bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of drought stress and temperature on spread of barley yellow dwarf virus (BYDV)
Authors: Smyrnioudis I. N. , Harrington R. , Katis N. , Clark S. J. 
Published: March 2003

Summary1 The effect of drought stress and temperature on the dispersal of wingless aphids Rhopalosiphum padi (L.) and the pattern of spread of BYDV (barley yellow dwarf virus) within wheat plants in controlled environment chambers was quantified. Combinations of three different drought stress levels, unstressed, moderate and high stress level, and three different temperatures, 5 ± 1 °C, 10 ± 1 °C, and 15 ± 1 °C, were investigated.2 With increased temperature there was an increase in the mean distance of visited plants from the point of release and in the number of plants visited and infected with BYDV. Drought stress had no effect on mean distance moved by aphids at any temperature or on plants infected with virus at 10 °C and 5 °C. When plants were drought stressed, the numbers of plants visited and infected were greater at 15 °C than at 10 °C and 5 °C.3 A greater proportion of plants visited by aphids was infected with BYDV when plants were stressed than when not stressed. At 15 °C a greater proportion of these plants was infected than at lower temperatures. There was no difference between treatments in the numbers of aphids present at the end of the experiment.4 It is concluded that drought stress and temperature are of considerable importance in virus spread.
Orientation of Colorado potato beetle to natural and synthetic blends of volatiles emitted by potato plants
Authors: Dickens Joseph C. 
Published: March 2003

Summary1 Behavioural responses of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), to volatiles emitted from solanaceous host plants (potato and tomato), a non‐host legume (soybean), and 13 synthetic blends or three individual chemicals emitted by potato plants were investigated in laboratory bioassays.2 Both male and female CPB were attracted to volatiles emitted by mechanically damaged potato foliage, but not to mechanically damaged tomato foliage; CPB offered a choice between the two damaged solanaceous plants did not show a preference.3 Among 16 odourous blends or individual chemical components of potato plant emissions tested, six blends were attractive, two were repellent, and eight elicited no preference in laboratory bioassays. Volatile blends containing relatively high amounts of the green leaf volatiles (E)‐2‐hexen‐1‐ol and (Z)‐3‐hexen‐1‐ol, or the sesquiterpene β‐ caryophyllene, were unattractive or repellent. Minimal blends attractive to CPB were comprised of (Z)‐3‐hexenyl acetate (±)‐linalool and methyl salicylate: the combination of all three chemicals elicited sexually dimorphic attraction of males; two component blends comprised of (Z)‐3‐hexenyl acetate and either (±)‐linalool and methyl salicylate attracted both sexes. Individual compounds were inactive. No significant difference was noted between two attractive blends, or an attractive synthetic blend vs. mechanically damaged potato foliage.4 These results show that CPB are attracted to blends of specific chemicals emitted by their host plants and provide a basis for the use of plant attractants as a component of integrated management of pestiferous populations.
Effectiveness of gypsy moth mating disruption from aerial applications of plastic laminate flakes with and without a sticking agent
Authors: Thorpe K. W. , Leonard D. S. , Mastro V. C. , McLane W. , Reardon R. C. , Sellers P. , Webb R. E. , Talley S. E. 
Published: March 2003

Summary1 The plastic laminate flake formulation, Disparlure II, is currently the only gypsy moth mating disruption product available for aerial application. The elimination of a sticking agent from the formulation would reduce costs, simplify application, and make it possible to apply the product without specialized equipment.2 A test was conducted in wooded plots in Virginia during 1997 and 1998 to determine whether a sticking agent is necessary. Treatment effectiveness was assessed from the rates of male moth capture in pheromone‐baited traps and mating success of both laboratory‐reared and wild females.3 Male moth capture was reduced 75.6 and 92.9% in plots treated with flakes without and with a sticking agent, respectively. The percentage of mated females that produced egg masses with more than 5% fertile eggs was reduced by 86.3 and 99.5% in plots treated with flakes without and with a sticking agent, respectively.4 Moth capture and mating success of laboratory‐reared females did not differ significantly between plots treated with flakes with and without a sticking agent. However, the consistently greater reduction in mating success in both years provides strong evidence that mating disruption is less effective when flakes are applied without a sticking agent. The proportion of wild egg masses collected in 1998 with more than 5% fertile eggs was significantly higher under the no‐sticking agent treatment.5 In special situations where the use of a sticking agent may be problematic, such as in residential areas, the data indicate that a high level of mating disruption is likely to occur even without the use of a sticking agent.
Seasonal synchrony of life cycles between the exotic predator, Pseudoscymnus tsugae (Coleoptera: Coccinellidae) and its prey, the hemlock woolly adelgid Adelges tsugae (Homoptera:Adelgidae)
Authors: Cheah Carole A. S. ‐J. , McClure Mark S. 
Published: March 2003

