bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flight behaviour of Encarsia formosa in response to plant and host stimuli
Authors: Guerrieri Emilio 
Published: October 2003

AbstractThe flight behaviour of Encarsia formosa Gahan (Hymenoptera: Aphelinidae), a parasitoid of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) has been studied in response to the following natural components: bean plant (Phaseolus vulgaris L.) infested with T. vaporariorum (PHC, plant host complex), host damaged bean plant from which whiteflies were removed (HDP, host damaged plant), T. vaporariorum third instar larvae (H, host), uninfested bean plant (P, plant) and T. vaporariorum empty pupal cases (EPC, empty pupal cases). A combination of chemical and visual stimuli is necessary in host location from a distance by E. formosa and seems to deeply affect the dispersal of this parasitoid. The presence of host (PHC, H) or of its parts (EPC) led to a substantial increase of oriented flights suggesting the occurrence of host derived chemicals. At a closer range, a combination of visual and chemical stimuli deriving from all the components of the plant host complex elicited the transition flying‐landing and the following landing on the source.
Effects of wind on movement of Diachasmimorpha longicaudata, a parasitoid of tephritid fruit flies, in a laboratory flight tunnel
Authors: Messing R. H. , Klungness L. M. , Jang E. B. 
Published: October 2003

AbstractCohorts of mass‐reared adult female Diachasmimorpha longicaudata (Ashmead), parasitoids of tephritid fruit fly larvae, were released in a laminar air flow wind tunnel to study the effects of air movement on flight and walking behaviors. Wind in the tunnel was cycled on and off at intervals to simulate gusty conditions observed in the field. Wind speed influenced parasitoid movement during both the wind‐on periods and during the calm intervals between gusts. Wind speeds of 0.8 m per second suppressed flight and walking behaviors, while wind speeds of 0.4 m/s stimulated both flight and walking behaviors. There was an exponential increase in the ratio of activity in calm to activity in wind as wind speed increased.
The influence of previous host age on current host acceptance in Trichogramma
Authors: Reznik S. Ya. , Umarova T. Ya. , Voinovich N. D. 
Published: October 2003

Abstract Trichogramma principium Sug. & Sor. females were sequentially offered two portions of the grain moth (Sitotroga cerealella Oliv.) eggs, either young (1‐day old) or old (eggs that had developed 6 days at a temperature of 20 °C). The probability of host acceptance depended not only on current host age, but also on the age of the previously offered host. Particularly, Trichogramma females more often oviposited in old host eggs when previously offered young eggs (35–45% of Trichogramma females laid eggs) compared to females which were sequentially offered two portions of old eggs (15–20% of Trichogramma females laid eggs). In other words, parasitization by Trichogramma was stable even when transferred from young (preferred) to old (usually rejected) eggs. Dissections showed that refusing females had significantly more mature eggs than ovipositing females, independent of host age. Among ovipositing females, wasps provided with young hosts had fewer mature ovarial eggs than wasps provided with old hosts. Supposedly, Trichogramma females offered old hosts require a higher motivation to oviposit and have a correspondingly higher egg load than females offered young (preferred) hosts.
Sex‐allocation behaviour of a solitary ectoparasitoid: effects of host‐patch characteristics and female density
Authors: Gauthier Nathalie , Monge Jean‐Paul , Huignard Jacques 
Published: October 2003

AbstractThe sex‐allocation behaviour of the solitary ectoparasitoid Dinarmus basalis (Hymenoptera: Pteromalidae) was investigated by examining the female's response to two proximal factors: the host‐patch characteristics and the conspecific female density in the patch. The offspring sex‐ratio of single females presented with unparasitised hosts was female biased (approximately three daughters to one son in the progeny) whatever the host density tested. The sex‐ratio in the presence of hosts parasitised by a conspecific 48 h beforehand was male biased. The proportion of male offspring also increased when the number of conspecific females exploiting the patch changed from a single female to a group of females, whatever the group size. No sexual differences in mortality as a result of larval competition on superparasitised hosts were observed. The offspring sex‐ratios observed in response to the host‐patch characteristics were the result of manipulation of the egg fertilisation by the females during the oviposition phase. Thus, the variability of the sex‐ratio in response to an increase in the number of conspecific females in the same patch represented a reduction in egg fertilisation. These results are analysed with regard to the predictions of Local Mate Competition theory and the females' host discrimination ability.
Effects of previous plant infestation on sieve element acceptance by two aphids
Authors: Prado Ernesto , Tjallingii W. Freddy 
Published: October 2003

