Original Paper

Biological Invasions

, Volume 16, Issue 1, pp 13-22

Larval morphology and host use confirms ecotypic variation in Cactoblastis cactorum (Berg)

  • Christopher P. BrooksAffiliated with Department of Biological Sciences and Geosystems Research Institute, Mississippi State University Email author 
  • , Brice H. LambertAffiliated with Department of Biological Sciences and Geosystems Research Institute, Mississippi State University
  • , Kristen E. SaubyAffiliated with Department of Biological Sciences and Geosystems Research Institute, Mississippi State UniversityDepartment of Biology, University of Florida
  • , Gary N. ErvinAffiliated with Department of Biological Sciences and Geosystems Research Institute, Mississippi State University
  • , Laura VaroneAffiliated withFuEDEI Fundación para el Estudio de Especies Invasivas
  • , Guillermo A. LogarzoAffiliated withFuEDEI Fundación para el Estudio de Especies Invasivas

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Abstract

Despite their recognized importance in the literature, the contribution of native-range species interactions to invasion success has been inadequately studied. Previous authors have suggested that biases in the sampling of propagules from the native range might influence invasion success, but most contemporary invasion hypotheses focus on the development of novel interactions or a release from native consumers and competitors. When ecotypic variation exists in native host-consumer associations, the specific pattern of sampling across ecotypes could determine invasion success, especially when the genetic diversity among exotic propagules is low. The South American cactus moth, Cactoblastis cactorum (Berg), is an oligophagous consumer whose larvae feed on prickly pear cacti (subfamily Opuntioideae). The moth was collected from a small geographic area along the Argentina-Uruguay border in 1925 and was introduced to multiple continents as a biological control species, which has subsequently invaded North America. Here we show that groups defined by genetic structure in this species’ native range are concordant with distinct patterns of host association and larval morphology. Furthermore, in Florida populations, morphological traits have diverged from those found in the native range, and patterns of host association suggest that strong biases in host preference also occur in invasive populations. The documented history of C. cactorum introductions confirms that multiple attempts were made to export the moth, but that only a single ecotype was exported successfully. Additional work will be necessary to determine whether the observed host biases in North America reflect a rapid adaptation to naïve hosts or a conservation of traits related to specific aspects of the host-consumer association.

Keywords

Ecotype Cactoblastis cactorum Argentina Florida Opuntia