Preference and survival of Cactoblastis cactorum on a diversity of host plants in the insects? native Argentine range, OR, ?Does mother know best??

VARONE, LAURA; MANTECA ACOSTA, MARIANA; LOGARZO, GUILLERMO A.; HIGHT, STEPHEN M.; CARPENTER, JAMES E.

San Diego, California

Congreso; The 58th Annual Meeting of the Entomological Society of America; 2010

A central aspect in biology and ecology is to determine the combination of factors that influence the distribution of species. In the case of herbivorous insects, the distribution of herbivorous species is necessarily associated with their host plants, a pattern often referred to as ?host use?. Novel interactions that arise during a biological invasion can have important effects on the dynamics of that invasion, especially if it is driven by only a subset of the genetic diversity of the invading species. This is the case of the well-known South American cactus moth, Cactoblastis cactorum, a successfully used biological control agent of non-native Opuntia cacti in Australia and South Africa, but now threatening unique cactus diversity and agriculture in North America. We studied the patterns of host plant usage by and host plant availability for C. cactorum under field conditions in Argentina, covering the geographical range of the four C. cactorum phylogroups and the recently documented southern distribution. We also assessed female preference and larval performance under laboratory conditions. Cactoblastis cactorum showed a geographical pattern of host use in its native range that was related to host availability. Laboratory assays of female preference showed some degree of preference to oviposit on O. ficus-indica, O. leucotricha and O. quimilo, but it was not positively correlated with the performance of larvae. These findings contribute to the further comprehension of the host use dynamics of C. cactorum in the insects? native range, and could provide useful information for assessing the risk and future spread of this insect in North America.