Number 18 May 2001

What’s New In Biological Control of Weeds?

Gall Are Go! What’s Inside? This autumn, we have been March. “With such a Gall Flies Are Go! 1 delighted with the promising start we will be performance of two of our extremely surprised if the Tell Me More... 2 newer agents, the mist flower doesn’t readily establish in gall fly (Procecidochares alani) New Zealand,” said Chris. If Hot Gossip 3 and the Scotch thistle gall fly you are out and about in mist Gorse Colonial ( stylata). flower country, keep your eyes peeled for the characteristic Hard Shoot The mist flower gall fly was swellings that stunt the plant’s Hieracium Hearing released for the first time in growth. Weeds CRC February and astounded its liberators by getting straight The Scotch thistle gall fly was Money Talks 4 down to business. “As soon as released in Rodney (north of we opened the lid the flies Auckland) just before You Ain’t Nothing made a beeline for their host Christmas 1998, and more but a Hound Moth 5 and began laying eggs right in recently in Canterbury, front of our eyes,” enthused Marlborough, and Southland. Desperately Seeking Chris Winks. “It makes a We are now confident that this change from having agents seed-feeding fly is a permanent Agents 6 simply disappear into the wide resident after finding infested blue yonder.” It wasn’t flower heads for the third year Posters Galore! 9 surprising then, but still in a row at Rodney this enormously pleasing, to autumn. The Winter Activities 10 find galls showing up Marlborough in the field in and Southland What's New in Biological Control of Weeds? Number 18 May 2001

sites haven’t been checked yet, but a recent visit to one of the Canterbury ones (near Lincoln) revealed lots of infested flower heads; more than enough to enable harvesting to begin already. Like nodding thistle flowers infested with nodding thistle gall fly (Urophora solstitialis), infested Scotch thistle flower heads are easy to spot once you get your eye in. The shiny white pappus hairs remain attached to the flower Infested Scotch thistle flowerhead that has been cut in half to show the larvae inside heads giving them a tufty appearance, and the flower latter symptom as Scotch thistle to check for infested flower heads are hard and lumpy. Be flower heads have extremely heads is in the autumn when the careful how you verify the vicious spines! The best time plants are beginning to dry off.

Tell Me More...

Question: How can I tell the three (Urophora cardui) has an the flies on is often the best thistle gall flies apart? obvious thick black “W” on quick guide. Nodding thistle each wing. The differences gall flies prefer nodding and The three thistle gall flies are between the wing markings of plumeless thistles. Scotch extremely similar in size and the nodding thistle gall fly thistle gall flies prefer Scotch appearance, but they can be (Urophora solstitialis) and thistle but may occasionally distinguished by the markings Scotch thistle gall fly attack Californian thistles, on their wings if you can get (Urophora stylata) are quite whereas Californian thistle them to sit still long enough! subtle (see below). The gall flies tend to stick to their The Californian thistle gall fly species of plant that you find namesake.

Scotch thistle gall fly Nodding thistle gall fly Californian thistle gall fly 2 What's New in Biological Control of Weeds? Number 18 May 2001

Hot Gossip

After several years of struggling we finally managed to rear respectable numbers of the gorse colonial hard shoot moth (Pempelia genistella). This allowed us to supply five regional councils this autumn with a shipment each of the tiny first-instar caterpillars (the stage after they hatch from the egg and before their first moult). “Providing they survive relocation, the caterpillars will feed on the foliage and grow slowly over Gorse colonial hard shoot moth larvae the winter in communal webs,” explained Hugh Gourlay. Come spring the (Cheilosia urbana), and another Lynley helped to make this caterpillars will become more hover fly that feeds on the leaf idea a reality by interviewing active and put on a growth axils and rosette crowns researchers at CSIRO in spurt, ending up quite large (Cheilosia psilophthalma). Canberra and Perth, the Keith (about 2.5 cm long). Their Turnbull Research Institute in webs also become more In February Lynley Hayes Melbourne, and the University obvious, reaching up to about spent a fortnight in of Adelaide and drafting the 20 cm across. as a guest of the Co-operative text. “It was really fascinating Research Centre for Weed to find out what our An application to release three Management Systems (Weeds Australian colleagues have new hieracium agents was CRC). The Weeds CRC was been up to,” explained Lynley. lodged with the formed in 1995 as a joint “We have a number of projects Environmental Risk venture bringing together in common such as broom Management Authority Australia’s best weed busters and thistles, but they also (ERMA) in January. Despite to tackle a billion dollar have some completely the fact that no one made a problem. The Weeds CRC has different ones that I was less submission opposing the put out many excellent familiar with like horehound release of these new agents, publications (see (Marrubium vulgare) (see “You ERMA held a public hearing www.waite.adelaide.edu.au/ Ain’t Nothing but A Hound in early May to allow all the CRCWMS) but felt there was a Moth”, pg. 5), Paterson’s issues to be fully discussed. need to produce a popular curse (Echium plantagineum) Hopefully they will soon give summary that explains the and double gee (Emex us the thumbs up to release a status of its biological control australis).” The finished midge that galls the plant programmes to all the grass product is expected to hit (Macrolabis pilosellae), a hover roots workers who have the streets around the middle fly that feeds on the roots participated in some capacity. of the year. 3 What's New in Biological Control of Weeds? Number 18 May 2001

