bluuebunny/crossref_metadata_2025_split huggingface dataset:
Greenhouse and field evaluations of transgenic canola against diamondback moth, Plutella xylostella, and corn earworm, Helicoverpa zea
Authors: Ramachandran Suresh , Buntin G. David , All John N. , Raymer Paul L. , Stewart C. Neal 
Published: October 2003

AbstractCanola (Brassica napus L.) cultivars Oscar and Westar, engineered with a Bacillus thuringiensis (Bt) cryIA(c) gene, were evaluated for resistance to lepidopterous pests, diamondback moth, Plutella xylostella L. (Plutellidae) and corn earworm, Helicoverpa zea (Boddie) (Noctuidae) in greenhouse and field conditions. In greenhouse preference assays conducted at vegetative and flowering plant stages, transgenic plants recorded very low levels of damage. A 100% diamondback moth mortality and ≈90% corn earworm mortality were obtained on transgenic plants in greenhouse antibiosis assays. The surviving corn earworm larvae on transgenic plants had reduced head capsule width and body weight. Mortality of diamondback moth and corn earworm were 100% and ≈95%, respectively, at different growth stages (seedling, vegetative, bolting, and flowering) on the transgenic plants in greenhouse tests. In field tests conducted during 1995–1997, plots were artificially infested with neonates of diamondback moth or corn earworm or left for natural infestation. Transgenic plants in all the treatments were highly resistant to diamondback moth and corn earworm larvae and had very low levels of defoliation. Plots infested with diamondback moth larvae had greater damage in both seasons as compared with corn earworm infested plots and plots under natural infestation. After exposure to defoliators, transgenic plants usually had higher final plant stand and produced more pods and seeds than non‐transgenic plants. Diamondback moth injury caused the most pronounced difference in plant stand and pod and seed number between transgenic and non‐transgenic plants. Our results suggest that transgenic canola could be used for effective management of diamondback moth and corn earworm on canola.
Melon aphid performance on chrysanthemum as mediated by cultivar, and differential levels of fertilization and irrigation
Authors: Bethke James A. , Redak Richard A. , Schuch Ursula K. 
Published: October 2003

AbstractPopulation parameters of the melon aphid, Aphis gossypii Glover, were compared for insects grown on six cultivars of chrysanthemum, Dendranthema grandiflora Tzvelev (‘Fontana’, ‘Iridon’, ‘Pink Lady’, ‘Splendor’, ‘White Diamond’, and ‘White View Time’) fertilized with 3 different levels of nitrogen (80, 160 and 240 mg N/l) and 2 levels of irrigation (high 300 ml and low 210 ml every other day). Fecundity, longevity, and survivorship of aphids were significantly affected by the cultivar treatment, but were not affected by irrigation or fertilizer treatments or by any combination of interactions among cultivar, fertilizer and irrigation. Significantly fewer aphids survived on the cultivar ‘Pink Lady’ (populations reduced by 20.8%) than any other cultivar examined. Intrinsic rates of increase (rm), finite rates of increase (R0), and population doubling times (DT) for aphids were different among fertilizer levels and cultivars, but were not different among irrigation levels. There were no significant fertilizer by irrigation interaction effects upon rm, R0, or DT. The highest rate of fertilizer applied (240 mg N/liter) adversely affected the intrinsic rate of increase of melon aphids; however, aphid intrinsic rate of increase was weakly correlated with foliar soluble protein levels (r= 0.989, P = 0.0954). Foliar soluble protein levels were not associated with fertilization treatment. Melon aphids perform consistently better on the cultivars ‘White Diamond’, ‘Fontana’, and ‘Splendor’, relative to those aphids growing on ‘Iridon’, ‘Pink Lady’, or ‘White View Time’. In general, melon aphids performed best on ‘White Diamond’ and poorest on ‘Pink Lady’.
Probing and feeding characteristics of the greenhouse whitefly in association with host‐plant acceptance and whitefly strains
Authors: Lei H. , Tjallingii W. F. , van Lenteren J. C. 
Published: October 2003

