and color on the selection of oviposition sites by females of Chaetorellia australis Hering (Diptera, Tephritidae) originating from infested yellow starthistle (YST) Centaurea solstitialis L. (Asteraceae, Cardueae) heads, was studied in the laboratory by direct observation of females sitting on or attempting to oviposit into different objects. Artificial substrates made of yellow‐colored parafin wax mimicking the natural oviposition sites (floral buds of YST), were used to study the effect of shape and size. The results revealed that spherical and conical objects of a total surface area of 310 mm2, were visited more frequently than cylindrical and cubical ones of the same surface area. Also more females were observed and more oviposition attempts were recorded on spheres of 5 and 10 mm diameter than of 15 and 20 mm diameter. Yellow and orange dry YST heads, colored by dipping in molten colored ceresin wax, were preferred for oviposition to black, green, blue, red and white ones. The observed preference for certain colors depended primarily on the color hue and not on the intensity of the total reflected light. The females responded positively to hues reflecting maximally between 560 and 610 nm, optimum at 590 nm, while hues reflecting below 540 nm and especially between 400 and 500 nm appeared to have no positive effect.
The dynamics of leaf surface wetness of sorghum seedlings in relation to resistance to the shoot fly, Atherigona soccata
Authors: Nwanze K. F. , Sree P. S. , Butler D. R. , Reddy D. D. R. , Reddy Y. V. R. , Soman P.
Published: April 2011

In quantitative measurements of leaf surface wetness (LSW) of the central whorl leaf of sorghum seedlings in August (rainy season) and November (post‐rainy season), the highest amount (6.29 mg of water) was recorded in August in the shoot fly Atherigona soccata (Diptera: Muscidae), susceptible sorghum genotype CSH 1, while the lowest (0.07 mg) was recorded in November in the resistant genotype IS 18551. Studies on diurnal fluctuation revealed that LSW was lowest at sunset, was highest between 02.00 and 04.00 h (closely corresponding with hatching of shoot fly eggs) and dropped before sunrise. This fluctuation was associated with the evaporation of water from the plant during the night. More LSW accumulation occurred during the main crop season (June‐October) than in the post‐rainy season (November‐April). Annual fluctuation of LSW followed trends similar to the population dynamics of shoot fly and crop infestation and were correlated with rainfall, temperature and relative humidity. Measurements of leaf temperature and the vapour pressure gradient between the leaf and the air indicated that leaf surface water originates from the plant. This was further supported by the different amounts of LSW on susceptible and resistant cultivars with similar microclimatic conditions.
Demographic analyses of organophosphate‐resistant and susceptible strains of greenhouse whitefly, Trialeurodes vaporariorum, on three cotton cultivars
Authors: Omer A. D. , Leigh T. F. , Carey J. R. , Granett J.
Published: April 2011

Laboratory experiments were conducted using organophosphate‐resistant and susceptible strains of greenhouse whitefly, Trialeurodes vaporariorum Westwood, to assess age‐specific vital rates in individually‐held adults, and development and survival in preadults on three cotton cultivars at 27 ± 1 °C, 50 ± 10% RH, and a photoperiod of 16:8 (L:D). Female whiteflies lived longer than males, with a maximum life expectancy of 29 days. Heaviest egg laying occurred at ages between 7 and 18 days when individual whiteflies laid > 10 eggs/day. Greenhouse whitefly populations doubled weekly, with stable age distribution of 63% eggs, 28% larvae, 5% pupae, and 4% adults. Analysis of various life history parameters that combine aspects of survival, developmental rates, and fecundity indicated no consistent differences in reproductive fitness between the two greenhouse whitefly strains. Of the three cotton cultivars tested, Pima S‐6 was most susceptible, Acala SJ‐2 was intermediate and Gumbo 500 was most resistant to greenhouse whitefly. Resistance of Gumbo 500 was expressed as slower developmental rates, reduced survival to adulthood, lower reproductive rates, and lower intrinsic rate of increase.
Effects of azadirachtin after systemic uptake into Brassica oleracea on larvae of Pieris brassicae
Authors: Arpaia S. , VAN Loon J. J. A.
Published: April 2011