AbstractProbing behaviour as affected by a previous infestation was studied in two aphid species on their respective host plants. Probing behaviour by Aphis fabae (reported to have beneficial effects when living in colonies) and Rhopalosiphum padi (without known beneficial effects) was studied using the electrical penetration graph (EPG) technique. In A. fabae the main effects were longer and more continuous sap ingestion, and less salivation into sieve elements before sap ingestion. These suggest phloem factors. Nevertheless, mesophyll and non‐vascular tissues are likely to be involved to a lesser extent, as reflected by fewer non‐probing periods before the first phloem phase on previously colonised leaves as compared to clean leaves. Total honeydew production increased on a previously colonised leaf due to the prolonged sap ingestion periods but the excretion rate was not affected, indicating that the ingestion rate remained unaltered. R. padi did not show responses to previous colonisation. It is hypothesized that the changes in probing behaviour are due to changed plant properties, chemical contents of sieve element sap and/or physiological changes induced by the saliva from the colony.
Effects of lectins, CRY1A/CRY1B Bt δ‐endotoxin, PAPA, protease and α‐amylase inhibitors, on the development of the rice weevil, Sitophilus oryzae, using an artificial seed bioassay
Authors: Pittendrigh B.R. , Huesing J.E. , Shade R.E. , Murdock L.L. 
Published: October 2003

AbstractAn artificial maize seed bioassay was developed to evaluate potential resistance factors against the rice weevil, Sitophilus oryzae. Weevils reared in artificial seeds compared to those reared in whole maize seeds: (i) developed faster, (ii) had similar within‐seed developmental mortalities, (iii) were lighter in weight upon emergence and (iv) oviposited the same number of eggs. Using this bioassay we found that E‐64, a cysteine protease inhibitor, decreased the number of emerged adults per seed and delayed within‐seed developmental time, suggesting that the rice weevil utilizes a cysteine protease to digest its dietary protein. Weevils fed inhibitors of trypsin and chymotrypsin, Bowman‐Birk and Kunitz inhibitors respectively, developed normally. Para‐amino‐l‐phenylalanine (PAPA), a non‐protein amino acid implicated as an insect resistance factor in Vigna vexillata, was lethal at dietary levels of 0.2% (w/w) and higher. An extract from Amaranthus caudatus seeds delayed the developmental time of the rice weevil at dietary levels of 0.2% (w/w) and increased mortality at dietary levels of 1.0% (w/w). Several proteins tested, including Griffonia simplicifolia agglutinin II, phytohemagglutinin extract containing common bean α‐amylase inhibitor, pokeweed agglutinin, Bacillus thuringiensis CRY1A/CRY1B endotoxin, and an α‐amylase inhibitor from wheat, had no effect on the rice weevil. The artificial maize seed bioassay was adapted by pelleting the seed for use with an ultrasonic insect feeding monitor to determine the finding activity of rice weevils as they developed from egg hatch to pupation.
Seasonal abundance of the neotropical brown stink bug, Euschistus heros, in overwintering sites, and the breaking of dormancy
Authors: Panizzi Antônio R. , Vivan Lúcia M. 
Published: October 2003

AbstractThe seasonal abundance of the neotropical brown stink bug, Euschistus heros (Heteroptera: Pentatomidae), in overwintering sites in northern Paraná state, Brazil (latitude 23°11′ S, longitude 51°11′ W) was monitored from September 1994 to August 1995. The breaking of dormancy (oligopause) was studied in the laboratory by comparing the feeding activity and reproduction of adults collected in the field under different physiological conditions (i.e., dormant and non‐dormant). No bugs were found in overwintering sites during the summer (December to February) and during early autumn (March). From mid‐autumn to winter (April – August), the number of E. heros captured in these sites gradually increased, decreasing thereafter with the start of spring in September. Dormant and non‐dormant E. heros taken to the laboratory and maintained at 25 ± 1 °C, 65 ± 5% r.h., and L14: D10 photoperiod, and given suitable food (soybean pods or seeds), began feeding immediately. The number of stylet sheaths deposited/day on the food was greater for non‐dormant than for dormant adults. Feeding activity was greater on immature pods than on mature seeds of soybean. Dormant females placed under suitable biotic and abiotic conditions took ca. 2 weeks to start reproduction, in contrast to non‐dormant females, which reproduced immediately.
Effects of natural enemies on relative fitness of Heliothis virescens genotypes adapted and not adapted to resistant host plants
Authors: Johnson M. Tracy , Gould Fred , Kennedy George G. 
Published: October 2003

