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Host plant chemical cues

Unlike parasitoids of other insect orders that have host-seeking larvae, most parasitic hymenoptera lay their eggs on, in, or very close to a host individual [11]. This requires the adult female to find a suitable host, often with the aid of chemical cues from host frass, pheromones, plant volatiles emitted upon host feeding or egg-deposition, silk, honeydew and other secretions. She may then chemically mark the host following oviposition to reduce superparasitism by herself or intra- and inter-specific insects [11]. [Pg.146]

Tetratrophic interactions between a host plant, a phytophagous pest (primary host), a hymenopteran parasitoid or symbiont (secondary host) and a hymenopteran hyperparasitoid (which parasitizes the secondary host) are of considerable importance, because hyperparasitism can significantly reduce populations of economically beneficial parasitoids [11]. Hyperparasitoids use host-marking (=spacing) pheromones, sex pheromones [12], and host-detection cues [42], but they also show additional chemically mediated interactions with the other partners. These include detection of the primary host s secretions by the hyperparasitoid [43], detection of plant volatiles by the hyperparasitoid [44], and detection of the hyperparasitoid s secretions by the primary host [45] or by the secondary host. The latter causes the secondary host to avoid locations where the hyperparasitoid is foraging [46]. [Pg.146]

The selection or avoidance of potential host plants by phytophagous Insects Is guided by a complex combination of physical and chemical stimuli. Color, shape and olfactory cues may play a role In the Initial orientation, whereas acceptance or rejection of a plant depends on texture as well as chemical stimulants or deterrents. Initiation of feeding Is stimulated or deterred by the presence or absence of specific chemicals or groups of chemicals, many of which have been Identified. The selection of a suitable plant for ovlposltlon Is also crucial for survival of the progeny of most herbivorous Insects, but the chemical factors Involved are known In relatively few cases. Ovlposltlon stimulants and deterrents often appear to be quite different from the chemicals that elicit or Inhibit feeding responses of larvae. [Pg.199]

Chapters in this volume consider how plants use chemicals to defend themselves from insect herbivores the complexity of floral odors that mediate insect pollination tritrophic interactions of plants, herbivores, and parasitoids, and the chemical cues that parasitoids use to find their herbivore hosts the semiochemically mediated behaviors of mites pheromone communication in spiders and cockroaches the ecological dependence of tiger moths on the chemistry of their host plants and the selective forces that shape the pheromone communication channel of moths. [Pg.347]

Leaf surface compounds provide important information about host-plant acceptability to coleopteran insects. Although the tortoise beetle, Cassida canaliculata, is only weakly attracted to odors from host plants, it shows strong preferences for host plants when additional contact cues are provided.64 The cottonwood leaf beetle, Chrysomela scripta, which is a pest of cottonwood, poplar, and willow, is stimulated to feed by leaf surface chemicals produced by a beetle-preferred poplar clone 65 The feeding stimulants have been isolated and identified as 1-docosanol, 1-tetracosanol, 1-hexacosanol, 1-octacosanol, 1-triacontanol, and... [Pg.574]

Over 20,000 terpenoids have been identihed (1), and more are being discovered continuously. Plant terpenoids are important in both primary and secondary (speciahzed) metabolism. Their importance in primary metabolism includes physiological, metabolic, and stmctural roles such as plant hormones, chloro-plast pigments, roles in electron transport systems, and roles in the posttranslational modihcation of proteins. In secondary metabolism, the roles of plant terpenoids are incredibly diverse but are associated most often with defense and communication of sessile plants interacting with other organisms. Examples include terpenoid chemicals that form physical and chemical barriers, antibiotics, phytoalexins, repellents and antifeedants against insects and other herbivores, toxins, attractants for pollinators or fruit-dispersing animals, host/nonhost selection cues for herbivores, and mediators of plant-plant and mycorrhiza interactions (2, 3). [Pg.1834]

