Associated fauna at one site of Cirsium vulgare (Savi) Ten., (Compositae: Cynareae) B. MICHAUX Zoology Department, Auckland University, Private Bag, Auckland, N e w Zealand ABSTRACT The fauna associated with C. uulgare were collected from rosettes, flowers, and seed heads at Kaukapakapa, 40 km north-west of Auckland. This fauna can be characterised as non-specific, non-damaging, and impoverished with respect to Diptera and Coleoptera when compared with European and Asiatic faunas collected from either C. uulgare or other Cirsium spp. Possible control agents discussed in the literature are detailed. Keywords: Cirsium uulgare, associated fauna, biological control, New Zealand. INTRODUCTION Documenting the fauna associated with a prospective target weed in its country of introduction is an initial requirement when assessing the feasibility of biological weed control. Such knowledge allows the selection of exotic control candidates that will damage parts of the plant only lightly damaged in the country of introduction (Harris 1971), or may reveal accidentally introduced insects, eliminating them from future study (Batra et al. 1981). There are a number of ways of interfering with the life cycle of C. uulgare and other fecund, short-lived plant species. These include destroying seedlings, rosettes, mature plants, flowers, seeds, or interfering with seed germination. For reasons detailed in Michaux (1984), it was not thought probable that suitable control candidates could be found to destroy mature plants before seed could be set. The effort associated with collecting the fauna was concentrated on rosettes, flowers, and seed heads, because the destruction of immature plants and reproductive stages appeared to offer the best chance of exerting biological pressure on this weed. METHODS Rosettes were collected from a n area of high thistle density at approximately monthly intervals while they were present from April to October 1982 at Kaukapakapa. Each month 20 rosettes up to 20 cm in diameter were cut just below ground level and placed in 28 cm x 20 cm paper bags. Each bag was then fitted with a glass vial and hung close to a window. As specimens appeared in the glass vial they were removed and preserved in 70% alcohol. The contents of the bags were also examined regularly until the rosettes had dried out. N e w Zealand Entomologist, 1989, Vol. 12 14 Twenty flowers and 20 seed heads were collected monthly while they were present (October 1982 to March 1983) from various sites around Kaukapakapa and bagged as described earlier. Flowers and seed heads were retained for up to a month to ensure that a complete collection of faunal parasites was obtained. Specimens were preserved in 70% alcohol prior to identification. RESULTS Fauna associated with thistle rosettes The fauna associated with C. vulgare rosettes is summarised in Table 1. Tebenna bradleyi Clarke (Lepidoptera: Chorentidae) larvae were found on rosettes throughout the growing season and fed on the leaves. Numbers of this species were never large. Various Thysanoptera are ubiquitous on rosettes throughout the growing period, often being common enough to be observed on flowers and the underside of rosette leaves. Large numbers of aphids, particularly Capitophorus elaeapni. (Del Guer.) over-winter on the rosettes. A hymenopteran parasite of aphids, Aphidius sp. has also been recorded from rosettes. Both thrips and aphids are small, sap-feeding insects that are unlikely to inflict any more than minor damage. Pseudococcus longispinus (Targ.) Tozz (Homoptera: Pseudococidae), which penetrates surface tissue and then feeds from the sap, was observed occasionally. The taproots of some larger rosettes were rotten and inhabited by a number of Collembola and the bulb mite Rhizog&hus robini Claparede. However, it was clear that these organisms were living within the damaged roots rather than causing the damage. A rust, identified as Puccinia cnici Mart., was found on a small number of rosettes. Infrequent outbreaks of rust are said by local farmers to affect Cirsium vulgare. Table 1: Fauna associated with thistle rosettes Fungivorous or saprophagous Pradaceous or parasitic Phytophagous COLEOPTERA Anisomeristes sp. Antheta sp. Microcryptorhy ncus perpusillus COLEOPTERA Stethorus bijidus LEPIDOPTERA Tebenna bradleyi DIPTERA chironomid larvae psychodid larvae ACARI various phytoseiid, parasitid and laelapid mites ACARI Tydeus sp. Rhizoglyphus robini