AbstractWe investigated the potential of two natural enemies of Heliothis virescens (F.) (Noctuidae) to affect its rate of adaptation to tobacco containing Bacillus thuringiensis Berliner toxin. Larval fitness of two laboratory strains of H. virescens, one adapted to B. thuringiensis toxin and one not adapted, was compared on toxic and nontoxic plants, in the presence of the parasitoid Campoletis sonorensis (Cameron) (Ichneumonidae) or the entomopathogenic fungus Nomuraea rileyi (Farlow) Samson. By exposing larvae to plants and enemies for no more than 24 h, we focussed on the behavioral rather than physiological component of their interaction with toxic plants and natural enemies.Parasitism of H. virescens larvae by C. sonorensis during exposure periods of 1–4 h was lower on toxic plants than nontoxic plants and was lower for nonadapted larvae than for toxin‐adapted larvae. Decreased larval feeding damage on toxic versus nontoxic plants, and by nonadapted versus adapted larvae, may explain differences in parasitism, because C. sonorensis locates host larvae using cues from damaged plants. Effects of plant toxicity and larval strain on H. virescens survival were numerically consistent with effects on parasitism, but they were not statistically significant. When mean larval survival is used to estimate fitness of the nonadapted genotype relative to the toxin‐adapted genotype, we find that C. sonorensis is expected to delay adaptation to toxic plants.Percent infection by N. rileyi of H. virescens larvae exposed to fungus‐treated plants for 24 h was greater when plants were toxic, and was greater for nonadapted larvae than toxin‐adapted larvae. There were corresponding decreases in larval survival on toxic compared to nontoxic plants, and of nonadapted compared to adapted larvae. Interaction of effects of plant line and larval strain on survival was significant in the presence of fungus, but not in the absence of fungus, which indicates that the effect of toxic plants on the relative fitness of toxin‐adapted and nonadapted larvae was mediated by fungus. As in the interaction with C. sonorensis, behavior of larvae on plants may explain differences in susceptibility to N. rileyi. Because nonadapted larvae moved more than toxin‐adapted larvae on toxic plants, nonadapted larvae may have been more likely to encounter a lethal dose of conidia. In contrast with C. sonorensis, N. rileyi, which decreased the fitness of the nonadapted genotype relative to the adapted genotype, is expected to accelerate adaptation to toxic plants.
Mechanisms of resistance to Colorado potato beetle in several potato lines and correlation with defoliation
Authors: Horton David R. , Chauvin R.L. , Hinojosa Tonya , Larson Duane , Murphy Clifford , Biever K. Duane 
Published: October 2003

AbstractEight potato (Solanum tuberosum L.) lines and a control (cv. Russet Burbank) were screened for suitability to Colorado potato beetle, Leptinotarsa decemlineata (Say) (Chrysomelidae), and for defoliation levels in the field to determine whether laboratory‐obtained measures of performance are useful for predicting defoliation. Several lines caused reduced larval growth rates and survival compared to the control. Forty‐eight hour weight gains by fourth instar larvae, after adjustment for consumption rates, were reduced on three lines, suggesting that these lines had antibiosis‐like effects. Lines having very low suitability in the laboratory showed very low defoliation levels in the field, whereas lines that were highly suitable in the laboratory tended to suffer extensive defoliation in the field. Correlation analyses suggested that fourth instar growth rates or larval survival rates are useful measures for predicting defoliation in the field.
Significance of penetration and metabolism on topical toxicity of diflubenzuron in Spodoptera littoralis and Spodoptera exigua
Authors: Smagghe Guy , Auda Mahroussa , Van Laecke Kristiaan , Degheele Danny 
Published: October 2003

