bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of Eretmocerus eremicus to skylight and plant cues in a vertical flight chamber
Authors: Blackmer J.L. , Cross D. 
Published: October 2003

AbstractIn the southwestern United States, Eretmocerus eremicus (Hymenoptera: Aphelinidae) is a native parasitoid of the Bemisia complex (Homoptera: Aleyrodidae). However, little information currently exists on its potential as a biological control agent of whiteflies or on the factors that influence its tendencies to disperse. In this study, we examined the flight behavior of male and female E. eremicus in response to skylight (here simulated by a mercury‐vapor lamp) and plant cues (a 550‐nm filtered light) in a vertical flight chamber. Approximately 90% of the parasitoids took off in response to the skylight cue. Both sexes were capable of sustained flights in excess of 60 min; however, males had higher rates of climb than females (3.31±0.17 and 2.63±0.19 cm s−1, respectively). When a plant cue was presented during the parasitoid's phototactic flight, four relatively distinct responses were observed. Fifty‐one percent of the individuals responded to the plant cue throughout their flight by flying toward or by landing on the cue. The majority of these parasitoids were females. Approximately 12% of the wasps exhibited an intermittent, positive response to the plant cue. Twenty percent exhibited a ‘migratory’ response. These parasitoids, which were predominantly males, failed to respond to the plant cue until they had flown for a considerable period. Finally, 17% failed to respond to the target during their flight. Approximately 37% of the individuals that showed a positive response to the plant cue actually landed on it and the majority of these were female. The differential response to the plant cue by male and female parasitoids could be, in part, because females are driven to locate hosts in which to oviposit, and males are driven to find mates.
Survival in Dalbulus leafhopper vectors improves after exposure to maize stunting pathogens
Authors: Ebbert Mercedes A. , Nault Lowell R. 
Published: October 2003

AbstractUsing D. maidis and pathogen isolates collected at three field sites along an altitudinal gradient in Mexico, we compared survival in leafhoppers exposed to healthy maize to those exposed to maize infected with one of four isolates of maize stunting pathogens: two isolates of the corn stunt spiroplasma (CSS, Spiroplasma kunkelii) and two of the maize busby stunt phytoplasma (MBSP). Survival improved after exposure to either plant pathogen under both the cooler and warmer environmental conditions D. maidis is likely to encounter during the dry season. Survival varied among leafhoppers from the different field sites, suggesting that gene flow between these populations is limited. The leafhoppers responded differently to the four isolates (i.e., we noted significant population by exposure interactions), but we found no difference between MBSP and CSS exposure. Finally, we found evidence of local adaptation in one leafhopper population to sympatric, as compared to allopatric, plant pathogens. We have shown with this and our earlier study that aspects of the interaction phenotype in the association between D. maidis and the plant pathogens are mutualistic and that this association has considerable potential as a model for studies of local adaptation.
Host plant selection by Helicoverpa spp. in chickpea‐companion cropping systems
Authors: Sequeira R.V. , McDonald J.L. , Moore A.D. , Wright G.A. , Wright L.C. 
Published: October 2003

AbstractThe potential of companion crops to serve as diversionary hosts for ovipositing Helicoverpa spp. moths in chickpea cropping systems was evaluated in a field experiment. Patterns of egg distribution by Helicoverpa spp. within paired combinations of chickpea and each of six companion crop species were documented in a split‐plot design sampled four times during the 1999 winter growing season. Chickpea was attractive to ovipositing Helicoverpa moths from as early as 14 days after planting and throughout the experimental period. The companion crop species varied in relative attractiveness to ovipositing moths but none was able to effectively divert Helicoverpa egg pressure away from chickpea for the duration of the experiment. Of all Helicoverpa spp. larvae recorded from all samples and crop combinations, 98.3% were found on chickpea. A marked aggregative oviposition behaviour of Helicoverpa spp. on tall weeds growing through the chickpea canopy was recorded. The relevance of observed patterns of host selection and inferred moth behaviour to management of Helicoverpa populations on chickpea are discussed.
Dispersal of Acalitus essigi to blackberry (Rubus fruticosus agg.) fruit
Authors: Davies Jamie T. , Allen Geoff R. , Williams Margaret A. 
Published: October 2003

