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  • 1
    ISSN: 1573-1561
    Keywords: Trichogramma ; Hymenoptera ; Trichogrammatidae ; kairomone ; Heliothis zea ; biological control ; pest management ; parasitoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A kairomone from adultHeliothis zea (Boddie) scales is an important factor in the host selection process ofTrichogrammapretiosum Riley. If the host density is sufficiently high (i.e., 1 egg/500 cm2) and higher), a complete coverage or solid treatment of kairomone spray may be the optimum for increasing parasitization rates, but this is not the case at lower host densities (e.g., 1 egg/2000 cm2). At the lower densities, the kairomone must be distributed in such a way as to retain the parasitoids in the target area without inhibiting their movement from one ovi-position site to the next. Simulated moth scale particles appear to fill this need since their density can be regulated to provide the optimum frequency of parasitoid stimulation and thus maximum rates of parasitization at prevailing host densities.
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  • 2
    ISSN: 1573-1561
    Keywords: Kairomone ; Heliothis zea ; Lepidoptera: Noctuidae ; Microplitis croceipes ; Hymenoptera: Braconidae ; diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Heliothis zea (Boddie) larvae were reared on fresh plant material (cowpea cotyledons) or on an artificial laboratory diet. Effect of these two diets on the kairomonal activity of the frass and cuticle from the larvae, as well as the kairomonal activity of the diets themselves, forMicroplitis croceipes (Cresson) was determined. Diet was found to significantly affect the kairomonal activity of the frass although the diets themselves were not active.
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  • 3
    ISSN: 1573-1561
    Keywords: Kairomone ; parasitoids ; biological control ; Trichogramma pretiosum ; Hymenoptera ; Trichogramma tidae ; Heliothis zea ; Lepidoptera ; Noeturidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The behavioral response ofTrichogramma pretiosum Riley females to the kairomone found inHeliothis zea (Boddie) moth scales is examined.
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  • 4
    ISSN: 1573-1561
    Keywords: Acids ; moth scales ; Heliothis zea ; kairomones ; parasitoids ; biological control ; Trichogramma pretiosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Acids found in moth scales of laboratory-rearedHeliothis zea (Boddie) moths are hexanoic, heptanoic, octanoic, nonanoic, 2- (or 3-) furan carboxylic, phenylacetic, benzoic, sorbic, and 4-hydroxybenzoic acid. The last two of these acids are preservatives added to the artifical diet as sorbic acid and methyl-p-hydroxybenzoate. FemaleTrichogramma pretiosum Riley exhibited increased rates of parasitization ofH. zea eggs in the presence of some of these compounds in laboratory experiments. Exposure to a mixture of all of these compounds did not increase parasitization, and the elimination of acids from the crude moth-scale extract did not reduce parasitization by the wasps.
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  • 5
    ISSN: 1573-1561
    Keywords: Gossypium hirsutum ; cotton ; parasitoids ; Microplitis croceipes ; Cotesia marginiventris ; plant–insect interactions ; volatile semiochemicals ; systemic induction ; plant defense ; host-searching behavior ; generalist ; specialist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Cotton plants under herbivore attack release volatile semiochemicals that attract natural enemies of the herbivores to the damaged plant. The volatiles released in response to herbivory are not only released from the damaged leaves but from the entire cotton plant. We found that cotton plants that released myrcene, (Z)-3-hexenyl acetate, (E)-β-ocimene, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene, (E)-β-farnesene, and (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene systemically from undamaged leaves of caterpillar damaged plants were attractive to the generalist parasitoid Cotesia marginiventris and the specialist parasitoid Microplitis croceipes. Plants from which the caterpillar damaged leaves were removed and that released those compounds systemically were significantly preferred over undamaged control plants in two-choice experiments in a flight tunnel. Artificially damaged cotton plants that released green leafy volatiles and constitutive terpenoids were less attractive for M. croceipes and C. marginiventris. Only C. marginiventris preferred artificially damaged plants over undamaged control plants, whereas M. croceipes showed no preference. The apparent lack of specificity of systemically released compounds in response to different herbivores feeding on the lower leaves is discussed.
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  • 6
    ISSN: 1572-8889
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Females of Cotesia marginiventris(Cresson), a generalist larval parasitoid, were observed to respond to host related odors in a four-arm olfactometer. The females were significantly more responsive to the odors after a brief contact experience with host-damaged leaves contaminated with host by products. During the experience, actual encounters with hosts were not required to improve subsequent responses to host-related odors. The response to odors of the plant-host complex with which parasitoids had experience was significantly higher than the response to odors of an alternative plant-host complex. This suggests that the experience effect is due, at least partly, to associative learning. We suspect that females of this generalist parasitoid, as was recently found for those of a specialist, recognize specific semiochemicals when they contact frass of suitable host larvae. The parasitoids, subsequently, associate the surrounding odors with the possible presence of hosts, and use these odors as cues in their search for more hosts. This could be an important component in the host-searching behavior of many parasitoids.
