Biocontrol introduction
Target pest: Cardiaspina fiscella (Hemiptera: Aphalaridae), brown lace lerp
Agent introduced: Psyllaephagus gemitus (Hymenoptera: Encyrtidae)
Imported:
Withers & Bain (2000) - accidentally introduced. First detected in New Zealand (in the Northland and Auckland regions) in November 1999.
Import notes:
Withers & Bain (2000), Withers (2001) - it is most likely that the P. gemitus was naturally introduced with its host, C. fiscella, either at the time of the initial incursion that led to the establishment of C. fiscella or at a subsequent incursion. However, an illegal deliberate importation of the parasitoid cannot be completely ruled out.
Establishment:
Withers (2000) - Psyllaephagus gemitus was first reared from C. fiscella in Northland in December 1999. By June 2000, the parasitoid was widely established in the North Island, from Bay of Plenty to Northland.
Impacts on target:
Withers & Bain (2000) - populations of C. fiscella in Northland appear to have decreased wherever P. gemitus is present, and tree recovery is noticeable. Parasitism rates of C. fiscella are very high. In regions where the parasitoid is not present, such as coastal Bay of Plenty, trees of host species Eucalyptus saligna and E. botryoides are in poor health through continuing defoliation.
Impacts on non-targets:
Withers & Bain (2000) - while the benefits of the establishment of P. gemitus in New Zealand are becoming apparent [see Withers & Bain (2000) entry in ‘Impacts on target’ section] the risk to native and beneficial psyllids (such as the broom biocontrol agent Arytanilla spartiophila) have not been determined.
General comments:
Withers & Bain (2000) - brown lace lerp, Cardiaspina fiscella, was first discovered in New Zealand in May 1996 near Auckland airport. It now ranges from Whangarei in the north to Rotorua in the south and Gisborne in the east, and has seriously defoliated Eucalyptus saligna and E. botryoides, rendering many trees moribund. Psyllaephagus gemitus was investigated in 1997 as a possible biocontrol for C. fiscella and in 1999 the Environmental Protection Authority granted permission to import the parasitoid into quarantine for host range testing [see EPA (1999) entry in ‘EPA applications’ section]. However, it was never imported into quarantine as it was discovered in November 1999 attacking C. fiscella in the Northland and Auckland regions.
EPA Applications:
EPA (1999a) - 13 April 1999: application by New Zealand Farm Forestry Association to import the parasitoid Psyllaephagus gemitus into containment for environmental safety and efficacy testing as a control agent for Cardiaspina fiscella. EPA Application # NOC98006, approved with controls 2 June 1999. [NB: this approval was never utilised - see Withers & Bain (2000) entry in ‘General comments’ section.]
References
EPA (1999a). Application to EPA (NOC98006) to import the parasitoid Psyllaephagus gemitus into containment for environmental safety and efficacy testing as a control agent for Cardiaspina fiscella. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/NOC98006
Withers T, Bain J (2000). Mysterious arrival of Cardiaspina parasitoid. New Zealand Tree Grower 21(2): 33
Withers TM (2001). Colonization of eucalypts in New Zealand by Australian insects. Austral Ecology 26: 467-476 https://doi.org/10.1046/j.1442-9993.2001.01140.x