AbstractHost‐plant and whitefly strain effects and their interactions on the probing and sap feeding of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), have been investigated in this study using the DC‐EPG (Electrical Penetration Graph) technique. Whiteflies generally displayed fewer but longer probes on highly acceptable cucumber than on less acceptable tomato. Both whitefly strains, the T(omato)‐strain and the C(ucumber)‐strain, showed a significantly lower number of phloem phases on cucumber than on tomato. However, the duration of total phloem phases achieved by either of the whitefly strains on these two host plants was not significantly different. These data indicate that a more continuous phloem feeding has occurred on cucumber plants. Indeed, the percentage of phloem feeding time after the first sustained phloem phase (longer than 15 min) was higher on cucumber for the C‐strain whiteflies. When comparing these two whitefly strains, the T‐strain whiteflies probed less frequently but longer than the C‐strain whiteflies did on both host plants. Also, the T‐strain whiteflies displayed a longer duration of total phloem phases on tomato. An interaction between the whitefly strain and plant effects was detected on a parameter, which showed that whiteflies probed significantly longer before reaching the first phloem phase on the host plants that had been previously experienced. In conclusion, both plant species and whitefly strains affect whitefly's probing and feeding behaviour, though plant effects are much stronger.
Response of five insect herbivores to multiple allelochemicals under fluctuating temperatures
Authors: Stamp Nancy E. , Osier Tod L. 
Published: October 2003

AbstractAnalysis of the combined effects of allelochemicals on insect herbivores is useful because there may be adverse additive or even synergistic effects. Analysis of the simultaneous effects of temperature and alleochemicals is also necessary because these factors may interact. We examined the effects of three allelochemicals found in tomato (chlorogenic acid, rutin and tomatine) and thermal regime (21:10 °C and 26:15 °C, representing spring and summer respectively) on five insect herbivores (a Solanaceae specialist, Manduca sexta, and the polyphagous Heliothis virescens, Pseudoplusia includens, Spodoptera frugiperda and Trichoplusia ni). There were allelochemical interactions and thermal regime‐allelochemical interactions for all species, and so the patterns were complex. In some cases, paired allelochemicals or the combination of three allelochemicals showed adverse additive effects on insect performance. But that was not always the case, and there were only a few examples of synergism. Negative effects of the allelochemicals were sometimes, but not always, damped by the cooler thermal regime. Comparing the growth rates of the five species in this study with those of a previous study (a total of seven species) revealed five patterns. For two of three pairs of closely‐related species, the paired species had distinctly different patterns. For example, for H. virescens, tomatine prevented development and chlorogenic acid slowed growth, whereas for Helicoverpa zea, tomatine just slowed growth and the phenolics had little effect. The specialist Manduca sexta had a pattern that was midway between patterns of the generalists; it was not the most tolerant of the allelochemicals.
Response to orphaning in two Neotropical termites: Armitermes euamignathus and Embiratermes festivellus
Authors: Costa‐Leonardo Ana Maria , Soares Helena Xavier , Barsotti Raquel Cristina 
Published: October 2003

AbstractIn this paper we examine the potential of the termites Armitermes euamignathus Silvestri: 1901 and Embiratermes festivellus (Silvestri, 1901) (Isoptera, Termitidae, Nasutitermitinae) to produce neotenics experimentally. Three nests of the mound‐building termite A. euamignathus, from the Brazilian cerrado, had their primary queens removed in August 1994. After 12 months, only one mound survived; it had a normal appearance. In this healthy, orphaned colony we found the primary king, six physogastric nymphoid female replacement reproductives, two ergatoid female replacement reproductives, 46 nymphs, several presoldiers, soldiers, workers, larvae and many eggs. These data show that neotenics in A. euamignathus may originate from both workers and nymphs, but nymphoids are produced in larger numbers. The biometric study of nymphs and nymphoids suggests that these brachypterous neotenics were derived from third instar nymphs after a single moult or from four instar nymphs after a reduction of wing bud length. A piece of an E. festivellus nest with some third instar nymphs, soldiers and workers was kept under laboratory conditions. After 12 months, the whole experimental subcolony was examined and appeared to contain two pigmented nymphoid females, two pigmented nymphoid males, only one larva, seven nymphs of the same instar, 148 workers, five soldiers and many eggs. These results also indicate the capacity of the termite E. festivellus to produce nymphoid neotenics. These neotenic females were laying eggs, but they were not physogastric after a year, unlike some nymphoids of the same species collected from natural colonies.
The involvement of acetylcholinesterase in resistance of the California red scale Aonidiella aurantii to organophosphorus pesticides
Authors: Levitin Emanuel , Cohen Ephraim 
Published: October 2003

