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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 11 (1995), S. 990-995 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1939
    Keywords: Nutritional indices ; Host switching ; Gypsy moth ; Food utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A large proportion of gypsy moths (Lymantria dispar (L.)) are likely to experience multiple species diets in the field due to natural wandering and host switching which occurs with these insects. Nutritional indices in fourth and fifth instar gypsy moth larvae were studied in the field for insects that were switched to a second host species when they were fourth instars. The tree species used as hosts were northern pin oak (Quercus ellipsoidalis E. J. Hill), white oak (Q. alba L.), big-tooth aspen (Populus grandidentata Michx.), and trembling aspen (P. tremuloides Michx.). Conclusions of this study include: 1) Insects which fed before the host switch on northern pin oak performed better after the host switch than did insects with other types of early dietary experience. While the northern pin oak-started insects had very low relative food consumption rates on their second host species immediately after the switch, one instar later they had the highest ranked consumption rates. During both instars they had the second highest efficiencies of converting ingested and digested food to body mass. High food consumption rates and relatively high efficiency of food conversion helped these insects to obtain the highest ranked mean relative growth rates in the fifth instar compared to the relative growth rates obtained by insects from any of the other first host species. 2) Among the four host species examined, a second host of trembling aspen was most advantageous for the insects. Feeding on this species after the switch led to higher larval weights and higher relative growth rates for insects than did any of the other second host species. The insects on trembling aspen attained excellent growth despite only mediocre to low food conversion efficiencies. The low efficiencies were offset by high relative food consumption rates. 3) Low food consumption rates often tend to be paired with high efficiency of conversion and vice versa. 4) There is no discernable tendency for the first plant species eaten to cause long-term inductions which affect the ability of gypsy moths to utilize subsequent host plants. Insects did not tend to consume more, grow faster, or be more efficient if their second host plant was either the same as their rearing plant or congeneric to it. Methods are delineated which allow values of nutritional indices to be obtained for insects on intact host plants under field conditions. These methods are useful for the purpose of answering questions about the relative effects that different diet treatments have on insect response.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1939
    Keywords: Lymantria dispar ; Dispersal ; Maternal effects ; Vitellin ; Yolk proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract North American gypsy moths disperse as newly hatched larvae on wind currents in a behavior called ballooning. Because ballooning occurs before neonates begin to feed, resources used in dispersal are limited to those carried over from the egg. We show that nutritional experience of the maternal parent can influence the tendency of offspring to disperse, and that resource provisioning of eggs by the maternal parent affects the duration of the window for disperal. Offspring of females from defoliated sites had a lower tendency to balloon in a wind tunnel than larvae from females which had not experienced nutritional stress associated with host defoliation. The number of eggs in an egg mass, a reflection of the maternal parent's nutritional experience, also contributed to the predictive model for dispersal that included defoliation level. Egg weight and the levels of two yolk proteins, vitellin (Vt) and glycine-rich protein (GRP), however, had no influence of the proportion of ballooning larvae. The length of survival without food, and thus the maximum period of time for dispersal, was correlated with levels of Vt and GRP, but not with egg weight. The level of defoliation at the site from which the maternal parent was collected was not related to the longevity of offspring, nor did it have a significant effect on the levels of Vt, GRP or egg weight. Levels of hemolymph proteins arylphorin and vitellogenin in the maternal parent during the prepupal stage had no influence on levels of yolk proteins, larval longevity, or tendency to balloon.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1939
    Keywords: Lepidoptera ; Salicaceae ; Herbivory ; Resource allocation ; Chemical defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cottonwood tree, Populus deltoides, continues to produce leaves late into the growing season, exposing midseason herbivores to leaves of a wide range of maturity. Gypsy moth larvae preferred and grew best on the oldest cottonwood leaves and suffered higher mortality and 85% less growth when fed young, expanding leaves. Concentration of phenolics in the youngest leaves was 3 times that in the oldest leaves and was negatively correlated with caterpillar growth rate. The active phenolics were not identified; tannin was present but its concentration changed more with season than leaf age.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1939
    Keywords: Host switching ; Insect/plant interactions ; Gypsy moth ; Diet sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of various single and two species diets on the performance of gypsy moth (Lymantria dispar (L.)) were studied when this insect was reared from hatch to population on intact host trees in the field. The tree species used for this study were red oak (Quercus rubra L.), white oak (Q. alba L.), bigtooth aspen (Populus grandidentata Michaux), and trembling aspen (P. tremuloides Michaux). These are commonly available host trees in the Lake States region. The study spanned two years and was performed at two different field sites in central Michigan. Conclusions drawn from this study include: (1) Large differences in gypsy moth growth and survival can occur even among diet sequences composed of favorable host species. (2) Larvae that spent their first two weeks feeding on red oak performed better during this time period than larvae on all other host species in terms of mean weight, mean relative growth rate (RGR), and mean level of larval development, while larvae on a first host of bigtooth aspen were ranked lowest in terms of mean weight, RGR, and level of larval development. (3) Combination diets do not seem to be inherently better or worse than diets composed of only a single species; rather, insect performance was affected by the types of host species eaten and the time during larval development that these host species were consumed instead of whether larvae ate single species diets or mixed species diets. (4) In diets composed of two host species, measures of gypsy moth performance are affected to different extents in the latter part of the season by the two different hosts; larval weights and development rates show continued effects of the first host fed upon while RGRs, mortality, and pupal weights are affected strongly by the second host type eaten. (5) Of the diets investigated in this study, early feeding on red oak followed by later feeding on an aspen, particularly trembling aspen, is most beneficial to insects in terms of attaining high levels of performance throughout their lives.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 22 (1977), S. 236-242 
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Quatorze espèces d'Aphides appartenant aux sous-familles des Aphidinae et Chaitophorinae ont été testées pour leur réponse à la phéromone d'alarme EBF, sur la base de la dose limite efficace et du type de réponse par dispersion des individus. Les doses d'EBF nécessaires pour disperser 50% des individus chez l'espèce la plus sensible sont de 0,02 ng, contre 100 ng pour l'espèce la moins sensible. Certaines espèces se dispersaient en marchant pour de faibles doses et en se laissant tomber pour de fortes doses; d'autres se dispersaient seulement en marchant, quelle que soit la dose. La sensibilité et le mode de réponse à la phéromone sont en relation avec la densité des groupements et avec le fait que l'espèce est ou non myrmécophile.
    Notes: Abstract Threshold dosage and type of dispersive response by aphids to the alarm pheromone, (E)-β-farnesene, were determined for fourteen species in the subfamilies Aphidinae and Chaitophorinae. Dosage required to disperse 50% of the most and least sensitive species was 0.02 ng and 100 ng, respectively. Some species dispersed at low dosages by walking and at high dosages by falling; others dispersed only by walking regardless of dosage. Sensitivity to alarm pheromone and type of dispersive response are interrelated with aggregation density and whether the aphid is myrmecophilous.
    Type of Medium: Electronic Resource
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