2] surface area of nonionic carbonaceous resin (Ambersorb 563, Rohm and Haas, Philadelphia, Pennsylvania, USA) was buried within the root mass of each Centaurea at the time of transplanting.
04 g when neighboring Centaurea had been attacked by cabbage loopers, but was 0.
Contrary to expectations for biocontrols in general, in both experiments, Centaurea that had been exposed to herbivory had greater negative effects on Festuca than Centaurea that were kept free from herbivory; and, in the field experiment, Agapeta did not significantly decrease Centaurea biomass.
First, Centaurea plants may have grown faster after they experienced herbivory and, thereby, reduced resources available for other species.
Cnicin, a defensive chemical in Centaurea species that has been found to deter herbivory (Landau et al.
Sugar release to the rhizosphere of plants, which increased for Centaurea when grazed by Trichoplusia, is an important and readily available source of energy for microorganisms (Ocampo and Azcon 1985).
However, the fact that herbivory on Centaurea showed significant negative indirect effects on Festuca, under two very different sets of experimental conditions, suggests that these general indirect effects are robust.