bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parasitism of the grasshopper Melanoplus sanguinipes by a sarcophagid fly, Blaesoxipha atlanis: influence of solitary and gregarious development on host and parasitoid
Authors: Danyk T. , Johnson D.L. , Mackauer M. 
Published: October 2003

Abstract Blaesoxipha atlanis (Aldrich) (Diptera: Sarcophagidae) is a common parasitoid of the grasshopper Melanoplus sanguinipes (F.) (Orthoptera: Acrididae) in western Canada. We tested the hypothesis that B. atlanis can develop as either a solitary or a gregarious parasitoid, and assessed the influence of parasitism on the growth and survival of infected grasshoppers. Males and females of M. sanguinipes were parasitized manually with one, two, or three first‐instar larvae of B. atlanis in the laboratory. Parasitism was more deleterious to males than females of M. sanguinipes; females are larger than males. Host survival and longevity declined with the number of larvae per host in a sex‐specific manner. In females, 39%, 24%, and 8% of hosts containing, respectively, one, two, and three sarcophagid larvae survived parasitism. Although 41% of single‐parasitized males survived, all males containing more than one larva died. Variations in host quality as measured by dry mass explained much of the response to parasitism in male, but not female, hosts. Parasitoid larvae, apparently, did not cause significant physical damage to host organs and tissues but instead functioned as a metabolic sink. The greater metabolic activity associated with egg production could account for the relatively higher tolerance to parasitism of female, as opposed to male, grasshoppers. Developmental time, adult size, and percentage survival of B. atlanis declined with the intensity of parasitism, especially in parasitoids developing in male hosts. Females developing gregariously contained fewer ovarioles at eclosion than counterparts developing as solitary larvae. The mean body size of field‐collected B. atlanis did not differ from that of laboratory‐reared parasitoids developing singly in a host. Gregarious development is an alternative strategy to solitary development that may enable B. atlanis to maintain population numbers during periods of grasshopper scarcity.
15N‐marked aphids for predation studies under field conditions
Authors: Nienstedt K.M. , Poehling H.M. 
Published: October 2003

AbstractIndividuals ofSitobion avenae (F.) (Homoptera: Aphididae) were marked with the stable isotope 15N through feeding on cereal seedlings which were immersed in a15N‐enriched nutrient solution. Increased 15N‐contents were obtained in all aphids with no detrimental effect on survival and fertility. When 15N‐marked aphids were transferred to non 15N‐enriched seedlings, after a short initial decreasing phase, 15N‐contents remained nearly constant in time. A content of 10% 15N in the nutrient solution of the seedlings was sufficient for marking the aphids.
Effects of agricultural diversification on the abundance, distribution, and pest control potential of spiders: a review
Authors: Sunderland Keith , Samu Ferenc 
Published: October 2003

AbstractA review of the literature showed that spider abundance was increased by diversification in 63% of studies. A comparison of diversification modes showed that spider abundance in the crop was increased in 33% of studies by ‘aggregated diversification’ (e.g. intercropping and non‐crop strips) and in 80% of studies by ‘interspersed diversification’ (e.g., undersowing, partial weediness, mulching and reduced tillage). It is suggested that spiders tend to remain in diversified patches and that extending the diversification throughout the whole crop (as in interspersed diversification) offers the best prospects for improving pest control. There is little evidence that spiders walk in significant numbers into fields from uncultivated field edges, but diversification at the landscape level serves to foster large multi‐species regional populations of spiders which are valuable as a source of aerial immigrants into newly planted crops. There are very few manipulative field studies where the impact of spiders on pests has been measured in diversified crops compared with undiversified controls. It is encouraging, however, that in those few studies an increased spider density resulted in improved pest control. Future work needs are identified.
Olfactory responses of two species of grasshoppers to plant odours
Authors: Chen H.H. , Kang L. 
Published: October 2003

