bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specificity of constitutive and induced resistance: pigment glands influence mites and caterpillars on cotton plants
Authors: Agrawal Anurag A. , Karban Richard 
Published: October 2003

AbstractCotton plants contain suites of phytochemicals thought to be important in defense against herbivores, some of which are localized in pigment glands which contain gossypol and other terpenoid aldehydes. The simple genetic basis for the expression of these glands has led to the development of near‐isogenic glanded and glandless genotypes. Glands may also be phenotypically induced by herbivory. We determined the consequences of constitutive and induced gland expression on two types of herbivores, spider mites (cell content feeders) and noctuid caterpillars (leaf chewers).Induction of glands was strongly dependent on the density of attackers. Spider mite herbivory on cotyledons (1) increased the density (but not total number) of glands on cotyledons linearly, (2) increased the density and total number of glands on the first true leaf linearly, and (3) affected the density and total number of glands on the second true leaf non‐linearly, compared to controls. Neither constitutive nor induced expression of glands affected mite population growth. An equal reduction of mite population size on induced glanded and glandless plants (50%) relative to uninduced controls indicated that factors other than glands were associated with induced resistance to mites. Constitutive gland expression had a strong negative impact on caterpillar performance, reducing growth by 45%. Induced resistance to caterpillars was three times stronger in glanded genotypes than in glandless genotypes, indicating that factors associated with induced resistance to caterpillars are strongly associated with glands. Three cotton varieties were highly variable in their constitutive and induced resistance to mites and caterpillars.Thus, defense of cotton plants against herbivores can be roughly categorized as constitutive and inducible factors associated with terpenoid aldehyde containing pigment glands that are effective against caterpillars, and factors not associated with glands that are effective against mites.
Orientation behaviour of the predatory hemipteran Perillus bioculatus to plant and prey odours
Authors: van Loon Joop J.A. , de Vos Eline W. , Dicke Marcel 
Published: October 2003

AbstractThe pentatomid predator P. bioculatus responded by positive odour‐conditioned anemotaxis when exposed to airborne volatiles emitted by potato plants damaged by Colorado potato beetle larvae, whereas intact potato plants and non‐feeding larvae as odour sources failed to elicit anemotaxis. Walking tracks of adult predators had higher values of straightness and upwind fixation when odours emanating from mechanically damaged plants were encountered than tracks registered in response to air carrying volatiles from intact plants, but these parameters returned to control values within 1–2 h after damage was caused. In contrast, air led over plants damaged by beetle larvae elicited orientation responses at least 3 hours after feeding damage ceased. The combination of chemical data on headspace composition, olfactory sensitivity established in electro‐antennogram studies and behavioural data presented here imply a role of sesquiterpenoid plant volatiles as odorous cues eliciting attraction of this predator to damaged potato plants.
Physical features of grass leaves influence the placement of eggs within the plant by the Hessian fly
Authors: Kanno H. , Harris M.O. 
Published: October 2003

AbstractHessian fly eggs are more likely to be found on adaxial rather than abaxial surfaces of wheat leaves. These leaf surfaces differ in their physical features: the adaxial side of the leaf has parallel grooves and ridges while the abaxial side is relatively smooth. We used leaf models to investigate the relationship between Hessian fly egglaying and these physical features. When both sides of a green paper leaf model were treated with a wheat leaf extract, but only one side of the model was scored with parallel grooves, the grooved side received more eggs than the smooth side. As the number of grooves per surface increased from 0 to 10, eggs per model increased. When grooves and the wheat leaf extract were tested together and separately, the grooves significantly increased egg numbers in the presence, but not the absence, of wheat extract. In contrast, wheat extract increased egg numbers both in the absence and presence of grooves. Molding techniques were used to recreate the physical features of the adaxial and abaxial leaf surfaces of five grasses. For four of the grass genotypes (a triticale, two common wheats, and a durum wheat), patterns of egglaying on real leaves and molded models were similar, i.e., adaxial leaf surfaces and adaxial molded models were preferred over abaxial leaf surfaces and abaxial models. On the fifth grass, oat, preferences for the adaxial side of real leaves and for adaxial models were not as obvious. We conclude that the adult female Hessian fly obtains information about the leaf surface through her tactile and/or kinesthetic senses and uses this information when making egglaying decisions.
Host‐plant selection by insects – a theory based on ‘appropriate/inappropriate landings’ by pest insects of cruciferous plants
Authors: Finch S. , Collier R.H. 
Published: October 2003

