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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 77 (1995), S. 323-334 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; Epiphyas postvittana ; orientation ; movement ; colour ; stemmata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When neonate larvae of a leafroller moth,Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) were released into the middle of a circular arena with blue paper on one side of the arena and apple foliage on the other side, more larvae walked towards the apple foliage. These oriented responses were enhanced, in terms of the number of larvae responding, by increasing the amount of light reflected from or transmitted through apple foliage. Larvae also responded to painted targets, and specifically to targets reflecting light in the region of 470–570 nm (green-yellow region to the human eye). When the amount of 470–570 nm reflected from targets was reduced, numbers of larvae responding to targets decreased. The addition of 400–500 nm reflected light to 470–570 nm reflected light also resulted in a reduction of oriented responses to targets. Tests using neutral colours (white, black, and a series of greys) indicated that, in the absence of targets reflecting primarily in the 470–570 nm region, larvae oriented towards targets with low levels of reflectance. When the orientation of walking larvae was measured at various distances from targets of different colours or diameters, targets subtending 5–8 degrees elicited responses from 50% of all larvae. Behaviour other than walking was also influenced by visual stimuli: fewer larvae spun down on a silken thread when blue paper was placed beneath a walking platform than when brown or green papers were present.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 74 (1995), S. 125-135 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; brownheaded leafroller ; pheromone ; orientation ; Epiphyas postvittana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A sex pheromone-baited delta trap was found to be inefficient at eliciting landing and entering of the trap by maleCtenopseustis obliquana. The inefficiency of the delta trap related to turbulence altering the pheromone plume and the concomitant effect on the flight manoeuvres of male moths. In the wind tunnel, high proportions of males flew upwind and landed on the sides, outside, of the trap, but only a relatively small proportion of these males entered the trap and contacted the sticky surface. When males approached the delta trap, they tended to fly in wide zigzags (i.e., large inter-track reversal distances) and at an altitude near the top of the trap, where the trap was relatively narrow in width (compared to the bottom). Thus, these flight manoeuvres largely precluded males from entering the trap. Greater numbers of male moths entered the trap when: (i) the front barriers of the delta trap were removed, (ii) pheromone dosage was increased to 300 μg, and (iii) the trap design was changed to a rectangular one. The first two changes appeared to influence the flight manoeuvres of males (who appeared to fly with narrower inter-track reversal distances), while the third change apparently did not affect the glight manoeuvres of males, but rather allowed more males to enter the trap because of the greater area of the entrance. The low trap catches of maleC. obliquana in the field are also a consequence of the glue which is currently used. After contact with this glue most males are able to escape, flying off the sticky surface and losing contact with the pheromone. A field trial found that delta traps with another glue caught more than three times the number of males of the related tortricid moth,Epiphyas postvittana, than delta traps with the currently used glue.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 83 (1997), S. 147-159 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; visual stimuli ; tactile stimuli ; generalist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bioassay to test the ovipositional responses of the generalist herbivore, Epiphyas postvittana, was developed, and various non-chemical factors that influenced the laying, and number of eggs laid, by females were tested. In choice experiments using various models, surface texture was found to be an important factor influencing ovipositional behaviour, with females preferring to lay on smoother rather than rougher surfaces. Another surface texture feature that influenced oviposition was a raised wax ridge on a smooth surface. The wax ridge stimulated more eggs to be laid within close proximity to the ridge. Observations of females showed that the increased numbers of eggs laid on models with a wax ridge resulted not from increased landing, time spent, or numbers of eggs laid per ovipositional bout, but rather through an increased probability of ovipositing after landing on models with a wax ridge compared to models without the ridge. Spatial features of the models were also found to influence egglaying by females. Females showed a tendency to lay on the upper rather than the lower surface of models, although this appeared to depend upon how stimulatory the upper surface of the model was. Females also laid more eggs on models with a dense array of leaves than on models with a more spread-out array.
