bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geographic variation in the field response of male European pine sawflies, Neodiprion sertifer, to different pheromone stereoisomers and esters
Authors: Anderbrant O. , Löfqvist J. , Högberg H.‐E. , Hedenström E. , Baldassari N. , Baronio P. , Kolmakova G. , Lyons B. , Naito T. , Odinokov V. , Simandl J. , Supatashvili A. , Tai A. , Tourianov R. 
Published: October 2003

AbstractThe European pine sawfly, Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae), is a widespread and economically important forest insect. The sex pheromone communication system of this species has been previously investigated in North America, Japan and Europe, with the acetate or propionate of the alcohol (2S,3S,7S)‐3,7‐dimethyl‐2‐pentadecanol (diprionol) shown to be the main pheromone component. In some locations, male attraction either increased or decreased by the addition of the (2S,3R,7R)‐diprionyl acetate isomer. However, these studies were made with different batches of synthetic pheromones, with different types of traps and according to different procedures, so the observed differences might not reflect true geographic variation. Here we investigate the geographic pattern of male sawfly response by using identical chemicals, traps and experimental procedures at eight field sites ranging from Japan in the east to Canada in the west. We found an increased inhibitory effect of the (2S,3R,7R)‐isomer from Japan and Siberia to Europe. At the eastern sites, increasing amounts of the (2S,3R,7R)‐isomer up to and equal to the amount of the (2S,3S,7S )‐isomer, did not influence the trap catch, whereas at sites in Europe, as little as 1% of the (2S,3R,7R)‐isomer almost completely inhibited the attraction. The response of the North American population was intermediate. The only site in which the (2S,3R,7R)‐isomer was essential for the attraction of males was in Siberia. A similar pattern was found for the (2S,3R,7S)‐isomer. Both the acetate and the propionate form of the (2S,3S,7S)‐isomer were attractive by themselves in Japan, Europe and North America, and neither the (2S,3R,7S)‐isomer nor the (2S,3R,7R)‐isomer alone were attractive, in the acetate or propionate form. We discuss the significance of our findings for the development of more efficient monitoring schemes and for the causes of population divergence and speciation in the European pine sawfly.
Host stage preference and sex allocation in Aenasius vexans, an encyrtid parasitoid of the cassava mealybug
Authors: Bertschy Catherine , Turlings Ted C.J. , Bellotti Anthony , Dorn Silvia 
Published: October 2003

AbstractThe solitary endoparasitoid Aenasius vexans Kerrich (Hymenoptera: Encyrtidae) is used for augmentative releases against the cassava mealybug, Phenacoccus herreni Cox & Williams (Sternorrhyncha: Pseudococcidae), an important pest on cassava in South America. In light of the need for large numbers of high quality females, experiments were conducted on host stage suitability and sex allocation. In choice and no‐choice experiments, individual female wasps were offered second and third instar, as well as adult, hosts. During the first five days after emergence, the wasps showed a steady increase in the number of hosts they successfully parasitised per day, but the respective secondary sex ratio for each instar remained constant. Parasitism was highest for third instar hosts in no‐choice tests, while in choice tests parasitism was highest in both third instars and adults. The later the developmental stage of the host at oviposition, the faster the parasitoids developed and emerged, and for each host stage, the development time of males was shorter than for females. The sex ratio of the wasps emerging from hosts that were parasitised as second instars was strongly male‐biased, while the apparently preferred later stages yielded significantly more females than males. Female and male A. vexans emerging from hosts parasitised at the third instar were significantly larger than for the other stages. This may explain the preference for the third instar as well as the female‐biased sex ratio, as size is usually positively correlated with higher fitness, especially in females. The results suggest that third instar hosts are the most suitable for rearing high numbers of large females.
Searching and oviposition behavior of a mymarid egg parasitoid, Anagrus nigriventris, on five host plant species of its leafhopper host, Circulifer tenellus
Authors: Al‐Wahaibi A.K. , Walker G.P. 
Published: October 2003

