Biocontrol introduction
Target pest: Agromyzidae (Diptera: Agromyzidae), leaf miners
Agent introduced: Diglyphus minoeus (Hymenoptera: Eulophidae)
Imported:
1969-71
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. The first shipment arrived in October 1969 and included 734 adult Diglyphus spp. Between November 1969 and January 1970 a further nine consignments arrived, totalling 100 Diglyphus spp. adults and 2,210 host larvae parasitised by Diglyphus spp. Records suggest that adults emerged from 10-45% of the larvae. Sixteen more shipments between February 1969 and April 1971 included 11,821 adult Diglyphus spp. of which more than 11,000 survived to be available for release. In total, there were eight shipments of host larvae and 19 of adult Diglyphus. The species of Diglyphus sent to New Zealand were later identified as D. minoeus, D. isaea and D. sp. nr. chabrias.
Released:
1969
Release details:
Cameron et al. (1989) - about 250 of the adult Diglyphus spp. imported in October 1969 [see Cameron et al. (1989) entry in ‘Import notes’ section above] were apparently released in Nelson in the South Island. Most of the adults, including those emerging from imported host larvae, from the November 1969 - January 1970 shipments were released near Nelson, but 350 were released near Hamilton in the North Island. Of the more than 11,000 adults that survived the February 1969 - April 1971 importations, 9,113 were released near Ashburton in South Canterbury, South Island and 768 were released at Lincoln, near Christchurch, South Island; there are no records concerning the remainder. In total, at least 10,495 Diglyphus spp. adults were released. [The numbers of each species released - identified after releases were made as D. minoeus, D. isaea and D. sp. nr. chabrias - is unknown.]
Establishment:
Cameron et al. (1989) - there are no records of recoveries of D. minoeus or D. sp. nr. chabrias. Diglyphus isaea had apparently already established in New Zealand prior to the deliberate introductions as part of the biocontrol programme against agromyzids.
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.
