Biological control of the invasive weed Brazilian pepper with Gracillariidae species of leaf blotchers

The host range of several species of leaf blotchers (Lepidoptera: Gracillariidae) were studied to assess their suitability as a biological control agents of Schinus terebinthifolius Raddi (Anacardiaceae), a serious environmental weed in the USA and elsewhere in the world. The host range was determined in the laboratory with adult no-choice oviposition and larval development tests. Seventeen plant species in 10 Anacardiaceae genera were selected based on taxonomic relatedness to S. terebinthifolius, economic importance, and availability. Additional information was obtained by sampling foliage of S. terebinthifolius and six other South American native Anacardiaceae species in north-eastern Argentina. The host range of these species was related to plant chemistry factors (terpenoids, urushiols, amino acids, sugars,) and phylogenetic proximity to the weed. Different Gracillariidae species had different host ranges, but in general nearly all tested plant species were accepted for oviposition. Incipient mines successfully developed into complete mines, pupae and adults on R. aromatica, R. copallinum, S. molle and S. terebinthifolius. In the field, although Gracillariidae spp showed a clear preference for S. terebinthifolius, the realized host-range included three other Schinus species (S. lentiscifolius, S. longifolius, S. weinmannifolius) and one Astronium species (A. balansae). In conclusion, these Gracillariidae species will not be considered for the biological control of S. terebinthifolius in continental US. However, the utilization of this species in other infested areas, such as Hawaii and Australia should be further discussed.