Petioles of intact cabbage leaves were placed in azadirachtin solutions for 24 h. Azadirachtin or active metabolites of this compound appeared to be translocated systemically as performance of first instar larvae of Pieris brassicae L. placed on disks from those leaves was affected. The position within a leaf from which disks were excised did not affect the extent of these effects, indicating a homogeneous distribution of active compounds in the laminar tissue. At doses ranging from 1–10 ppm of azadirachtin in the solution taken up by the leaves, gain of larval fresh weight and leaf area consumed were reduced. These effects were dose dependent up to 60–90 ppm. At 10 ppm and higher doses no larva reached the second instar within 72 h. Mortality during the 72 h period was highest at 10 ppm, due to the coincidence of lethal action with ecdysis in combination with the effect on developmental rate. Azadirachtin solutions applied directly to the surface of leaf disks in order to produce known doses on a leaf fresh weight basis gave results similar to the systemic treatment for weight gain, leaf area consumed and developmental rate, while mortality was higher in the latter treatment.
Foraging of Rhagoletis pomonella flies in relation to interactive food and fruit resources
Authors: Averill A. L. , Prokopy R. J.
Published: April 2011

Up to this point, quantitative aspects of the resource foraging behavior of tephritid fruit flies have been examined at what has been termed the first level of a four‐level hierarchical framework. This framework has been constructed to facilitate an operational approach to investigating foraging behavior within a dynamic, state‐variable mode of analysis. First‐level examination involves tracking the behavior of tephritids in situations comprised of a single type of essential resource where just a single factor shaping foraging behavior is manipulated experimentally. Here, we investigated the foraging behavior of Rhagoletis pomonella (Walsh) flies at the second operational level in the hierarchy: a semi‐natural environment comprised of patches of potted host trees that simultaneously harbored two types of essential resources: food and oviposition sites. Mature, fed females that were marked and released into the center tree of five‐tree patches remained significantly longer and laid significantly more eggs over two days in patches containing both food (protein and carbohydrate) and oviposition sites (hawthorn fruit) than in patches containing oviposition sites alone. Our findings lead us to speculate that odor of abundant natural food could result in accumulation of both sexes in species of trees whose fruit emit no attractive odor and are not permanent hosts of R. pomonella, but which could receive eggs and support larval development of temporary populations of food‐seeking flies.
Mating disruption for control of damage by codling moth in Virginia apple orchards
Authors: Pfeiffer D. G. , Kaakeh W. , Killian J. C. , Lachance M. W. , Kirsch P.
Published: April 2011

Polyethylene dispensers (Shin Etsu) containing 172 ml of the sex pheromone, (E,E)‐8–10‐dodecadien‐1‐ol (63%), dodecenol (31%) and tetradecenol (6%), of codling moth (CM), Cydia pomonella (L.), were placed in apple orchards in Virginia. Two blocks of about 2 ha each were treated in 1989, and three in 1990. Dispensers were placed in trees at a density of 1000/ha shortly after apple bloom. Male orientation to pheromone traps was almost totally disrupted (a few males were captured at high population densities). In 1989, the Daleville pheromone‐treated block had 0.9% and 0.8% CM‐injured fruit in the center and edge, respectively; 0% and 39.5% injured fruit were found in the conventional control and abandoned blocks, respectively. The Criglersville orchard (‘organically’ managed, with high CM density) CM harvest injury was 16.0%, 16.5%, 34.5%, and 26.5% in the pheromone‐treated center and edge, organic control and abandoned blocks, respectively. In 1990, the Daleville CM harvest injury was 4.7%, 7.3%, 1.1%, 0.3% and 58%, in the pheromone‐treated center and edge, control center and edge, and abandoned blocks, respectively (possible reasons for the high injury in this block are discussed). Harvest injury in the Fincastle pheromone‐treated and control blocks were 0.7% and 0%, respectively. The Criglersville orchard yielded 17%, 19% and 20% CM‐injured fruit at harvest in the pheromone‐treated, organic control and abandoned blocks, respectively. Pheromone release rate was calculated as 37 mg/ha/h in 1989.
The responses of the cabbage seed weevil (Ceutorhynchus assimilis) to the odour of oilseed rape (Brassica napus) and to some volatile isothiocyanates
Authors: Bartlet E. , Blight M. M. , Hick A. J. , Williams I. H.
Published: April 2011