oribatids COLLEMBOLA unidentified HYMENOPTERA Basus seminulum Stephanodes ?sirnilis Aphidius sp. Diapriidae COLLEMBOLA unidentified HEMIPTERA Pseudococcus lon,@spinus Capitophorus elaeagni Aulacorthum solani Myzus ornatus M . persicae Brachycaudus helichrysi pentatomid eggs and nymphs (Dictyotus caenosus and Nezara viridula?) THYSANOPTERA Thrips nigropilosus Apterothrips secticornis Chirothrips manicatus Streptothrips tuberculatus Frankliniella occidentalis N e w Zealand Entomologist, 1989, Val. 12 15 Fauna associated with thistle flowers and seed heads These results are summarised in Table 2. Phytophagous insects associated with this species utilized the plant in a number of ways. Thysanoptera were found within the flower head, reaching their highest density in December. The occurrence of larvae indicated that at least some thrip species oviposited within the capitulum of C. vulgare. Thrips have a variety of feeding habits but the majority are likely to be blossom feeders, although larvae of Thrips tabaci may also be predaceous on mites (Mound & Walker 1982). Thrip damage in flowers was limited to small numbers of individual florets within the capitulum. Table 2: Fauna associated with flowers and seed heads Fungivorous or saprophagous Predaceous or parasitic Phytophagous COLEOPTERA COLEOPTERA LEPIDOPTERA Cortinicara hirtalis Anistomeristes sp. Cyphon sp. Anthrenocerus australis Coccinella undeci impunctata Chloroclystis laticostatus C. testulatus Heliothis anniger confertus Tebenna bradleyi DIPTERA ACARI Lonchoptera furcata Amblyseius cucumeris Ololaelaps paratasmanicus Gelechioidea phoridae larvae psychodid larvae Erythraeidae PSOCOPTERA unidentified HEMIPTERA HEMIPTERA Oechalia schellembergii COLLEMBOLA unidentified HYMENOPTERA Teleonomus sp. Trichogramma sp. Trissolcus sp. Aphidius sp. Capitophorus elaeagni Aulacorthum solani Bmchycaudus helichysi Nysius huttoni Dictyotus caenosus Nezara viridula Rhypodes clavicornis Aphelinus humilis Chyrsocharis pubicorni~ Dacnusa areolaris Diglyphus sp. Anacharis zealandica Dinocampus coccinellae THYSANOPTERA Thrips obscuratus T. tabaci Anaphothrips dubius Apterothrips secticornis Haplothrips niger Frankiniella occidentalis Hemiptera were found externally on buds, flowers, and seed heads, and aphids were seen moving between individual florets. It is likely that Hemiptera fed at the base of the involucre bracts, although the larger pentatomids may pierce the receptacle. Any damage to the seeds would be indirect, a consequence of stress resulting from factors such as nutrient deficiency. The Lygaeidae (Hemiptera), which feed directly on seed, were represented by N y s i m huttoni White. The most pronounced visual damage was caused by lepidopteran larvae feeding on florets. During the summer months it was quite usual to see a number of flower heads in which all the individual florets were destroyed. A number of these damaged flower heads were collected in order to estimate the viability of the seeds they contained. These heads were bagged and examined a week later when it was found that the floral tissue had regrown. It seems likely that in the field larvae would leave a flower head after consuming all the floral tissue, either to pupate or to move on to other flowers, leaving the flower head to restore itself. No data exist on the magnitude of the damage that these insects cause, but considering that randomly sampled seed collections consistently gave viability results in excess of 80%, this damage is unlikely to be significant. A number of fungi were also observed growing on seeds during germination trials. 16 New Zealand Entomologist, 1989, Vol. 12 These fungi were largely restricted to hollow seeds and probably represented seed coat flora. They include: Epicoccum sy., Phoma sp., Cladosporum sp., Botrytis sp., Fusarium sp., Diaporthe perniciosa and Alternuria sp. Apart from Alternaria sp., which may be weakly pathogenic, all are saprophytes and are typically transferred by wind or water splash. In comparing the fauna associated with the rosettes, flowers, and seed heads of C. vulgare in the Auckland areas with those lists published for the United Kingdom (Redfern 1968), Europe (Zwolfer 1965), and AsidJapan (Zwolfer 1973), it is apparent that the fauna in this area is deficient in Diptera and Coleoptera (particularly the family Curculionidae) some of which are known to cause significant damage to this species in its native range. DISCUSSION Apart