Damage in Cactaceae, their geographic distribution and new evidences

Abstract

Background: Field observations of damage in columnar cacti of central Mexico, and previous evidence in scientific literature, indicated the absence of systematic information about kinds of damage, vectors, and pathogens, in this botanical family.Questions: How is the knowledge of damage and defense mechanisms in cacti? Is there a pattern in causal agents and their geographical distribution in the Americas?Methods: A database of 58 taxa by 51 types of damage was developed from literature recorded in ISI Web of Knowledge, Cabdirect, and Google Scholar, and it was analyzed by multivariate methods.Results: From 1,500 species of Cactaceae, only 58 have been studied through this scope. Subfamily Cactoideae has been the most studied, in particular tribe Echinocereeae (= Pachycereeae columnar cacti). Multivariate analysis grouped cacti according to the kind of damage: biotic, or abiotic. Damage due to biotic factors was sub-grouped depending on the herbivores. Damage by abiotic factors is more frequent in extreme latitudes. Fourteen species of columnar cacti were reported with herbivory and rot damage in Central Mexico, of which eight represent new records of damaged cacti.  Conclusions: The evidence from field observations, and few recent publications suggest that some generalist herbivores are becoming dangerous in this region, Future research is necessary in order to understand the dynamics of the dispersion of some kinds of damage, the role of human disturbance, and the role and changes in defense mechanisms in wild and domesticated cacti.