AbstractLaboratory toxicity bioassays using chlorpyrifos (Dursban) confirmed the notion that development of resistance is responsible for widespread failures to control the California red scale, Aonidiella aurantii (Mask.) by applying organophosphorus (OP) compounds in citrus groves in Israel. Higher Vmax values of acetylcholinesterase (AChE) activity (9–13 fold) were measured in resistant strains collected from the field as compared to a susceptible line. No differences were found with respect to Km values using acetylthiocholine iodide as a substrate, or degree of inhibition (expressed by IC50 values) by the OP compounds chlorpyrifos‐oxon and paraoxon and the carbamate pirimicarb. We suggest that resistance of the California red scale is caused by excess of AChE molecules able to bind and thus scavenge inhibitory OP compounds. This scavenging mechanism related to AChE may be similar in other insect species where elevated levels of detoxifying esterases were implicated in conferring OP resistance.
Optimal timing of the production of sexuals in bumblebee colonies
Authors: Beekman M. , Lingeman R. , Kleijne F. M. , Sabelis M. W. 
Published: October 2003

AbstractColonies of annual eusocial insects often produce only workers until they switch to the production of sexuals (queens and males). This switch from the ergonomic phase to the reproductive phase has been modelled by Macevicz & Oster (1976). Their model predicts that the production of sexuals should take place approximately one generation (one brood developmental period) before resources are depleted in order to maximise the number of sexuals. Bumblebees, however, produce sexuals early (relative to colony lifetime) when resources are still abundant and thus the model of Macevicz & Oster does not hold for these insects.Here we show that Macevicz & Oster's prediction hinges critically on their assumption that the egg laying rate of the queen is a function of the foraging effort of the workers. This assumption does not hold for bumblebees, where queens lay eggs at a constant rate. Taking this feature of bumblebees into account the model predicts early production of sexuals, since it does not pay to produce more workers and collect more resources than needed to raise sexuals.
Generation specific life history traits of winged Sitobion avenae
Authors: Helden A. J. , Dixon A. F. G. 
Published: October 2003

AbstractWhen reared under constant conditions from egg hatch the proportion of offspring of Sitobion avenae (F.) (Aphididae: Macrosiphini) that developed into winged individuals declined from the second to fourth generation. The winged individuals produced in these three generations showed a progressive decrease in their wet and dry weights and an increase in the length of their largest embryo with generation. The trend in winged individual production and also the trends in their size and reproductive strategy appear to be programmed and are similar to the generation specific strategies that have been described in other species of aphid.
Performance and seasonal abundance of the neotropical brown stink bug, Euschistus heros nymphs and adults on a novel food plant (pigeonpea) and soybean
Authors: Panizzi Antônio R. , Oliveira Émerson D. M. 
Published: October 2003