from slugs, that were observed to feed on seedlings, none of the fauna associated with (2. vulgare in this area of New Zealand causes significant damage. Although the associated fauna at other sites may be different, these results indicate that the fauna is entirely incidental. The rapid increase in population size of this weed, documented by Michaux (1984), must in part be the result of the absence of any significant biotic pressure on this species in New Zealand. When this weed was introduced from Europe, where it is of minor importance as a weed, it was without the complex of species usually associated with it. Any regulatory effect that some of these species may have on the weed is missing. It is, therefore, highly probable that control candidates can be found that will slow down the rate of population growth and, in conjunction with other control strategies, eventually control the weed. Information concerning possible control agents is available from the literature. Urophora stylata Fabricus (Diptera: Trypetidae), a gall forming fly, destroys seeds and has already been released in Canada (Batra et al. 1981; Harris & Wilkinson unpublished). A related species, U . cardui, has been released in New Zealand against C. arvense (DSIR unpublished internal report 1982). Larinus turbinatus Gyll., L. sturnus Schall., and L. carlinae 01. (Coleoptera: Curculionidae) have been reported by Zwolfer et al. (1971) to also feed on flower heads of various thistle species. Ostrina kasmirica Moore (Lepidoptera: Pyralidae) larvae mine the stems of C. wallichii which may have affinities with C. vukare (Zwolfer 1973). Porphyrinia spp. (Lepidoptera: Noctuidae) larvae enter shoots below terminal flower buds destroying them. Porphyrinia cochylionides Guenke is common in Japan on Cirsium spp. (Zwolfer 1973) and may be closely related to the rarer European P. purpurina Hb. which is recorded from C. vulgare (Zwolfer 1965). Finally, leaf feeding Cassida spp. (Coleoptera: Chrysomelidae) are described in Zwolfer & Eichorn (1966). The biology of C. rubiginosa Miill. is detailed in Ward & Pienkowski (1978a) and effects of parasitism on this species in North America by Ward & Pienkowski (1978b). ACKNOWLEDGEMENTS This work was carried out in partial fulfilment for the degree of MPhil at Auckland University. My thanks to Professor E. C . Young and Dr J. Ogden for discussion and comments on the manuscript. Insect identification was carried out at DSIR Entomology Division, Mt Albert. Fungi were identified by Professor F. Newhook and Dr B. P. Segedin at Auckland University. L. Michaux typed the manuscript. REFERENCES Batra, S. W. T.; Coulson, P. H.; Dunn, P. H . ; Boldt, P. E., 1981: Insects and fungi associated with Carduus thistles (Compositae). United States Department of Agriculture technical bulletin, No. 1616. Harris, P., 1971: Current approaches to biological control of weeds. Commonwealth Institute oJ Biological Control, technical communication No. 4: 67-76. Michaux, B., 1984: Biological control of Sco'tch thistle (Cirsium uulgare). Unpublished M.Phi1. thesis, University of Auckland, New Zealand. Mound, L. A , ; Walker, A. K., 1982: Terebrantia (Insecta: Thysanoptera), Fauna o f N e w Zealand No. I . Scientific Information Division, DSIR, Wellington. Redfern, M . , 1968: The natural history of the spear thistle. Field studies 2: 669-717. N e w Zealand Entomologist, 1989, Vol. 12 17 Ward, R. H.; Pienkowski, R. L., 1978a: Biology of Cassida rubiginosa, a thistle-feeding shield beetle. Annals of the Entomological Society of America 71: 585-591. -, 1918b: Mortality and parasitism of Cassida rubiginosa, a thistle-feeding shield beetle accidently introduced into North America. Environmental entomology 7: 536-540. Zwolfer, H., 1965: Preliminary checklist of phytophagous insects attacking wild Cynareae (Compositae) species in Europe. Commonwealth Institute for Biological Control, technical bulletin 6: 81-156. , 1973: A survey of weed insects in Japan, Iran, and Pakistan. Commonwealth Institute for Biological Control, progress report 30. , Eichorn, O., 1966: The host range of Cassida spp. (Col.: Chrysomelidae) attacking Cynareae (Compositae) in Europe. Zeitschrift fuer Angewandte Entomologie, 58: 384-397. , Frick, K. E. ; Andres, L. A,, 1981: A study of the host plant relationships of European members of the genus Larinus (Col. : Curculionidae). Commonwealth Institute for Biological Control, technical bulletin 14: 97-143.