AbstractSeven hypotheses, including the ‘Resource Concentration Hypothesis’ and the ‘Enemies Hypothesis’, have been put forward to explain why fewer specialist insects are found on host plants growing in diverse backgrounds than on similar plants growing in bare soil. All seven hypotheses are discussed and discounted, primarily because no one has used any of them to produce a general theory of host plant selection, they still remain as hypotheses. However, we have developed a general theory based on detailed observations of insect behaviour. Our theory is based on the fact that during host plant finding the searching insects land indiscriminately on green objects such as the leaves of host plants (appropriate landings) and non‐host plants (inappropriate landings), but avoid landing on brown surfaces, such as soil. The complete system of host plant selection involves a three‐link chain of events in which the first link is governed by cues from volatile plant chemicals, the central link by visual stimuli, and the final link by cues from non‐volatile plant chemicals. The previously ‘missing’ central link, which is based on what we have described as ‘appropriate/inappropriate landings’, is governed by visual stimuli. Our theory explains why attempts to show that olfaction is the crucial component in the central link of host plant selection proved intractable. The ‘appropriate/inappropriate landings’ theory is discussed to indicate the type of work needed in future studies to improve our understanding of how intercropping, undersowing and companion planting can be used to optimum effect in crop protection. The new theory is used also to suggest how insect biotypes could develop and to describe why pest insects do not decimate wild host plants growing in ‘natural’ situations.
Genetic analysis of resistance to azinphosmethyl in the pear psylla Cacopsylla pyri
Authors: Buès R , Toubon J.F. , Boudinhon L. 
Published: October 2003

AbstractLaboratory selection with azinphosmethyl had little effect on the chemical resistance in Cacopsylla pyri strains, in comparison to the original wild populations. The resistance ratio relative to a susceptible strain varied from 10‐ to 40‐fold depending on the generation studied. Crosses between two resistant strains and the susceptible strain show resistance to be autosomally inherited and semi‐dominant in expression. Backcrosses between F1 and the susceptible strain were unable to distinguish unabigously between monogenic and polygenic inheritance. In the majority of experiments, however, the overall dose‐response relationship for backcross progeny was consistent with a single gene hypothesis. Additional bioassays showed azinphosmethyl‐resistant strain to cross‐resistant monocrotophos and phosmet, but not carbamates, pyrethroids, amitraz or the organophosphates chlorpyrifos and mevinphos.
Life history comparison between two competitive Aleochara species in the cabbage root fly, Delia radicum: implications for their use in biological control
Authors: Fournet S. , Stapel J.O. , Kacem N. , Nenon J.P. , Brunel E. 
Published: October 2003

AbstractThis study evaluates the efficacy of Aleochara bilineata Gyll and Aleochara bipustulata L. (Coleoptera: Staphylinidae) as biological control agents against the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae). Biological and demographic characters are documented and comparisons made between the two species. The following results were obtained:

The reproductive potential and longevity of A. bipustulata females are significantly higher than those of A. bilineata. These differences are correlated with the biology and ecology of the hosts of both species.
Under laboratory conditions the rate of increase (rm) of both staphylinids species is significantly higher than that of the pest and their major competitor Trybliographa rapae West. (Hymenoptera:Figitidae). This may indicate that A. bilineata and A. bipustulata can be effective biological control agents.
Aleochara bilineata appears to be the most interesting biological control agent against D. radicum, because of its higher rate of increase, higher host specificity and host acceptance, and a development time which is well synchronised with that of its host. With its higher competitive ability, a population of A. bilineata may increase even if competition occurs. However, A. bipustulata presents interesting biocontrol characteristics, but the best strategy may be only to use the potential of its natural populations.
The role of chemical cues in host finding and acceptance by Callosobruchus chinensis
Authors: Ignacimuthu S. , Wäckers F.L. , Dorn S. 
Published: October 2003

AbstractWe studied the response of female Callosobruchus chinensis to chemical cues emitted by cowpea seeds at different stages of bruchid infestation (uninfested, egg carrying, L1‐, and L4‐infested). Olfactory attractiveness was determined in Y‐tube olfactometer assays by testing individual seed categories against either clean air or uninfested seeds. Oviposition preferences between uninfested and infested seeds were determined in petri‐dish choice‐experiments. The olfactometer assays revealed that weevils discriminate between seeds containing different stages of developing bruchids on the basis of olfactory cues. While odors from uninfested and egg‐carrying seeds acted as attractants, odors from L1‐ and L4‐infested seeds failed to induce a positive response by the bruchids. When given a choice between uninfested and infested seeds in the olfactometer, weevils preferred uninfested seeds over L1‐ and L4‐infested seeds, but failed to distinguish between uninfested and egg‐carrying seeds. In the oviposition experiment as well, bruchids showed a distinct preference for uninfested seeds when offered in combination with L1‐ and L4‐infested seeds. This experiment further showed a reduced acceptance of egg carrying seeds. Our results indicate that C. chinensis females use chemical information during both host searching and host acceptance. Volatiles from uninfested or egg carrying seeds act as attractants, while deterrence increases as development of bruchid immature stages progresses.
Effects of carbaryl exposure on the last larval instar of Xanthocnemis zealandica– fluctuating asymmetry and adult emergence
Authors: Hardersen Sönke 
Published: October 2003

