Prospects for the Biological Control of Rosa Rubiginosa (Sweet Brier)

18 Plant Protection Quarterty VOI.5( 1) 1990 Molloy's records and NZLRI data arises be· ca use the NZLRI mapping failed to record Prospects for the biological control of Rosa rubiginosa R. mbiginosa where it was only a minor com (Sweet Brier) in New Zealand ponent of vegetation, or where it occurred in smalilocaliscd peekets. Hu nt er ( 1983) noted that R. mbiginosa P. Syrett, DSIR Plant Protection, Christchurch, New Zealand was most prominent in areas with less than • 1400 mm rainfall per annum on soils with a pronounced seasonal moisture deficit. On Summary tribution has been mapped using the M olesworth Station, it was particularly abun There has been renewed interest in the im NWASCO (Natioinal Water and Soi l Con· dant in areas with rai nfall less than 750-1000 plementation of a program for the biological serva tion Organi7..at ion) Ncw Zealand Land mm per annum (S tevens and Hughes 1973). control of Rosa rubiginosa (swcct bricr) from Resource Invent ory (NZLRI) (Hunter T he authors commented, however, that its high country pastoral farmers in the South (983). R. mbiginosa was recorded as present abundance might be related more to sparse Island of New Zealand. This has led to the on 443,800 ha of the South [sland, typically cover by ot her plants than as a result of a reassessment of early exploratory work: in associated with unimproved pasture and light preference for dry sites. This view is su p Europe and the preparation of an economic scrubland. Concentratcd infcstations oc ported by the especia lly high density and bet· evaluation of a biological control program. curred in inland M arlborough, sou th Canter ter growth of R. mbiginosa in locally damp Extensive work was carried Qut in the bury and inland O tago. Resu lts of a survey areas such as stream gullies. Molloy (1976) 1960s to identify insects from Europe which carried out by l3ascand and Jowett (1982) found that plants occurred to a maximum might be suitable for introduction into New showed a similar distribution. I-I owever, M ol altitude of 750- 1200 m a.s. 1. but Stevens and Zealand. The results of this work arc sum loy ( l964a) has recorded that by the 1960s it Hughes ( 1973) noted that their vigour was marized here and used in conjunction with was prese nt in almost every county through not affected by altitude to at least 1200 m information on the current status of R ru out the country. loc discrepancy between a.s.l. biginosa in New Zealand to discuss the bene fits and difficulties of reactivating a biological control program against this weed. The most promising species for introduction are the gall formers Diplo/epis rosae and D. mayri (Hymenoptera: Cynipidae), lbe stem-mining buprcslid Agrilus aunchalceus (Coleoptera: Buprestidac), Nolocelia rosaeco/ana and EucosmD pauperana (Lepidoptera: Ole lhreutidae) whose larvae feed on buds and young shoots, and the lcafminer Tischera an gustico/e/Ja (Lepidoptera: Tischeriidae). Introduction Distribution and weed status of Rosa rubiginosa. Rosa mbiginosa L. is a European plant, oc curring from southern Sca ndinavia to north ern and eastern Spain. It is found eastwards into western Asia and north-west India and ·1 has become naturalised in North America (Clapham et at. 1987). It was recorded as a troublesome weed in South Africa by Neser and Annecke ( 1973), who reported it to be spreading along roads and banks, in grass land and mountain areas, and included it in a list of 17 exotic weed species under consid eration for biological control. In Australia R. nlbiginosa bas been re cordp.d as an important weed in southern New South Wales, South Australia, Tasma nia and Victoria (Parsons 1973), but no at· tempt has been made to control it biOlogi cally. In New Zealand R. mbiginosa (Figure I) was first recorded growing as a garden plant in 1835 (MOlloy 1964a), and, although widely used for ornamental purposes, was recog nized as a weedy species and classified as a noxious plant in 1900. It was probably initially imported as seed (MOlloy 1964a), and seeds are dispersed by grazing animals and by birds (Stevens and Hughes 1973). Its curreot dis· Figure 1. Rosa rubiginosa in pasture al Lake Pukaki, South Island, New Zealand. Plant Protection Quarterly VOI.5(1) 1990 19 Thickets of R. ntbiginosa usually develop (Meeklah and Mitchell 1973, 1981, Bristol Identification ofsuirable candidtues for in on the most fertile sites, occupying good po 1981, Meeklah and Cherry 1984), but m rroduction as biological conrrol agents. tential forage areas and preventing passage most situations this must be accompanied by of stock (Stevens and Hughes 1973). Thus a program of past ure improvement to pre Between 1962 and 1967 the Commonwealth on low productivity grasslands the weed can vent regrowth of suckers and seedlings. On Institute