Abstract1 The seasonal synchrony between the exotic predator, Pseudoscymnus tsugae and its prey, the hemlock woolly adelgid, Adelges tsugae, was investigated in field cages and in the forest in Connecticut, U.S.A. from 1997–1999.2 In early spring, egg to adult development took 45 d at 18.7 °C, 39.7 d at 20.2 °C and 31.5 d at 22.7 °C. Earliest emerging F1 adults mated and oviposited in the same year. whereas F1 and F2 females emerging later in the summer mated and reserved most of their egg complement for the following year.3 A second generation of P. tsugae is possible in Connecticut but may be delayed by cool mid‐spring temperatures. Individuals of three generations of P. tsugae, including overwintering survivors, may coexist in July and August and adults can be found year‐round with A. tsugae in infested hemlock forests.4 A linear regression model for development from egg to adult under field temperatures gave good agreement with results from constant temperature findings. The model predicted a lower development threshold of 9.5 °C and a sum of effective temperatures of 405 day °C. Development time of P. tsugae is shorter relative to its prey A. tsugae and generation time ratios of predator to prey was 0.16–0.5, with an advantage conferred on the coccinellid.5 Overwintering ability and behaviour were determined in 1998–1999 and adults remained on infested hemlock branches throughout a mild winter, becoming reproductively active in mid‐April. Peak oviposition period extended from April to July, in synchrony with peak oviposition and developing stages of two generations of A. tsugae.
Insect growth‐reducing and antifeedant activity in Eastern North America hardwood species and bioassay‐guided isolation of active principles from Prunus serotina
Authors: Omar S. , Lalonde M. , Marcotte M. , Cook M. , Proulx J. , Goel K. , Durst T. , Philogène B. J. R. , Arnason J. T. 
Published: March 2003

Abstract1 Thirty extracts of wood and bark of hardwood trees from Eastern North America were examined for insect growth‐reducing activity in a bioassay with European corn borer, Ostrinia nubilalis, and an antifeedant bioassay with the rice weevil, Sitophilus oryzae.2 Nine of the bark extracts and four of the wood extracts showed significant growth reducing effects at 0.5% in meridic diets, whereas only two bark extracts and one wood extract showed significant antifeedant effect at the same concentration.3 Slower growing tree species were more biologically active than fast growing ones. Isolation of the bioactive compounds in one of the active species, Prunus serotina, showed that naringenin, its derivative methoxynaringenin, and eriodictyol were responsible for the antifeedant effects.
Recapture of Ips typographus L. (Col., Scolytidae) with attractants of low release rates: localized dispersion and environmental influences
Authors: Franklin Anne J. , Debruyne Catherine , Grégoire Jean‐Claude 
Published: March 2003

