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  • Aphytis melinus  (5)
  • glandular trichomes  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Volatile cues used by the parasitoid, Aphytis melinus, for host location: California red scale revisited (1998)
    Springer
    Entomologia experimentalis et applicata 88 (1998), S. 235-245 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003400215721
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  • 2
    Electronic Resource
    Electronic Resource
    Priming Aphytis: behavioral modification of host selection by exposure to a synthetic contact kairomone (1996)
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 263-269 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193445
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  • 3
    Electronic Resource
    Electronic Resource
    Environmental variation in physical and chemical cues used by the parasitic wasp,Aphytis melinus, for host recognition (1994)
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 97-108 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02383544
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  • 4
    Electronic Resource
    Electronic Resource
    Innate and Learned Cues: Scale Cover Selection by Aphytis melinus (Hymenoptera: Aphelinidae) (1998)
    Springer
    Journal of insect behavior 11 (1998), S. 463-479 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022307211699
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic and Environmental Variation in Acyl Glucose Ester Production and Glandular and Nonglandular Trichome Densities in Datura wrightii (2000)
    Springer
    Journal of chemical ecology 26 (2000), S. 2801-2823 
    Details
    ISSN: 1573-1561
    Keywords: Acyl sugar esters ; glandular trichomes ; water availability ; genetic variation ; allocation cost ; chemical defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Natural populations of Datura wrightii in southern California are dimorphic for trichome type. Some plants within populations produce greater than 85% glandular trichomes, whereas other produce mainly nonglandular trichomes. Glandular trichome exudates in D. wrightii consist of glucose esterified with straight chain C6–C9 acids. These exudates, and similar exudates in other species, confer resistance to several insect herbivore species. We tested the hypothesis that water was limiting sugar ester production and examined the extent to which trichome density was determined by environmental factors by measuring the concentrations of sugar esters and the densities of trichomes on leaves of plants grown under different irrigation treatments. Water did not limit sugar ester production, as unwatered plants produced 36% more millimoles of glucose esters per square centimeter of leaf surface than did watered plants. Although the addition of water increased leaf size, densities of both nonglandular and glandular trichomes did not change with leaf length or area, suggesting that plants having larger leaves initiated more trichomes in order to maintain nearly constant densities. Millimoles of sugar esters produced did not correlate with densities of glandular trichomes, suggesting that other factors in addition to glandular trichome number govern the production of sugar esters for plant defense.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026493927622
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  • 6
    Electronic Resource
    Electronic Resource
    Identification and synthesis of a kairomone inducing oviposition by parasitoidAphytis melinus from California red scale covers (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 1721-1736 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00982303
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  • 7
    Electronic Resource
    Electronic Resource
    Biological Activity of Datura wrightii Glandular Trichome Exudate Against Manduca Sexta Larvae (1998)
    Springer
    Journal of chemical ecology 24 (1998), S. 1529-1549 
    Details
    ISSN: 1573-1561
    Keywords: Tobacco hornworm ; Solanaceae ; insect–plant interactions ; glandular trichomes ; exudate ; resistance polymorphism ; oviposition choice ; acyl sugar esters ; Lepidoptera ; Sphingidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Natural populations of Datura wrightii in southern California consist of two distinctly different phenotypes. The leaves of one phenotype are densely covered with nonglandular trichomes and feel velvety. The other phenotype is covered with larger type IV glandular trichomes that excrete a sticky exudate. Neonate larvae of M. sexta reared on velvety leaves developed significantly faster than larvae on sticky leaves. Larvae on sticky leaves took 28% longer to reach the prepupal stage. Survival and pupal weight were not significantly different between the two groups. First instars of M. sexta had a significantly higher consumption rate on velvety leaves than on sticky leaves. Removal of the exudate from stickly leaves significantly increased larval consumption rates compared to unwashed controls. Female moths did not show an oviposition preference; both in the lab and in the field the two trichome phenotypes of D. wrightii received similar egg loads. Because there were no significant differences in other nutritional factors between the two plant phenotypes, we concluded that the exudate was responsible for the effect. We isolated a complex mixture of sugar esters (SE) as the biologically active compounds in the exudate of D. wrightii. The SE mixture was composed of glucose esterified with several combinations of straight chain C6–C9 acids. By comparing GC-MS spectra of synthetic SE with the SE extracted from D. wrightii, we identified one of the SE as 3′-O-hexanoyl glucose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020963817685
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