03644nas a2200433   4500008004100000020001400041245010700055210006900162260001200231300001200243490000700255520252000262653002302782653001602805653001402821653001702835653001102852653002102863653002102884653001802905653001402923653001402937653001502951653001302966653001402979653002002993653001603013653001403029653001303043653001403056653001603070653001403086653001703100653001903117100001803136700001503154700001703169856002403186       2000                        eng d  a0030-129900aHow leaf domatia and induced plant resistance affect herbivores, natural enemies and plant performance0 aHow leaf domatia and induced plant resistance affect herbivores   c2000///  a70 - 800 v893 aPredators 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 additively10aBIOLOGICAL-CONTROL10aCOMMUNITIES10aCOMMUNITY10aCONSEQUENCES10aCOTTON10aDECIDUOUS FOREST10aDEFENSE STRATEGY10aFLOWER THRIPS10afood webs10aherbivory10aHOST-PLANT10amultiple10aMUTUALISM10aNATURAL ENEMIES10aPOPULATIONS10apredation10aPREDATOR10apredators10aRECRUITMENT10aSEEDLINGS10aSPIDER-MITES10aTROPHIC LEVELS1 aAgrawal, A.A.1 aKarban, R.1 aColfer, R.G.  uISI:00008622740000802646nas a2200301   4500008004100000020001400041245009300055210006900148260001200217300001600229490000700245520185300252653001702105653001202122653002302134653002302157653001502180653001302195653001402208653001302222653002102235653001602256653001302272653000902285653000902294100001702303856002402320       2004                        eng d  a0012-965800aTrait-initiated indirect effects due to changes in consumption rates in simple food webs0 aTraitinitiated indirect effects due to changes in consumption ra  c2004///  a1029 - 10380 v853 aThis article explores the potential indirect effects due to changes in consumption-related traits of a focal prey species in each of two simple food webs. The systems considered are: one predator exploiting two independent prey, and one predator exploiting two prey that use a common limiting resource. In each system, the indirect effect of a change in a consumption-related parameter of one prey species on the population density of the other prey is determined. When prey only share a predator, the change in one prey’s density produced by a change in the other prey’s vulnerability to the predator is determined by whether or not that second prey is initially overexploited; i.e., whether its exploiter’s intake decreases with an increase in the attack rate. Increases in the vulnerability of an overexploited prey decrease the predator population and thereby indirectly increase the population size of the second prey. Increases in the vulnerability of a prey that is not overexploited have the opposite effects on both the predator and second prey populations. Both of these outcomes can be reversed by strong direct density dependence in the predator, provided the predator exhibits satiation. In the food web with a shared food and a shared resource, increases in predator vulnerability of the more vulnerable prey species always increase the population size of the more resistant prey species. However, increases in the vulnerability of the more resistant prey can either increase or decrease the population size of the more vulnerable prey species. When the more resistant prey becomes better at capturing the resource, the less resistant may either increase or decrease. Overexploitation also explains these outcomes. General principles for understanding the consequences of changes in vulnerabilities or attack rates are discussed10aCONSEQUENCES10aDENSITY10aDENSITY DEPENDENCE10aDENSITY-DEPENDENCE10aDEPENDENCE10afood web10afood webs10aFOOD-WEB10aindirect effects10aPOPULATIONS10aPREDATOR10aPREY10aSIZE1 aAbrams, P.A.  uISI:00022076660001401956nas a2200265   4500008004100000020001400041245008600055210006900141260001200210300001600222490000700238520123500245653001201480653001201492653001401504653002101518653002601539653001701565653003101582653001301613653001401626653000901640100001701649856002401666       2007                        eng d  a0012-965800aDefining and measuring the impact of dynamic traits on interspecific interactions0 aDefining and measuring the impact of dynamic traits on interspec  c2007///  a2555 - 25620 v883 aTrait- and density-mediated indirect effects describe different pathways by which indirect interactions in food webs are propagated from one species to another, through changes in intermediate species. A series of articles in Ecology has progressively altered the original definitions of "trait-mediated’’ to the point where understanding is being impeded. The most recent of these articles are two meta-analyses that use "trait-mediated’’ to describe the demographic costs to a prey species of employing anti-predator defenses. These same articles introduce a companion term, "density-mediated interaction,’’ apparently to describe direct and indirect interactions that only involve changes in population density due to consumption by predators. This new terminology has many disadvantages, including ( 1) using a general term for a relatively narrow group of processes; ( 2) using "mediated’’ in a manner inconsistent with existing terminology; ( 3) confusing the accepted definitions of different types of indirect effects; and ( 4) providing a highly incomplete measure of the impact of behavior on the predator - prey interaction. Solutions to these problems and the meaning of the meta-analyses are discussed10adefense10aecology10afood webs10aindirect effects10aindirect interactions10ainteractions10aINTERSPECIFIC INTERACTIONS10aPREDATOR10apredators10aPREY1 aAbrams, P.A.  uISI:000250714200016