Insects are the most diverse group animals on earth, with approximately five million species described to date (Novotny et al. 2002). Amidst this great diversity are adaptations common to all insects that maximize inclusive fitness in their respective habitats. One such fundamental adaptation is the ability to respond to cues in the environment, in particular the ability to detect external biological compounds via a chemical sensor. The sophisticated olfactory system of insects is able to sense volatile odorants derived from prey, host plants, and conspecific individuals. These compounds are detected by olfactory receptor neurons (ORNs) housed in the antennae, and these ORNs relay information about food sources, oviposition sites, and mates that leads to behavior based on neural responses mediated by the ORNs. The binding... [Pg.133]

In this paper we have only discussed chemical contact cues used by insects to identify ovipositional sites. In nature, olfactory, mechanical, and visual stimuli may also be important in the location, recognition, and acceptance of host plants. Much work remains to be done in this area. We believe that multidisciplinary teams are needed to work toward a more complete understanding of insect-plant interactions. With the knowledge obtained, plants can be more readily designed to naturally resist insect damage. [Pg.276]

Wickremasighe, M. G. V. and H. F. Emden, Reactions of adult female parasitoids, particularly Aphidius rhopalosiphi to volatile chemical cues from host plants of their aphid prey. Physiol. Entom., 17, 297-304 (1992). [Pg.41]

Animals live in a world of chemical communication and receive both olfactory and visual cues that indicate appropriate host plants. When the animal has located the flower against the generally green background, it may be attracted to the nectar by nectar guides on the petals. These are derived from differential distribution of pigments within the flower tissue. The biochemistry of plant pollination mechanisms has not been studied extensively. [Pg.177]

Aphids have flexible, stylet-like mouthparts adapted for probing of plant tissues. By this means, the aphid must use chemical cues from the plant to determine if the plant is a suitable host (host plant quality), where the aphid is on the plant, the location of the stylet within the plant tissues, and the direction to probe to locate the plant phloem (Campbell and Dreyer, 1990 Dreyer and Campbell, 1987). Aphids avoid many of the toxic compounds stored in plant cells by probing between the cell walls. These insects are able to penetrate the intercellular spaces by producing a variety of digestive enzymes which depolymerize the pectins and hemicelluloses forming the intercellular-cell wall matrix. Aphid-host plant compatibility is associated to the extent that these enzymes depolymerize their respective substrates, and a reduced rate of depolymerization is often associated with host plant resistance. Differences in methoxylation, acetylation, or neutral sugar composition in the matrix polysaccharides are often involved in this reduced depolymerization. Further, specific breakdown products from depolymeri-... [Pg.262]

After phytophagous insects have located a potential host plant using visual and olfactory cues, contact with the plant surface seems to be essential before feeding or oviposition are initiated (Alfaro et al., 1980 Blaney and Duckett, 1975 Calvert, 1974 Calvert and Hanson, 1981 Chapman, 1977 Ma and Schoonhoven, 1973 Rottger, 1978 Stadler, 1976, 1977,1980 see also Scriber, Chapter 7). Chemical analysis of the leaf surfaces with the exception of cuticu-lar waxes ( -alkanes) are sparse (Chapman, 1977). Although the chemistry of... [Pg.17]

Some of the problems in understanding the behavioral processes that are involved in discriminating host from nonhost are illustrated by the design of bioassays to identify specific oviposition stimulants for swallowtail butterflies. At one time, it was generally believed that insects utilized specific secondary plant compounds as token or sign stimuli to identify their hosts (Verschaffelt 1911 Dethier 1941 Fraenkel 1959, reviewed by Feeny et al. 1983). A great deal of effort was expended to identify such token stimuli, and most of it was unsuccessful the behavior of host selection was rarely linked to a single plant chemical. Instead, host selection came to be appreciated as the end result of several behavioral responses to a number of physical, chemical, and visual cues (reviewed by Miller Strickler 1984). [Pg.229]

Filella, I., Bosch, J., Llusi J. et al. (2011) Chemical cues involved in the attraction of the oligolectic bee Hoplitis adunca to its host plant Echium vulgare. Biochem. System. Ecol. 39,498. [Pg.217]


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