bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical and chemical plant characters inhibiting the searching behaviour of Trichogramma chilonis
Authors: Romeis J. , Shanower T.G. , Zebitz C.P.W. 
Published: October 2003

AbstractSeveral plant characters are known to affect the searching behaviour and parasitization efficiency of Trichogramma spp. (Hymenoptera: Trichogrammatidae). In this study, plant characters contributing to the low Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) egg parasitism levels on pigeonpea (Cajanus cajan (L.) Millspaugh) were investigated. The efficiency of T. chilonis on pigeonpea was dependent on the plant structure on which the host eggs were found. In a cage experiment, more than 55% of eggs placed on leaves were parasitized, while 1% of eggs on calyxes and no eggs on pods were parasitized. In a filter paper bioassay, parasitoids were deterred by acetone and hexane surface extracts from pigeonpea pods but showed no response to water extract. The searching behaviour of the parasitoids was not affected by different solvent extracts from the surface of pigeonpea leaves. In a four‐armed airflow olfactometer, T. chilonis was repelled by volatiles from pigeonpea pods but showed no response to volatiles derived from hexane extract of pod surfaces. Volatile infochemicals and hexane surface extracts from pods of two wild Cajanus species, C. scarabaeoides (L.) Thours and C. platycarpus (Bentham) van der Maesen, were similarly deterrent to T. chilonis. The movement of the parasitoids on pigeonpea pods and calyxes was inhibited by long trichomes and wasps were trapped by sticky trichome exudates. Parasitoids walked significantly faster on leaves than on pods. The walking speed on both pods and leaves increased significantly after washing with hexane. The results presented in this paper show that the plant growth stage and the plant structures preferred by H. armigera for oviposition are the least suitable for T. chilonis, contributing to the low parasitoid efficiency on pigeonpea.
Fecundity and juvenile survival of Bembidion lampros and Tachyporus hypnorum
Authors: Petersen Mette K. 
Published: October 2003

AbstractFecundity and development from first instar larvae to adult beetles were studied for Bembidion lampros Herbst (Coleoptera; Carabidae) and Tachyporus hypnorum F. (Coleoptera; Staphylinidae). Both species reproduce in arable fields, where they are known to contribute to the natural control of cereal aphids. They are univoltine and have similar life cycles and development times. T. hypnorum females laid approximately 3 times more eggs than B. lampros females. Relative lifetime fecundity of B. lampros was very low with an average of 10 eggs per female. Based on the time where half of the populations had dispersed from the overwintering sites into an arable field B. lampros started egg‐lay 100°D (°C>9) and T. hypnorum 200°D (°C>3) after dispersal. Mortality in the juvenile stages was found to be an important factor in the population dynamics of both B. lampros and T. hypnorum. The survival from first instar larvae to adults was on average 34% for B. lampros independent of soil type, 21% for T. hypnorum developed in sandy soil and 49% when developed in clayey soil under semi‐field conditions. Enlargement of B. lampros and T. hypnorum populations to increase the natural control of aphids during their establishment in cereal fields may be possible if the conditions for juvenile development are improved.
Potential application of the entomopathogenic fungus, Nomuraea rileyi, for control of the corn earworm, Helicoverpa armigera
Authors: Tang Li‐chang , Hou Roger F. 
Published: October 2003

AbstractThe entomopathogenic fungus, Nomuraea rileyi, caused 90.5–100% mortality in fourth‐instar larvae of the corn earworm, Helicoverpa armigera, when applied at 107 conidia/ml to corn silks, and leaves of soybean, tomato and chrysanthemum. The LT50 was 5.9–6.7 days. The fifth‐instar larvae showed a mortality of 94.6% on soil with 20% water content, and 41.7% on 10% water content when the soil surface was sprayed with 108 conidia/ml suspension. Five fungicides, eight insecticides and nine herbicides, which are commonly used in corn fields, were evaluated for inhibition to conidial germination by a paper disk test. Among them, only two fungicides, viz., maneb and propineb, were highly inhibitory, while insecticides and herbicides examined were not inhibitory to the fungus. Field applications of N. rileyi conidial suspension to neonate larvae were found to be as effective as 40.46% carbofuran (EC) at 800‐fold dilution in controlling corn earworm based on marketable ears. It is thus suggested that N. rileyi has potential to be a microbial control agent for this insect.
Treatment of adult Coleoptera with a chitin synthesis inhibitor affects mortality and development time of their progeny
Authors: Elek Jane A. 
Published: October 2003