Abstract1 The dispersal of Ips typographus L. (Col., Scolytidae) was studied using a mark–release–recapture approach in a grid of traps equipped with pheromone lures of release rates of about 8.4 mg/day of 2‐methyl‐3‐buten‐2‐ol (MB) and 0.29 mg/day of (S)‐cis‐verbenol (cV) in experiment 1, and 1.2 mg/day of MB and 0.04 mg/day of cV in experiment 2.2 We investigated whether beetle dispersal reflected the simple diffusion pattern observed in previous I. typographus experiments, for which attractant release rates generally approached 50 mg/day of MB and 1 mg/day of cV. We also examined how environmental parameters (wind) and human activities (felling) could influence the beetles' flight.3 The recapture percentage was higher in experiment 1 than in experiment 2: respectively, 7.0% (with 64 traps) and 2.3% (with 100 traps) of the beetles that took off were caught in the traps.4 With the higher release rate (experiment 1), trap catches decreased with increased distance, whereas with the lower release rate (experiment 2), trap catches rose between 50 and 100 m then decreased with increasing distance.5 Flight was little orientated by prevailing wind directions, a feature probably explained by the low wind speeds (0–1.2 m/s) observed throughout the study.6 High trap catches of unmarked beetles close to areas undergoing thinning activities suggest that the presence of freshly cut spruce and larch material could have an influence on dispersal, attracting the beetles into the felling area. Spatial analyses show that capture patterns were autocorrelated up to distances of about 250 m.
Arthropod diversity of exotic vs. native Robinia species in northern Arizona
Authors: Degomez Tom , Wagner Michael R. 
Published: March 2003

Summary1 Arthropods were collected on native locust, Robinia neomexicana A. Gray, and exotic Robinia pseudoacacia L. in northern Arizona over a 2‐year period to determine the number of arthropod species and number of individuals present.2 More arthropod species were found on the native (251) than on the exotic Robinia (174).3 Greater species diversity was likewise found on the native than the exotic. The five most numerous insects collected each year accounted for 81% to 91% of the total number collected on the exotic and native Robinia in 1997 and 1998. Only 12 species occurred on both the native and exotic Robinia in both years.4 These findings are discussed in the context of using exotic trees in plantations and ecological theory regarding rates of arthropod species accumulation on exotic hosts.
Plant quality vs. risk of parasitism: within‐plant distribution and performance of the corn leaf aphid, Rhopalosiphum maidis
Authors: Gonzáles Wilfredo L. , Gianoli Ernesto , Niemeyer Hermann M. 
Published: March 2003

Summary1 Colonies of the aphid Rhopalosiphum maidis on Johnsongrass, Sorghum halepense, usually occur inside the whorl. The present work assessed the role of two biotic factors, plant quality and parasitism by Lysiphlebus testaceipes, in determining within‐plant distribution and performance of R. maidis. The mean relative growth rate of aphids inside the whorl and on a mature leaf was compared, and the concentration of hydroxamic acids in those tissues determined as an indicator of plant quality. Parasitism effectiveness and parasitoid behaviour were evaluated using three treatments: aphid colonies placed (1) wholly inside the whorl, (2) on the inner and outer surfaces of the whorl, and (3) on a mature leaf.2 The mean relative growth rate of aphids was lower on the whorl than on the mature leaf, and hydroxamic acid concentration in the whorl was higher than in the mature leaf.3 The number of parasitized dead aphids (mummies) inside the whorl was considerably lower than in the other two treatments. Mummies were present in 80% of the replicates in the whorl, whereas mummies were present in all replicates of the other treatments.4 Host location time of the parasitoid was increased on the mature leaf compared with the other treatments. No significant differences in the residence time of the parasitoid in the aphid colony occurred between treatments.5 Host location time showed a negative correlation, and residence time of the parasitoid a positive correlation with the number of aphids on the outer surface of the whorl.
Pheromone‐mediated mass trapping and population diversion as strategies for suppressing Carpophilus spp. (Coleoptera: Nitidulidae) in Australian stone fruit orchards
Authors: James David G. , Vogele Beverley , Faulder Richard J. , Bartelt Robert J. , Moore Christopher J. 
Published: March 2003

