bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proximate and ultimate factors influencing oviposition site selection by endoparasites on conifer seed cones: two sympatric dipteran species on larch
Authors: McClure Martha , Quiring Dan T. , Turgeon Jean J. 
Published: October 2003

AbstractA three‐year field study was carried out to investigate proximate and ultimate influences on oviposition site selection by Strobilomyia laricis Michelsen and S. viaria (Huckett) (Diptera: Anthomyiidae), two sympatric flies whose maggots develop in young seed cones of eastern larch, Larix laricina (Du Roi) K. Koch. In 1990 and 1991, when the cone crop was light, the egg distribution at peak egg lay was uniform for both species, suggesting that females of both species recognized and avoided oviposition sites previously occupied by conspecifics. Strobilomyia viaria, which emerged two weeks after S. laricis, also avoided ovipositing on seed cones occupied by S. laricis. Thus, the egg distribution of S. laricis determined, to a large extent, the distribution of S. viaria. In 1992, a year when the cone crop was very light, and egg densities per cone were high, ovipositing females of both species apparently preferred cones with few versus many conspecifics. Host size also influenced oviposition site selection in S. laricis and S. viaria. In two of three years, both species selected longer cones for oviposition. A significant proportion of the variation in egg densities of both species was attributable to trees but not to cone density per tree. Egg distribution was influenced occasionally by cone phenology and cone location within tree crowns.During the only year when egg densities per cone were high, preference for unoccupied oviposition sites resulted in increased larval survival, and in one of the other two years, preference for longer cones resulted in greater weight by the end of larval development, suggesting that oviposition preferences were adaptative. Cone phenology (at the time of oviposition) and position (crown aspect or level) had no significant influence on larval weight. Our results are consistent with the hypothesis that oviposition preference and offspring performance should be closely linked when females oviposit on the host in which their offspring must complete development.
Plant penetration by pea aphids (Acyrthosiphon pisum) of different plant range
Authors: Wilkinson T.L. , Douglas A.E. 
Published: October 2003

AbstractPlant penetration by the stylets of six clones of the pea aphid, Acyrthosiphon pisum, on Vicia faba (acceptable to all clones) and Pisum sativum (acceptable to 3/6 clones) was investigated by the DC electrical penetration graph technique. In a 10 h recording period, 93% of 144 aphids exhibited sustained feeding on phloem sap. Significant interclonal differences were observed for the incidence of potential drops (indicative of brief punctures of plant cells) and the duration of waveform E1 (insect salivation into a sieve element). In addition, the total duration of the sieve element phase and the duration of completed ‘bouts’ of sustained feeding differed between the two test plants, in a fashion varying between clones. However, these differences could not be related to the acceptability of plants to the different aphid clones. The duration of the stylet pathway phase preceding the first sustained feeding on phloem sap did not vary significantly with either aphid clone or plant. It is concluded that the resistance of P. sativum to certain A. pisum clones does not arise from factors impeding either stylet penetration through the plant tissues or the maintenance of feeding from the sieve elements. It is proposed that host plant affiliation of A. pisum may be mediated primarily by specific olfactory or gustatory cues, before the aphid initiates stylet penetration of the plant.
Experimental induction and termination of non‐reciprocal reproductive incompatibilities in a parahaploid mite
Authors: Johanowicz Denise L. , Hoy Marjorie A. 
Published: October 2003

AbstractTwo experiments were conducted to investigate the relationship between rearing temperatures, the presence or absence of Wolbachia endosymbionts, and non‐reciprocal reproductive incompatibility in inbred lines of the parahaploid phytoseiid mite Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae).Heat‐treated females crossed with infected males reared at room temperature produced few eggs and high proportions of shriveled eggs. No female progeny were produced. The reciprocal cross was normal. A second experiment showed that the incompatible cross from the first experiment could be made compatible if the infected line was heat‐treated and those males crossed with the original heat‐treated females. Furthermore, a new incompatibility was induced in a formerly compatible cross when the newly heat‐treated females were crossed with males from their base colony. Heat‐treatment was correlated with the loss of Wolbachia in both experiments. Wolbachia may thus affect non‐reciprocal reproductive incompatibility in M. occidentalis, and may produce a unique incompatibility phenotype in this parahaploid species, including both reduced numbers of male progeny and a lack of female progeny.
Performance and feeding behavior of Ceratitis capitata: comparison of a wild population and a laboratory population
Authors: Bravo Iara Sordi Joachim , Zucoloto Fernando Sérgio 
Published: October 2003