AbstractA group of insect growth regulators, the chitin synthesis inhibitors (CSIs), are being more widely used as many insects have become resistant to broad‐spectrum insecticides. This study investigated the mode of action of one CSI, particularly looking at the delayed effect of treating adult insects on the survival and development of their progeny. The study describes the responses of adult stored grain beetles Sitophilus oryzae (L.) (Curculionidae) and Rhyzopertha dominica (F.) (Bostrichidae) to wheat treated with chlorfluazuron. For both species, wheat treated with chlorfluazuron reduced progeny survival at a constant rate from 1 day to 8 weeks after it had been treated. There was a direct, negative concentration‐time relationship between the treatment of the adults with chlorfluazuron‐treated wheat and the survival and developmental rate of their progeny. Adults that were pre‐exposed for one or more weeks before oviposition to wheat treated with chlorfluazuron had significantly lower progeny survival than adults that were not pre‐exposed. The EC95 values were 16‐fold higher for R. dominica and 40‐fold higher for S. oryzae from assays without pre‐exposure, than with pre‐exposure. Pre‐exposure of R. dominica with 0.1 mg kg−1 and of S. oryzae with 0.4 mg kg−1 of chlorfluazuron reduced progeny survival by 95%. Higher concentrations of chlorfluazuron produced a reduction in mean population developmental time of several days. These findings have important implications for bioassays of CSIs, since pre‐exposure of the adults can significantly reduce the numbers of F1 progeny. Therefore standard bioassays may seriously underestimate the efficacy of the CSI being assayed.
Instar‐dependent hemocyte changes in Pieris brassicae after parasitization by Cotesia glomerata
Authors: Bauer Evelyne , Trenczek Tina , Dorn Silvia 
Published: October 2003

Abstract Cotesia glomerata L. (Hymenoptera: Braconidae) is a parasitoid of early instar larvae of Pieris brassicae L. (Lepidoptera: Pieridae). Late instars of P. brassicae can more often overcome parasitization by hemocytic encapsulation of C. glomerata eggs. Short‐term hemocyte responses to parasitization were examined in third and fourth instar larvae of P. brassicae. Total and differential hemocyte counts did not differ between parasitized and unparasitized host larvae. A rapid, but temporary decrease of total hemocyte as well as plasmatocyte numbers was observed immediately after oviposition. Numbers of hemocytes adhering to tissues were shown to be the same in untreated, wounded and parasitized P. brassicae larvae by tracing hemocytes with monoclonal antibodies as markers. The in vitro spreading ability of hemocytes from unparasitized third and fourth instar larvae was lower than that of the last instar's; parasitization, however, had no influence on hemocyte spreading. We therefore suggest that the higher parasitization success of C. glomerata in earlier instars of P. brassicae is mainly due to the low spreading ability of the hemocytes. Abbreviations: ACS – anticoagulant saline; BSA – bovine serum albumin; DABCO – 1,4‐diazabicyclo‐[2,2,2]‐octane; DHC – differential hemocyte count; FITC – fluorescein isothiocyanate; GR – granular cells; LPS – lipopolysaccharide; mAb – monoclonal antibody; OE – oenocytoids; PL – plasmatocytes; PRO – prohemocytes; PS – Pieris saline; PVP – polyvinylpyrrolidone; TBS – tris‐buffered saline; THC – total hemocyte count.
Studies of the growth, development and reproductive performance of the aphid Myzus persicae on artificial diets containing potato glycoalkaloids
Authors: Fragoyiannis D. A. , McKinlay R. G. , D'Mello J. P. F. 
Published: October 2003

AbstractPeach potato aphids Myzus persicae (Sulzer) (Homoptera: Aphididae) were reared on artificial diets containing the steroidal glycoalkaloids (GAs) α‐solanine and α‐chaconine in concentrations lower or similar to those observed in potato leaves. The adults proved to be susceptible to high concentrations (80–160 mg GA /100 ml of diet) showing reduced fecundity, diet uptake and increased mortality in comparison to controls. Ingestion of these artificial diets by nymphs delayed maturity and decreased the intrinsic rate of natural increase. GAs in low concentrations marginally stimulated the reproductive performance and diet acceptability of this aphid. The possibility of GAs exerting a defensive role in potato plants against aphids is discussed.
Nematode parasitism in a Danish drosophilid community: further evaluation of the disproportionate parasitism hypothesis
Authors: Hardy Ian C. W. , Gillis Jaklien E. M. 
Published: October 2003