AbstractSearching and oviposition behavior and parasitization ability of Anagrus nigriventris Girault (Hymenoptera: Mymaridae), an egg parasitoid of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), were examined on five host plant species of beet leafhopper: sugar beet (Beta vulgaris L.), red stem filaree (Erodium cicutarium[L.]), peppergrass (Lepidium nitidum Nuttall), desert plantain (Plantago ovata Forsskal), and London rocket (Sisymbrium irio L.). Beet leafhopper embeds its eggs in the tissues of these plant species. For each plant species, A. nigriventris behavior was examined on plants with and without beet leafhopper eggs. Experimental design was a 5 (plant species) by 2 (host eggs present/absent) factorial. Additionally within each treatment, parasitoid behavior was observed over a 22‐h period at five different observation periods: t=0, 3, 6, 9, and 22 h where t=0 h represents initial exposure of the insect with the plant. The behavioral events observed were: ‘fast walking’ (general searching), ‘slow walking’ (intensive searching), ovipositor probing, grooming, feeding, and resting. Significant differences (α=0.05) among plant species in time spent on the plant, percentage of host eggs parasitized, and behavioral variables associated with intensive searching and oviposition all indicated that the plant species fell into two groups: ‘preferred’ plants (sugar beet, London rocket, and peppergrass), and ‘unpreferred’ plants (filaree and plantago). These variables also indicated that the parasitoids spent more time on, searched more, probed more, and oviposited more in plants with host eggs than plants without host eggs. Consistent effects of time (over the observation periods from t=0 to t=22 h) generally were detected only in the preferred plant species that had host eggs present. In these cases, intensive searching and probing decreased as time advanced, while variables related to general searching (‘fast walking’) and abandoning host egg patches (leaving the plant) tended to increase over time.
Effect of variation in photoperiodic response on diapause induction and developmental time in the willow leaf beetle, Plagiodera versicolora
Authors: Ishihara Michihiro 
Published: October 2003

AbstractThe willow leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae) overwinters in adult diapause. In this study, the photoperiodic responses for diapause induction and developmental time were examined in the Ishikari (Hokkaido, Japan) population of P. versicolora. All females entered reproductive diapause under short daylength (L10:D14), but 31.7% of females did not enter diapause under long daylength (L16:D8). The developmental time from oviposition to adult emergence was significantly longer at L10:D14 than that at L16:D8. Norm of reaction curves illustrated variation among families in the photoperiodic responses for diapause induction and for developmental time. ANOVA indicated significant family × photoperiod interactions in the developmental time. At L16:D8, developmental time was positively correlated with the incidence of diapause in females. This means that a female having a longer developmental time tends to have a longer critical photoperiod. Such variation may be maintained by differences in selection pressures on the growth rate and the critical photoperiod for diapause induction between univoltine and bivoltine genotypes because Ishikari is located in a transitional area between populations with univoltine and bivoltine life cycles.
Foundations of spatial ecology: the reification of patches through quantitative description of patterns and pattern repetition
Authors: Dalthorp D. , Nyrop J. , Villani M.G. 
Published: October 2003

AbstractInsect populations tend to be patchy, and the nature of the patches is a critical component of ecology. Predator‐prey interactions, coexistence of competing species, survival of rare species as habitat is destroyed, and damage to crops are just a few examples of spatially‐dependent ecological processes. For want of tractable quantitative approaches, understanding of spatial ecology has lagged far behind recognition of its importance. We assert that a quantitative foundation of a spatial ecology involves the reification of patches as objects of study. We introduce two new measures of patch dynamics: total covariance for comparing degrees of patchiness between populations, and quantile variance for quantifying the constancy of dispersion patterns through time. These new measures, in combination with the long‐established spatial covariance from geostatistics, comprise a rudimentary toolbox for reification of patches and empirical field studies in spatial ecology.
Spatial ecology of the Japanese beetle, Popillia japonica
Authors: Dalthorp D. , Nyrop J. , Villani M.G. 
Published: October 2003

