Biocontrol introduction
Target pest: Coleophora alcyonipennella (Lepidoptera: Coleophoridae), small clover casebearer
Agent introduced: Neochrysocharis trifolii (Hymenoptera: Eulophidae) = Chrysonotomyia trifolii, Closterocerus trifolii
Imported:
1961, 1962, 1967, 1968, 1969
Import source:
1961, 1969 near Freiburg, Germany; 1961, 1962, 1967, 1968, 1969 Avignon, France via Delémont, Switzerland
Import notes:
Cameron et al. (1989) - Neochrysocharis trifolii was imported in 1961, 1962, 1967, 1968 and 1969 under the name Neochrysocharis sp. [See Taxonomic note, species level (6 January 2025) and Taxonomic note, genus level (6 January 2025) entries in 'General comments' section below for taxonomic details]. It was not considered the most desirable agent as its synchronisation with the host was thought to be less precise than others and it was not released until 1967. It was imported as field-collected, encased, fourth instar host larvae, either Coleophora frischella or C. deauratella. Coleophora deauratella, collected from near Freiburg, Germany, were imported in 1961 and 1969; C. frischella were collected from Avignon, France in 1961, 1962, 1968 and 1969 and reared in Delémont, Switzerland prior to shipping to New Zealand. Neochrysocharis trifolii emerging from the C. frischella material imported in 1961 were preserved as reference specimens. The 1962 shipment contained an estimated 70 N. trifolii mummies; emerging adults were left to die. The 1967 shipment contained 25 N. trifolii mummies; one male and 58 females emerged and were used to establish a laboratory culture, but the second generation contained only males. Wasps from the 1968 shipments were used to establish a culture; after three generations approximately 1,600 adults were released. The 1969 shipment was expected to contain about 100 N. trifolii mummies; adults were intended for direct field release and establishing a laboratory culture. The culture was an almost complete failure and release details were not recorded. [NB: there may be some doubt about the identity of the Coleophora species reported in this entry as C. frishcella. Cameron et al. (1989) reported C. frischella and C. spissicornis present in New Zealand, but it is now considered very likely that it is C. alcyonipenella rather than C. frischella present in New Zealand - see Taxonomic note (22 September 2025) entry below in 'General comments' section. Coleophora spissicornis has subsequently been synonymised with C. mayrella - see the introduction entries for the agents imported against C. mayrella for details.]
Released:
1967
Release details:
Cameron et al. (1989) - a single adult was released in 1967, though the location is not recorded. In 1968, 1,600 adults were released at Palmerston North, Manawatu in the North Island. It may have been released in 1969 but numbers and location were not recorded.
Establishment:
Cameron et al. (1989) - establishment was confirmed in January 1977 when two N. trifolii mummies were found in a collection of 253 C. frischella first generation larvae at Lincoln, Canterbury in the South Island, 450 km south of the Manawatu, North Island release site. By the following generation, in mid-March, parasitism had increased to 6.2% and by the first generation of 1978 to 27.8%. A survey in 1982 found N. trifolii established throughout Canterbury and Manawatu (North Island) with parasitism rates of 49.7% and 10.3% respectively.
Impacts on target:
Cameron et al. (1989) - of the parasitoids introduced against Coleophora spp. [C. frischella and C. spissicornis] only Bracon variegator [established in 1966] and N. trifolii have established. While they were not deemed the most desirable, in the absence of competition from the parasitoids more closely synchronised with the hosts B. variegator and N. trifolii have achieved the aim of controlling Coleophora spp. admirably. It is now rare for Coleophora spp. infestations in white clover seed crops to reach an economically damaging level or require control with insecticides.
Cameron et al. (1993) - Neochrysocharis trifolii, in conjunction with Bracon variegator [see the B. variegator introduction entry], is categorised as exerting “substantial” control (defined as “other control measures are only occasionally required”) over Coleophora spp. [C. frischella and C. spissicornis].