AbstractThe nematodes Parasitylenchus diplogenus and Howardula aoronymphium (Allantonematidae) are parasites of drosophilids (Diptera). Nematodes were found in 3/14 drosophilid species sampled in Danish woodlands: Drosophila phalerata Meigen (3.5% parasitism) was parasitized by H. aoronymphium and D. obscura Fallén (0.5%) and D. subobscura Collin (2.1%) by P. diplogenus. Parasitism was generally rare, and few drosophilid species parasitized, compared to elsewhere in Europe. Parasitism was positively correlated with relative host abundance both within Denmark and across communities, suggesting that species diversity is promoted by a disproportionately high parasitism of more common host species. The prevalence of H. aoronymphium, but not P. diplogenus, parasitism is positively related to temperature across communities.
Development of pheromone‐based mating disruption for control of the eye‐spotted bud moth, Spilonota ocellana
Authors: McBrien H. L. , Judd G. J. R. , Borden J. H. 
Published: October 2003

AbstractThe potential for pheromone‐based mating disruption of eye‐spotted bud moth (ESBM), Spilonota ocellana (Denis & Schiffermüller) (Lepidoptera: Tortricidae), in apple orchards in the Okanagan Valley of British Columbia was examined in small‐plot trials. In a preliminary experiment, treatment of the orchard atmosphere with a 99:1 blend of Z8‐tetradecenyl acetate (Z8‐14:OAc) and Z8‐tetradecenyl alcohol (Z8‐14:OH) completely inhibited captures of male ESBM in pheromone‐baited traps, but treatment with Z8‐14:OAc alone did not. Therefore, all subsequent trials used the two‐component blend as a disruptant. Mean catches of male ESBM in traps baited with 0.1, 1, 10, or 20 mg of 99:1 Z8‐14:OAc and Z8‐14:OH were significantly reduced (81–97%) in pheromone‐treated plots relative to similar traps placed in control plots. In both control and treated plots, there was a significant positive relationship between trap bait dose and trap catch. In pheromone‐treated plots, this suggests that high doses of trap baits over‐ride the camouflage effect of disruption or overcome the effect of sensory adaptation and habituation. The number of virgin‐female baited traps capturing at least one male ESBM was reduced by 96%, and mating of virgin females on mating tables was reduced by 95% in plots treated with the two‐component pheromone. The total amount of Z8‐14:OAc released from pheromone disruption dispensers during the latter field trials was estimated to average 6.4 g ha−1 over 11 days or 26.4 mg ha−1 h−1. The low levels of Z8‐14:OH released from disruption dispensers could not be estimated by GC analysis. Dispensers loaded with a 99:1 blend of Z8‐14:OAc and Z8‐14:OH were highly attractive to males in baited traps, indicating that they have the potential to induce false trail following.
Endogenous and exogenous factors affecting parasitism of gypsy moth egg masses by Ooencyrtus kuvanae
Authors: Hofstetter Richard W. , Raffa Kenneth F. 
Published: October 2003

AbstractFactors affecting the orientation, reproduction, and sex ratio of the egg parasitoid Ooencyrtus kuvanae Howard were examined. Adult females were attracted to airborne volatiles from the egg mass and accessory gland of the primary host, the gypsy moth Lymantria dispar L. Visual cues also affected host selection. Background colors against which egg masses were placed affected oviposition preference. In the absence of egg masses, color variation did not affect wasp behavior. Light is required for parasitism by O. kuvanae. The age and density of both the host and parasitoid affected wasp reproduction and sex ratios. Older egg masses issued relatively fewer wasps and higher proportions of males than did young egg masses. Likewise, wasp reproduction and the proportion of females declined with wasp age. Larger egg masses produced more wasps and lower proportions of males than did smaller egg masses. The number of offspring per female, and the proportion of female offspring, were inversely related to wasp density. Implications to biological control of the gypsy moth and parasitoid ecology are discussed.
Inter‐ and intra‐ species differences in plants as hosts to Tyria jacobaeae
Authors: Tinney G. W. , Hatcher P. E. , Ayres P. G. , Paul N. D. , Whittaker J. B. 
Published: October 2003