Summary1 Five experiments were conducted during 1995–99 in stone fruit orchards on the Central Coast and in inland New South Wales, Australia, on the use of synthetic aggregation pheromones and a coattractant to suppress populations of the ripening fruit pests Carpophilus spp. (Coleoptera: Nitidulidae).2 Perimeter‐based suppression traps baited with pheromone and coattractant placed at 3 m intervals around small fruit blocks, caught large numbers of Carpophilus spp. Very small populations of Carpophilus spp. occurred within blocks, and fruit damage was minimal.3 Carpophilus spp. populations in stone fruit blocks 15–370 m from suppression traps were also small and non‐damaging, indicating a large zone of pheromone attractivity.4 Pheromone/coattractant‐baited suppression traps appeared to divert Carpophilus spp. from nearby (130 m) ripening stone fruit. Ten metal drums containing decomposing fruit, baited with pheromone and treated with insecticide, attracted Carpophilus spp. and appeared to reduce populations and damage to ripening fruit at distances of 200–500 m. Populations and damage were significantly greater within 200 m of the drums and may have been caused by ineffective poisoning or poor quality/overcrowding of fruit resources in the drums.5 Suppression of Carpophilus spp. populations using synthetic aggregation pheromones and a coattractant appears to be a realistic management option in stone fruit orchards. Pheromone‐mediated diversion of beetle populations from ripening fruit may be more practical than perimeter trapping, but more research is needed on the effective range of Carpophilus pheromones and the relative merits of trapping compared to attraction to insecticide‐treated areas.
Disruption of sexual communication in the mirid bug Lygocoris pabulinus by hexyl butanoate
Authors: Groot Astrid T. , Drijfhout Falko P. , Heijboer Anneke , Van Beek Teris A. , Visser J. Hans 
Published: March 2003

Summary1 The metathoracic scent gland in Lygocoris pabulinus contains mostly hexyl butanoate. As secretions of this gland in Heteroptera may serve as an alarm pheromone, we determined whether hexyl butanoate is released by disturbed bugs, and whether this compound disrupts sexual attraction of L. pabulinus males towards females.2 Undisturbed males and females, and disturbed males released less than 100 ng/h hexyl butanoate, whereas disturbed females released a highly variable amount, ranging from 25 ng/h to more than 1 μg/h.3 In the field, traps with virgin females and rubber septa containing 20 mg hexyl butanoate, caught a total of one male in a month. In control traps without hexyl butanoate, 36 males were caught in the same period.4 In Y‐track olfactometer tests, males were not attracted to virgin females when a dispenser with 20 mg hexyl butanoate was placed in the bottle with females. Males were attracted to females when the dispenser was placed downwind from the females, but upwind from the point of male release.5 These results suggest that males are not repelled by hexyl butanoate, but that this compound inhibits sex pheromone release in females. Application possibilities for pest management are discussed.
Distribution and abundance of aphidophagous hoverflies (Diptera: Syrphidae) in wildflower patches and field margin habitats
Authors: Sutherland Jamie P. , Sullivan Matthew S. , Poppy Guy M. 
Published: March 2003

Summary1 The spatial and temporal variations in aphidophagous syrphid abundance were recorded over two seasons in wildflower resource patches sown in a winter barley crop and associated field margins. Standard census techniques and sticky board trapping were used to assess numbers of syrphids, whilst weekly flower head counts were used to quantify the floral resources available in each of the patches.2 The field margin supported a greater diversity and density of syrphids than the within‐crop wildflower patches, despite having a relatively lower flower head density. Presumably this was in response to other resources that field margins offer, namely additional aphid resources, shelter from predation, lekking sites and suitable flight‐paths.3 The commonest species of syrphid, Episyrphus balteatus, demonstrated a very positive habitat association with the field margin and was rarely reported in the field patches. Therefore, it may be an unsuitable candidate for the biological control of aphids via augmentation of numbers using non‐host resources.4 Patch size and shape had little effect on the spatial distributions of syrphids, probably because of the adult syrphids' high mobility.5 Of greater influence was the number of flowers contained in each habitat patch. Typically, patches with higher numbers of flowers had significantly greater aggregations of hoverflies. Habitat manipulation by the provision of flowers in patches seems to increase the local density of hoverflies. Further work is necessary to establish the importance of flower density in enhancing the control of pest populations.
Influence of crop edges on movement of generalist predators: a diffusion approach
Authors: Bommarco Riccardo , Fagan William F. 
Published: March 2003

