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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 88 (1998), S. 235-245 
    ISSN: 1570-7458
    Keywords: foraging behavior ; olfactometer ; host location ; Aonidiella aurantii ; Aphytis melinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 263-269 
    ISSN: 1570-7458
    Keywords: Aphytis melinus ; kairomone ; O-caffeoyltyrosine ; host recognition ; learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The introduced parasitoid, Aphytis melinus DeBach (Hymenoptera: Aphelinidae), utilizes a kairomone, O-caffeoyltyrosine, to recognize California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae). Wasps used in augmentative release programs for California red scale on California citrus are reared on oleander scale, Aspidiotus nerii Bouché (Homoptera: Diaspididae), themselves reared on squash. The goals of this study were: 1) to determine if long-term rearing on oleander scale had caused A. melinus to develop a preference for oleander scale, and 2) to determine if the preference of oleander-reared A. melinus for California red scale might be enhanced by exposing them to synthetic O-caffeoyltyrosine prior to release. Wasps that were removed from their hosts as pupae and allowed to emerge as adults isolated from their hosts retained a strong preference for California red scale regardless of rearing host. This preference was reduced if wasps were allowed to emerge from oleander scale, thus acquiring early adult experience with oleander scale. The preference for California red scale was restored, however, by exposing wasps reared on oleander scale to synthetic O-caffeoyltyrosine prior to bioassay. Exposure of A. melinus reared in commercial insectaries to O-caffeoyltyrosine prior to release may be a means to improve the effectiveness of such wasps in augmentative release programs to control California red scale.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 97-108 
    ISSN: 1570-7458
    Keywords: Aphytis melinus ; Aonidiella aurantii ; kairomone ; O-caffeyoyltyrosine ; host recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract O-caffeoyltyrosine is a host recognition kairomone forAphytis melinus DeBach (Aphelinidae) found in the covers of its host, California red scale,Aonidiella aurantii (Maskell) (Diaspidae). This study tests the hypothesis that the concentration ofO-caffeoyltyrosine and scale cover size are reliable indicators of scale body size, an important component of host quality forA. melinus, over a range of scale rearing conditions. Both scale cover area andO-caffeoyltyrosine concentrations were only qualitatively related to scale body size during the third instar, the scale life stage most suitable forA. melinus. Scale cover area andO-caffeoyltyrosine concentrations were reduced, relative to scale body size, when scale were reared on bark and leaves compared to fruits. Scale cover area andO-caffeoyltyrosine concentration were also relatively reduced when scales were reared in mid-summer compared to spring and fall, and when reared on orange cultivars compared to lemon cultivars in the field. Finally, scale cover area andO-caffeoyltyrosine concentration were reduced when scale were reared at 52% compared to 100% humidity in the laboratory. Scales appear to be chemically conspicuous toA. melinus for a short period of the time in which they are physiologically susceptible. Scales that minimize their cover size and maximize the incorporation rate ofO-caffeoyltyrosine into covers may minimize their conspicuousness toA. melinus. Minimizing scale cover size, but not necessarily incorporation rates, may make scales more vulnerable to predators, however.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of insect behavior 11 (1998), S. 463-479 
    ISSN: 1572-8889
    Keywords: Aphytis melinus ; Aonidiella aurantii ; experience ; learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aphytis melinus recognizes and accepts covers of its host, California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae), before assessing the size or quality of the scale body beneath. We evaluated the role of a non-volatile kairomone, O-caffeoyltyrosine, and prior experience with hosts on the recognition (antennal drumming) and acceptance (ovipositor probing) of scale covers differing in age and, therefore, size. We tested several hypotheses concerning the role of experience with hosts on host recognition and acceptance. The first predicts that experience with a particular host size leads to increased selection of that host size in the future. The second predicts that the “quality” of the experience with hosts sets a threshold of quality for future acceptance. We manipulated the quality of wasp experience with hosts by exposing some wasps to high-quality hosts (large scale insects under large covers) and other wasps to low-quality hosts (small scale insects under small covers and small scale insects under large covers). Control (naive) wasps were held without experience with hosts. Wasps were then offered five size classes of covers directly after removal from the scale insects (unmanipulated) or after removing the kairomone from the covers (kairomone-free). For covers with natural levels of kairomone, no effect of experience with hosts on host recognition was observed. When the kairomone was removed, however, any experience with hosts increased recognition compared to naive wasps. Moreover, experienced wasps preferentially recognized covers of the size to which they had experience. Results for host acceptance differed from those for host recognition. Wasps given experience with large hosts accepted more covers with kairomone than wasps in other treatments, but the size preference did not vary among treatments. When the kairomone was removed, however, wasps given experience with large hosts under large covers preferred larger covers. Host recognition and acceptance are controlled by different behavioral mechanisms. Prior experience with hosts does not alter host recognition but does affect the rate of acceptance. The quality of the experience does not affect the acceptance of covers containing natural levels of kairomone but does affect host acceptance when the kairomone is removed. Experience with hosts alters the motivation of wasps to accept covers, and the direction of this effect is determined by the size (quality) of body the wasps were given during the experience.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 31-35 
    ISSN: 1570-7458
    Keywords: host quality ; nitrogen ; survival ; Leptinotarsa decemlineata ; Lycopersicon esculentum ; plant virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Pour vérifier l'hypothèse selon laquelle une contamination par un virs végétal peut accroître la consommation de plantes délaissées ou partiellement résistantes, nous avons examiné les interactions entre Leptinotarsa decemlineata Say, Lycopersicon esculentum Mill., et le virus de la mosaïque du tabac (TMV). La survie des larves de L. decemlineata a augmenté avec la contamination par TMV; les teneurs en azote et en tomatine étaient toutes deux plus élevées dans les plantes contaminées par le virus. La survie a augmenté linéairement avec la teneur en azote, mais sans dépendre de la teneur en tomatine. L'influence positive pour L. decemlineata de la contamination par le virus peut être attribuée au moins en partie à la teneur en azote plus élevée. Nos résultats correspondent à l'hypothèse selon laquelle la consommation de plantes délaissées ou partiellement résistantes peut être augmentée par la contamination virale, et que cette contamination peut faciliter l'adaptation d'insectes phytophages sur des plantes marginalement consommables.