AbstractThe eriophyoid mite, Acalitus essigi (Hassan), is hypothesised to be responsible for redberry disease of blackberry (Rubus fruticosus L. agg.) fruit. Infested fruit ripen unevenly with affected drupelets becoming hard, inedible and bright red, whereas unaffected drupelets ripen evenly. As a first step toward possible control of this disease, the method and timing of dispersal of A. essigi onto developing blackberry fruit was examined. No mites were found on unopened flower buds or open flowers. However, infestation of fruit was found to commence during the green stage of fruit development and significantly increase during the red fruit stage. Although redberry symptoms were not observed, experimental exclusion of A. essigi to prevent the mite moving up the pedicel of open flowers by a sticky barrier significantly reduced A. essigi populations within the resultant fruit by over five fold that of control fruit. Although very low levels of aerial dispersal onto fruit cannot be discounted it was concluded that non‐aerial or crawling dispersal via the fruit pedicel was the dominant method of blackberry fruit infestation.
Response of Oligota kashmirica benefica, a specialist insect predator of spider mites, to volatiles from prey‐infested leaves under both laboratory and field conditions
Authors: Shimoda Takeshi , Takabayashi Junji 
Published: October 2003

AbstractWe investigated the response of the specialist insect predator Oligota kashmirica benefica (Coleoptera: Staphylinidae) to volatiles from lima bean leaves infested with the spider mite Tetranychus urticae (Acari: Tetranychidae), both in a Y‐tube olfactometer and in a field in Kyoto, Japan. Adult male and female predators were significantly more attracted to T. urticae‐infested leaves than to clean air. Adult male and female predators were not more attracted to uninfested leaves, artificially damaged leaves, or the spider mites and their visible products when compared to clean air. In a field trap experiment, 12 adult predators were caught in three traps containing T. urticae‐infested lima bean plants over 13 days, whereas no adult predators were trapped in three traps containing uninfested lima bean plants during the same period. These results showed that O. kashmirica benefica adults responded to herbivore‐induced plant volatiles from T. urticae‐infested lima bean leaves under both laboratory and field conditions.
Host‐recognition kairomone from Sogatella furcifera for the parasitoid Anagrus nilaparvatae
Authors: Lou Yong‐gen , Cheng Jia‐an 
Published: October 2003

AbstractA kairomone produced by the rice white‐backed planthopper Sogatella furcifera (Horvath) for the mymarid egg parasitoid Anagrus nilaparvatae Pang et Wang was investigated. Eggs, female and male adults, nymphs, exuvia, honeydew, nymph‐damaged plants and plants with S. furcifera eggs all elicited searching behavior in the parasitoid. Eggs, female adults and plants with eggs were the most attractive, while exuvia and honeydew evoked the weakest responses. The active compound(s) from S. furcifera female adults, nymphs and plants with eggs could be effectively extracted with methanol, acetone, n‐hexane, ethyl ether and dichloromethane. Isolation of the active chemical(s) in three solvent extracts, the acetone and n‐hexane extracts of S. furcifera female adults, and the acetone extract of S. furcifera nymphs, was accomplished by thin‐layer chromatography. Only one fraction was active and had the same chemical properties in the three solvent extracts. Infra‐red analysis of this fraction revealed a kind of ester with saturated and unsaturated fatty acids, which was previously found to be active in the same compound as the extracts from the nymphs and female adults of the rice brown planthopper, Nilaparvata lugens (Stål), and identified as palm oil. The results are discussed in relation to host location by A. nilaparvatae.
The effects of laboratory culturing on (Z)‐9‐tricosene (muscalure) quantities on female houseflies
Authors: Noorman Nico , Den Otter Cornelis J. 
Published: October 2003