AbstractPigeonpea, Cajanus cajan (L.) Millsp. (Leguminosae) was found as a novel food plant of the neotropical brown stink bug, Euschistus heros (F.), in Paraná State, Brazil. Laboratory studies indicated nymphs performing better when fed on immature pods of soybean, Glycine max (L.) Merrill (Leguminosae), than on immature pods of pigeonpea. Female nymphs required 1.7 d less to complete development and tended to have a lower mortality on soybean (17.5%) than on pigeonpea (25.0%). At emergence, fresh body weight was greater on soybean than on pigeonpea. Adult E. heros performed better on soybean than on pigeonpea. After 120 d, ≈35% of adults were alive on soybean and 30% on pigeonpea; 93.3% of females oviposited on soybean, and 73.3% on pigeonpea, with an oviposition delay of ≈17 days on pigeonpea compared to soybean. Fecundity was ≈63% greater on soybean than on pigeonpea, and adult body weight gain for females and males at different ages was ≈6–36% greater on soybean than on pigeonpea. E. heros colonized soybean during January–March, from the pod‐setting and filling stages (R3–R6) to maturity (R7–R8), and pigeonpea during April–June. These results indicate that E. heros has expanded its host range to pigeonpea in Brazil; pods of this plant are suitable food, and can support the insect during autumn‐early winter, after soybean harvest, and before it enters into partial hibernation.
The cowpea aphid, Aphis craccivora, host plant odours and pheromones
Authors: Pettersson J. , Karunaratne S. , Ahmed E. , Kumar V. 
Published: October 2003

AbstractOlfactometer experiments were conducted with apterae and alatae of the cowpea aphid, Aphis craccivora, Koch (Hom.:Aphidoidea). The occurrence of density dependent related pheromones and odour response to their host plant Vigna unguiculata was studied. Apterae responded with positive anemotaxis to air passed over both small groups of apterae and alatae (≤10 individuals) but negatively to air that passed over a bigger group (≥20 individuals). Alatae responded in the same way to groups of apterae but were repelled by alatae independent of the size of the group applied as odour source in the olfactometer, except when exposed to air passing ten alatae feeding on cowpea leaves. This may be due to interaction between aphid pheromones and host plant odour. Both apterae and alatae showed a general attraction to green plants and were also able to distinguish between other host plants and cowpea, which was the original host of the aphid clone used in the experiments. When attacked by aphids, the cowpea plant responded with a temporal increase in attractivity that reached a maximum after 48 h and had disappeared after one week.
Monitoring spruce web‐spinning sawflies Cephalcia spp.: the correlation between trap catches and soil sampling
Authors: Battisti A. , Rodeghiero M. 
Published: October 2003

AbstractThe web‐spinning sawflies of the genus Cephalcia Panzer (Hymenoptera, Pamphiliidae) are usually monitored by sampling prepupae in soil and by catching adults with visual traps, including yellow sticky traps. However, adult catches have never been compared with the actual density of prepupae. In this paper, a relationship is presented between the catches of Cephalcia arvensis Panzer adults (mostly males) and the number of prepupae ready to emerge (pronymphs) in an outbreak area of spruce forest (Picea abies Karsten) in the Southern Alps (Asiago, Italy). A significant linear relationship between the logarithmic estimates of the two variables was found. The model includes a spatial autoregressive parameter because adult catches were spatially correlated. The relationship allows to know whether or not the defoliation threshold of 20 pronymphs/m2 in spring samples is being exceeded, based on the number of adults caught on yellow sticky traps (defoliation threshold of 14.26 adults/trap). The variance not explained by the model is probably due to the flight behaviour of adult males, to the low precision of the estimated pronymph density at low population levels, and to the attraction of males by few females that are trapped and remain alive. The model was validated in a large monitoring programme of undamaged alpine spruce forests and allowed detection of two newly infested stands out of six that were considered at risk of defoliation, because of adult catch exceeded the threshold. Low adult catches were always associated with absence of defoliation. Our conclusion is that trapping of adult sawflies is a cheaper and easier monitoring method than prepupae sampling in the soil. This makes earlier detection of outbreaks possible, and consequently more efficient control.
Comparative histopathology of some Diptera and Crustacea of aquatic alpine ecosystems, after treatment with Bacillus thuringiensis var. israelensis
Authors: Rey D. , Long A. , Pautou M.P. , Meyran J.C. 
Published: October 2003

