The establishment and spread of Tamarixia triozae, a parasitoid of the potato psyllid, in New Zealand

Abstract

The release of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae), a parasitoid of the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), resulted in the successful establishment of the parasitoid in New Zealand. The parasitoid was released at more than 30 sites by the final year of the three-year study throughout New Zealand. Its continued presence over the three-year study was confirmed in two regions (Hawke’s Bay and Canterbury). At one site in Canterbury, the parasitoid was released only in the first summer of this study (Nov. 2017–Feb. 2018). It was recovered from potato psyllid infested African boxthorn (Lycium ferocissimum Miers) foliage in the second and third summers at this site, demonstrating the parasitoid’s ability to survive over successive winters. We found T. triozae parasitized nymphs at 24 sites of the 86 potato psyllid host plant sites surveyed within a 25 km radius of known release sites in Hawke’s Bay. The parasitoid was found up to 24 km from the nearest known release site in Hawke’s Bay. In Canterbury, the parasitoid was found up to 0.6 km from a known release site. Parasitism rates of 13.7–15.6% were estimated based on two post-release survey methods employed in this study. The parasitoid also feeds on psyllid nymphs so its establishment may lead to helping to reduce or delay potato psyllid populations from reaching damaging levels. Long-term monitoring is needed to determine the consequences of importing T. triozae on populations of potato psyllid.