AbstractElectroantennogram (EAG) responses were recorded from two species of oedipodine grasshoppers, Oedaleus decorus asiaticus L. (graminivorous) and Angaracris barabensis Pall. (forbivorous), to volatiles emitted by chopped leaves of ten plant species. Male O. d. asiaticus showed much stronger EAG responses than conspecific females and both sexes of A. barabensis. Sexual differences in EAG responses correspond to different numbers of antennal sensilla of both sexes and to certain behavioural and morphological factors as well. The overall EAG response profiles of the two grasshopper species to the ten plant odours were similar. However, adaptation to host odour might have occurred because of differences in their feeding habits. Females of the graminivorous O. d. asiaticus possess a significantly higher olfactory sensitivity for poaceous plant species than A. barabensis, while the forbivorous A. barabensis showed significantly higher EAG responses to Allium senescens (Liliaceae), and a tendency of high responses to composite plant species in comparison with O. d. asiaticus.
Effects of crowding on populations of Aedes albifasciatus larvae under laboratory conditions
Authors: Gleiser Raquel M. , Urrutia Jorge , Gorla David E. 
Published: October 2003

Abstract Aedes (Ochlerotatus) albifasciatus (Macquart 1838) (Diptera: Culicidae) is a neotropical flood water mosquito, incriminated as the main vector of the western equine encephalitis virus, and which affects beef and milk production in central Argentina. The short time required to hatch and develop from egg to adult, usually in temporary pools, suggests a strategy which allows for exploitation of transient pools, thus evading predation and interspecific competition. Under these conditions intra specific competition could represent a major density‐dependent source of larval mortality, but the relative importance of density‐dependent regulation of mosquito populations has generated controversy. Therefore we examined the effects of larval density on basic population characteristics of Ae. albifasciatus in the laboratory. Larvae were obtained by synchronous hatching of eggs laid by field‐trapped females. Emerging larvae (L1) were used to build cohorts of different initial densities, kept in plastic trays with 400 ml of distilled water, and food supplied daily during the first 10 days (0.1 g per larvae day−1). Age‐specific development time and specific and relative mortality were estimated, and their relation to initial larval density was assessed through linear and non‐linear regressions and correlation analysis. First hatching was registered 3 h after flooding the eggs. Higher levels of pre‐adult mortality were detected in groups with higher densities. Specific mortality and average time to enter a stage of L1 to L3 could directly be related to initial larval density, but no significant relations were found for L4 and pupae. Results suggest that crowding could be a factor capable of regulating the density of natural populations of Ae. albifasciatus.
The making of a pest: recruitment of Meligethes aeneus onto oilseed Brassicas
Authors: Hokkanen Heikki M.T. 
Published: October 2003

AbstractPopulations of the rapeseed pollen beetle Meligethes aeneus F. (Col., Nitidulidae) from areas with 0–16 years of history of intensive rapeseed growing were compared for key ecological characters. During the first 16 years of rapeseed cultivation the reproductive success of M. aeneus increased 200–300% over that of the beetles living on the natural host plants, cruciferous weeds. The increase was linear over time and statistically highly significant, and it did not appear to be related to food quality or to the size of the beetles. During the same period the tolerance to intraspecific competition decreased, possibly due to the relative absence of such competition on the new crop. Furthermore, the optimum population density for M. aeneus to maximize the size of its next generation on summer turnip rape was determined to be 0.5–1.0 beetles/plant, which is slightly below the economic threshold for chemical control (1 beetle/plant). Therefore the practical protection of the rapeseed yield also ensures the highest possible pest population size for the next year. These mechanisms may in part explain the particular noxiousness of the species as a pest all over Europe. In general these data show that after the introduction of a new crop plant into a region, significant changes during the recruitment process in a pestiferous insect may take place, contributing to the future pest status of the insect. It is suggested that such genetic and ecological changes in insects may be a more common mechanism than previously thought in initiating and sustaining pest outbreaks, and that conventional pest management methods may enhance that effect.
The spatio‐temporal distribution of adult Ceutorhynchus assimilis in a crop of winter oilseed rape in relation to the distribution of their larvae and that of the parasitoid Trichomalus perfectus
Authors: Ferguson A.W. , Klukowski Z. , Walczak B. , Perry J.N. , Mugglestone M.A. , Clark S.J. , Williams I.H. 
Published: October 2003