The responses of the cabbage seed weevil, Ceutorhynchus assimilis Payk. (Coleoptera: Curculionidae) to volatiles from oilseed rape (Brassica napus L.) were tested using a linear track olfactometer. Weevils were attracted towards the odour of rape during a short period before diapause and for most of their post‐diapause life. Odours from both the flowering and green parts of the plant were attractive, but the odour of a non‐host plant (Bellis perennis L.) was not. An entrainment extract of flowering rape volatiles in pentane was attractive, but significantly less so than the odour of flowering rape itself. Attraction was found to 3‐butenyl and 4‐pentenyl isothiocyanate (NCS), but not to 2‐phenylethyl isothiocyanate. A mixture of the three NCSs was more attractive than the individual NCSs. However, the concentration required to produce a response was still relatively high. Isothiocyanates, along with other volatiles from rape, probably play a role in host plant recognition by the seed weevil.
Sex pheromones in the cereal aphid parasitoids Praon volucre and Aphidius rhopalosiphi
Authors: Decker U. M. , Powell W. , Clark S. J.
Published: April 2011

Laboratory and field experiments provided evidence for the release of sex pheromones by virgin female Praon volucre Haliday and Aphidius rhopalosiphi De Stefani‐Perez (Hymenoptera: Braconidae, Aphidiinae). In Petri dish biosassays, rubber or vermiculite models treated with crude virgin female extracts were frequently approached by males and elicited rapid wing‐fanning behaviour and copulation attempts. Delta‐shaped water traps containing live virgin females caught large numbers of conspecific males when placed in winter wheat crops. Trapping slightly below crop height resulted in higher catches than trapping above the crop canopy.
Variation in flight response of the specialist parasitoid Macrocentrus grandii Goidanich to odours from food plants of its European corn borer host
Authors: Udayagiri Sujaya , Jones Richard L.
Published: April 2011

The specialist parasitoid Macrocentrus grandii Goidanich (Hymenoptera: Braconidae) appears to parasitize its polyphagous host, European corn borer (Ostrinia nubilalis (Hübner)) (Lepidoptera: Pyralidae), in only certain habitats. To determine whether it differed in its olfactory response to host‐habitat odours, volatiles from four plants were isolated using Tenax. Wind tunnel bioassays of the extracts revealed that, besides corn which was tested in an earlier study, olfactory stimuli for attraction of M. grandii females were present in potato and snap bean but not in pepper or soybean. To further characterize the response to pepper and soybean, these extracts were bioassayed in combination with an attractive extract. The results indicated that pepper volatiles evoked a neutral response in M. grandii while response to soybean volatiles appeared to be neutral or slightly negative. The innate response to soybean volatiles was altered to one of attraction after oviposition experience on soybean. Seven days after oviposition, experienced females continued to respond positively to soybean volatiles. Components of soybean volatiles responsible for the change in flight behaviour resulting from oviposition experience were eluted by nonpolar and slightly polar solvents. These results support the idea that plant odour may be a factor determining the range of plants on which M. grandii parasitizes its host. The study indicates the occurrence of associative learning of plant‐related volatiles during oviposition in M. grandii, and suggests the involvement of diverse plant compounds in the learning process.
Reduction of black vine weevil larval growth by vesicular‐arbuscular mycorrhizal infection
Authors: Gange A. C. , Brown V. K. , Sinclair G. S.
Published: April 2011

Larvae of Otiorhynchus sulcatus (black vine weevil) were reared at three densities (zero, two or eight), on plants of Taraxacum officinale (dandelion) with and without infection by the mycorrhizal fungus Glomus mosseae. On plants without the fungus, survival of larvae to late final instar was 84%, but this was only 43% on infected plants. The differential survival of larvae was evident in their effects on plant biomass. Significant interactions were found between larval density and infection, indicating that mycorrhizal presence mitigated the effects of herbivory at the low larval density. Infection by G. mosseae thus conferred some degree of resistance in roots to this insect and the consequences of this for horticultural and natural situations are discussed.
Variation in performance on two grape cultivars within and among populations of grape Phylloxera from wild and cultivated habitats
Authors: Hawthorne D. J. , Via S.
Published: April 2011