AbstractA cornerstone of spatial ecology is the quantification of the patchy nature of animal and plant populations in space. By using spatial covariance, total covariance, and quantile variance, we found that patchiness of Japanese beetle grub populations varied more between years than between fairways at a central New York golf course. We also observed that populations tended to shrink and swell around patches with perennially low density, that locations with perennially low grub density were associated with high soil organic matter content, and that locations with frequently high grub density were associated with intense adult beetle activity in the vicinity.
Host suitability, quality and host size preference of Leptomastix epona and Pseudaphycus flavidulus, two endoparasitoids of the mealybug Pseudococcus viburni, and host size effect on parasitoid sex ratio and clutch size
Authors: Karamaouna Filitsa , Copland Michael J.W. 
Published: October 2003

AbstractFive host size classes which mostly consisted of one host stage (first, second, third instar nymph, young adult and preovipositing adult) of the mealybug Pseudococcus viburni (Signoret) Fernald, 1903 [Hemiptera: Pseudococcidae] were tested for susceptibility and suitability for the solitary parasitoid Leptomastix epona (Walker) Graham, 1969 and the gregarious Pseudaphycus flavidulus (Brèthes) De Santis, 1964 [both of them Hymenoptera: Encyrtidae] in no choice experiments. Hosts larger than 1 mm (third instar) were suitable for the development of the parasitoids. Choice experiments with all the host size classes offered simultaneously showed that L. epona and P. flavidulus are parasitoids of mainly larger hosts (>1 mm, third instar nymphs) therefore the parasitoids exploit the same host range. In L. epona, a faster development and a larger size of wasps occurred in host size class 1.83–2.33 mm (young adult mealybugs) indicating a greater host quality compared to other sizes. Proportion of male offspring decreased with the host size following the host size distribution models. In P. flavidulus there was no effect of host quality (size at parasitism) on developmental time, sex ratio or parasitoid size and fecundity. Larger clutch sizes of P. flavidulus emerged from larger hosts but overall this parasitoid was able to parasitize smaller hosts (<1 mm, second instar nymphs) compared to L. epona. Experience of oviposition for 24 h does not seem to affect host size preference or sex ratio of the offspring in L. epona. Implications of the findings for mass‐rearing and single applications of the parasitoids for the purpose of a biological control programme are discussed.
Wolbachia‐induced parthenogenesis in the egg parasitoid Telenomus nawai
Authors: Arakaki Norio , Noda Hiroaki , Yamagishi Kenzou 
Published: October 2003

AbstractTwo egg parasitoid species, Telenomus nawai and Telenomus spec. are similar morphologically but they have been treated as different species because of their different reproductive forms, arrhenotoky and thelytoky. Male progeny were produced from the thelytokous colony of Telenomus spec. (TT) by heat and antibiotic treatments. These males mated successfully with females of arrhenotokous colony of T. nawai (AT) and the females produced on average 19.1% males. This percentage did not differ from that obtained from AT females mated with AT males (19.4%). Diagnostic PCR indicated that TT is infected with Wolbachia; antibiotic treatments eliminated Wolbachia from TT. These facts suggest that Wolbachia causes thelytoky and Telenomus spec. (TT) is conspecific with T. nawai (AT).
Increasing the effectiveness of spring trap crops for Leptinotarsa decemlineata
Authors: Hoy C.W. , Vaughn T.T. , East D.A. 
Published: October 2003

AbstractInsecticide resistance problems have increased interest in trap crops as a cultural control strategy for overwintered Colorado potato beetle adults, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae). Growers in the north central United States have noticed and treated concentrations of adults at the edge of some of their potato fields each spring. Based on sampling in commercial potato fields over a 2‐year period, early planted fields that are adjacent to the previous year's potato crop are most likely to have concentrations of adults at the field edge. Frequency of fields with significantly more adults at the edges than in the center sections as well as adult population density in the center sections of fields declined with both distance from the previous potato field and later planting date. The effects of both physical and chemical barriers to movement into potato fields from the field edges were studied in small plot trials and at the edges of commercial potato fields. In small plot trials, physical barriers had a greater impact than chemical barriers on adult beetle movement from a potato trap crop to the protected potatoes beyond the barrier. Barrier treatments reduced beetle numbers in and just beyond the barrier in commercial fields, but the effects were localized and no significant reduction of beetles was observed further into the field. Beetle flight was hypothesized to be responsible for the localized effects of barrier treatments and the lack of edge concentrations in later planted and more distantly rotated fields. In field studies, larger potato plants attracted more colonizing potato beetles than smaller plants. Attracting Colorado potato beetles to trap crops containing potato plants that were larger than those in the remainder of the field, however, provided no significant reduction of beetles in the remainder of the field. We found little opportunity to reduce beetle populations with trap crops at the edges of potato fields without controlling the adults in the trap crop itself. Growers can exploit naturally occurring concentrations of adults at the edges of early and adjacent potato plantings if they are prepared to monitor and regularly treat the field edges.
Comparison of DIMBOA concentrations among wheat isolines and corresponding plant introduction lines
Authors: Ni Xinzhi , Quisenberry Sharron S. 
Published: October 2003