    Notes: Abstract Infection by tobacco mosaic virus improved the suitability of tomato, Lycopersicon esculentum Mill. for survival of Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae. This improvement was due, at least in part, to the increase in total nitrogen content of virus-infected plants. The simultaneous increase in tomatine content had no discernable effect on L. decemlineata survival. Our results are consistent with the suggestions that virus infection may improve the suitability of partially resistant or non-preferred hosts, and that virus infection may facilitate the adaption of phytophagous insects to such ‘marginal’ host plant species.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 15 (1989), S. 2379-2390 
    ISSN: 1573-1561
    Keywords: Acidic fog ; Phaseolus lunatus ; Trichoplusia ni ; cabbage looper ; Lepidoptera ; Noctuidae ; nitrogen ; free amino acid ; soluble protein ; plantinsect interactions ; air pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phaseolus lunatus L. (Henderson Bush lima beans) were exposed to 2 hr acidic fogs with 2.5∶1.0 (v/v) nitrogen-sulfur ratio typical of the west coast of the United States. Fogs with pH values of 2.0 (P 〈 0.01,t tests), 2.5 (P 〈 0.05), or 3.0 (P 〈 0.01) increased percent total nitrogen (dry weight) of foliage as compared to plants subjected to control fogs with a pH of 6.3–6.5. Fresh weight concentrations of soluble protein and certain free amino acid concentrations were increased by plant exposure to acidic fogs with a pH of 2.5 (t tests,P 〈 0.05). Concentrations of free amino acids considered essential for insect growth, as well as nonessential and total free amino acids were not significantly affected by any treatment (P 〉 0.05,t test). Water content (%) of foliage was not changed significantly (P 〉 0.05,t test) by exposure to any of the fogs.Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) larvae ate significantly more foliage and gained significantly more weight on plants treated with 3.0 pH fogs (P 〈 0.01,t test). Several potential explanations are offered for the lack of significant weight gain by larvae on plants in which soluble protein levels, free amino acid concentrations, or percent total nitrogen contents were enhanced by acidic fogs with a pH of 2.5 and 2.0. No larval feeding preference was detected for foliage exposed to acidic versus control fogs, and no significant differences were detected in percent survival ofT. ni eggs exposed to acidic or control fogs. Some implications of acidic fogs for population dynamics ofT. ni are discussed.
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  • 7
    ISSN: 1573-1561
    Keywords: Ozone ; nutrition ; insect-plant interactions ; nitrogen ; secondary plant compounds ; Keiferia lycopersicella Lepidoptera ; Gellechiidae ; tomato ; Lycopersicon esculentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Tomato pinworms,Keiferia lycopersicella (Walsingham), survived better and developed faster on tomato plants,Lycopersicon esculentum Mill., damaged by ozone than on plants not subjected to ozone fumigation. Other measures of fitness, including survival during pupation, sex ratio of adults, female longevity, and fecundity, were not affected. Analyses of ozonated foliage at zero, two, and seven days following fumigation demonstrated a transient but significant increase (18–24%) in soluble protein concentration. Although the concentration of the total free amino acids in ozonated foliage did not increase significantly, significant changes were observed in at least 10 specific amino acids, some of which are critical for either insect development or the production of plant defensive chemicals. A reduction in total nitrogen in ozonated foliage at seven days postfumigation indicated that nitrogen was being translocated to other portions of the plant. The implications of increases in assimilable forms of nitrogen in ozonated foliage, which lead to improved host-plant suitability for insect herbivores, are discussed both in relation to some current ecological theories and in regard to pest-management strategies.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 19 (1993), S. 1721-1736 
    ISSN: 1573-1561
    Keywords: Kairomone ; oviposition stimulant ; O-caffeoyltyrosine ; Aphytis melinus ; Hymenoptera ; Encyrtidae ; Aonidiella aurantii ; Homoptera ; Diaspididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The parasitoid waspAphytis melinus uses a kairomone from the cover of its scale host, California red scale (Aonidiella aurantii), as an oviposition stimulant. The kairomone was isolated from extracts of scale covers, and identified asO-caffeoyltyrosine by a combination of spectroscopic methods. The kairomone was synthesized, and the synthetic compound was determined to be as active as the chemical isolated from scale covers.
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