Biocontrol introduction
Target pest: Caliroa cerasi (Hymenoptera: Tenthredinidae), cherryslug, pear slug
Agent introduced: Otlophorus congruens (Hymenoptera: Ichneumonidae) = Rhinotorus congruens
Imported:
1929? 1972, 1973, 1974
Import source:
Austria (1972), France (1972, 1973, 1974), Germany (1972, 1973)
Import notes:
Cameron et al. (1989) - in 1929, 6,524 C. cerasi cocoons from France and England were sent to New Zealand. There is no record of O. congruens emerging from these, but a 1936 publication records that O. congruens, as Mesoleius caninae, was released in New Zealand in 1929; however, there is no other record of this. [NB: there is some uncertainty about what this taxon would have been; M. caninae has been considered a synonym of O. congruens but is currently considered a separate valid species - see Taxonomic note (20 July 2024) entry in ‘General comments’ section below.] In November 1972, 2,070 C. cerasi cocoons from Austria, France and Germany were sent to New Zealand; O. congruens [referred to in Cameron et al. (1989) as Rhinotorus congruens - see Taxonomic note (20 July 2024) entry in ‘General comments’ section below] emerged from these cocoons and were reared on field-collected C. cerasi larvae, but the colony failed because many of the host larvae were killed by the protozoan Blastocrithidia caliroae. In October 1973, 4,750 C. cerasi cocoons from France and Germany arrived in New Zealand. Most were cool-stored until spring 1974, at which time seven male and 3 female O. congruens emerged. Rearing continued for another year; C. cerasi continued to emerge in the following spring, as did one O. congruens individual. Another shipment of cocoons (6,300, from France) arrived in October 1974, and cool-stored until spring 1975, at which time some [the number is unstated] O. congruens emerged but were not released.
Released:
1929?, 1974
Release details:
Cameron et al. (1989) - a 1936 publication records that O. congruens, as Mesoleius caninae, was released in New Zealand in 1929, but there is no other record of this. [NB: there is some uncertainty about what this taxon would have been; M. caninae has been considered a synonym of O. congruens but is currently considered a separate valid species - see Taxonomic note (20 July 2024) entry in ‘General comments’ section below.] A small number (the exact number is unknown) of O. congruens were released at two sites in Auckland in the North Island in 1974, from material imported into New Zealand in October 1973, and from which O. congruens emerged in the spring of 1974.
Establishment:
Cameron et al. (1989) - no attempt has been made to check for the establishment of O. congruens since the releases in Auckland in 1974; but it is very unlikely that enough were released to establish a viable population.
General comments:
Taxonomic note (20 July 2024) - the currently accepted name for this biocontrol agent is Otlophorus congruens (Holmgren, 1858) (see, for example, Zwakhals et al. 2021). Zwakhals et al. (2021) summarise the nomenclature of this taxon as follows: “Holmgren (1858) described the species as Mesoleius congruens. Thomson (1894) moved the species to Spudaeus, an emendation of Spudaea Förster, 1869, but Schmiedeknecht (1913-1925) retained the species in Mesoleius. Aubert (1976) transferred the species to Otlophorus, but as Townes (1970) said ‘this is a heterogeneous genus’. Carl (1976) presents information about the life history under the name Rhinotorus congruens, where Rhinotorus is a replacement name for the pre-occupied name Spudaea.” Mesoleius caninae is listed as a valid species separate from O. congruens by Broad (2016), who notes that it was “transferred from Otlophorus (where it is listed as a synonym of O. congruens (Holmgren) by Yu and Horstmann 1997) by Kasparyan (2000).”
References
Broad GR (2016). Checklist of British and Irish Hymenoptera - Ichneumonidae. Biodiversity Data Journal 4 (2016) https://doi.org/10.3897/BDJ.4.e9042
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.
Zwakhals CJ, Blommers LHM, Mol AWM (2021). Some European Ichneumon wasps (Hymenoptera, Ctenopelmatinae) reared from sawflies (Hymenoptera, Symphyta). Entomologische Berichten 81(5): 195-205 https://www.researchgate.net/publication/357332532_Some_European_Ichneumon_wasps_Hymenoptera_Ctenopelmatinae_reared_from_sawflies_Hymenoptera_Symphyta