AbstractToxicity assays indicated that when diflubenzuron (DFB) was topically applied on larvae of the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval), and the beet armyworm, Spodoptera exigua (Hübner), estimated LD50 values were similar, reaching 0.47 and 0.44 ng/larva, respectively. This study evaluated the importance of the rate of uptake and excretion, and of enzymatic metabolism in building up an insecticidal toxicity after topical application on the insect cuticle in both species. In general, penetration of DFB in S. littoralis was about 2‐fold higher than in S. exigua, whereas metabolic breakdown was of minor importance in S. littoralis as compared with S. exigua. The current data indicate the importance of cuticle penetration and discuss that extrapolation from oral feeding toxicity results to topical toxicity data should be evaluated with caution, especially for insect growth regulators used in integrated pest management.
Effect of mannose‐binding lectin from peanut and pea on the stem borer Chilo partellus
Authors: Law Ian J. , Kfir Rami 
Published: October 2003

AbstractA mannose‐binding lectin found in vegetative tissues of peanut, Arachis hypogaea, was compared with mannose‐binding lectin from pea, Pisum sativum, for toxic effects on larvae of the stem borer Chilo partellus (Swinhoe). After 10 days, the mortality of larvae fed on artificial diet containing 0.5% (m/m) peanut lectin was 46.2%. The mortality of larvae fed on 1.0% peanut lectin was similar (48.1%) but insects were significantly smaller than those of the 0.5% treatment. Larvae of both lectin treatments stopped feeding within three days. Larval size and mortality was not significantly reduced by 0.1% peanut lectin and 1% heat‐treated lectin did not show toxic effects. The mannose‐binding lectin from pea was not toxic to C. partellus at concentrations up to 1%. Peanut lectin bound to the apical membranes of columnar epithelial cells in the mid‐gut of C. partellus. This suggests that peanut lectin has an antinutritive action and that it may protect vegetative tissues of peanut against insect pests.
A comparison of live versus kill pitfall trapping techniques using various killing agents
Authors: Weeks Ronald D. , McIntyre Nancy E. 
Published: October 2003

AbstractWe compared the efficacies of two arthropod pitfall trapping techniques: live (dry) trapping and kill trapping with three killing agents (water, ethylene glycol, and the recently developed propylene glycol, whose efficacy has not been previously assessed). Kill pitfall traps caught more species than did live pitfalls. Forty‐one species were collected only from kill traps (3 being unique to water, 11 to ethylene glycol, and 8 to propylene glycol), 12 were collected only from live traps, and 32 were collected from both kill and live traps. The same average number of individuals per species was caught for most of those taxa that were collected in both trap types, indicating that better retention of captured arthropods by the killing agent was not responsible for the differences observed in the two pitfall trapping methods. There were no significant differences in captures between propylene and ethylene glycol traps or between water and live traps. Because of species‐specific differences in the efficiencies of live and kill pitfall trapping, cross‐study entomological comparisons made using kill pitfall trapping and live pitfalling may be confounded.
Fungal endophytes of wild barley and their effects on Diuraphis noxia population development
Authors: Clement S.L. , Wilson A.D. , Lester D.G. , Davitt C.M. 
Published: October 2003

AbstractLaboratory experiments were conducted to compare the expression of Diuraphis noxia (Mordvilko) (Homoptera: Aphididae) resistance in four plant introduction (PI) lines of wild barley (Hordeum) infected with different species or strains of endophytic fungi (tribe Balansieae, family Clavicipitaceae, Neotyphodium gen. nov. [formerly Acremonium]). Aphid densities were significantly lower on endophyte‐infected plants of PI 314696 (H. bogdanii Wilensky) and PI 440420 (H. brevisubulatum subsp. violaceum (Boissier & Hohenacker)), compared with densities on endophyte‐free plants of both PI lines in population growth experiments. This endophyte‐ associated resistance was the result of antibiosis effects or starvation. In other experiments, endophyte‐free plants of PI 269406 and PI 440413 (H. bogdanii) were not superior to endophyte‐infected conspecifics as host plants of D. noxia. Our results demonstrate the influence of host plant species/genotype and endophyte species/strain on expression of aphid resistance, provide an explanation of the high levels of D. noxia resistance in PI 314696 and PI 440420 previously reported in the literature, and underscore the potential importance of endophytic fungi in conferring insect resistance in wild barley.
Oviposition preference of western flower thrips for cucumber leaves from different positions along the plant stem
Authors: Jan, de Kogel Willem , van der Hoek Marieke , Mollema Chris 
Published: October 2003