When an indigenous insect becomes a pest, comparisons of performance of pest and non‐pest populations on crop plants and of genetic variation in that performance may provide insight into the evolution of pest populations. To measure such genetic variation, 8–15 clones of the grape phylloxera (Daktulosphaira vitifoliaeFitch) were collected from wild grapevines in each of 3 geographically isolated sites (populations) and from commercial vineyards in northern California. A complete life table was made for clonal replicates from populations collected from wild grapevines on each of two commercial grape cultivars, the susceptibleVitis vinifera(L.) cultivar Cabernet Sauvignon, and the phylloxera‐resistant rootstock ‘AxR# 1’. Variation in mean performance on these two hosts was partitioned among clones within collection sites and among sites. Performance measures included an individual analog to the intrinsic rate of increase (r), age at first oviposition, fecundity in the first ten days of reproduction, total fecundity, and longevity. The overall performance of phylloxera from the wild grapevines on the resistant cultivar AxR# 1 was greater than or equal to that on the susceptible cultivar Cabernet Sauvignon. There was significant variation among clones within populations from wild grapes in the rate of increase on ‘AxR# 1’ and marginally significant clonal variation in some of the component parameters. There was no significant variation among clones within populations on ‘Cabernet Sauvignon’ and no significant differences between populations on either crop in any trait.

In a second experiment we compared the relative performance of 15–17 clones from wild grapevines and from commercial vineyards when reared on ‘Cabernet Sauvignon’ and ‘AxR# 1’. Phylloxera from commercial vineyards had much higher overall performance on ‘Cabernet Sauvignon’ than did phylloxera from the wild grapevines. Phylloxera from the commercial vineyard also had higher performance on ‘Cabernet Sauvignon’ than on ‘AxR’ l' but the performance of the phylloxera from wild and commercial grapes did not differ on ‘AxR# 1’.

Our results show that there is genetic variation in traits related to performance on a resistant root‐stock within these indigenous non‐pest populations of phylloxera, but not among them. The pattern of performance of pest and non‐pest populations on two commercial cultivars suggests that current levels of phylloxera performance on crop cultivars are the result of adaptation to those cultivars which has occurred while phylloxera has been associated with viticulture. Implications of these results for understanding the recent adaptation of phylloxera to ‘AxR# 1’ in California are also discussed.
Reproduction and resource utilization of the ambrosia beetle, Xylosandrus mutilatus, in field and experimental populations
Authors: Kajimura H. , Hijii N.
Published: April 2011

The reproduction process of the ambrosia beetle, Xylosandrus mutilatus (BLANDFORD) (Coleoptera: Scolytidae), was examined by successive censuses of field populations and by artificial rearing experiments. The reproductive strategy is discussed in relation to utilization of fungal resources, the amount of which was evaluated by total gallery length (main gallery and side galleries) for the field populations or fungal area in the laboratory. Fecundity of mother adults increased with the expansion of gallery systems for cultivating their associated fungi. The number of offspring also depended on the amount of fungal resource, whereas the variation of female body size within a brood was not affected by the fungal amount. The body size apparently declined with delay in larval feeding period expressed as the order of pupation and eclosion in the field and with decreasing fungal area per larva in the laboratory. These results suggested that the combination of resource‐dependent oviposition by a mother beetle and dominant resource utilization by earlier‐hatched individuals in a brood can contribute to the efficient production of larger females when resources are limited.
Population and individual polyphagy in the grasshopper Taeniopoda eques during natural foraging
Authors: Howard Jerome J. , Raubenheimer David , Bernays Elizabeth A.
Published: April 2011

Dietary patterns of free‐foraging individuals of the polyphagous grasshopper Taeniopoda eques Burmeister (Romaleidae) were studied at three desert grassland sites in southern Arizona. At the population level this species was highly polyphagous at all sites, but showed evidence of selectivity in terms of frequency of feeding relative to frequency of contacts with resources. Most feeding bouts were very short, suggesting that most plants were relatively unpalatable. Both diet diversity and the mean length of feeding bouts varied among the study sites, primarily because highly preferred resources and plant tissues were not encountered with equal frequency at all sites. Individual insects were highly polyphagous. Dietary overlap calculations showed that insects at a given site generally consumed diets less similar than the resources they contacted. This result does not support the idea that all insects preferred the same subset of resources. Most differences in diet among individuals were probably due to environmental heterogeneity, but factors such as sequence of encounter, compensatory feeding on complementary resources, and intrinsic differences in preference may also have contributed to variation in diets.
Effect of different narcosis procedures on initiating oviposition of prediapausing Bombus terrestris queens
Authors: Tasei J.N.
Published: April 2011