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  • 4
    ISSN: 1572-8889
    Keywords: orientation ; turbulence ; visual cues ; Lepidoptera ; Tortricidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A small (2.5-cm-wide) vertical (10-cm-high) white object influenced the sex pheromone-mediated flight and landing behaviors of maleEpiphyas postvittana. When the vertical object was positioned on a horizontal surface to the side (3–5 cm) and upwind of a pheromone source (in the middle of the surface), the distribution of landing positions of males on the surface was different from that when the object was not present; males tended to land in positions skewed toward the side of the source that the object was on. The closer the object was positioned to the source, the greater the number of males that landed on the object (rather than on the horizontal surface). This difference in landing positions (when the object was present) corresponded with changes in the flight tracks; the tracks of males flying to the surface with an object were skewed toward the object and had higher amplitude intertrack reversal distances than the tracks of males flying to a surface without a vertical object. Positioning of a vertical object progressively upwind of the source resulted, apparently, in decreased effects on the landing (and presumably flight) behavior of males. The effect of the vertical object on the flight and landing behaviors of males corresponded largely with changes in pheromone plume structure (visualized with smoke) induced by the extra turbulence in the airflow over the source. Thus it appears that the vertical object influences the behavior of maleE. postvittana largely through the olfactory sensory modality. However, when a clear, Mylar object, in place of the white object, was placed on the surface, more males landed on the Mylar object (than did on the white object), suggesting that the vertical object may also influence the behavior of males through the visual modality.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 24 (1998), S. 1251-1275 
    ISSN: 1573-1561
    Keywords: Lepidoptera ; Tortricidae ; chemical stimuli ; tactile stimuli ; light-brown apple moth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Stimuli from the plant Camellia japonica that influence the host-finding and acceptance behaviors of adult females of the generalist herbivore Epiphyas postvittana were investigated. In a binary choice test in a small (35-cm-diam.) arena, females discriminated between a plant and a laminated card model, laying many more eggs on the plant. Observations of females showed that the greater number of eggs laid on the plant were primarily due to on-plant behaviors, with females spending significantly more time per visit on the plant than on the model. Interestingly, females landed a similar number of times on the plant as on the model, suggesting that volatile chemicals from the plant did not influence host-finding. This observation was further supported by wind-tunnel studies, in which females showed little or no upwind flight activity in response to plants and laid similar numbers of eggs on upwind and downwind plants. Leaf surface texture, a combination of smoothness and fine structure (consisting of the midvein and other raised leaf veins), was found to stimulate egg laying by females. Methanol, dichloromethane, and pentane extracts were made of the waxes on the leaf surface. Of these three extracts, only the nonpolar (pentane) one stimulated egg laying by females. Although we did not find a role for volatile plant chemicals in host finding, they appeared to stimulate increased egg laying when the female was on the plant. It appears likely that these chemical and tactile stimuli in C. japonica are general stimuli, which may be found in a large number of plants and, in combination with the feeding preferences of the larva, may explain the generalist herbivorous nature of this pest.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 91 (1999), S. 287-295 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; oviposition ; host deprivation ; lightbrown apple moth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of mating, age at mating, the presence or absence of a plant leaf, and the deprivation of a suitable ovipositional substrate during when the first ovipositional bout after mating would normally take place, on the lifetime fecundity and fertility (percentage of fertile eggs laid) of female Epiphyas postvittana were investigated. Mating had a significant effect on lifetime fecundity, with mated females laying 2.5 times more eggs than virgin females. Age at mating had a significant effect on both fecundity and fertility, both declining with increasing age when the female was mated. In the presence of a leaf of C. japonica, mated females had a greater lifetime fecundity than when no leaf was present; females in the presence of a C. japonica leaf consistently laid more eggs each day during the first 4–6 days after mating than females without a leaf. When females were deprived of a suitable ovipositional substrate, for the first 22 h after mating, they were significantly less fecund over their lifetime than were control females. Finally, in no-choice tests with three plants of different acceptability to females, the fecundity of females differed in the order C. japonica 〉 Urtica ferox 〉 Tibouchina multiflora. This different fecundity appeared to be inversely related to the pubescence of the leaves, suggesting that leaf texture may be a suitable antixenotic resistance factor for crops to be protected from this insect. These results suggest that strategies whereby mating is delayed or oviposition reduced within a critical period after mating, may result in significant reductions in pest populations.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 92 (1999), S. 53-62 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; host selection ; correlation ; lightbrown apple moth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polyphagous leafroller moth, Epiphyas postvittana, is a pest of many fruit crops in New Zealand. Since the larva is highly mobile, host selection in this insect may involve both the adult female and the larva. In order to test the relative importance of the adult female and the neonate larva in the selection of host plants, the ovipositional preferences of females, and the preferences or acceptances of neonate larvae towards 26 plant species, consisting of 15 plants considered hosts and 11 not considered hosts, were investigated. In the ovipositional tests, the mean preferences of females for hosts and non-hosts were very similar. In contrast, larvae showed a significantly greater mean preference or acceptance towards hosts than to non-hosts, in both choice and no-choice bioassays, respectively. There were highly significant correlations between the preferences and acceptances of larvae for plants in the choice and no-choice tests. In the no-choice tests, there was a highly significant correlation between the acceptances of neonate larvae towards plants after one and three days (i.e., acceptances changed little over time). Moreover, in these no-choice tests, there was a significant negative correlation between larval acceptance at 1 day and larval mortality after 3 days; that is, the less acceptable a given plant at 1 day, the more likely larvae would fail to establish, feed, and survive on it by three days. Female and larval preferences towards the various plants were also negatively correlated. Together, these data suggest that the selection of a plant for the neonate larva to feed on is largely governed by the preferences of the larva, rather than by the preferences of the female. However, selection of a plant for oviposition by the female, may be important in host selection for reasons unrelated to larval preferences, for example, by encouraging dispersal, perhaps to other plant species, of the neonate larvae and thereby decreasing intersibling competition.
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