Longtailed mealybug - classical biological control in New Zealand

Longtailed mealybug was introduced to New Zealand without its full complement of natural enemies. Classical biological control involves introducing one or more of these exotic parasites and predators in an attempt to reduce pest populations. Such programmes to control mealybugs, including longtailed mealybug, have been operated in New Zealand since 1897, when the ladybird, Cryptolaemus montrouzieri, was introduced (see Table). This species and the aphelinid wasp, Coccophagus gurneyi, were successfully established through these programmes but all but one (a native hover fly) of the other natural enemies of longtailed mealybug have arrived here by accident. The Rhyzobius spp. ladybirds (see Table) were introduced primarily against scale insects but recent studies have reported another Rhyzobius sp. feeding on longtailed mealybug in New Zealand

Insect species and source Date Status
Chrysopa spp., Chrysopa ramburi Schneider, Australia 1891, 1921 Chrysopa sp. was recorded feeding on mealybugs in Auckland and Whangarei in 1898 but there have been no recent records. Chrysopa species appear not to have established in New Zealand.
Coccophagus gurneyi CompĖre, Australia 1933 About 27,000 adults of this parasitoid were liberated from Nelson to the Bay of Islands, from an initial colony of four females and one male. It is now widespread in pest mealybug populations throughout New Zealand
Cryptolaemus montrouzieri Mulsant, Australia 1897-98
1923-25		 This ladybird is locally common in the north of the North Island, particularly in citrus and persimmon orchards, and in vineyards. For many years it appeared to be confined to Northland but has now been recorded from the Bay of Plenty and Gisborne. Its ability to spread further south is probably limited by the cooler climate.
Rhyzobius ventralis (Erichson), Australia 1905 This predatory ladybird is well established as a predator of gum tree scale, Eriococcus coriaceus Maskell, brown soft scale, Coccus hesperidum L., and other scale insects. It is not known whether it feeds on citrophilus mealybug (see comment above).
Rhyzobius forestieri (Mulsant), Australia 1899 The status of this ladybird in New Zealand is uncertain because its early importations probably included R. ventralis. It is not known whether it feeds on citrophilus mealybug (see comment above).