Four experiments aimed at the stimulation of starting oviposition were carried out with bumblebee queens (Bombus terrestris L.) from colonies belonging to the ecotype of Central Western France and reared in a glasshouse. After mating, queens were narcotized with carbon dioxide, confined singly in small boxes (11 times 5 × 4.5 cm) and kept in a dark room at 28–29 °C and 60%‐65% r.h. They were fed on a sugar solution and a pollen‐syrup mixture. No effects were discernible if the narcosis was applied 20 to 30 days after mating instead of 5 days, nor if the queens were submitted to a 4 to 5 day period at 34 °C following narcosis. Survival rates ranged from 65% to 68%. If the queens were reared under fluorescent tubes (L8:D16) after narcosis the mean delays to egg‐laying were significantly reduced compared to a dark treatment (21 days instead of 39), as was their variability (s.e. = 1.6 day instead of 3.1 days). The survival rates were respectively 73% and 67%. Under the same photoperiod (L8:D16) the CO2 narcosis repeated at a 24h interval had the same efficacy whether its duration was 10 min or 5 min. The delays to egg‐laying were respectively 20 days (s.e = 1.5) and 25 days (s.e. = 4.8) with survival rates close to 73%. Egg‐laying could also be induced in non‐narcotized queens with a survival rate of 54% and delays to oviposition close to those of queens narcotized 2 times 10 min.
Increase in activity density and species number of carabid beetles in cereals as a result of strip‐management
Authors: Lys Jon‐Andri , Zimmermann Manfred , Nentwig Wolfgang
Published: April 2011

In 1990 and 1991, we monitored the abundance of a carabid community in a 8 ha winter cereal field. The field was subdivided by five 1.5 m wide weed‐strips leaving 12, 24 and 36 m between the strips. In 1990 significantly higher activity densities and number of species were found in the strips. In 1991, however, both number of species and activity densities of ground beetles in the weed‐strips and the cereal parts in between were similar. In 1991, activity density in cereal parts between weed‐strips was significantly higher than in a bordering control area. Most of the activity densities of all 23 abundant species were significantly higher in the strip‐managed area than in the control area. Furthermore, the number of species in the strip‐managed area was higher. In addition, most sampling dates (1990 and 1991) revealed a significant negative regression between activity density and distance from the first strip, i.e. width of the cereal parts between the strips. Strip‐management seems to be a way to increase ground beetle densities considerably by providing better food supplies and more suitable overwintering sites.
‘Osmotic pump‘ feeding by coreids
Authors: Miles P. W. , Taylor G. S.
Published: April 2011

Species of Coreidae (Heteroptera) cause ‘water soaked’ lesions in their food plants. Such insects typically feed from parenchyma in and surrounding vascular tissues and also cause acropetal wilting and necrosis of small diameter shoots. Feeding by Mictis profana (Fabr.) in South Australia on the shoots of Acacia iteaphylla F. Muell. ex Benth. was found to cause a local, concurrent increase in both water content and free amino acid concentration, consistent with phloem unloading. Coreids, unlike other groups of phytophagous Heteroptera, secrete a salivary sucrase (α‐D‐glucohydrolase, EC 3.2.1.48) as probably the sole salivary carbohydrase, and tissues attacked by M. profana showed more sucrose hydrolysing activity than unattacked. The salivary enzyme is postulated to cause unloading of solutes into the apoplast due to the osmotic effects of conversion of endogenous sucrose to glucose and fructose, allowing the insect to suck the leaked contents of many cells from a single locus. The term ‘osmotic pump feeding’ is proposed for such a process. In demonstrations of its feasibility, infiltration of shoots with mixtures of glucose and fructose stoichiometrically equivalent to isosmotic sucrose increased the amounts of tissue sap and amino acid that could be sucked from the tissues; similarly, invertase and 1 M sugars forced into the extracellular space of stem sections increased the amino acids offloaded into the bathing solutions.
Comparison of the effect of hydroxamic acids from wheat on five species of cereal aphids
Authors: Givovich Arturo , Niemeyer Hermann M.
Published: April 2011