AbstractFluctuating asymmetry (FA), a measure of developmental stability, has been suggested as a monitoring tool for environmental pollution. Aquatic pollution events are often transitional and the level of FA in populations exposed to such incidents has not yet been investigated. Research into the morphological effects of transitional pollution also provides a tool to elucidate the timing and duration of any ‘window of opportunity’ for the determination of FA in the developing organism. The present study was undertaken to investigate if exposure of the last instar of the damselfly Xanthocnemis zealandica (McLachlan) (Zygoptera: Coenagrionidae) to different levels of insecticidal stress resulted in different levels of FA in the wings of the adult insects and if adult emergence was altered by different concentrations of pesticide. Three concentrations of carbaryl (40 ppb, 2 ppb and 0.1 ppb) and a control were used. The emergence success of the damselflies was not affected by any treatment, but the insecticide had a stimulatory effect on the developing larvae. Exposure of the last instar of X. zealandica to carbaryl at 40 ppb had no consistent effect on FA in metric traits and increased FA in meristic traits compared with the control. Segregation of the emerged adults into two groups revealed more details about the ‘window of opportunity’ in the meristic traits. Larvae which had already completed more than half of their development when the experiment started did not show significant differences in the level of FA. In contrast, damselflies which were exposed for more than half of the final instar showed a clear difference in their levels of FA. The greater difference in the latter group was mainly caused by a decrease of FA in the controls rather than by an increase in the treatment. These data suggest that the ‘window of opportunity’ for the determination of the level of FA of the meristic traits in damselfly wings closes approximately halfway through the final larval instar.
Host‐stage selection by Trybliographa rapae, a parasitoid of the cabbage root fly Delia radicum
Authors: Neveu Nathalie , Krespi Liliane , Kacem Nabila , Nénon Jean‐Pierre 
Published: October 2003

AbstractHost‐stage selection by Trybliographa rapae Westwood (Hymenoptera: Figitidae) was studied in choice and no‐choice experiments in the laboratory. The parasitoid was able to reproduce in first, second, and third instars of the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae), but oviposition occurred more frequently in third instars when all three developmental stages were offered simultaneously. Oviposition in third instars increased the rate of development of offspring and their body size, but did not alter sex ratio. Results are discussed in the light of predictions made by the theory of optimal host acceptance.
Realized heritability of behavioral responsiveness to an oviposition deterring pheromone in the azuki bean weevil Callosobruchus chinensis
Authors: Tanaka Yoshinari 
Published: October 2003

AbstractArtificial selection was conducted to reduce the behavioral responsiveness of female bruchid beetles, Callosobruchus chinensis, to the oviposition deterring pheromone excreted by conspecific females. Significant responses to selection were observed after two generations of selection. Realized heritability was estimated as 0.052 ± 0.017 from cumulative responses regressed on cumulative selection differentials. These results indicate that this pheromone communication system has significant additive genetic variance needed for its evolution.
Host regulation by the aphid parasitoid Aphidius ervi: the role of teratocytes
Authors: Falabella Patrizia , Tremblay Ermenegildo , Pennacchio Francesco 
Published: October 2003

AbstractThe biochemical profile and metabolism of Acyrthosiphon pisum (Harris) (Homoptera, Aphididae) are markedly altered and redirected in response to parasitization by the endophagous braconid Aphidius ervi Haliday (Hymenoptera, Braconidae). In the present study, the role played in the host regulation process by teratocytes, cells deriving from the dissociation of the embryonic membrane of the parasitoid, is taken into consideration. The protein synthesis activity of these cells of embryonic origin is analysed in vitro and an essential characterization of those proteins de novo synthesized and released in the incubation medium is provided. Teratocytes, obtained by dissecting parasitized host aphids, 3, 4 and 5 days after parasitoid oviposition, were incubated in vitro and, at the end of the incubation period, were separated from the medium for SDS‐PAGE analysis of both cellular and secreted proteins. Various cellular proteins were more abundant as the time between parasitization and teratocyte collection increased. Furthermore, two proteins, showing an approximate molecular mass of 15 kD (p15) and 45 kD (p45) respectively, were abundantly secreted in the incubation medium by 5 day‐old teratocytes. Incubations in presence of 35S radiolabelled amino acids indicated that p15 and p45 are both synthesized by A. ervi teratocytes. The amino acid composition of these two proteins was similar to that reported for other insect proteins with a demonstrated nutritional function. The p45 protein was found to be glycosylated. A tentative physiological model describing the host regulation role played by different parasitoid‐derived factors is proposed.
The role of plant chemical cues in determining host preference in the generalist aphid parasitoid Aphidius colemani
Authors: Storeck A. , Poppy G.M. , van Emden H.F. , Powell W. 
Published: October 2003