AbstractExperiments were carried out to test the performance and some aspects of feeding behavior in two populations of Ceratitis capitata (a population reared in the laboratory for 16 years, i.e., approximately 160 generations, and a wild one obtained from infested coffee, Coffea arabica grains). Two types of food were used in the experiment: an artificial yeast diet used for laboratory rearing and papaya (Carica papaya), a natural host of the fly. The performance parameters tested were percent emergence, time to emergence, adult female size, and egg production during the pre‐oviposition phase (first five days of adult life). The behavioral aspects tested were food preference by newly hatched larvae, induction, estimated ingestion of the two diets, whether the larvae placed on one diet stayed there or moved to the other diet, and acceptance of food for oviposition. The results indicated that the performance of the wild population was superior when the flies fed on papaya, whereas the performance of the laboratory population was similar with the two diets; the wild population showed a strong preference for papaya in all choice experiments, whereas the laboratory population showed no diet preference; the females of the wild population only oviposited on pieces of papaya that had not been peeled, and did not oviposit in the artificial diet; the females of the laboratory population oviposited indiscriminately on unpeeled and peeled papaya and on the artificial diet.
Experimental studies to evaluate spray applications of a mycoinsecticide against the rice grasshopper, Hieroglyphus daganensis, in northern Benin
Authors: Thomas M. B. , Blandford S. , Gbongboui C. , Lomer C. J. 
Published: October 2003

AbstractThree experiments were conducted to examine the effects of spray applications of a mycoinsecticide against the rice grasshopper, Hieroglyphus daganensis, in northern Benin. The experiments were designed to expand on previous evaluation studies and contribute to a better understanding of the overall impacts of mycoinsecticide applications. The first experiment showed that acquisition of spores from the spray residue had a significant effect on mortality rate and a greater single influence on mortality than direct contact with spores from the spray aerosol. The second and third experiments revealed the mycoinsecticide to have sub‐ and pre‐lethal effects, causing a significant reduction in per capita feeding rate and increasing susceptibility to predation. The significance of these results for the overall impact of spray applications and for development of comprehensive evaluation methods are discussed.
Variable growth and reproduction response of the spruce shoot aphid, Cinara pilicornis, to increasing ozone concentrations
Authors: Holopainen Jarmo K. , Kössi Sonja 
Published: October 2003

AbstractSpruce shoot aphid, Cinara pilicornis Hartig (Homoptera: Lachnidae), is an aphid species that has shown enhanced performance on trees exposed to SO2 or mixtures of air pollutants, whereas results with ozone have been contradictory. Using a 4‐week chamber fumigation experiment, we tested how different population dynamic parameters of aphids are affected by ozone (O3). Mean relative growth rate (MRGR), development time and reproduction rate of C. pilicornis were determined using 7h day‐time O3 concentrations of 0, 40, 80 and 160 ppb. Development period from birth to reproductive stage was fastest at 80 ppb during early shoot elongation, while reproduction and intrinsic rate of population increase was not significantly affected by ozone concentration. There was a significant negative correlation between ozone concentration and the MRGR of first instar nymphs in the third fumigation week. In feeding test performed on seedlings after fumigation, the MRGR was reduced on shoots which had been exposed to 80 ppb O3. The results suggest that elevated O3 concentration during early shoot elongation period may stimulate population development of C. pilicornis, but on maturing shoots, high O3 concentration has a negative effect on aphid performance. This might be due to accelerated ageing of O3 exposed shoots.
Herbivore‐induced emissions of maize volatiles repel the corn leaf aphid, Rhopalosiphum maidis
Authors: Bernasconi Marco L. , Turlings Ted C. J. , Ambrosetti Lara , Bassetti Paolo , Dorn Silvia 
Published: October 2003