Feeding behaviour of five species of cereal aphids in wheat seedlings differing in hydroxamic acid (Hx) levels, was monitored via electrical penetration graphs (EPG). Aphid species could be grouped as sensitive to the feeding deterrent effect of Hx in the seedlings (Rhopalosiphum padi, Schizaphis graminum, Sitobion avenae, and Metopolophium dirhodum) or insensitive to them (Rhopalosiphum maidis). However, when feeding behaviour was studied in artificial diets containing Hx, all species were equally sensitive to Hx. The behaviour of R. maidis was further compared with that of R. padi through detailed EPG analysis. It was found that the insensitivity of R. maidis to Hx in seedlings may be due to a feeding strategy avoiding contact with the compounds by decreasing the number of cellular punctures in live tissues other than sieve elements during its way to the phloem.
Behavioral differences between hawthorn‐origin and apple‐origin Rhagoletis pomonella flies in patches of host trees
Authors: Luna Ivan G. , Prokopy Ronald J.
Published: April 2011

We compared patterns of patch residence and oviposition of Rhagoletis pomonella (Diptera: Tephritidae) females that originated as larvae from hawthorn or apple trees and were released into patches of host trees containing hawthorn or apple fruit in an open field. There were no detectable differences between hawthorn‐origin females in patches of hawthorns and apple‐origin females in patches of apples in numbers of females observed on food, fruit or foliage or in numbers of eggs laid in fruit during the course of the 7‐h experimental period. Apple‐origin females in patches of hawthorns behaved similarly to hawthorn‐origin females in patches of hawthorns. In contrast, hawthorn‐origin females in patches of apples differed significantly from apple‐origin females in patches of apples. The former were observed on fruit only 40% as often and laid only 20% as many eggs before departing a patch. Our findings support the hypothesis of G. L. Bush that R. pomonella flies of hawthorn and apple origin represent distinct host races.
Hypersensitive response of wheat to the Hessian fly
Authors: Grover Paul B.
Published: April 2011

Hessian fly Mayetiola destructor (Say) larvae are able to obtain food from their host plant without inflicting mechanical damage to the plant surface, apparently by secreting substances which elicit release of nutrients from plant cells surrounding the feeding site. Cells of fully susceptible plants retain their normal appearances, while in resistant plants extensive areas of cellular collapse occur. These responses indicate that hypersensitivity is the basis of wheat's resistance to the Hessian fly. The fly's feeding mechanism more closely resembles that of a pathogen than of a phytophagous insect; correspondingly, both the genetic relationship and resistance mechanism of the host plant to the parasite are of the sorts commonly associated with bacterial and fungal pathogens.
Reproduction and survival of the predatory bug Orius albidipennis on various arthropod prey
Authors: Chyzik R. , Klein M. , Ben‐Dov Y.
Published: April 2011

The daily rate of oviposition, fecundity, survival and adult longevity of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) were studied in the laboratory in Israel. These parameters were compared on three arthropod prey species: the two‐spotted spider mite, Tetranychus urticae Koch; the onion thrips, Thrips tabaci Lindeman; and eggs of the almond moth, Ephestia cautella Walker. The fecundity and survival on the thrips diet (217.2 eggs/female and 98.7%, respectively) and on moth eggs (184.1 eggs/female and 84.6%, respectively) were significantly higher than on the spider mite diet (110.9 eggs/female and 40.4%, respectively). Female longevity was significantly higher on Ephestia eggs (63.0 days) than on thrips (45.1 days) and mites (35.1 days). There were no significant differences in male longevity among the three diets (57.5, 64.1 and 54.5 days, respectively).
Breeding behaviour, relatedness and sex‐investment ratios inLeptothorax tuberumFabricius
Authors: Pearson B. , Raybould A. F. , Clarke R. T.
Published: April 2011

The ant speciesLeptothorax tuberumwas shown to be predominantly monogynous. Queens usually mate once only but some nests may have a multiply‐mated queen or are partially or serially polygynous. As expected from these results, within nest relatedness between workers and between workers and alate queens was found to be high. Almost fifty percent of nests had no nest queen which may indicate high queen mortality, queens leaving to found new nests or nest fragmentation. Observed female investment frequencies (IFo) were not significantly different from those expected on the basis of worker control of sexual production and the relatedness estimates of workers to alate queens and workers to males calculated from isozyme data (IFE). These values were not consistent with queen control. There was no evidence for lower IFos in queenless nests nor for higher IFos in larger nests classified by worker number. When nests were classified by sexual productivity, however, there was a strong rank correlation between productivity and female bias. This is the first study of an ant species to test observed IF against expected IF calculated without inferring between caste relatedness from worker data or pooling of data from different castes.