Target pest: Pseudococcus viburni (Hemiptera: Pseudococcidae) = Pseudococcus affinis, Pseudococcus obscurus, obscure mealybug
Agent introduced: Cryptolaemus montrouzieri (Coleoptera: Coccinellidae)
1897, 1921-25 Australia; 1923-1926 California, USA (originated from Australia)
Cameron et al. (1989) - two consignments were sent from Australia in 1897; liberations were made from the the first consignment, from New South Wales, but there were no recoveries. It was subsequently suggested they were not 'the right species'. The second consignment, from Brisbane, definitely was C. montrouzieri but only 19 of 200 individuals survived the journey, no eggs were laid and the colony died out. At about this time a grape grower privately imported a consignment of C. montrouzieri eggs from which he established a thriving colony. The colony was purchased by the Department of Agriculture and maintained for releases between 1898 and 1901.
1897? 1898? [see Cameron et al. (1989) entry in 'Import details' section regarding uncertainty about the identity of 1897 release]
Cameron et al. (1989) - released in Whangarei, Auckland and Wellington in 1897 from the first importation of that year [see Cameron et al. (1989) entry in 'Import notes' section]. Beetles from a private importation [see Cameron et al. (1989) entry in 'Import notes' section] were widely distributed throughout New Zealand 1898-1901. Cryptolaemus montrouzieri was relocated from Auckland populations to South Canterbury for use against gum tree scale (Eriococcus coriaceus) in 1905. Releases from the 1921-26 importations from Australia and California, USA were as follows: 21 adults and 3 pupae from Australia were released in Nelson in 1921; 9 adults from USA released in Hastings in 1923; around 500 were released in Auckland and Hastings and 450 in Nelson and Blenheim in 1924 (mostly from Australia); 42 adults from USA were released at Motueka in 1924; 50 adults from Australia were released in Hawke's Bay in 1924.
Cameron et al. (1989) - appeared not to establish from the 1897 releases, which may not, in fact, have been C. montrouzieri [see Cameron et al. (1989) entry in 'Import details' section]. Considered to be established in Hawke's Bay and Whangarei by 1926. Cryptolaemus montrouzieri remains locally common from Auckland northwards but has not been recorded from other horticultural regions of New Zealand for many years. Its inability to persist in cool climates has been noted in the many countries into which is has been imported.
Impacts on target:
Cameron et al. (1989) - initially very successful against mealybugs (for which it was primarily imported) and also against gum tree scale (Eriococcus coriaceus) on Norfolk pines, but by 1909 it was recognised it could not survive in the cooler parts of New Zealand, which has significantly restricted the long term effectiveness of C. montrouzieri in this country. Its current impact on mealybugs in northern orchards is unknown, but it may be a significant control agent in unsprayed citrus orchards in Northland, where mealybugs are not usually a pest, possibly because they are controlled by C. montrouzieri.
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.