AbstractThe effect of three food plants, Senecio jacobaea L., Senecio vulgaris L. and Tussilago farfara L., and rust infection of two of them on the performance and host choice of Tyria jacobaeae L. was assessed. The nitrogen content of healthy and infected food plants was measured.Larvae reared on S. vulgaris had a lower relative consumption index and higher efficiency of conversion of ingested food than those reared on the other two species. These differences were correlated with the higher nitrogen content of S. vulgaris compared to T. farfara and S. jacobaea. Larvae reared on T. farfara were significantly smaller at pupation than those reared on the other species. In both larval and adult choice tests between healthy plants of the three species, S. jacobaea was always the preferred host plant. Adults completely avoided T. farfara in oviposition choice tests.Infection of S. vulgaris with Coleosporium tussilaginis (Pers) Lev. had no effect on larval performance. Infection of S. vulgaris with Puccinia lagenophorae Cooke. caused differences in larval performance. Infection of T. farfara with C. tussilaginis had a detrimental effect on larval performance: larvae were smaller, fed for longer and had lower growth rates than those reared on healthy T. farfara. Healthy T. farfara had a higher leaf nitrogen content than the infected T. farfara. In choice tests against healthy leaves, larvae avoided leaves of both S. vulgaris and T. farfara infected with C. tussilaginis. Larvae and adults showed no preference between S. vulgaris leaves infected with P. lagenophorae or healthy leaves.In the field, factors such as plant size may be important in dictating adult and larval preference for a particular host plant species. Rust infection of some species influenced larval performance and host choice, demonstrating the importance of studying multitrophic aspects of plant – insect interactions.
Onset of a decline in the quality of sugar beet as a host for the aphid Myzus persicae
Authors: Kift N.B. , Dewar A. M. , Dixon A. F. G. 
Published: October 2003

AbstractThe results presented in this paper suggest that sugar beet became less suitable as a host for aphids after late June and early July, when the plants were at the 10–12 leaf stage. This was indicated by a faster rate of aphid mortality and greater incidence of dark stomach deposits after this time. Increased aphid mortality coincided with a change in physiology of sugar beet leaves from being net sinks to sources of assimilate. Aphids which fed on older leaves, irrespective of plant age, suffered greater mortality than those feeding on young heart leaves. The incidence of dark deposits in aphid stomachs associated with this mortality was greater on outer than on inner leaves of old, mature and young plants. It is suggested that the incidence of the dark deposit is an indicator of declining plant quality. The consequences of this for the spread of beet yellowing viruses are discussed.
Partitioning two‐ and three‐trophic‐level effects of resistant plants on the predator, Nabis roseipennis
Authors: Pfannenstiel R.S. , Yeargan K.V. 
Published: October 2003

AbstractTwo‐ and three‐trophic‐level effects of resistant soybean plants on the development and fecundity of the predator Nabis roseipennis Reuter (Hemiptera: Nabidae) were determined. The nabids, like many hemipteran predators, feed on plants as well as arthropod prey. The life history traits of N. roseipennis when feeding on Pseudoplusia includens (Hübner) (Lepidoptera: Noctuidae) fed the resistant soybean cultivar PI 229358 or the susceptible Cobb' and while exposed to these resistant and susceptible soybean cultivars or a no‐plant control were determined. Nymphal survival of N. roseipennis was unaffected by either prey or plant treatment. Development time was extended and fecundity of N. roseipennis was reduced by feeding on prey fed the resistant plant but not by exposure to resistant soybean plants. Thus, three‐trophic‐level effects of the resistant cultivar PI 229358 on prey quality were more important than two‐trophic‐level effects of direct plant feeding on development and fecundity of N. roseipennis. Consistency of these results with those of other predatory hemipterans and the potential impact of diet composition on the effects of resistant plants are discussed.
Copulation behaviour of Lygocoris pabulinus under laboratory conditions
Authors: Groot Astrid T. , van, der Wal Erna , Schuurman Antje , Visser J. Hans , Blommers Leo H.M. , van Beek Teris A. 
Published: October 2003

