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  • 11
    Electronic Resource
    Electronic Resource
    Relationships between leaf age and the food quality of cottonwood foliage for the gypsy moth, Lymantria dispar (1987)
    Springer
    Oecologia 72 (1987), S. 527-532 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00378978
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  • 12
    Electronic Resource
    Electronic Resource
    Generalist caterpillar prey are more palatable than specialists for the generalist predator Iridomyrmex humilis (1989)
    Springer
    Oecologia 79 (1989), S. 427-430 
    Details
    ISSN: 1432-1939
    Keywords: Iridomyrmex humilis ; Predation ; Host range ; Prey acceptability ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments are described which test the hypothesis that more host-specific species of caterpillars should be less aceptable to a generalist predator than polyphagous species. Caterpillars of all species were tested in paired choice tests with the Argentine ant, Iridomyrmex humilis. Experiments were replicated ten times, videotaped and later analyzed. Brightly colored specialist species (normally considered to be aposematic) were clearly the least palatable, while more cryptic specialists were also significantly less acceptable than generalists overall. Leaf-tying species were considered separately; all were highly palatable independent of host range. The results indicate that among caterpillars that do not construct leaf shelters, those with a wide post range are more acceptable than those with a narrow host range. This is consistent with the notion that generalist predators provide selection pressure favoring narrow host range in their herbivorous prey.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384324
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  • 13
    Electronic Resource
    Electronic Resource
    The adaptive significance of alpine melanism in the butterfly Parnassius phoebus F. (Lepidoptera: Papilionidae) (1986)
    Springer
    Oecologia 70 (1986), S. 205-213 
    Details
    ISSN: 1432-1939
    Keywords: Parnassius ; Lepidoptera ; Radiation ; Temperature ; Melanism ; Thermoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The adaptive significance of alpine melanism, the tendancy for insects to become darker with increased elevation and latitude, was investigated using the butterfly Parnassius phoebus. The effects on temperature dependent activity of five components of overall wing melanism, as well as size, were examined. The components of wing melanism examined were the transparency of the basal hindwing and distal fore-wing areas, the width of the black patch in the basal hind-wing area and the proportion of black to white scales in that area, and the proportion of the distal fore-wing covered by predominantly black scaling. The body temperature of dead specimens was correlated with air temperature, solar radiation, the width of the black patch at the base of the wings, and the proportion of black to white scales at the base of the wings. The minimum air temperatures and solar radiation levels required for initiation of flight did not vary with wing melanism of P. phoebus, in contrast to the results found for Colias butterflies by Roland (1982). However, under environmental conditions suitable for flight initiation, males with a higher proportion of black to white scales in the basal area of the hind-wing, and wider basal black patches, spent a greater proportion of time in flight at low air temperatures and low insolation. Increased basal wing melanism was also associated with increased movement of males within a population. In contrast, melanism in the distal area of the wings has no effect on activities which are dependant on body temperature. The amount of time spent feeding did not vary with differences in wing melanism. I suggest that in dorsal basking, slow-flying butterflies (Parnassius) basal wing color affects body temperature primarily during flight (rather than while basking), such that butterflies with darker wing bases cool down less rapidly because they absorb more solar radiation during flight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379241
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  • 14
    Electronic Resource
    Electronic Resource
    Facilitative interactions between two lepidopteran herbivores of Asimina (1989)
    Springer
    Oecologia 78 (1989), S. 214-219 
    Details
    ISSN: 1432-1939
    Keywords: Asimina ; Facilitation ; Defoliation ; Herbivory ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Insect herbivores that require young foliage for successful larval development are often restricted to a single generation during a year by the scarcity of suitable food over most of the growing season. The major specialist herbivore attacking shrubs in the genus Asimina in Florida, Eurytides marcellus, requires young foliage for successful larval development. Field manipulations were used to investigate the role of the young foliage produced by Asimina in response to defoliation by the late-season feeder Omphalocera munroei, a second specialist herbivore of Asimina in Florida, in maintaining Eurytides populations during the summer months when young foliage is otherwise scarce. Defoliation by Omphalocera proved to be the major inducer of young growth during the summer because Omphalocera defoliated Asimina shrubs so frequently and severely. When compared to young leaves produced in the absence of damage, the teaves produced by Asimina in response to defoliation were equally as suitable as food for Eurytides larvae and as acceptable as oviposition sites by Eurytides females. The availability of young foliage in an Asimina population was correlated with the size of the associated Eurytides population. The combination of regular, severe defoliation by Omphalocera and lack of a defensive response to damage by Asimina lead to a positive affect of Omphalocera on Eurytides population size, and may be central to other facilitative interactions between herbivores as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377158