of Biological Cont rol (CIBC) in seriously deplete available pasture. Molloy much of the sparse, dry hill country where Delemont, Switze rland undertook a survey (1966) argued that populations of R. mbigi the weed is of greatest concern, this is either of prospective insect control agents for Rosa nosa had become static: spectacular in impractical or uneconomic. Two high cou n rubiginosa in Europe for the New Zealand creases in the early 1950s were the result of try runs in the Mackenzie country are suc Department of Scien tific and Indust rial Re rabbit control, (previously grazing by rabbits cessfully using goats to control the weed search (DSffi). and sheep had controlled the weed) but that (McKinnon 1982). As with other weed con About 450 insect species were reported as other plant cover also increased following trol programs employing goats this can be feeding on wild roses in Europe (Eichhorn the reduction in grazing pressu re, the com very effective provided that the land owner is 1967, Herting 1964, ScbrOder 1967, petitive advantage of R. ntbiginosa disap interested in farming goats. Scheibelreiter 1969, ZwOlfer 1964). The peared and few new plants established. He most promising species was the gall wasp supported this theory by showing that many Insect fauna of Rosa rubiginosa in New Diplolepis rosae (L.) (Hymenoptera: Cynipi dae) which showed potential to be both dam existing sma ll plants were actually quite old Zealand aging and host specific. Other possibilit ies (Molloy 1967). Thus the problem was re The only specialised insect feeding on R. includedAgri/us aurichalceus Redt. (Coleop duced to the removal of existing plants. robiginosa in New Zealand is the rose seed tera: Buprestidae) and several microlepidop Although R. rnbiginosa may be relatively cbalcid Megastigmus aculeatus Swederus tera feeding on shoots and you ng foliage. easily contro lled where a good swa rd is main (Hymenoptera: Torymidae) a European in However, the project was terminated in 1%7 tained, and is not a problem in sown pasture sect which was probably introduced with and no introductions were made. (Molloy 1964a) it is still of major concern to seeds. No detailed assessment has been Many of the insects recorded from Rosa in farmers in some South Island areas Twenty made of its impact on seed production in Europe were generalist feeders and were five years after Molloy's work there are still New Zealand, although Molloy (l964b) re quiCkly eliminated from further considera many plants less than 25 years Old . [n a sur corded that typically 9% of seeds were in tion. ZWOlfer(I964) concluded that no Cole vey of South Island fa rmers ca rried out dur fested with larvae of M. acu/eatlls. Indica optera were restricted to the genus Rosa. He ing 1977 -8 (Bascand and Jowett I 982) R. rn tions from observations made in Europe noted, however, that A. aurichalceus was biginosa was perceived as a serious problem (Eichhorn 1967) are that the percentage of highly damaging to R. rubiginosa which was in Otago and Marlborough and had minor to seeds att acked there is very low (see belOW). the preferred host. As few as 20-30 larvae serious ratings in canterbury. In this same Eichhorn noted that infestation rates were were capable of severely damaging and even survey farmers ranked it fifth in importance higher in warmer areas indicating that it killing a shrub of R. rubiginosa. Although as a serious problem weed behind barley could be better suited to the New Zealand ZwOlfer collectedA. aurichalceus from other grass (Hordeum murinum), gorse (Ulex eu climate. However, all specimens collected wild Rosa spp. and suggested that it might ropaeus), nodding thistle (Carduus nutans) were from species of Rosa other than R ro also attack cultivated roses, he was unable to and broom (Cylisus scoparius). R. rnbiginosa biginosa, which does not appea r to be the substan tiate literature records from Rubus was top of the list of weeds of major eco preferred host (Kurir 1975). spp. by personal observation. SchrOder (pers. nomic significance to high country runhold Other phytophagous species which have comm.) has suggested that the A. aurichal ers surveyed in 1982 (Kerr and Lefever been recorded by Spiller and Wise (1982) cellS complex would be worth further investi 1984) with 52% of runs reporting this weed from R rnbiginosa in New Zea land include gation. A strai n specific to R rubiginosa of concern. From a questionnaire to rangers Macrosiphwn rosae (L.), the rose aphid, a could possibly be identified. of National Parks and Reserves it was re common and widespread pest of cu ltivated From among the Lepidoptera, Hymenop ported present in 10 out of 55 responses and roses; Chae/osiphon letrarhodum (Walker), tera and Diptera attaCking Rosa, Herting as a problem weed in one of these (S.M.

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