AbstractThe spatio‐temporal distribution of Ceutorhynchus assimilis Payk. (Coleoptera: Curculionidae) adults caught in a rectangular grid of flight traps in a crop of winter oilseed rape (Brassica napus L.) was mapped and was analysed using Spatial Analysis by Distance IndicEs (SADIE). Their distribution was compared to that of their larvae and that of their parasitoid Trichomalus perfectus (Walker) (Hymenoptera: Pteromalidae) in pods. The distribution of immigrating C. assimilis adults was consistent with their arrival at the crop boundaries and movement within the crop towards its centre. Adult C. assimilis were aggregated at all times, invasion being on two fronts, leading to the formation of two major clusters within the crop. Large areas of the crop remained relatively unpopulated. During the emigration phase, numbers declined simultaneously in all parts of the crop. The distributions of adult and larval C. assimilis and of larval T. perfectus were spatially associated. The distribution of the parasitoid did not show a density dependent relationship with that of its host. We discuss the movements of insects which underlie their population distributions, the value of integrating spatial information into improved management strategies for C. assimilis and the potential for the spatial targeting of insecticides to reduce the amount applied and to conserve T. perfectus.
Host recognition cues of the granary weevil parasitoid Lariophagus distinguendus
Authors: Steidle Johannes L.M. 
Published: October 2003

AbstractHost recognition was examined in Lariophagus distinguendus (Förster), a parasitoid of larvae of the granary weevil Sitophilus granarius (L.) that live endophytically in wheat grains. On encountering a grain infested with S. granarius, females of L. distinguendus behave in a set sequence. First they show antennal drumming on the grain, second they tap with the tip of the abdomen on the grain surface, third they drill into the grain and then insert their ovipositor. Bioassays revealed that drumming and drilling was stimulated by non‐volatile chemicals present on the grain‐host complex. Host faeces and herbivore damaged grain material stimulated the most activity, followed by artificially damaged grain, and healthy grain. This is the first report on non‐volatile chemicals released from herbivore‐damaged seeds as signals for foraging parasitoids. Volatile chemicals from the faeces alone were not active. Experiments on the use of physical cues revealed that the presence of a three‐dimensional structure increased the response towards chemicals from the faeces. The shape (ovoid or rectangular solid) and colour (brown or white) of the structure had no impact. Thus, physical cues alone were insufficient to stimulate host recognition behaviour, but acted by increasing the response towards the chemical stimuli.
Behavioural observations of Pieris brassicae larvae indicate multiple mechanisms of action of analogous drimane antifeedants
Authors: Messchendorp L. , Gols G.J.Z. , van Loon J.J.A. 
Published: October 2003