AbstractUsing gas chromatography the relative amounts of (Z)‐9‐tricosene (muscalure) and some other hydrocarbons on the cuticle of 1‐ to 20‐day‐old houseflies (Musca domestica L.) from different strains were determined. Flies from a WHO strain, in culture since 1961, and first‐generation laboratory‐cultured flies from two wild‐type strains from a poultry breeding and a cow‐house with pigsty, respectively, were compared. On WHO females hydrocarbons with 23–25 C atoms constituted about 65% of the total hydrocarbons, whereas on wild‐type females less than 2% of these compounds was present. (Z)‐9‐tricosene comprised up to 20–30% of the total hydrocarbons on 5‐ to 20‐day‐old WHO females, whereas less than 0.5% (Z)‐9‐tricosene was present on the wild‐type females. We also compared the amounts of (Z)‐9‐tricosene and some other hydrocarbons on female houseflies, kept in culture in the laboratory for several generations. It appeared that whereas on first‐generation wild‐type females hardly or no (Z)‐9‐tricosene could be detected, the amounts of this substance had increased considerably after some tens of generations in the laboratory. It is suggested that this was due to selection in subsequent generations of high‐density populations. Production of (Z)‐9‐tricosene and of tricosane was shown to be closely linked. Selection did not affect the production of other cuticular hydrocarbons by the females. It is suggested that in mixed populations (both sexes together in a cage) in the course of time (Z)‐9‐tricosene is transferred from females to males and (Z)‐9‐heptacosene from males to females. It is concluded that reproductive ability of houseflies does not primarily depend on the amounts of (Z)‐9‐tricosene on females, although higher amounts of this substance may increase contacts between males and females.
Macrolophus caliginosus: Functional response to whiteflies and preference and switching capacity between whiteflies and spider mites
Authors: Enkegaard Annie , Brødsgaard Henrik F. , Hansen Dorthe L. 
Published: October 2003

AbstractLaboratory experiments were performed with adult female Macrolophus caliginosus Wagner (Heteroptera: Miridae) at 22°C on bean plants to determine the functional response towards whiteflies, as well as the preference and switching capacity between the two prey species: whiteflies and spider mites. Predation of females presented with first instars of Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) was of a Type III functional response. The observed maximum predation was approximately 75 first instars at high prey densities within a 24‐h period. The preference of M. caliginosus females between eggs of T. vaporariorum and Tetranychus urticae Koch (Acarina: Tetranychidae) changed with the ratio of offered prey. The preference for T. vaporariorum eggs increased non‐linearly with increasing proportions of this prey type. The average maximum predation of whitefly and spider mite eggs were approximately 166 and 111 eggs per day, respectively, at the highest ratio of the two preys. The proportion of M. caliginosus females found on the test plants at the end of the experiment increased with prey density suggesting that this mirid spends more time in areas with high prey density. Macrolophus caliginosus females are voracious predators of eggs and first instars of T. vaporariorum as well as of spider mite eggs and may thus be a valuable addition to existing methods of biological control of T. vaporariorum and T. urticae.
Identification of further sex pheromone synergists in the codling moth, Cydia pomonella
Authors: Witzgall Peter , Bengtsson Marie , Rauscher Stefan , Liblikas Ilme , Bäckman Anna‐Carin , Coracini Miryan , Anderson Peter , Löfqvist Jan 
Published: October 2003

AbstractPheromone gland extracts of codling moth females were examined by gas chromatography coupled with mass spectrometry and electroantennography. Nine compounds elicited antennal activity: the main pheromone compound codlemone (E,E)‐8,10‐dodecadienol, the E,Z and Z,E isomers of codlemone, codlemone acetate (E,E)‐8,10‐dodecadienyl acetate, codlemone aldehyde (E,E)‐8,10‐dodecadienal, the monounsaturated alcohols (E)‐8‐dodecenol and (E)‐9‐dodecenol, and dodecanol. In wind tunnel experiments, addition of dodecanol, the E,Z isomer of codlemone and codlemone acetate augmented male attraction to codlemone at the proportions found in female glands. Larger amounts of the E,Z isomer of codlemone and codlemone acetate had a strong antagonistic effect on male attraction. The identification of pheromone synergists in codling moth is of importance for the development of pheromone‐ based control methods.
Effect of juvenile hormone on caste determination and colony processes in the bumblebee Bombus terrestris
Authors: Bortolotti L. , Duchateau M.J. , Sbrenna G. 
Published: October 2003