Kaur et al. (2024) - prior to the introduction of two biocontrol agents [N. trifolii and Bracon variegator] in the 1960s, the clover-feeding moths Coleophora frischella and C. spissicornis seriously hindered red and white clover seed production in New Zealand. These biocontrol agents were highly successful, resulting in the total suppression of clover casebearer seed pests until the arrival of Coleophora deauratella, first detected in New Zealand in 2016 [see Kaur et al. (2024) entry in ‘Non-target impacts’ section of the Bracon variegator introduction record].
General comments:
Taxonomic note, genus level (6 January 2025) - this species was originally described in 1961 by Erdös as Neochrysocharis trifolii. Bouček (1988, in Hansson (1990)) synonymised Neochrysocharis with Chrysonotomyia, though Hansson (1990) considered Neochrysocharis to be a valid genus. Gumovsky (2001) synonymised Neochrysocharis with Closterocerus, but Burks et al. (2011) removed Neochrysocharis from synonymy with Closterocerus and reinstated it as a valid genus.
Taxonomic note, species level (6 January 2025) - there is some uncertainty over whether N. trifolii is a separate species or whether it is a variant of N. formosa. Neochrysocharis formosa, described by Westwood in 1888, is a morphologically variable species with a wide host range. Neochrysocharis trifolii was described more recently (by Erdös in 1961) and was subsequently synonymised with N. formosa (Hansson 1990) and then resurrected from synonymy (Askew et al. 2001). It is likely that N. formosa is a species complex (Askew et al. 2001), and further work is needed to determine its limits. If we accept the current view that N. trifolii is a valid species, as does both Broad (Hymenoptera of the British Isles checklist - accessed 6 January 2025) and Noyes (2019) (Universal Chalcidoidea Database - accessed 6 January 2025), it is likely that this is what was introduced into New Zealand against Coleophora. Specimens reared from Coleophora sp. have been identified by Z. Bouček as N. trifolii (NZAC04161499, D. Ward, Landcare Research, pers. comm.). However, it is also likely that N. formosa has been accidentally introduced into New Zealand and is established here as an agromyzid parasitoid; specimens reared from leafminers on jacaranda in Auckland in 1989 have been identified as N. formosa by J. Berry (NZAC04163195, D. Ward, pers. comm.). Note: the species epithet is variously reported as formosa and formosus. According to Noyes (2019) (Universal Chalcidoidea Database - accessed 6 January 2025), Neochrysocharis formosa is an invalid name, and this source gives “Neochrysocharis formosus (Westwood, 1833)” as the valid name. However, Hansson (1990) and Askew et al. (2001) and many other sources use “formosa”. Xu et al. (2022) state “N. formosa (also known as Neochrysocharis formosus, but here we accept that the gender of Neochrysocharis, based on the Greek ending -charis, is feminine)…”
Taxonomic note (22 September 2025) - Coleophora frischella has been reported present in New Zealand as the white-tipped clover casebearer by Cameron et al. (1989) and many other authors. However, it is very likely that the species reported from New Zealand as C. frischella is, in fact, C. alcyonipennella. Dugdale (1988) does not report C. frischella from New Zealand. He notes that the name frischella has been used for Coleophora specimens here, but he regards these as misidentifications of C. trifolii, and regards Coleophora alcyonipennella as a synonym of C. trifolii. However, Stubner (2007), in his revision of the C. frischella taxonomic group, considered C. frischella, C. alcyonipennella and C. trifolii all to be valid names (i.e. valid, separate species). Coleophora alcyonipennella, but not C. frischella or C. trifolii, is reported to be present in New Zealand by Biota of New Zealand (Landcare Research Biota of NZ - accessed 22 September 2025) and the New Zealand Arthropod Collection (Landcare Research SCNZ - accessed 22 September 2025).
References
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Xu X, Hoffmann AA, Umina PA, Coquilleau MP, Gill A, Ridland PM (2022). Identification of two leafminer parasitoids (Hymenoptera: Eulophidae), Neochrysocharis Formosa and Proacrias sp. from Australia, with both showing thelytoky and infection by Rickettsia sp. Austal Entomology 61(3): 358-369 https://doi.org/10.1111/aen.12602