AbstractWe tested 11 analogous synthetic drimane antifeedant compounds for their feeding inhibiting effects on larvae of the large white butterfly Pieris brassicae L. (Lepidoptera: Pieridae) in no‐choice tests on the host plant Brassica oleracea L. Furthermore, we observed larval feeding behaviour in no‐choice tests to analyze temporal effects of five drimanes. The results show that the five analogous antifeedants differentially influence feeding behaviour and locomotion activity. Warburganal and polygodial are most likely sensory mediated antifeedants. Habituation to these compounds occurs soon after the onset of the tests (i.e., within 0.5–1.5 h). Compound 5 and confertifolin are probably not direct, sensory mediated antifeedants. After 0.5–1.5 h of exposure, these compounds inhibit not only feeding, but also locomotion behaviour, indicating postingestive, toxic effects. Isodrimenin inhibits feeding from the onset of the test and is probably a sensory mediated antifeedant. No habituation occurs to this compound, indicating that isodrimenin is either a very strong antifeedant or that it additionally has postingestive, toxic effects. Topical application of the drimanes on the larval cuticle revealed feeding inhibiting effects, but these could not be related to the occurrence of postingestive feeding inhibiting effects, indicating that this method is inappropriate to show possible postingestive effects of drimanes in P. brassicae. In conclusion, the behavioural observations performed in this research indicate that analogous drimanes inhibit feeding by P. brassicae larvae through multiple mechanisms of action. The results show that, when developing a structure activity relationship (SAR) for a series of antifeedants, it is important to distinguish the mode of action which underlies inhibition of feeding.
Selection of hibernation sites by Anthonomus pomorum: preferences and ecological consequences
Authors: Toepfer St. , Gu H. , Dorn S. 
Published: October 2003

AbstractThe apple blossom weevil, Anthonomus pomorum (L.) (Coleoptera: Curculionidae), has a long period of aestivo‐hibernation in the adult stage lasting from summer to early spring of the following year. Potential hibernation sites within an apple orchard consist of high‐stem rough‐bark trees or dwarf smooth‐bark trees. Field release‐recapture experiments in 2 consecutive years showed that 64 and 47% of the weevils remained in the vicinity of the release sites in an area of high‐stem trees and dwarf trees, respectively. The dispersing weevils moved over an average distance of 5.5 m in the dwarf tree area, as compared to 3.8 m in the high‐stem tree area. The prevalent direction of dispersal was along tree rows in both areas. Some weevils displayed, after release in mid‐July, a directional dispersal to the adjacent forests. Others, released in the dwarf tree area, dispersed towards the area of high‐stem rough‐bark apple trees. Experiments simulating various hibernation sites demonstrated that the litter of dry leaves was the most preferred overwintering shelter, yielding a relatively high survival rate. Branches with rough bark ranked second, while branches with smooth bark, grass and pure soil were not favourable for overwintering. Flight tendency in newly emerged weevils of summer generation was significantly higher in June/July than in August/September. This corresponds to the dispersal behaviour in the field. The timing of spring colonisation of apple trees was similar for weevils overwintering within the orchard and for those from outside. These results suggest that modern, dwarf apple orchards offer unfavourable conditions for overwintering, but that the relatively small proportion of weevils which manage to reach the adjacent forests find optimal hibernation sites there.
Genetic, biochemical, and behavioral uniformity among populations of Myzus nicotianae and Myzus persicae
Authors: Clements Kieran M. , Sorenson Clyde E. , Wiegmann Brian M. , Neese Paul A. , Roe R. Michael 
Published: October 2003

AbstractPrior to designation as distinct species, an appellation presently in question, the tobacco aphid, Myzus nicotianae Blackman (Homoptera: Aphididae), was classified as a tobacco‐feeding form of the green peach aphid, Myzus persicae (Sulzer). In this study, RAPD polymorphisms distinguished members of the Myzus persicae complex (M. persicae and M. nicotianae) from three outgroup Myzus species (M. cerasi (F.), M. hemerocallis Takahashi, and M. varians Davidson). Polymorphisms within the complex did not separate populations on the basis of host association (tobacco versus other host plants) or geographic origin (collections from the United States, Europe, and Japan). Similarly, while GC‐MS analysis of cuticular hydrocarbon profiles revealed both developmental and inter‐populational differences within the M. persicae complex, it did not separate populations of tobacco feeding aphids from those collected off non‐tobacco hosts. Finally, with the exception of their responses to a choice between lettuce and collards, the host preference behavior of a green peach aphid population, a red tobacco aphid population, and a green tobacco aphid population was indistinguishable in host preference experiments. These results add to a growing body of evidence suggesting M. nicotianae and M. persicae are conspecific.
Flower preference behaviour of western flower thrips in the Similkameen Valley, British Columbia, Canada
Authors: Pearsall Isobel A. 
Published: October 2003