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  • 7
    ISSN: 1572-8889
    Keywords: Hymenoptera ; Braconidae ; Microplitis croceipes ; cotton ; cowpea ; parasitoid ; host location ; kairomones ; olfaction ; induced plant responses ; learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was conducted to determine the primary source of volatile cues within the plant-host complex used by hostseeking freeflying female Microplitis cro-ceipesCresson in flight tunnel bioassays. In single-source and two-choice tests, using wasps given an oviposition experience on either cotton (Gossypium hirsutum)or cowpea (Vigna unguiculata)seedlings damaged by corn earworm (CEW; Helicoverpa zeaBoddie), the damaged seedlings were significantly more attractive than the CEW frass, which was in turn more attractive than the larvae themselves. In a series of two-choice wind-tunnel tests, the discriminatory ability of the wasps was examined, following various oviposition experiences. Significantly more wasps flew to plants with “old” damage than to plants with “fresh” damage, regardless of whether they had experience on fresh or old damage. In a comparison of plant species, wasps with only one experience on either hostdamaged cotton or host-damaged cowpea were unable to distinguish between them, and showed no preference for either plant, whereas wasps with multiple experiences on a particular plant preferentially flew to that plant in the choice test. In comparing hosts with nonhosts, wasps successfully learned to distinguish CEW from beet armyworm (BAW; Spodoptera exigua)on cotton but were unable to distinguish CEW from either BAW or cabbage looper (Trichoplusia ni)on cowpea. The results show the important role played by plant volatiles in the location of hosts by M. croceipesand indicate the wasps’ limitations in discriminating among the various odors. The ecological advantages and disadvantages of this behavior are discussed.
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  • 8
    ISSN: 1570-7458
    Keywords: Heliothis ; kairomone ; parasitoid searching behavior ; Trichogramma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Trichogramma pretiosum Riley, parasitoïde généraliste des oeufs de lépidoptères, intensifie sa prospection sur des emplacements, contaminés par une kairomone associée aux pontes d'Heliothis zea Boddie (Lep. Noctuidae). Au laboratoire T. pretiosum cherchera les emplacements contaminés, abandonnant les morceaux de papier filtre standardisés (de 10 cm de diamètre) si aucun hôte n'est découvert dans les 60 à 180 secondes. Le temps total et le temps de prospection passés sur les emplacements sur lesquels des hôtes ont été découverts présentent une meilleure corrélation avec le nombre d'hôte attaqués (Nha) par morceau de papier qu'avec la densité réelle des hôtes. La perception de la densité d'hôte par morceau de papier est souvent incorrecte dans ce sens. Le temps de palpation (Th) et le temps dépensé à palper à nouveau des hôtes déjà parasités correspondent à une dépense importante du temps passé sur le morceau de papier. Les différentes hypothèses qui ont été utilisées pour expliquer la distribution du temps de prospection par d'autres parasitoïdes et prédateurs semblent inapplicables à T. pretiosum. Le taux de retour sur des hôtes parasités par rapport au nombre d'hôtes attaqués semble affecter les dépenses de temps de cette espèce. Les résultats d'observations antérieures dans les champs sont comparés aux observations de laboratoire du comportement de prospection.
    Notes: Abstract Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae), a generalist parasitoid of lepidopteran eggs, intensifies search in patches contaminated by a kairomone associated with Heliothis zea (Boddie) (Lepidoptera: Noctuidae) oviposition sites. In the laboratory the parasitoid will search any kairomone-treated patch, abandoning standardized (10 cm diam) patches if no hosts are located within 60–180 sec. Total time and searching time on patches in which hosts are discovered are more highly correlated with the number of hosts attacked (Nha) per patch than with actual host density. The parasitoid's perception of host density per patch is often “incorrect” in this sense. Handling time (Th) and time “wasted” in re-handling hosts parasitized earlier in the patch visit consume a large proportion of total patch time. Several hypotheses which have been suggested to explain patch time allocation by other parasitoids and predators appear inapplicable to T. pretiosum. The ratio of re-encounters with parasitized hosts to the number of hosts attacked appears to affect the allocation of patch time by this species. The results of previous field experiments are compared to laboratory observations of searching behavior.
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  • 9
    ISSN: 0739-4462
    Keywords: parasitoid ; plant-insect interactions ; learning ; biological control ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Chemical cues enable female parasitic wasps to locate the eggs, larvae, or other life stages of the insects in or on which they place their eggs. These chemical signals, or semiochemicals, may be produced by the hosts and/or by the plants on which the hosts feed. The composition of the chemical signal often differs with different species of hosts or with different plants. New evidence suggests that the wasps exploit semiochemicals emitted by plants in response to insect herbivore feeding. The wasps learn to respond to the different blends of chemicals that indicate the location of their hosts and they can be trained to respond to a specific odor blend. Thus, it may be possible to increase their effectiveness for biological control by conditioning them, prior to their release, to search for a target pest in a particular crop. © 1993 Wiley-Liss, Inc.
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  • 10
    Publication Date: 2006-08-19
    Description: The ability of many insects to learn has been documented. However, a limited number of studies examining associative learning in medically important arthropods has been published. Investigations into the associative learning capabilities of Culex quinquefasciatus Say were conducted by adapting methods commonly used in experiments involving Hymenoptera. Male and female mosquitoes were able to learn a conditioned stimulus that consisted of an odor not normally encountered in nature (synthetic strawberry or vanilla extracts) in association with an unconditioned stimulus consisting of either a sugar (males and females) or blood (females) meal. Such information could lead to a better understanding of the ability of mosquitoes to locate and select host and food resources in nature. ©2006 Springer-Verlag
    Print ISSN: 0028-1042
    Electronic ISSN: 1432-1904
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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