Establishment of Citrostichus phyllocnistoides (Hymenoptera: Eulophidae) as a biological control agent for the citrus leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae) in Spain

A program of introduction of exotic parasitoids for the biological control of the citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) was carried out in València (Spain) between 1996 and 1999. Eleven species of parasitoids were imported through a total of 37 shipments coming from nine countries. Six species were released in the field, the encyrtid Ageniaspis citricola (Logvinosvskaya), and the eulophids Quadrastichus sp., Semielacher petiolatus (Girault), Galeopsomyia fausta LaSalle, Cirrospilus ingenuus (Gahan), and Citrostichus phyllocnistoides (Narayanan). A. citricola was recovered in summer in many release points, reaching nearly 50% of parasitism and dispersing more than 300 m, but it was not able to overwinter. Quadrastichus sp. and S. petiolatus established temporarily in some sites, but produced little differences in parasitism or density of host population. In 1999, a substantial expansion of C. phyllocnistoides of more than 30 km in all directions was observed from one release point. In 2000 and 2001 this parasitoid expanded to all citrus grown in continental Spain and the Balear Islands, becoming the most abundant parasitoid in all the orchards, and displacing native and other introduced parasitoids. As a consequence, parasitism on second instars increased from less than 16% to 65% and on third instars from 35–38% to 59%. Overall, the mean percentage of parasitism increased from 20–25% to near 60%. Apparently, C. phyllocnistoides reduced by 34% the number of eggs and early instars of the host, and by 72% the number of adults. Damage to citrus foliage decreased by 56%.