AbstractAs a prerequisite to the elucidation of the sex pheromone of the green capsid bug Lygocoris pabulinus (L.), we studied the bug's reproductive development and behaviour. When kept under long‐day conditions (L18:D6) at 25 °C, both males and females start to copulate 4 days after the final moult. Second matings occur in some females, even on consecutive days. The premating period is 10 min on average and copulation lasts 1 to 2 min. At long range, when males are attracted to traps baited with live females, we did not observe a specific calling position of the females. At short range, a characteristic courtship behaviour of the females was not observed either. Males showed a characteristic vibration of the abdomen, which was repeated several times before copulation. This behaviour can be used as a bioassay to test potential sex pheromone compounds.
The circadian rhythm of sperm release in the codling moth, Cydia pomonella
Authors: Giebultowicz Jadwiga M. , Brooks Nicole L. 
Published: October 2003

AbstractThe release of sperm bundles from testes to the vas deferens is controlled by a circadian clock in several moth species. We investigated the pattern of sperm release in the codling moth, Cydia pomonnella L. (Lepidoptera: Tortricidae). Sperm release in the codling moth follows a two‐step rhythm in light‐dark cycles: sperm is released from the testis before lights‐off, remains in the vas deferens during the dark phase and is transferred to the seminal vesicles after lights‐on. This rhythm continues in constant darkness indicating that it has a circadian nature. The release of sperm is asynchronous in moths held in constant light. In contrast to previously investigated moths, constant light has no adverse effects on the male reproductive capacity in the codling moth.
Volatile cues used by the parasitoid, Aphytis melinus, for host location: California red scale revisited
Authors: Morgan David J.W. , Hare J. Daniel 
Published: October 2003

Abstract Aphytis melinus DeBach (Hymenoptera: Aphelinidae) is a biological control agent of diaspidid scale insects. The parasitoid has a narrow host range but its hosts are polyphagous. We determined the source of volatile cues the wasp uses to locate its few host species when those hosts occur on more than one host plant species. We addressed four questions in regard to the use of volatile cues in host location of California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae): (1) Does A. melinus use volatile cues to assist in host location? (2) Are these cues innately recognized or learned? (3) Are cues produced by female California red scale, or from other sources? (4) Are the cues specific to the host or host plant? These questions were tested through the use of a Y‐tube olfactometer. Female A. melinus used volatile cues to orient toward both infested and uninfested host plant material. Wasps learned these cues by associating odors from the host plant with host presence. They had no innate preferences for scale insect or host plant volatile stimuli. Contrary to previous studies, we found no evidence of orientation toward the female‐produced sex pheromone of California red scale, nor to volatile cues from the attacked host stage. Wasps given experience with scale insects growing on lemon fruit subsequently oriented toward lemon and orange fruit and leaves. The scale species with which the wasp was given experience did not affect this preference. Wasps given experience with California red scale growing on squash did not orient toward infested lemon fruit. The host ranges of the parasitoid and its hosts are used to explain the adaptive value for the evolution of learned rather than fixed responses to cues used in foraging behavior.
Differential ovicidal and larvicidal resistance to benzoylureas in the codling moth, Cydia pomonella
Authors: Sauphanor Benôit , Brosse Veronique , Monier Catherine , Bouvier Jean C. 
Published: October 2003

AbstractFrench populations of the codling moth Cydia pomonella (L.) (Lepidoptera, Tortricidae), a major pest in apple and pear orchards, have developed resistance to different classes of insecticides including the benzoylurea diflubenzuron, a chitin synthesis inhibitor. Ovicidal tests performed on two susceptible strains and one strain selected for its resistance to diflubenzuron revealed the same order of magnitude in resistance ratios to this compound (30‐fold) and two other benzoylureas teflubenzuron and flufenoxuron (22‐ and 11‐fold, respectively). Field rates of these three compounds induced a 45–55% decrease in hatching in the resistant strain, compared to over 90% in the susceptible insects. Despite a 52‐fold ovicidal resistance ratio to the juvenile hormone analog fenoxycarb, this compound induced a 85% decrease in hatching in the resistant strain. Conversely the newly hatched larvae of the resistant strain exhibited a 45 000‐, 33‐ and 2.1‐fold resistance ratio to diflubenzuron, teflubenzuron and flufenoxuron, respectively. The latter value was not significant, and the field rate of flufenoxuron killed over 97% of the resistant larvae while diflubenzuron had no effect. This lack of relationship between ovicidal and larvicidal resistance may be due to different transport properties together with differential enzymatic metabolization. Our results may limit the validity of substitution instars, which approach is frequently used for resistance monitoring. More importantly for resistance management, the resistance of different target instars to each compound has to be considered when establishing control strategies.