The fly has been a successful biocontrol agent in dry area of Hawii, so understanding the factors that determine its effectiveness represent a major challenge for the future. he expects demand only to increase for current agents and for new agents. In the long term, galled plants may display reduced competitive ability and lower lifetime reproductive success, but the short term increases in seed production it generates suggest it may be favouring its host’s range expansion. The insectary is testing both gall fly and stingless wasps to see how both biocontrol agents work against the knapweed. Clearly Procecidochares utilis is not providing effective biocontrol of Ageratina adenophora in Southwest China so far. However, the increase in above-ground vegetative biomass associated with branching resulted in less efficient capitulum production relative to vegetative growth. Elevating densities of seropositive mice may increase risk of hantavirus infection in humans and significantly alter hantavirus ecology. Alternanthera philoxeroides, a tip gall fly Clinodiplosis alternantherae failed host range tests by. Furthermore, seed numbers in capitula from galled and un-galled stems were similar, and galling resulted in only slightly reduced seed weights. A potential biocontrol agent for alligator weed. Stems with galls were more likely to be branched and produced more capitula. adenophora sites of Southwest China that were invaded at different times and support different densities of the insect. We examined the abundance and impact of P. Its galling is known to stimulate production of side branches in plants under laboratory conditions. gallprovincialis, and the western Atlantic populations of the European green. The stem-galling fly Procecidochares utilis has been widely introduced to help control Ageratina adenophora, a globally significant weed, but its impact has been inconsistent and in places ineffective. been an increased interest in biological control agents in last decade. The adult flies are active in spring, and females lay eggs on the green flower buds. Under some circumstances, overcompensation can even occur, with plant reproduction temporarily increasing rather than decreasing in response to herbivory. The Scotch thistle gall fly (Urophora stylata) is native to Europe and is a classical biocontrol agent for Scotch thistle that was released in New Zealand in 1998. Many natural enemies have provided successful control, but the impacts of herbivorous insects on their hosts are highly variable and context dependent. Growth and flowering can be retarded, but this agent alone does not kill plants or prevent spread. Classical biological control of invasive plants depends on the introduction of host-specific natural enemies.