Biocontrol introduction
Target pest: Agromyzidae (Diptera: Agromyzidae), leaf miners
Agent introduced: Chryrsocharis sp. (probably pubicornis) (Hymenoptera: Eulophidae)
Imported: Accidental introduction
Import notes:
Cameron et al. (1989) - Chrysocharis sp. (probably C. pubicornis) was not introduced to New Zealand as part of the biocontrol programme against Agromyzidae [see entries for other agents introduced against Agromyzidae]. Prior to the introductions for the biocontrol programme, Chrysocharis sp. (probably C. pubicornis) had already been recorded as parasitising Chromatomyia syngenesiae [see Cameron et al. (1989) entry in 'General comments' section below].
Establishment:
Cameron et al. (1989) - Chrysocharis sp. (probably C. pubicornis) was already established in New Zealand prior to the commencement of the biocontrol programme against Agromyzidae.
Impacts on target:
Cameron et al. (1989) - a report in 1923 recorded 90% parasitism of the agromyzid Chromatomyia syngenesiae [see Cameron et al. (1989) entry in 'General comments' section below] but did not identify the parasitoid species. Another report in 1937 claimed that 40-65% parasitism of C. syngenesiae was normal; this parasitoid was presumably Dacnusa areolaris [see the D. areolaris introduction entry]. Leaf-mining Agromyzidae do not appear to be as economically important in New Zealand as they are overseas. Parasitoids [including Chrysocharis sp. (probably C. pubicornis)] 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.
References
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.