AbstractWhile the distribution of herbivorous insects over leaves along the stem often shows a peak at some distance from the apex this does not necessarily reflect an innate preference as alternative explanations can be provided such as impact of predators and inter‐ or intraspecific competitors. It is of interest to determine which factors shape the distribution of insects over the leaves of a plant. Do leaves from different positions differ in suitability for insects and is that reflected in the insect's preference, or are other factors involved? In this paper we assess how the herbivorous insect western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), chooses among leaves from different positions relative to the apex of cucumber, Cucumis sativus (L.) plants. On leaf discs of a susceptible and three partially resistant cucumber accessions, thrips reproduction was highest on apical leaves and lowest on basal leaves. In dual‐choice essays thrips females preferred younger leaves over older leaves for oviposition in all cucumber accessions tested, as was predicted from the no‐choice assay. This indicates that differences in leaf suitability are an important factor in determining thrips distribution on cucumber plants.
Searching behaviour of Encarsia formosa as mediated by colour and honeydew
Authors: Romeis J. , Zebitz C.P.W. 
Published: October 2003

AbstractThe habitat‐ and host‐searching behaviour of female Encarsia formosa Gahan (Hymenoptera: Aphelinidae) was assessed using an airflow olfactometer and a filter paper test. Responses to different odour cues, colours, host‐produced honeydew, non‐host honeydew and single carbohydrates were determined. The parasitoid was not attracted to or arrested by odours emanating from clean tobacco leaves, tobacco leaves heavily infested with the host Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) and covered with honeydew, or honeydew alone. However, E. formosa females showed a significant response to green light transmitted through a tobacco leaf. The yellow part of the spectrum was partly responsible for this response. Thus, the long‐range orientation is random with respect to the presence of hosts. Filter paper tests showed that the short‐range searching behaviour is influenced by water soluble, non‐volatile contact‐kairomones contained in the host‐produced honeydew. Contact with honeydew excreted by L3/L4 T. vaporariorum resulted in longer searching times than honeydew from adult T. vaporariorum or L3/L4 Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). No difference was found between the response to honeydew excreted by adult and L3/L4 B. tabaci. The parasitoids' response to honeydew was unaffected by the host plant on which the whiteflies had fed. Non‐host honeydew and single carbohydrates also affected the searching behaviour of E. formosa but to a lower extent than host honeydew. The possible differences in the carbohydrate and amino acid composition of the honeydew excreted by different life‐stages of T. vaporariorum and B. tabaci are discussed.
Cage experiments on Orius tantillus predation of Helicoverpa armigera
Authors: Sigsgaard L. , Esbjerg P. 
Published: October 2003

AbstractThe role of Orius tantillus (Motschulsky) (Hemiptera: Anthocoridae) in the predation of H. armigera was studied on both sorghum (Sorghum bicolor L.) and pigeonpea (Cajanus cajan L.), the predominant intercrop of small farmers in Andhra Pradesh, India. Adult Orius tantillus was observed in cages where there were eggs and first‐instar larvae of H. armigera on sorghum and pigeonpea. We found that O. tantillus had two diurnal peaks of activity, after sunrise and before sunset. O. tantillus was found preying on first‐instar larvae and not on eggs. However, a later immunoassay of O. tantillus collected on sorghum during a peak period of H. armigera oviposition activity showed that predation of eggs did occur under certain conditions. The activity of O. tantillus on sorghum was significantly higher on the flowers than elsewhere but this was not the case on pigeonpea. Therefore O. tantillus was a significantly more efficient predator on sorghum than on pigeonpea. The results indicate that O. tantillus could be an important predator of early stages of an H. armigera infestation, particularly in sorghum.