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  • 15
    Electronic Resource
    Electronic Resource
    Relative nutritional quality of C3 and C4 grasses for a graminivorous lepidopteran, Paratrytone melane (Hesperiidae) (1992)
    Springer
    Oecologia 92 (1992), S. 97-103 
    Details
    ISSN: 1432-1939
    Keywords: C3 and C4 grasses ; Lepidoptera ; Hesperiidae ; Paratrytone melane ; Nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We tested the hypothesis that C4 grasses are inferior to C3 grasses as host plants for herbivorous insects by measuring the relative performance of larvae of a graminivorous lepidopteran, Paratrytone melane (Hesperiidae), fed C3 and C4 grasses. Relative growth rates and final weights were higher in larvae fed a C3 grass in Experiment I. However, in two additional experiments, relative growth rates and final weights were not significantly different in larvae fed C3 and C4 grasses. We examined two factors which are believed to cause C4 grasses to be of lower nutritional value than C3 grasses: foliar nutrient levels and nutrient digestibility. In general, foliar nutrient levels were higher in C3 grasses. In Experiment I, protein and soluble carbohydrates were digested from a C3 and a C4 grass with equivalent efficiencies. Therefore, differences in larval performance are best explained by higher nutrient levels in the C3 grass in this experiment. In Experiment II, soluble carbohydrates were digested with similar efficiencies from C3 and C4 grasses but protein was digested with greater efficiency from the C3 grasses. We conclude (1) that the bundle sheath anatomy of C4 grasses is not a barrier to soluble carbohydrate digestion and does not have a nutritionally significant effect on protein digestion and (2) that P. melane may consume C4 grasses at compensatory rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317268
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  • 16
    Electronic Resource
    Electronic Resource
    Migration of moth species in a network of small islands (1996)
    Springer
    Oecologia 108 (1996), S. 643-651 
    Details
    ISSN: 1432-1939
    Keywords: Migration rate ; Lepidoptera ; Mark-recapture study ; Population density ; Movement behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rapidly increasing fragmentation of natural landscapes decreases the ability of many species to reach the smaller and more isolated patches of habitat in a metapopulation. The densities of local populations of several moth species and the butterfly Hipparchia semele in a network of small islands, and the rates of inter-island movement and movement patterns, were investigated, to determine the factors affecting the rate and pattern of movements. The estimated population densities ranged from 0.001 to 0.2 individuals/m2. The observed emigration and immigration rates depended on island isolation and various traits of the species, with great variability in migration rates among species. Thin-bodied, slow-flying species did not move among the islands, whereas many robust, fast-flying species moved among the islands relatively frequently. Migration rate increased significantly with body size and was significantly higher in oligophagous than in polyphagous species, suggesting that these factors are important determinants of the migration rate of the species. Migration rate was low when the surface temperature of the sea was low, and a greater proportion of individuals emigrated from small than large patches of habitat. The migration distances of female noctuids were shorter than those of males and those of both sexes of the butterfly H. semele. The observed movement patterns are consistent with a metapopulation structure in most of the moth species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329038
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  • 17
    Electronic Resource
    Electronic Resource
    Red receptors dominate the proximal tier of the retina in the butterfly Papilio xuthus (1996)
    Springer
    Journal of comparative physiology 178 (1996), S. 55-61 
    Details
    ISSN: 1432-1351
    Keywords: Electrophysiology ; Lepidoptera ; Photoreceptor ; Spectral sensitivity ; Vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. The ommatidia of the butterfly Papilio have a fused and tiered rhabdom. The distal tier of the rhabdom is made up of four distal photoreceptors (R1–4), whereas the proximal tier is made up of four proximal (R5–8) and one basal photoreceptor cell (R9). 2. We first confirmed by light microscopy that the ommatidia of Papilio are not twisted, i.e. have the same spatial organization all about the longitudinal axis. The polarization method, previously applied to the distal tier, hence is applicable to identify the photoreceptor location from the peak angle of the polarization sensitivity. 3. We determined the polarization and spectral sensitivity of in total 109 proximal and basal photoreceptors in the lateral looking eye region. All of the photoreceptors were either green or red type, most of which fall into three classes as judged by the peak angles of the polarization sensitivity: around 40°, 150°, and 180° (= 0°) with respect to the dorso-ventral axis. The first two classes are formed by the proximal photoreceptors with straight microvilli oriented at the average angle of 39° (R6, 8) and 144° (R5, 7) respectively, and the third is formed by the basal photoreceptors R9 with straight microvilli oriented at 180° (= 0°). The mean polarization sensitivity (PS = maximal sensitivity/minimal sensitivity) was about 2. 4. 75% of the proximal and 48% of the basal photoreceptors were of the red type. 5. A single ommatidium of Papilio appears to contain two to four types of spectral receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189590
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  • 18
    Electronic Resource
    Electronic Resource