AbstractTo investigate the role of juvenile hormone (JH) in caste determination, first and second instar larvae of Bombus terrestris were topically treated with one of three doses (2, 10, or 20 μg/larva) of JH dissolved in acetone. Treated larvae belonged to very young colonies that had just been started by their queen. Therefore, all larvae were supposedly destined to develop into workers. Our study demonstrates that a single application of JH in the first or second instar can lead to the development of queens and that this effect is dose‐ and instar‐dependent. The brood (second, or third brood of the colony) to which the larvae belonged also had an effect. A clear size dimorphism of the female castes exists in B. terrestris. In this study, however, intermediates also developed from treated larvae. In fact, even untreated larvae in a treated colony developed into queens and intermediates, depending on the total dose of JH applied to the colony. There are no indications that a larva, once determined to become a queen, can be forced to become a worker by means of malnutrition. Treatment with JH also had an influence on colony processes. For instance, the appearance of queen larvae resulted in the advanced start of reproduction by workers and egg robbery, the so called competition point. This indicates again the close relationship between queen rearing and the queen‐worker conflict. However, the ultimate function of this casual connection is still unclear. Further, the queen reacted to the treatment by switching to the laying of haploid eggs at an earlier date in the colony development compared to untreated colonies.
Exploring the foraging environment of a natural enemy of Callosobruchus maculatus: Spatial egg distribution in stored cowpea
Authors: Stolk C. , Stein A. , Slumpa S.B. , Tiase S.K. , van Huis A. 
Published: October 2003

AbstractKnowledge of the spatial distribution of stored product insects may reduce the dependency on chemicals for control of these insects. Biological control, for instance, could be improved based on such knowledge. In this paper we describe the three‐dimensional spatial oviposition pattern of Callosobruchus maculatus in stored cowpea. Individual C. maculatus females oviposited in clusters of 70 ± 15 (SD) eggs. These clusters were variable in shape. In any cluster 90 to 95% of the eggs fitted into a volume of 19.1 ± 3.5 cm3. The egg density was highest (0.6 eggs bean−1) at the center of a cluster and decreased towards the periphery. A statistically significant relationship existed between the number of eggs n in a cluster and the cluster volume, V(cm3): V= 11.5 + 0.11n. We also investigated the spatial egg distribution of beetles which emerged from egg clusters such as those produced by individual females. Their oviposition was not confined to one specific area but was scattered throughout the bean mass. A point pattern analysis showed that the density of the ‘parent’ cluster had no effect on the spatial egg pattern. These results give insight into the foraging environment which the egg parasitoid Uscana lariophaga, a promising candidate for biological control of C. maculatus, is facing. We argue that the probability p of encountering at least one other bean with eggs after a parasitization is a function of the number n of beans that are visited: p= 1 − 0.42 (0.37)(n−1).
Variation in damage to cotton affecting larval feeding preference of Spodoptera littoralis
Authors: Anderson P. , Jönsson M. , Mörte U. 
Published: October 2003

AbstractFeeding experiments with larvae of Spodoptera littoralis were performed with leaves from cotton plants subjected to damage and from undamaged plants. In the experiments, four different time intervals (1, 3, 7, and 14 days) after damage induction and two different levels (high and low) of herbivore damage were tested. Seven days after damage induction larvae fed less on the young top leaves from damaged plants for both levels of damage. At the high damage level, the larvae fed less on leaves from the damaged plants after just three days, and this effect still remained 14 days after damage infliction. When mature leaves from the middle of the plant were compared, no difference between treatments was observed.Two plant sizes were tested, small plants with 4–5 true leaves and large plants with 8–10 true leaves. In small plants the induced changes affecting larval feeding were found mainly in the youngest leaf at the top of the plant, while in large plants the induced effects were found in both the youngest and the second youngest leaves.In plants subjected to artificial damage, larvae fed less on top leaves of the damaged plants when compared to leaves from undamaged plants. When leaves from plants that had been artificially damaged were directly compared with leaves from plants damaged by herbivores, larvae fed more on the youngest leaves from artificially damaged plants when the plants were large. In small plants no significant difference was found when comparing artificial and herbivore damage.
The effect of the ectoparasitic mite, Varroa destructor on adult worker honeybee (Apis mellifera) emergence weights, water, protein, carbohydrate, and lipid levels
Authors: Bowen‐Walker Peter L. , Gunn Alan 
Published: October 2003

