@article {967,
	title = {How leaf domatia and induced plant resistance affect herbivores, natural enemies and plant performance},
	journal = {Oikos},
	volume = {89},
	year = {2000},
	note = {Journal
English
Article
MUNKSGAARD INT PUBL LTD
3
APR
299ZB
COPENHAGEN
Agrawal AA Univ Toronto, Dept Bot, 25 Willcocks St, Toronto, ON M5S 3B2, Canada
OIKOS
35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK},
	month = {2000///},
	pages = {70 - 80},
	abstract = {Predators and plant resistance may act together to control herbivorous arthropod populations or antagonistically, which would reduce the control of pest populations. In a field experiment we enhanced predation by adding simulated leaf domatia to plants. Leaf domatia are small structures that often harbor predaceous arthropods that are potentially beneficial to the plant. We also manipulated host plant duality by inducing resistance with controlled. early season exposure of seedlings to spider mite herbivory. Our manipulations had profound consequences for the natural community of arthropods that inhabited the plants. Leaf domatia had a direct positive effect on abundances of two species of bugs and one species of thrips, all of which are largely predators of herbivores. On leaves with domatia, each of the predators was found inside the domatia two to three times more often than outside the domatia. Eggs of predaceous bugs inside leaf domatia were protected from parasitism compared to eggs outside the domatia. The positive effects of leaf domatia on predator abundances were associated with reduced populations of herbivorous spider mites, aphids, and whiteflies. Plants with experimental leaf domatia showed significantly enhanced reproductive performance. Induced resistance also affected the community of arthropods. Of the abundant predators, all of which also fed on the plant, only minute pirate bugs were negatively affected by induced resistance. Populations of herbivorous spider mites and whiteflies were directly and negatively affected by induction. In contrast, aphid populations were higher on plants with induced resistance compared to uninduced plants. Effects of induced resistance and domatia were additive for each of the predators and for aphids. However, spider mite and whitefly populations were not suppressed Further by employing both induced resistance and domatia compared to each strategy alone. Our manipulations suggest that plant defense strategies can have positive effects on some species and negative effects on others. Negative effects of "resistance trails" on predators and positive effects on some herbivores may reduce the benefits of constitutive expression of resistance traits and may favor inducible defense strategies. Multiple plant strategies such as inducible resistance and morphological traits that aid in the recruitment of predators of herbivores may act together to maximize plant defenses, although they may also be redundant and not act additively},
	keywords = {BIOLOGICAL-CONTROL, COMMUNITIES, COMMUNITY, CONSEQUENCES, COTTON, DECIDUOUS FOREST, DEFENSE STRATEGY, FLOWER THRIPS, food webs, herbivory, HOST-PLANT, multiple, MUTUALISM, NATURAL ENEMIES, POPULATIONS, predation, PREDATOR, predators, RECRUITMENT, SEEDLINGS, SPIDER-MITES, TROPHIC LEVELS},
	isbn = {0030-1299},
	url = {ISI:000086227400008},
	author = {Agrawal,A.A. and Karban,R. and Colfer,R.G.}
}
@article {1115,
	title = {Restructuring of Lepidoptera communities by introduced Vespula wasps in a New Zealand beech forest},
	journal = {Oecologia},
	volume = {119},
	year = {1999},
	note = {Journal
English
Article
SPRINGER VERLAG
3
JUN
210WU
NEW YORK
Beggs JR Landcare Res, Private Bag 6, Nelson, New Zealand
OECOLOGIA
175 FIFTH AVE, NEW YORK, NY 10010 USA},
	month = {1999///},
	pages = {565 - 571},
	abstract = {Introduced social wasps (Vespula vulgaris) reach high densities in some New Zealand beech forests, because honeydew provides an abundant high-energy food source. We manipulated wasp density to estimate an "ecological damage threshold" for large, free- living Lepidoptera larvae. There will be a continuum of ecological damage thresholds for wasp density depending on the prey species or habitat. Experimentally placed small caterpillars had a significantly higher survival rate than large caterpillars, and the survival rate of both groups decreased with increasing wasp density. Spring-occurring caterpillars have a probability of surviving of 0.90-0.95, assuming wasps are the only source of mortality. However, at the peak of the wasp season we predict caterpillars would have virtually no chance (probability of 10(-78) to 10(-40)) of surviving to adults. Wasp abundance must be reduced by at least 88\% to conserve the more vulnerable species of free-living caterpillars at wasp densities similar to those observed in our study sites. This equates to a damage threshold of 2.7 wasps per Malaise trap per day. It was exceeded for about 5 months of the year in non-poisoned sites. There are currently no biological or chemical control techniques available in New Zealand that will reduce wasp abundance below this damage threshold throughout the year. Our models show that most Lepidoptera with spring caterpillars will be able to persist, but species with caterpillars occurring in the peak wasp season will be eliminated},
	keywords = {ABUNDANCE, BRACKEN, COMMUNITIES, COMMUNITY, DAMAGE, ecological impact, EXTRAFLORAL NECTARIES, HYMENOPTERA, INSECTS, larvae, LEPIDOPTERA, MORTALITY, phenology, POPULATIONS, predation, PREY, shared predator, SPHECOPHAGA-VESPARUM-VESPARUM, VESPIDAE, Vespula, VULGARIS, ZEALAND BEECH FOREST},
	isbn = {0029-8549},
	url = {ISI:000081128300012},
	author = {Beggs,J.R. and Rees,J.S.}
}
