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Biocontrol introduction

Target pest: Eriosoma lanigerum (Homoptera: Pemphigidae), woolly apple aphid

Agent introduced: Aphelinus mali (Hymenoptera: Aphelinidae)

Imported: 1921

Import source: Washington State, Connecticut and Arkansas, USA.

Released: 1921-24

Release details: Cameron et al. (1989) - initial releases failed with the exception of 3 males and 2 females; it was from these individuals the subsequent release programme was developed. 1921-22 3,000 were released at Nelson. In 1922-23 30,000 were released throughout the country. In 1923-24 90,000 were released.

Establishment: Camerson et al. (1989) - widespread throughout New Zealand by 1925.

Impacts on target: Cameron et al. (1989) - had almost eliminated E. lanigerum from orchards by 1925. Outbreaks of E. lanigerum occasionally occur in orchards where pesticide use disrupts biocontrol. Rogers et al. (2015) - In New Zealand E. lanigerum management currently relies entirely on biological control, predominantly by A. mali. This provides effective control in the absence of disruptive insecticides. A severe and damaging outbreak of E. lanigerum in Hawkes Bay in 2007-08 was primarily caused by application of the insecticide spinetoram, but other insecticides can contribute to the instability of this biocontrol system. Since 2008 apple growers have reduced their use of disruptive pesticides, especially spinetoram,thiacloprid and carbaryl. Although E. lanigerum populations took several seasons to stabilise, there has not been a widespread outbreak since this period.

References

Cameron PJ, Hill RL, Bain J and 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.

Rogers DJ, Lo PL and Walker JTS (2015). Vulnerability of pest management in New Zealand apples: pesticide toxicity to Aphelinus mali (Hymenoptera: Encyrtidae) New Zealand Plant Protection 68: 299-305

Tillyard RJ (1923). History of the introduction of beneficial insects into New Zealand. Proceedings of the Pan-Pacific Science Congress, Australia, 383-390.