AbstractWet weight, dry weight and water contents of emerging honeybees (Apis mellifera L. [Hymenoptera: Apidae]) infested with the ectoparasitic mite Varroa destructor (Anderson) (Acari: Varroidae) were all negatively correlated with increasing numbers of mites. It was estimated that for every female mite present during the bees' development, the host would lose three percent of its body water. Parasitised bees also emerged with lower head and abdomen concentrations of protein and with lower abdominal carbohydrate concentrations. Lipid concentrations were not detectably affected by V. destructor infestation. The losses of metabolic reserves were not, however, judged to be serious enough to be directly responsible for the high bee mortality and ultimate colony collapse that are associated with the arrival of Varroa in a hive. Some 8.5% of the emerging bees exhibited morphological deformities and deformity was positively correlated with increasing numbers of mites in brood cells. Deformed bees were, however, found in all categories of parasitosis, suggesting that other factors, such as infectious agents, may be involved. Mites that fed on either live or dead U14C‐ labelled bees acquired the label within 24 h and it was calculated that an adult female mite consumes 0.67 μl haemolymph 24 h−1. It was also demonstrated that 14C was transmitted to a previously non‐radio‐labelled bee when a mite that had been feeding on a labelled bee changed hosts. The level of transfer was above that which could have arisen through contamination of the mites' mouthparts and supports the suggestion that Varroa is an important vector of pathogens such as viruses.
Isolation and characterization of a galactorhamnan polysaccharide from the seed coat of Canavalia ensiformis that is toxic to the cowpea weevil (Callosobruchus maculatus)
Authors: Oliveira A.E.A. , Sassaki G.L. , Iacomini M. , da Cunha M. , Gomes V.M. , Fernandes B.K.V.S. , Xavier‐Filho J. 
Published: October 2003

AbstractWe have isolated a water‐soluble polysaccharide from the Jack bean [Canavalia ensiformis (L) DC] seed coat that was shown to be highly detrimental to larval development of the cowpea weevil (Callosobruchus maculatus) (Coleoptera: Bruchidae). Determination of the composition and structure of this polysaccharide showed that it is a galactorhamnan with an Mw of 883.0, containing 92% rhamnose and 8% galactose. The polymer is formed by a main chain of rhamnose (1 → 2) substituted at O‐4 by galactose nonreducing end‐units. Immunolocalisation by light and electron microscopy showed that this polysaccharide is localised in the innermost cell layer of the seed coat and also in cotyledon tissues in the cytoplasm space. The presence of this toxic polysaccharide in the testa of a non‐host seed may have been important for the evolutionary discrimination of legume seeds by bruchids.
Pathway phase waveform characteristics correlated with length and rate of stylet advancement and partial stylet withdrawal in AC electrical penetration graphs of adult whiteflies
Authors: Jiang Y.X. , Walker G.P. 
Published: October 2003

AbstractA technique was developed for measuring the length of stylet insertion during adult whitefly probing. The distance that the labium shortens during a probe was shown to be equal to the length of stylets that were inserted into the plant tissue. The length of labial shortening then was measured in high‐magnification video recordings of adult female silverleaf whitefly, Bemisia argentifolii, in conjunction with recording electrical penetration graphs (EPGs – AC method). Using a split‐screen device, video images of the whitefly's labium during a probe and the EPG waveforms produced during the probe were recorded simultaneously on the same video tape. On playback, changes in labial length could be measured during specific EPG waveforms to determine the length of stylet insertion that occurred during the waveforms. The focus of the study was on two characteristics of the pathway phase sawtooth waveform: the frequency of voltage peaks and the increase in voltage level that occurs over time during sawtooth waveforms. The rate of stylet penetration was significantly and positively correlated with frequency of sawtooth waveform voltage peaks (r2= 0.33) and the length of stylet penetration was significantly and positively correlated (second‐order polynomial) with the relative difference in voltage level between the beginning and end of the sawtooth waveform (r2= 0.43). Stylet advancement did not appear to occur during the few low‐flat waveforms (unknown behavioral correlation) and high‐flat waveforms (phloem phase) that were observed. Voltage drops occur sporadically during sawtooth waveforms, and these were associated with partial stylet withdrawal (indicated when the labium increased in length, but the probe was not terminated) with an accuracy of 99%.