AbstractThe concentration of a hydroxamic acid, also known as DIMBOA (2,4‐dihydroxy‐7‐methoxy‐1, 4‐benzoxazin‐3‐one), in 6‐d old wheat seedlings was examined using reverse‐phase high performance liquid chromatography (HPLC). Wheat plant introduction (PI) lines PI 137739 (Dn1 gene), PI 262660 (Dn2 gene), and PI 294994 (Dn5 gene), the corresponding near‐isogenic lines‘Betta’‐Dn1, Betta‐Dn2 and Betta‐Dn5, and susceptible Betta wheat were used in the study. The Dn2 gene conferring Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae), tolerance was not related to DIMBOA concentration in wheat. Of the lines with Dn1 and Dn5 genes that confer antibiosis to D. noxia, only lines with the Dn5 gene showed increased DIMBOA accumulation. However, the Dn5 and the DIMBOA biosynthesis genes are not located in the same chromosome group. Possible relationship between the Dn5 gene and DIMBOA accumulation was discussed. This study indicates that DIMBOA concentration does not completely explain D. noxia resistance in the wheat lines examined and a comprehensive examination of other allelochemicals (e.g., phenolics) is necessary.
A comparison between two strains from Japan and Europe of Aphidius ervi
Authors: Takada Hajimu , Tada Eri 
Published: October 2003

AbstractA European strain of Aphidius ervi shall be introduced into Japan for the control of Macrosiphum euphorbiae on greenhouse tomatoes. We compared this strain, which is originating from The Netherlands (EVP), with a native strain from Hokkaido, Northern Japan (SPR) in several characteristics. The percentage of parasitism of SPR and EVP was significantly different, when attacking three aphid species: 13% and 30% on M. euphorbiae on tomato, 68% and 93% on Acyrthosiphon pisum on broad bean and 10% and 42% on Aulacorthum solani on sweet pepper, respectively. SPR and EVP differed morphologically (in the colouration of the petiole) and in the esterase banding patterns. Furthermore, cross mating experiments showed that SPR and EVP are partially reproductively isolated from each other. Complete reproductive isolation is evident in the one direction cross (EVP females and SPR males).
Host instar, body size and fitness in the koinobiotic parasitoid Aphidius nigripes
Authors: Cloutier C. , Duperron J. , Tertuliano M. , McNeil J.N. 
Published: October 2003

AbstractIn aphidiine parasitoids, resources for growth and adult body size increase with host instar used by ovipositing females, but the fitness consequences of body size on fitness are poorly documented. We compared the fitness of male and female A. nigripes adults that varied in size as a consequence of developing in different instars of their host Macrosiphum euphorbiae. When reproductive fitness was measured without considering time, female wasps from small and large hosts performed similarly, contributing 125–175 foundresses plus 100–180 sons to the next generation. However, when expressed as the innate capacity for increase (rm), female fitness correlated with host‐induced variation of wasp size, indicating that micropopulations initiated by large wasps would increase faster. In a wind‐tunnel, a sex pheromone plume from large female wasps induced more males to fly upwind when released at a distance of 50 cm downwind than small females, indicating that large females were sexually more attractive. With respect to male body size effects on fitness, large individuals performed similar to small ones, whether fitness was measured by lifetime mating frequency, fertile inseminations, or proportion of daughters among progeny born from their mates. When young naive males of unequal size were directly competing for mating with a virgin female, small and large males had equal mating success, and large individuals were no more successful than small ones at displacing a competitor already positioned on a receptive female. In a wind‐tunnel test where males were scored on their ability to reach a female pheromone source, small and large males were equally affected by wind speed but reached the source located 50 cm downwind in equal proportions, suggesting similar capacity for finding mates by flying upwind. Our results indicate that despite host resources not being fixed at the time of attack for the koinobiont A. nigripes, fitness consequences of resource limitation by the mother may be perceived to be greater for daughters than sons, which would explain male‐biased sex ratio in early‐instar hosts.
Foraging behaviour, host plant and host location in the aphid hyperparasitoid Euneura augarus
Authors: Völkl Wolfgang , Sullivan Daniel J. 
Published: October 2003

