INVESTIGADORES
SOSA alejandro JoaquÍn
congresos y reuniones científicas
Título:
The potential for biological control of lippia, Phyla canescens
Autor/es:
M.H. JULIEN; A.J. SOSA; M.G. TRAVERSA; M. FATEMI; E. GREIZERSTEIN
Lugar:
Vancouver
Reunión:
Congreso; 5th International Weed Science Congress; 2008
Resumen:
Lippia, Phyla canescens (Verbenaceae), is a low-growing herbaceous plant from South  America. It was introduced into Australia as an ornamental and now infests over 5 million hectares of grazing (mostly floodplains) and riparian land. It continues to spread and causes losses to the cattle industry exceeding $2.3 million annually. Lippia can be managed with cultivation, however, cultivation is not appropriate in many situations and habitats.  Similarly, management with herbicides is neither affordable, nor practical in many locations and not permitted along waterways. In 2005 a number of projects were initiated to improveour potential to control this weed. Surveys for potential biological control agents in  Argentina (native range) have identified 20 insect and about 15 fungi natural enemies.  These are being prioritized and studies are underway on the high priority species to develop rearing or culturing methods and to understand their biologies. Preliminary host range testing of the first insects is anticipated soon and a proposal to assess a rust is being  prepared. The taxonomy and distribution of lippia and related species is uncertain and  therefore their distributions are also unclear. Collections in South America, Australia andFrance (where it is also invasive) and molecular genetic analyses are determining where lippia occurs and the relationships between native and invasive range populations. This may help pinpoint the centres or origin of the invasive material and so help focus surveys for potential agents. Collections of other Phyla species, especially P. nodiflora, are being made with the intention of sorting out .the relationship between lippia and P. nodiflora. This isimportant because these two Phyla species only are reported from Australia and there is doubt that P. nodiflora is also exotic to Australia. Knowing this status will help determine the level of host specificity required for potential biological control agents for lippia.Analyses of pollen and root tip cells from lippia collected from the three countries is determining ploidy levels and the presence of hybridisation. Studies are also focusing on the biology, physiology and ecology of lippia to determine if there are key factors in itsenvironment and/or life cycle that might be exploited through biological control or integrated management. The overall aim of these projects is to develop better management strategies for lippia that compliment grazing strategies already in practice, to reduce  dependence on herbicides and to provide control measures where none arecurrently  available or practices, that is, in riparian and forested areas, and public and conservation lands.