AbstractWhen maize plants, Zea mays L., are mechanically damaged and the damaged sites are treated with caterpillar regurgitant, the plants will release a specific blend of volatiles. It is known that these volatiles can be attractive to natural enemies of herbivores. We hypothesise that the plant volatiles constitute part of the induced plant defence and that herbivores will be affected by the odours as well. In laboratory and semi‐field studies this hypothesis was tested for the aphid Rhopalosiphum maidis (Fitch) (Rhynchota, Sternorrhyncha, Aphididae).In a Y‐tube olfactometer significantly more aphids chose the odour of healthy, undamaged maize seedlings when tested against clean air or plants treated with regurgitant. Clean air was chosen more often when tested next to the odour of treated plants. This apparently repellent effect of the odour of treated plants was significant for winged aphids, but not for the wingless aphids.In field experiments aphids were released in the centre of circles of eight potted maize plants. Four plants in each circle were damaged and treated with caterpillar regurgitant while the other plants were left unharmed. At different intervals after aphid release, the number of aphids was counted on each plant. Significantly fewer winged and wingless aphids were found back on treated plants than on healthy plants.We suggest that herbivores may be repelled by the odours because they could indicate that: 1) the plant has initiated the production of toxic compounds; 2) potential competitors are present on the plant; 3) the plant is attractive to parasitoids and predators. Aphids may be particularly sensitive to induced maize volatiles because one of the major compounds emitted by the plant is (E)‐β‐farnesene, which is a common alarm pheromone for aphids. Collections and analyses of the odours emitted by crushed R. maidis confirmed that it too emits (E)‐β‐farnesene when stressed. The results are discussed in context of plant defence strategies and their possible exploitation for the control of pest insects.
Development, survival and fecundity of the urine fly, Scatella (Teichomyza) fusca and predation by the black dumpfly, Hydrotaea aenescens
Authors: Vibe‐Petersen Solveig 
Published: October 2003

AbstractDevelopment, survival and fecundity for Scatella (Teichomyza) fusca Maquart (Diptera: Ephydridae) were studied at 20 ± 1 °C and 85 ± 10% r.h. Mean (± S.E.) developmental times of eggs, larvae and pupae were 4.0 ± 0.06, 14.9 ± 0.19 and 14.6 ± 0.11 days, respectively, the mean (± S.E.) survival of the original egg cohort to the start of larval, pupal and adult stage being 77.2 ± 3.2%, 54.5 ± 2.6% and 47.9 ± 3.5%, respectively. Females and males displayed approximately straight survivorship curves during adult life, implying constant mortality rates. Mean (± S.E.) adult longevity was 41.6 ± 2.98 days for females and 51.2 ± 3.91 days for males. Assuming a stable age distribution the population consisted of 56% eggs, 31% larvae, 6% pupae and 7% adults. Oviposition peaked when females were 25 days old, and the highest reproductive values (RVx) (mean ± S.E.) ranged from 129.1 ± 7.57 to 138.5 ± 6.83 for individuals 17–27 days old. A female deposited a mean (± S.E.) of 614.7 ± 35.9 female eggs over a maximum life span of 93 days. The basic reproductive rate (R0) (mean ± S.E.) was 173.0 ± 14.2 female offspring per female and the intrinsic rate of natural increase of female individuals (r) (mean ± S.E.) was 0.088 ± 0.001 day−1. The mean (± S.E.) generation time (T) was 57.8 ± 0.78 days. In cultures with equal numbers of first instar S. fusca larvae and predacious third instar larvae of Hydrotaea aenescens (synonymous Ophyra aenescens) Wiedemann, mean (± S.E.) survival to the adult stage of S. fusca (16.7 ± 8.8%) was significantly lower than in controls with S. fusca alone (58.3 ± 7.4%). The potential significance of predation by H. aenescens on S. fusca in pig farms is discussed.
Genetic differentiation of groundnut seed‐beetle populations in Senegal
Authors: Sembène Mbacké , Delobel Alex 
Published: October 2003