Abstract Euneura augarus is a specialized ectohyperparasitoid of conifer lachnids, which causes considerable mortality in mummies of conifer lachnid parasitoids. For the search on a large scale, E. augarus females rely mainly on volatile secondary plant compounds of conifers to locate potential host plants. In the medium‐range (i.e., on a given host plant), females detect the presence of hosts either during spiral search flights or during search by walking. Search flights were more effective when mummies were dispersed, while clumped mummies were mainly found by walking. On ant‐attended trees, E. augarus was not able to forage successfully. Choice experiments with Aphidius ervi‐mummies showed that E. augarus is able to develop in species that are not attacked in the field. We hypothesize that the proximate mechanism of host plant specificity, and as a consequence, host aphid specificity seems to be the use of typical conifer volatiles for host finding which provide the ‘search image’ for the species.
Hyperparasitoid defense strategies against spiders: the role of chemical and morphological protection
Authors: Hübner Gerhard , Dettner Konrad 
Published: October 2003

AbstractThe aphid endohyperparasitoid Alloxysta brevis (Thomson) (Hymenoptera: Charipidae) applies defensive chemicals stored in mandibular gland reservoirs against attacking ants. Alloxystines can be divided into species capable of exploiting ant‐attended resources and into species exclusively reared from unattended aphid‐parasitoid systems. Mandibular secretions are found in species of both groups, with little variation in chemical composition. We show that the mandibular gland secretion does not only protect against ant attacks but acts as an overall defense agent against generalist predators like spiders. The protective success differed with the spider species. The web‐building spider Agelena labyrinthica (Clerck) (Araneae: Agelinidae) killed 57% of attacked A. brevis females, but sucked out only 8%. The smaller free‐hunting jumping spider Salticus scenicus (Clerck) (Araneae: Salticidae) failed in overwhelming or severely injuring A. brevis. The pattern of interactions showed striking similarities with interactions between A. brevis and the ant Lasius niger (Hymenoptera: Formicidae). Primary parasitoids which are lacking chemical defense and sufficient morphological protection suffered significantly higher mortality due to spider predation. Our results indicate that – additional to chemical defense‐ parasitoid survival depends on the specific morphological resistance against grip pressure during capture, and on the predator – prey size relationship.
Intraguild interactions in aphid parasitoids
Authors: Brodeur Jacques , Rosenheim Jay A. 
Published: October 2003

AbstractWe reviewed the literature on aphid parasitoids to determine the occurrence, nature and outcome of intraguild interactions. Intraguild interactions were described for larval, pupal and adult aphid parasitoids and by the type of natural enemy (fungus, predator, or parasitoid). They appear to be prevalent in most aphid parasitoid systems and, except for parasitoid‐parasitoid interactions, they are mostly asymmetric, with aphidophagous predators and pathogens killing parasitoids. The limited experimental evidence from field studies is insufficient to provide a comprehensive pattern of the consequences of intraguild interactions for aphid parasitoid populations in general and, more specifically, for the efficacy of biological control. However, because intraguild interactions are widespread in aphid‐natural enemy communities and mostly detrimental to aphid parasitoids, we conclude that intraguild interactions have a primary effect in driving fluctuations in aphid parasitoid populations. Drawing on case studies, we further argue that intraguild interactions can substantially alter the effectiveness of aphid parasitoids as biological‐control agents.