Molecular and pheromone studies of Acrobasis nuxvorella

The pecan nut casebearer Acrobasis nuxvorella Nuenzig (Lepidoptera: Pyralidae) is the most damaging pest of pecan Carya illinoinensis (Wang) K. Koch (Fagales: Juglandaceae). A pheromone monitoring program for A. nuxvorella has been developed to assist growers in the timing of insecticide applications. The discovery that there are two sex pheromone types produced by A. nuxvorella has led to the complication of implementation of the pheromone monitoring program. One pheromone blend is produced by moths in the southern US, but not in Mexico While the other pheromone blend is produced by moths in the southern US and in Mexico. Because most male Lepidopterans respond only to a conspecific chemical signal, it was suspected that there were two strains of A. nuxvorella. In order to ascertain the relationship between the two postulated strains of A. nuxvorella, AFLP markers were developed and analyzed. Results of genetic analysis show that the genetic differentiation between these insects is not explained by pheromone type. This information is further supported by a pheromone assay in which a large proportion of male moths chose both pheromone blends when tested multiple times.