Abstract Caryedon serratus, the groundnut seed‐beetle, is a major pest of groundnut (Arachis hypogaea), an introduced legume in the subfamily Papilionoideae. Native hosts of C. serratus in Senegal include Bauhinia rufescens, Cassia sieberiana, Piliostigma reticulatum and Tamarindus indica, all of which belong to the legume subfamily Caesalpinioideae.The biology and natural history of C. serratus suggest that it is a candidate for population differentiation via host‐race formation. Evidence for host‐tree associated differentiation in C. serratus would be important for the design of rational pest management practices.To test this possibility, we analyzed the genetic structure of 20 adult collections of C. serratus from six sites in Western Senegal, on its five hosts. Results show a strong differentiation of insects from different host trees, with specimens from C. sieberiana possibly representing a sibling species and insects from B. rufescens a distinct host‐race.
Combined effects of allelochemicals, prey availability, and supplemental plant material on growth of a generalist insect predator
Authors: Weiser L. A , Stamp N. E. 
Published: October 2003

AbstractWe examined the effects of the presence of plant allelochemicals in prey diet, prey availability and supplemental plant material on the growth of the generalist predator Podisus maculiventris (Hemiptera: Pentatomidae). We tested two different nymphal stages of this predator. Third to fourth instar nymphs and fifth instar nymphs were fed a diet of prey (Manduca sexta larvae, Lepidoptera: Sphingidae) without allelochemicals in their diet or prey fed maximal levels of allelochemicals (tomatine, rutin and chlorogenic acid) found in their host plant (Lycopersicon esculentum). The nymphs were fed prey ad libitum, once every three days, or once every five days. They were given either no supplemental plant material or a 2 cm slice of green bean pod (Phaseolus vulgaris). We also conducted another experiment with fifth instar nymphs using the same conditions, except that mean levels of allelochemicals found in the host plant were fed to prey instead of maximal levels and the prey were provided either once a day or once every five days. For all experiments, prey scarcity depressed developmental rate, weight gain and relative growth rate. Overall, there was no negative effect of allelochemicals in the diet of the prey on these variables when predators were supplied with an excess of prey, but allelochemicals in the prey diet negatively affected these predators when prey were scarce. The addition of plant material to the diet of third to fourth instar nymphs did not have any effect on developmental rate, final dry weight, or relative growth rate. However, for fifth instar nymphs, the addition of plant material negatively affected these variables. Thus, the addition of plant material to the diet of the nymphs did not alleviate the negative effects of prey scarcity or allelochemicals in prey diet.
The effect of parasitism by Aphelinus abdominalis and drought on the walking movement of aphids
Authors: Honěk Alois , Jarošik Vojtěch , Lapchin Laurent , Rabasse Jean‐Michel 
Published: October 2003

AbstractThe effect of simulated plant stress and parasitism by Aphelinus abdominalis (Dalman) on the mobility of four species of aphids was investigated. The aphids were placed on water stressed potted plants or on excised leaf segments on dry or moist filter‐paper in Petri dishes. Winter wheat (Triticum aestivum) was infested with Metopolophium dirhodum (Walker), Sitobion avenae (F.) and Rhopalosiphum padi (L.) (segments only), aubergine (Solanum melongena) leaf segments with Macrosiphum euphorbiae (Thomas). The aphids that moved off the plants were removed and their development stage determined at 24‐h (drought‐stressed plants) or 3‐h (leaf segments) intervals. On intact plants, aphid larvae were reluctant to move, and only moved after moulting into adults. On cut leaves, young 1st and 2nd instar larvae were more reluctant to move than 3rd and 4th instar larvae and adults. The numbers moving were initially positively correlated with aphid population density, and in M. euphorbiae occurred mainly during the night. Depending on aphid species and parasitoid age, parasitism by A. abdominalis retarded or accelerated movement, but the differences between young and old larvae and adults persisted after parasitism. A. abdominalis lays male eggs in small hosts and female eggs in large hosts. Consequently, its sex ratio was affected by differential movement of the host aphids of the male and female parasitoids. Old larvae and adult aphids readily moved and carried off female parasitoids, while the small aphids were more likely to remain and give rise to male‐biased sex ratios.
Restricted host range of the weevil Aubeonymus mariaefranciscae, a new sugar‐beet pest
Authors: Marco V. , López‐Olguín J.F. , Ortego F. , Castañera P. 
Published: October 2003

