FNZ 13 - Encyrtidae (Insecta: Hymenoptera) - Encrytids in Biological Control
Noyes, JS 1988. Encyrtidae (Insecta: Hymenoptera). Fauna of New Zealand 13, 192 pages.
( ISSN 0111-5383 (print), ; no. 13. ISBN 0-477-02517-X (print), ). Published 09 May 1988
Encyrtids in Biological Control
The family Encyrtidae is one of the most important insect groups to be used in the biological control of insect pests. In a review of biological control edited by Clausen (1978) it is apparent that more species of Encyrtidae have been used than any other single family of insects except Coccinellidae and Braconidae. Clausen's review lists no fewer than 97 programmes worldwide in which at least partial control of the target pest species was achieved using encyrtids as the main controlling agent. Full economic control was achieved in 32 instances. Use of encyrtids has been greatest in the control of homopterous pests of agriculture and horticulture, notably of Coccidae and Pseudococcidae.
In New Zealand, encyrtids have been widely employed in the attempted control of several agricultural and horticultural pests since the early part of this century. Of the nine species recorded as having been introduced for this purpose, three have proved effective in controlling the target species. The first recorded introductions were in 1921, when Microterys flavus and Coccidoctonus dubius were liberated in the Nelson area. M. flavus was introduced against Coccus hesperidum, a pest of citrus and greenhouse plants, and has since controlled this pest to a considerable extent (Gourlay 1930b; Miller et al. 1936). C. dubius, a hyperparasite, was introduced in the mistaken belief that it was a primary parasite of Saissetia oleae. It has since been reared in small numbers, as a hyperparasite of pteromalid parasites of S. oleae and Eriococcus sp. (Valentine 1967). Metaphycus lounsburyi, a native of South Africa, was introduced into the Nelson area in 1922 against Saissetia oleae, a pest of fruit trees (Miller et al. 1936). It has become established, having recently been found in the Auckland area. A most successful introduction programme was then undertaken against the golden oak scale, Asterolecanium variolosum. This was proving to be a major pest of oak in many areas, and in 1923 a control programme was initiated using Habrolepis dalmanni. Between that year and 1928, eight consignments of the parasite were received from Washington State and released in the Christchurch and Nelson areas. The first adults were recovered in the field in 1925 in the Nelson area. and by 1933 the parasite had spread to most areas where the scale was present (Gourlay 1935). Control was achieved, and the scale is now no longer considered a pest (see Doull 1955).
Most subsequent control programmes have been less successful. Leptomastidea abnormis was introduced in an effort to control mealybug on fruit trees, but apparently it failed to become established (Miller et al. 1936). In 1933 Tetracnemoidea breivicornis was introduced from Australia against mealybug on fruit trees (Bartlett in Clausen 1978). Although it became established it has not been successful (Miller et al. 1936). Copidosoma desantisi (as C. koehleri) was imported from Australia in 1949 for release against Phthorimaea operculella, a pest of potato, but was not released. In 1964 Copidosoma koehleri was introduced from California for control of the same pest. It was released in several areas of both main islands (E.W. Valentine, pers. comm.), but apparently failed to establish. The most recent use of encyrtids in biocontrol programmes in New Zealand was the introduction in 1969 of Copidosoma floridanum from Australia for the control of Chrysodeixis eriosoma, one of the most serious pests of horticulture in New Zealand. The parasite has since become well established. and is proving effective as a controlling agent (Thomas 1975; as Litomastix sp.).
Other established species which may have been introduced for biocontrol purposes, but for which no introductions have been recorded, are: Encyrtus infelix to control Saissetia olea; Encyrtus lecaniorum to control Coccus hesperidum; Metaphycus timberlakei to control Parthenolecanium persicae; Tachinaephagus zealandicus to control synanthropic Diptera; and Tetracnemoidea peregrina and T. sydneyensis to control Pseudococcus longispinus.