Abstract1 Diffusion models were applied to recapture data for the generalist predator Pterostichus cupreus (Coleoptera: Carabidae) moving between two adjacent crop habitats (perennial ley and annual barley) first excluding, and then including, terms in the model quantifying the influences of edges on beetle movements.2 Adult beetles were released at the centre of experimental 3 × 3 m plots that overlapped the edge separating perennial ley (mixed perennial crop of grass and clover) and annual barley crops, both early and later in the growing season.3 Mathematical description of the data improved when the attractive or repulsive effects of habitat edges on dispersal were considered in the model.4 Early in the season, when a sharp habitat edge was present, P. cupreus beetles appeared ‘attracted’ to ley.5 Diffusion rates were consistently higher in barley than in ley early in the season, and vice versa late in the season. These patterns were probably linked to variation in prey availability.6 Despite the risk of experiencing food limitation in the annual crop, our analyses suggest that these beetles regularly move from ley into the early barley habitat and then continue to disperse within the barley, providing opportunities for enhanced biological control of pest species.
A field experiment on the effectiveness of spiders and carabid beetles as biocontrol agents in soybean
Authors: Vichitbandha Patchanee , Wise David H. 
Published: March 2003

Abstract1 Spiders and carabid beetles are abundant generalist predators that prey upon insect pests of soybean. A field experiment was conducted to determine the impact of spiders and carabids on soybean yield. Prior to planting, three 7 × 7 m plots were fenced in order to reduce spider and carabid immigration. Carabids that emerged within the plots were not removed, but spiders that ballooned into these predator‐reduction plots or that entered by climbing the fence were removed by pitfall trapping and searching the vegetation. Three unmanipulated, unfenced plots served as the control treatment.2 Densities of spiders on soybean vegetation, and activity‐densities of spiders and carabids determined by pitfall trapping, were c. 75% lower in the spider‐carabid reduction treatment than in control plots. Despite clear differences between treatments in numbers and activity of these major generalist predators, the weight of soybeans harvested did not differ between control and spider‐carabid reduction plots.3 Paralleling the absence of an effect of predator reduction on soybean yield was the absence of any significant difference between treatments in densities of whiteflies (Aleyrodidae), leafhoppers (Cicadellidae), thrips (Thysanoptera), Lepidoptera larvae and herbivorous Coleoptera.4 Our experiment provides no evidence that spiders and carabid beetles at ambient densities affect soybean yield. Low populations of pest species or low predation pressure on soybean pests by spiders and carabids at the ambient densities of this experiment could be responsible for this result.
Climate change and the outbreak ranges of two North American bark beetles
Authors: Williams David W. , Liebhold Andrew M. 
Published: March 2003

Abstract One expected effect of global climate change on insect populations is a shift in geographical distributions toward higher latitudes and higher elevations. Southern pine beetleDendroctonus frontalisand mountain pine beetleDendroctonus ponderosaeundergo regional outbreaks that result in large‐scale disturbances to pine forests in the south‐eastern and western United States, respectively. Our objective was to investigate potential range shifts under climate change of outbreak areas for both bark beetle species and the areas of occurrence of the forest types susceptible to them. To project range changes, we used discriminant function models that incorporated climatic variables. Models to project bark beetle ranges employed changed forest distributions as well as changes in climatic variables. Projected outbreak areas for southern pine beetle increased with higher temperatures and generally shifted northward, as did the distributions of the southern pine forests. Projected outbreak areas for mountain pine beetle decreased with increasing temperature and shifted toward higher elevation. That trend was mirrored in the projected distributions of pine forests in the region of the western U.S. encompassed by the study. Projected outbreak areas for the two bark beetle species and the area of occurrence of western pine forests increased with more precipitation and decreased with less precipitation, whereas the area of occurrence of southern pine forests decreased slightly with increasing precipitation. Predicted shifts of outbreak ranges for both bark beetle species followed general expectations for the effects of global climate change and reflected the underlying long‐term distributional shifts of their host forests.