AbstractThe extent of feeding, fecundity and fertility of a new sugar beet pest, Aubeonymus mariaefranciscae Roudier (Coleoptera: Curculionidae), on a range of plants from different families was determined. We have found that the adult weevils were only able to feed and oviposit on two closely related cultivated plants, beet and sugar beet, both subspecies of Beta vulgaris L., suggesting a restricted host range for this curculionid. None of 16 secondary metabolites (widely distributed among plants, and representative of different chemical groups), nor any of 19 non‐host extracts from 13 different families, deterred the adults of this curculionid from feeding on sugar beet. We found a phagostimulatory effect when beet and sugar beet homogenates from various plant tissues were supplied to adult weevils on weeds that they do not feed on. Conversely, no effect was observed when sucrose was provided. These findings suggest that host selection by A. mariaefranciscae adults is due to the presence of an undetermined phagostimulant compound(s) in beet and sugar beet, instead of the recognition of deterrent substances among the non‐host plants.
A portable electroantennogram sensor for routine measurements of pheromone concentrations in greenhouses
Authors: van der Pers J. N. C. , Minks A. K. 
Published: October 2003

AbstractMating disruption using pheromone dispensers is an emerging insect control method in greenhouses in the Netherlands. For routine measurements of the pheromone level in greenhouses a portable and compact device based on electroantennography (EAG) was developed. The instrument was tested in different greenhouses under varying conditions using antennae of males of the noctuid moth Chrysodeixis chalcites. Relative differences in pheromone concentration between greenhouses loaded with pheromone dispensers and control greenhouses could be measured in a reliable way. Changes in pheromone concentration were clearly demonstrated by measurements during the growing season. The advantages of the instrument presented over previously described devices are its true portableness, ease of use and uncomplicated measuring principle. The device can be operated routinely by non‐experts, and many measurements can be made in a short period of time. Preliminary outdoor measurements using antennae of male Cydia pomonella as sensor showed the potential of the instrument for use in the open field. The portable EAG sensor described here may provide a practical means for monitoring pheromone concentration and dispersal from dispensers applied for mating disruption.
Prey finding by larvae and adult females of Episyrphus balteatus
Authors: Bargen Holger , Saudhof Kathrin , Poehling Hans‐Michael 
Published: October 2003

AbstractThe prey‐location behaviour of larvae of Episyrphus balteatus DeG. (Dipt.: Syrphidae) was investigated in two different experimental set‐ups. First instar larvae exhibited directed search over short distances, guided by olfactory cues from aphids, but not from honeydew. However, second and third instars did not respond to aphid‐plant‐complex odours in a 4‐arm‐olfactometer. Aphid extracts, honeydew and sucrose were found to be feeding stimulants for the larvae. The oviposition behaviour of female syrphids was investigated in a series of two‐choice experiments: females were able to evaluate aphid numbers and adjust oviposition rates accordingly, with higher prey numbers eliciting increased oviposition, even when the aphids were removed at the start of the experiment. The presence of conspecific syrphid larvae did not inhibit oviposition when the females were deprived of suitable oviposition sides before the experiments were conducted.
Patterns of mating between two closely related ground crickets are not influenced by sympatry
Authors: Gregory Pamela G. , Remmenga Marta D. , Howard Daniel J. 
Published: October 2003

Abstract Allonemobius fasciatus (De Geer) and A. socius (Scudder) (Orthoptera: Gryllidae) are small ground‐dwelling crickets that meet and hybridize, to a limited extent, in a mosaic contact zone stretching from New Jersey to at least as far west as Illinois. To determine whether short‐range signals such as visual cues, tactile stimulation, or pheromones are important in limiting gene flow between A. fasciatus and A. socius we carried out a study in the laboratory. A male or a female was placed in a cage with an A. fasciatus and A. socius individual of the opposite sex and the outcome, a conspecific or a heterospecific mating, was recorded. Overall, conspecific matings occurred more frequently than heterospecific matings. However, individuals from areas of sympatry were no more likely to mate with a conspecific than were individuals from areas of allopatry. Thus, the challenge posed by a related species has not resulted in a strengthening of positive assortative mating in these crickets.