The Weta 51: 30-35 30

Parasitoids of annulata (Boisduval) (: )

BA Gresham, MK Kay*

Scion, Private Bag 3020, Rotorua 3046, New Zealand Telephone number: +64 7 343 5899 Emails: [email protected], [email protected]

Abstract

The endemic erebid is a common foliage feeder on many native and exotic (Compositae) and related in New Zealand, and plays host to a suite of known larval and pupal parasitoids. In 2010 and 2012 we made a number of collections of N. annulata from two modified habitats, exotic plantation forest and pasture, and reared three parasitoid species from these collections. Two of these parasitoid species, Diolcogaster perniciosus (Hymenoptera: Braconidae) and Echthromorpha intricatoria (Hymenoptera: Ichneumonidae), have previously been recorded from this host. The third parasitoid species, Meteorus pulchricornis (Hymenoptera: Braconidae), has not previously been recorded from Nyctemera annulata and is therefore a new host record for New Zealand.

Introduction

The endemic erebid moth Nyctemera annulata is a common foliage feeder on many native and exotic Senecio (Compositae) and related species in New Zealand. Larval host plants include the naturalised noxious weeds ragwort ( Gaertn. (syn. Senecio jacobaea L.)), on which it occasionally causes extensive defoliation, and German ivy (Delairea

31 Gresham and Kay odorata Lem. (syn. Senecio mikanioides Walp.)) (Spiller & Wise 1982; Somerfield 1984). Both larvae and pupae of N. annulata play host to a suite of known parasitoids (Early 1984b). The larvae are heavily parasitized by Microplitis sp. (Braconidae) (Syrett 1983), and Valentine (1967) recorded Apanteles spp. (Braconidae), Pales casta (Hutton) and P. nyctemeriana (Hudson) (Tachinidae) as larval parasitoids. More recently, Diolcogaster perniciosus (Wilkinson) (Braconidae) has also been recorded as a larval parasitoid (Saeed et al. 1999). The pupae are often parasitised by Echthromorpha intricatoria (F.) (Ichneumonidae) (Valentine 1967; Syrett 1983; Early 1984a, 1984b).

In 2009 we made an ad hoc collection of N. annulata larvae from exotic plantation forest, and subsequent rearing of those larvae revealed a species of parasitoid previously unrecorded from this host. In 2010 we made further field collections of N. annulata from two modified habitats, exotic plantation forest and pasture, with a final collection from exotic plantation forest in 2012. We present the results of the 2010 and 2012 collections here in this short paper.

Materials and Methods

Field collections

Collections of Nyctemera annulata larvae and pupae were made in March and April 2010 from a total of three North Island sites: Woodhill Forest, located on the coast northwest of Auckland (Pinus radiata plantation forest); Kaingaroa Forest, located in the Central North Island (Pinus radiata plantation forest); and pastoral land near Taupiri, in the Waikato region. Kaingaroa Forest was resampled in February 2012. Collection sites were selected based on previous observations of large resident populations of N. annulata. At each site, potential host plants as well as the soil beneath the plants and nearby inanimate objects were inspected, as final The Weta 51: 30-35 32 instar larvae are known to wander in search of suitable pupation sites. All developmental stages of N. annulata found were collected and returned to the laboratory for rearing.

Host rearing and parasitoid collection

Collected N. annulata host larvae and pupae were caged in a controlled- environment laboratory (at 20oC, 65% RH and 14 hour photoperiod). Host larvae were reared on cut host plant foliage (the same species from which they were collected – either Jacobaea vulgaris or Senecio sylvaticus L.) in groups of 10-20 within ventilated plastic pottles. Host pupae were held separately in ventilated plastic petri dishes. Host larvae and pupae were monitored closely and any parasitoids were collected as they emerged. All resulting parasitoid adults were either placed into 70% ethanol or kept dry for later identification.

Results and Discussion

Host plants

Nyctemera annulata was collected from ragwort (Jacobaea vulgaris) in Woodhill Forest and from the site near Taupiri, and from Senecio sylvaticus in Kaingaroa Forest. Senecio sylvaticus was particularly abundant in recently harvested areas of Kaingaroa Forest at the time of sampling.

Host

Nyctemera annulata and the closely-related Australian species N. amica (White) are capable of hybridisation, and a hybrid population is known to be established at Woodhill Forest (Kay 1980). Hybrid Nyctemera annulata x amica are readily distinguished from N. annulata by the larger white wing stripes and spots of the adult and the prominent hair pencils

33 Gresham and Kay extending from the head of late-instar larvae (Somerfield 1984). The specimens of Nyctemera collected in Woodhill Forest appeared to be N. annulata sensu stricto but some may have been introgressive hybrids.

Parasitoid records

Three hymenopterous parasitoids were reared from the collected N. annulata:

Diolcogaster perniciosus (Braconidae) A native gregarious larval endoparasitoid which is found throughout New Zealand, as well as eastern and southwestern Australia and Tasmania. Clarke (1996) records D. perniciosus from the closely-related Nyctemera amica in Tasmania. Previously recorded from Nyctemera annulata (Saeed et al. 1999).

Echthromorpha intricatoria (Ichneumonidae) A native solitary pupal endoparasitoid found throughout New Zealand and also in Australia. Polyphagous. Previously recorded from Nyctemera annulata (Valentine 1967; Early 1984a, 1984b).

Meteorus pulchricornis (Wesmael) (Braconidae) An exotic solitary larval endoparasitoid. Polyphagous. Accidentally introduced to New Zealand and is now widespread (Berry & Walker 2004). This is a new host record for New Zealand.

Acknowledgements

Thanks to Darren Ward (New Zealand Collection, Landcare Research) for identification of parasitoids. Voucher specimens have been deposited in the New Zealand Arthropod Collection (NZAC) and the Scion Forest Collection (FRNZ). Thanks to Mark Miller (Scion) for collections of insects and host plant material from Kaingaroa Forest. The Weta 51: 30-35 34

Thanks to Elizabeth Miller (Scion) for the identification of Senecio sylvaticus.

References

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Clarke AR. 1996. Parasitoids associated with a Tasmanian population of Nyctemera amica (White) (Lepidoptera: Arctiidae). Australian Entomologist 23 (1): 17-20.

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35 Gresham and Kay

Information Division, New Zealand Department of Scientific and Industrial Research, Wellington. 260 p.

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