AbstractThe host preference behaviour of the generalist aphid parasitoid Aphidius colemani was investigated using a Y‐tube olfactometer. Female A. colemani showed a preference for the host‐plant complex on which they had been reared, even though the same aphid host was involved, demonstrating a host plant preference. This preference was not evident when the parasitoids were dissected from their mummies prior to adult emergence. Host plant preference exhibited during host selection appeared to be induced by chemical cues encountered on the mummy case at the time of emergence, but preferences could be changed by subsequent foraging experiences. It is concluded that plant chemical cues play a major role in determining initial preferences through a process of emergence conditioning but that learning processes, involving cues encountered during oviposition in or contact with the host, can modify these initial preferences.
Influence of host distribution on foraging behaviour in the hyperparasitoid wasp, Dendrocerus carpenteri
Authors: Chow Andrew 
Published: October 2003

AbstractThe foraging behaviour of Dendrocerus carpenteri Curtis (Hymenoptera: Megaspilidae), an ectophagous hyperparasitoid of aphidiine wasps inside mummified aphids, was examined in the laboratory with an experimental system consisting of broad bean, Vicia faba L, the pea aphid, Acyrthosiphon pisum Harris, and a primary parasitoid, Ephedrus californicus Baker. Pea aphids parasitised by E. californicus often disperse from their feeding sites (or off host plants) before dying and mummifying. Response of female hyperparasitoids to host distribution was evaluated at two spatial scales. At the first scale, behaviour of hyperparasitoids was examined on individual plants with different densities of hosts. At the second scale, habitat complexity and host location were manipulated in large foraging cages containing several plants. I show that patterns of density‐dependent hyperparasitism can result from the foraging behaviour of D. carpenteri. However, dispersal of parasitised aphids may not reduce the incidence of hyperparasitism if hyperparasitoids systematically search the habitat.
Effects of wax bloom variation in Brassica oleracea on foraging by a vespid wasp
Authors: Eigenbrode Sanford D. , Rayor Linda , Chow Jennifer , Latty Paul 
Published: October 2003

AbstractForaging by individual Polistes dominulus (Christ) (Hymenoptera: Vespidae) was observed and compared on Brassica oleracea L. plants that differed in surface wax bloom. Twenty‐six wasps, previously trained to forage on plants for 4th instar Trichoplusia ni (Walker), were presented in the greenhouse with mixtures of plants with normal wax bloom or genetically reduced wax bloom, and on which T. ni caterpillars had been placed. During foraging, the wasps were observed to slip significantly more frequently from the leaf surfaces of normal‐wax bloom plants than from reduced‐wax bloom plants (129 vs 63 occurrences) and to retrieve significantly fewer pieces of caterpillar after attack on normal‐wax bloom plants (151 vs 223 pieces). Altogether the wasps retrieved 333 caterpillar pieces from reduced‐wax bloom plants and 248 pieces from normal‐wax bloom plants. Despite these differences, the number of caterpillars attacked and killed did not differ between the two wax bloom types (116 vs 121), nor did handling time for individual attacks (time from contact with prey until prey piece was carried to the nest) (170±12.5 s vs 180±10.5 s). Thus, in contrast with previous reports for smaller predators, wax bloom variation in B. oleracea did not influence the effectiveness of P. dominulus as a predator of T. ni.
Performance of leaf beetle larvae on sympatric host and non‐host plants
Authors: Ballabeni Pierluigi , Rahier Martine 
Published: October 2003

AbstractStudies asking the ability of insects to utilize novel host plants often use novel hosts that are allopatric with the insect population under investigation. However, since the outcomes of species interactions are often site‐specific, such studies cannot tell us whether a plant would actually be used by a given insect population if the plant grew sympatrically with it. We therefore performed a quantitative genetics experiment to analyse the performance of larvae of the leaf beetle Oreina elongata Suffrian (Coleoptera: Chrysomelidae, Chrysomelinae) on two host and three non‐host plants, collected from a site where insects and plants co‐occur in the Western Alps. When raised on the non‐host Petasites albus (L.), larvae were able to survive equally well as on the two hosts, Adenostyles alliariae (Gouan) and Cirsium spinosissimum (L.), whereas they did not survive on the two other non‐hosts, Peucedanum ostruthium (L.) and Rumex alpinus L. On P. albus, growth rate was slightly lower and development time slightly longer than on the two hosts. We found a genotype by environment interaction only for growth rate but not for development time and survival. However, the shape of the reaction norms of growth rates suggests that it is unlikely that selection could favour the inclusion of P. albus into the host range of the study population.