Biocontrol introduction
Target pest: Agromyzidae (Diptera: Agromyzidae), leaf miners
Agent introduced: Hemiptarsenus varicornis (Hymenoptera: Eulophidae) = Hemiptarsenus semialbiclavus
Imported:
1970-71 (also probably accidentally introduced and established prior to these deliberate introductions)
Import source:
Pakistan
Import notes:
Cameron et al. (1989) - because resources for mass-rearing in New Zealand were lacking, biocontrol agents for the biocontrol programme against agromyzids were reared in Pakistan and sent to New Zealand by the Commonwealth Institute of Biological Control in Pakistan. The host agromyzids in Pakistan from which all parasitoids for New Zealand were obtained were Chromatomyia horticola and Liriomyza brassicae. In November 1970, two consignments of agromyzid parasitoids from Pakistan included 218 adult parasitoids tentatively identified as Chrysocharis sp. These were subsequently determined to be Hemiptarsenus varicornis [introduced as, and recorded in Cameron et al. (1988) as, Hemiptarsenus semialbiclavus - see Taxonomic note (10 June 2026) in 'General comments' section below]. Three further shipments contained 553 adult H. varicornis.
Released:
1970
Release details:
Cameron et al. (1989) - in total, between December 1970 and March 1971, 653 H. varicornis were released at Lincoln, Canterbury, South Island on brassicas and Sonchus sp. and 100 at Ashburton, South Island on turnips.
Establishment:
Cameron et al. (1989) - Hemiptarsenus varicornis was probably already present in New Zealand parasitising Agromyzidae before the leaf miner biocontrol programme began. Hemiptarsenus sp. had been recorded associated with various crops, including brassicas, and had been recorded parasitising the agromyzids Liriomyza chenpodii and Cerodontha australis [see Cameron et al. (1989) entry in 'General comments' section below]. This was probably H. varicornis.
Impacts on target:
Cameron et al. (1989) - Hemiptarsenus sp., probably H. varicornis, was probably already present in New Zealand parasitising Agromyzidae before the leaf miner biocontrol programme began. It had been recorded associated with various crops, including brassicas, and had been recorded parasitising the agromyzids Liriomyza chenpodii and Cerodontha australis [see Cameron et al. (1989) entry in 'General comments' section below]. Leaf-mining Agromyzidae do not appear to be as economically important in New Zealand as they are overseas. Parasitoids [including H. varicornis] already present in New Zealand prior to the biocontrol programme may restrict populations of potentially damaging agromyzid leaf miners. Assuming the speculation that Diglyphus isaea was already present in New Zealand is correct [see the D. isaea introduction entry], no new parasitoids of Agromyzidae became established as a result of the biocontrol programme.
General comments:
Cameron et al. (1989) - some species of Agromyzidae (leaf miner flies) present in New Zealand are serious pests overseas, but their pest status in New Zealand is uncertain. Liriomyza chenopodii may damage beet and spinach; Chromatomyia syngenesiae is mainly a pest in glasshouses, where it damages Asteraceae, especially chrysanthemums, though it has been regarded as not important in cultivated crops; Cerondontha australis is frequently found in many grasses, including cereals, though apparently does not cause significant damage. The cosmopolitan pest Liriomyza brassicae is not considered a significant pest in New Zealand. In the late-1960s reports of apparent agromyzid leaf miner damage to brassicas led to the instigation of the biocontrol programme against agromyzids. However, during the course of the programme it was discovered that the damaging leaf miners were not Agromyzidae but two species of Drosophilidae.
Taxonomic note (10 June 2026) - according to UCD (2023) (Universal Chalcidoidea Database - accessed 10 June 2026) the currently accepted name for this agent species is Hemiptarsenus varicornis, published in Bouček (1988).
References
Bouček Z (1988). Australasian Chalcidoidea (Hymenoptera). A Biosystematic Revision of Genera of Fourteen Families, with a Reclassification of Species. CAB International, Wallingford, United Kingdom, 832 pp.
Cameron PJ, Hill RL, Bain J, Thomas WP (1989). A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No 10. CAB International Institute of Biological Control. DSIR Entomology Division. 424p.
UCD Community (2023). Universal Chalcidoidea Database. Universal Chalcidoidea Database website https://ucd.chalcid.org