AbstractWestern flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), occur on most wildflowers, weed and ground cover flowers in the southern interior of B.C., Canada. Preference by WFT for naturally occurring ground cover blooms was determined in a series of choice trials aimed to examine the potential of using such flowers as trap crops under nectarine trees. The effect of height of flowers above ground level within an orchard was also examined to determine whether this may affect flower attractiveness. Although WFT showed consistent preferences for various flower types, no ground cover grown presently in this region appeared to have potential as an effective trap crop. The density of WFT landing on less preferred flower types was not reduced when more attractive flowers also were present, and WFT were found to distribute evenly over all flowers available. Western flower thrips responded to the density of flowers only in response to highly scented flowers, and were attracted equally to mixtures of colours and single colours of flowers. There was a consistent preference by WFT in the spring for flowers located at ground level.
Fitness effects of two facultative endosymbiotic bacteria on the pea aphid, Acyrthosiphon pisum, and the blue alfalfa aphid, A. kondoi
Authors: Chen De‐Qiao , Montllor Clytia B. , Purcell Alexander H. 
Published: October 2003

AbstractThe effects of two bacterial endosymbionts, designated PASS and PAR, were evaluated on the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera:Aphididae), in which they occur facultatively, and on the blue alfalfa aphid, A. kondoi Shinji, in which these bacteria have not been found in natural populations. Subclones of pea aphids and blue alfalfa aphids, derived from parent aphid clones that did not contain PASS or PAR, were infected with one or both bacteria, generating PASS‐ and/or PAR‐positive subclones with minimal genetic differences from the parent clones. Under laboratory conditions at 20 °C, PAR consistently reduced the fecundity (by between 19 and 60%) of subclones derived from three different parent pea aphid clones on bur clover, Medicago hispida Gaertn. PAR had intermediate effects on pea aphids reared on sweet pea, Lathyrus odoratus L., and had no significant effect on pea aphids on alfalfa, Medicago sativa L. The effect of PASS was either neutral or negative, depending on parent clone as well as host plant. Also at 20 °C, PASS reduced fecundity (70–77%) and longevity (40–48%), and increased the age of first reproduction (by up to 1.5 days) of blue alfalfa aphid reared on alfalfa and clover. PAR had a less dramatic effect (e.g., 30–39% reduction in fecundity) on these traits of blue alfalfa aphid. In contrast, PAR and PASS increased the fitness of pea aphid subclones of one parent clone reared for three generations at 25 °C on each of the three test plants. Without facultative bacteria, fecundity of the parent clone was reduced to a mean total of < 6 offspring per adult at this elevated temperature, but with PASS or PAR, mean total fecundity of its subclones was > 35. However, this ameliorative effect of facultative bacteria at 25 °C was not found for two other sets of parent clones and their derived subclones. Alate production in pea aphids was significantly increased in large populations of two PASS‐ and PAR‐positive subclones relative to their parent clones. Attempts to transmit PASS or PAR horizontally, i.e., from aphid to aphid via feeding on host plants (bur clover), were unsuccessful.
A natural flightless mutation in the ladybird, Harmonia axyridis
Authors: Tourniaire R. , Ferran A. , Giuge L. , Piotte C. , Gambier J. 
Published: October 2003

AbstractA homozygous flightless strain, obtained by selection from a laboratory population of Harmonia axyridis Pallas (Coleoptera, Coccinellidae), has been reared under controlled conditions since 1982 after sampling in China. The adults of this flightless strain have normal elytra and wings but drop almost vertically when they attempt to fly. The origin of this mutation, whether laboratory or natural, is discussed. As the mutation does not affect the fitness of the beetles, this flightless strain can be used in biological control. Releasing flightless adults rather than larvae should provide the potential for more continuous control of aphids by both larvae and adults.