    Latencies of behavioral response to interception of filaments of sex pheromone and clean air influence flight track shape in Heliothis virescens (F.) males (1996)
    Springer
    Journal of comparative physiology 178 (1996), S. 831-847 
    Details
    ISSN: 1432-1351
    Keywords: Heliothis ; Noctuidae ; Lepidoptera ; Plume structure ; Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1) Male Heliothis virescens moths flew upwind to pulsed pheromone plumes. Upon truncation of the pulsed plume males flew into clean air, turning their tracks crosswind (〉 60° relative to directly upwind direction at 0°) within an average of 0.27 s, and were casting, perpendicular to the wind-line (90°), within 0.43 s. 2) The characteristic casting flight in clean air consisted of left-right crosswind reversals, continuing for many seconds without further pheromonal stimulation. Males intercepting a single strand of pheromone during casting flight responded by surging upwind (track angles 〈 60°). The phasic surge lasted only 0.38 s before reverting to crosswind flight (〉 60°). 3) Average templates of responses in two and three dimensions were created. Males controlled their vertical deviations very tightly when in contact with pheromone but upon entering clean air, lateral and vertical excursions became much greater. 4) Males failed to sustain upwind flight to repetitively pulsed plumes generated at 〈 4 filaments/s. At the threshold frequency of 4 pulses/s we show that upwind flights were composed of reiterated surges followed by crosswind casting. As the pulse frequency increased, the tracks became straighter and the single filament cast-surge-cast template could be viewed only sporadically when, for example, a male apparently failed to intercept filaments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225831
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  • 19
    Electronic Resource
    Electronic Resource
    Localization of spectral receptors in the ommatidium of butterfly compound eye determined by polarization sensitivity (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 289-297 
    Details
    ISSN: 1432-1351
    Keywords: Electrophysiology ; Lepidoptera ; Photoreceptor ; Spectral sensitivity ; Vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. A butterfly Papilio has 5 types of spectral receptors in the compound eye. The spectral sensitivity of each type peaks in the UV, violet, blue, green, and red wavelengths, respectively. The green type contains two subtypes with and without a UV secondary peak. Here we studied the localization of these spectral receptors within the ommatidium. 2. An ommatidium contains 9 photoreceptors (R1–9), each of which is one of the 5 spectral receptor types. The photoreceptors bear parallel microvilli to form a nontwisted rhabdom, and thereby the photoreceptors are polarization sensitive. 3. We first examined the microvillar orientation by electron microscopy. The microvilli of R1, 2, and 9 are oriented dorso-ventrally (0°), whereas those of R3 and 4 are parallel to the antero-posterior axis (90°). The R5–8 bear microvilli diagonally: 45° for R6 and R8, 135° for R5 and R7. 4. We then recorded spectral and polarization sensitivities from single photoreceptors. The peak angle of the polarization sensitivity (θmax) of the UV, violet, and blue receptors were around 0°, whereas that of the green receptors was around 90°. In the double-peaked green receptors, the θmax at UV was also around 90°. The red receptors showed a θmax at around 35°. The polarization sensitivity ratio (PSmax/PSmin) of the double-peaked green receptors measured at UV was around 4, whereas the ratio of other receptors was around 2. 5. We conclude that R1 and R2 are either UV, violet, or blue receptors whereas R3 and R4 are green receptors. Some R6 and R8 are red receptors. We also conclude that the UV secondary peak in the double-peaked green receptor is not simply attributable to the coupling with UV receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223959
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  • 20
    Electronic Resource
    Electronic Resource
    High resolution measurement of atmospheric carbon dioxide concentration changes by the labial palp organ of the moth Heliothis armigera (Lepidoptera: Noctuidae) (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 317-324 
    Details
    ISSN: 1432-1351
    Keywords: Carbon dioxide ; Chemoreception ; Lepidoptera ; Microclimate ; Sensory transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In recordings of single unit action potentials, the responses of CO2-receptors in the labial palp organ of the moth Heliothis armigera to modulation of CO2-density around a background of 350 ppm were investigated. Modulation of CO2-density by square wave changes in concentration at constant barometric pressure evokes modulation of the spike rate. Modulation of CO2-density by square wave changes in barometric pressure at constant CO2-concentration evokes responses similar to those evoked by concentration modulation. For modulation depths of less than 1.5%, the output modulation depth is linearly related to the input; at higher modulation depths the gain decreases progressively. Using sinusoidal pressure modulation, the frequency dependence of both gain and output noise was determined over a range of 0.05 to 12.8 Hz. With increasing frequency the gain progressively increases at a rate of 2.4 dB/octave up to a maximum of 63 at 3 Hz; at higher frequencies, it decreases rapidly. The threshold sensitivity of the receptors, using input noise amplitude density as a criterion, is broadly tuned, with a minimum of 1 % contrast Hz-0.5 between 0.3 and 3 Hz. Using these figures, it is concluded that the sensory organ is capable of detecting fluctuations in CO2-density of 0.14% or 0.5 ppm. The results are related to the fluctuations in CO2-density which occur in a natural environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223962
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