AbstractSpecies of Diptera (larval Culicidae, Chironomidae and Simuliidae) and Crustacea (cladoceran adults) that are representative of the fauna of aquatic alpine ecosystems are routinely treated with Bacillus thuringiensis var. israelensis (Bti) for mosquito control. The toxicity of Bti on these organisms was investigated. Bioassays indicated that Bti used at the concentration for operational field application is deleterious to all dipteran species, but not to Cladocera. Histopathological observations reveal that, in all cases, the midgut epithelium is affected by Bti treatment. However, the vulnerability of epithelial cells to the microbial insecticide is different from one cell‐type to another, clear cells being more vulnerable than dark cells. Because of the concentration of clear cells within the anterior midgut of dipteran larvae, this region appears to be the first to show symptoms of intoxication through enhancing a natural process of cell turnover. The relative importance of such a vulnerable region in the midgut of dipteran larvae may account for the general efficacy of Bti to these species. Its harmlessness to Cladocera may be correlated to the relative scarcity of clear cells and their patchy distribution along the whole midgut together with important cellular renewal capacity of the epithelium.
Characterization of digestive proteases in the weevil Aubeonymus mariaefranciscae and effects of proteinase inhibitors on larval development and survival
Authors: Ortego F. , Farinós G.P. , Ruíz M. , Marco V. , Castañera P. 
Published: October 2003

AbstractThe major digestive proteinase activities of a new sugar beet pest, Aubeonymus mariaefranciscae Roudier (Coleoptera: Curculionidae), were characterized. Both larvae and adults of A. mariaefranciscae were found to use a complex proteolytic system for protein digestion based on at least trypsin‐, chymotrypsin‐, elastase‐, cathepsin D, leucine aminopeptidase‐, carboxypeptidase A‐ and carboxypeptidase B‐like activities. An azocaseinolytic activity at pH 5.0–7.0 was identified, that was not affected by specific inhibitors and activators, making its classification in any of the mechanistic classes established not possible. According to this proteolytic profile, several serine proteinase inhibitors were tested in vitro and in vivo to establish their potential as resistance factors against A. mariaefranciscae. Larvae fed from neonate to pupation on diets containing 0.2% (w/w) soybean Bowman‐Birk trypsin‐chymotrypsin inhibitor, soybean Kunitz trypsin inhibitor, turkey egg white trypsin inhibitor, or lima bean trypsin inhibitor endure lower survival rates and display significant delays in the developmental time to pupation and to adult emergence. Interestingly, the most significant levels of mortality (about 90%) occurred with larvae fed on diets containing a combination of two or three inhibitors, suggesting a synergistic toxicity.
Antifeedant effects of sublethal dosages of imidacloprid on Bemisia tabaci
Authors: Nauen Ralf , Koob Birgit , Elbert Alfred 
Published: October 2003

AbstractThe effects of sublethal dosages of the chloronicotinyl insecticide imidacloprid on different strains of the tobacco whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), have been studied after leaf dip and systemic application. All bioassays were performed with the insecticide susceptible strain, SUD‐S, and two Spanish biotypes, ALM‐2 and LMPA‐2, both resistant to conventional insecticides and with a lower susceptibility towards imidacloprid. Honeydew, excreted by all strains feeding on treated and untreated cotton leaf discs was quantified by photometric analysis of its carbohydrate content. EC50‐values for the depression of honeydew excretion in female adults after systemic application of imidacloprid were calculated at 0.037 ppm, 0.027 ppm and 0.048 ppm for strains SUD‐S, ALM‐2 and LMPA‐2, respectively, indicating no significant differences between strains in feeding behaviour throughout an 48 h testing period. Depending on the strain these EC50‐values were 150‐ to 850‐times lower than LC50‐values calculated for mortality in the same bioassay. Starvation tests revealed mean survival times of >48 h for female adults placed on agar without leaf discs, indicating that sublethal dosages of imidacloprid which caused antifeedant responses, were probably not covered in common 48 h systemic bioassays, used to monitor resistance to imidacloprid. Effects of sublethal dosages on honeydew excretion after leaf dip application seem to be minor. In choice situations with systemically treated and untreated leaf discs in a single container, female adults of B. tabaci showed a clear preference for the untreated leaf discs. However, when using leaf discs treated by painting the surface with imidacloprid in the same bioassay, feeding activities on treated and untreated leaf discs were not significantly different. The results of the present study demonstrate the antifeedant properties of imidacloprid on B. tabaci, which might play an essential role after soil application or seed treatment under field conditions.