Money Talks

When the payback time for (Weeds CRC) in Australia has research projects is many years recently taken this bull by the down the track it can be horns and asked a group of $ $ difficult to persuade the people economists to predict the in charge of the purse strings potential benefits of some of $ to stick with them, especially their research projects. The as our society increasingly results are astounding! expects instant gratification. It is soul-destroying for $ $4.5 million spent on researchers, not to mention reducing weeds in extremely wasteful, to pull the cropping situations is plug halfway through a long- expected to provide $124 term project because million in benefits over the stakeholders have become next 30 years (a 43% return $ impatient for results or have on investment). lost interest. $ A programme to prevent $ $2.2 million invested in Mexican feather grass The Co-operative Research developing integrated (Nassella tenuissima) and Centre for Weed pasture management to cotton thistle (Onopordum Management control Vulpia spp. is nervosum) from ever becoming Systems expected to deliver $496 problem weeds looks likely million of benefits over the to benefit the Australian same time frame (a economy by $83 million. whopping 62% return on investment). The bottom line is that well- targeted and timely research $ $5.9 million dedicated to a into controlling weeds can pay biological control project huge dividends in the long against Paterson’s curse run. This Australian (Echium plantagineum) looks Government has recognised likely to deliver $253 this in its recent decision to million in benefits over fund a second Weeds CRC for the next 50 years (a 45% a 7-year term (beginning in return on investment). July this year) in the face of strong competition from many $ $2.2 million spent other worthy contenders. developing a biological Our congratulations to all control project for bitou involved. Landcare Research bush (Chrysanthemoides signed a memorandum monilifera rotundata) of understanding with the could deliver $45 million first Weeds CRC and this of benefits (a 29% return time upgrades to supporting Paterson's Curse on investment). partner. 4 What's New in Biological Control of Weeds? Number 18 May 2001

You Ain’t Nothing but a Hound Moth

In New Zealand, horehound caterpillars had (Marrubium vulgare) is a taken another plant that you often seen quantum leap. around stock yards, and Dean Burgoyne, of other places that sheep tend the Robe District to congregate, especially in Council, Canterbury and Otago. confirmed that However, it is not the serious about 50% of weed here that it is across plants within the Tasman. Adult horehound plume moth 500m of the release site were Resourceful pioneers revealed that the had so badly damaged that they introduced horehound to become inbred and lost their looked like they were on the Australia for use as a special survival mechanism of way out. “I could easily count medicinal herb and for hiding away during the 100 caterpillars on some brewing beer. The plant has hottest months. The problem plants, and that was just the gone on to infest 26 million ha was quickly solved by big ones. I also found the and occurs in all states except bringing in some new blood, caterpillars had spread at the Northern Territory. and the moth is now well least 25 km away in an Southern and eastern parts of established in all areas. Craig easterly direction, and Australia are worst affected. Clarke, who studied the moth were pretty thick on patches The seeds come conveniently intimately for his PhD thesis, in between.” packaged inside sticky burrs suspects that the plume moth that are easily accidentally will do best in wetter areas. A second agent is being transported about the “In places where the plant released that may be more countryside by sheep and doesn’t die back over the adapted to the dry conditions kangaroos. A biological summer the moth can that prevail in many parts control programme has complete twice as many of Australia. Clearwing moth recently been instigated to generations and therefore do (Chamaesphecia mysiniformis) give the plant a taste of its twice as much damage, ” he caterpillars feed inside own medicine. explained. the roots and stems so they are more protected from the The first control agent for While it is still early days elements. The plant’s horehound, a plume moth some promising results have ability to move water and (Wheeleria spilodactylus), was already been achieved in nutrients around is released during the mid- South Australia. Around 800 compromised, resulting in 1990s. The caterpillar stage caterpillars were released at a smaller plants that are less munches the growing tips and site near Robe 3 years ago. able to cope with drought. stems, which weakens the After only 2 years there were The clearwing moth has only plant and limits flower and enough caterpillars present to been released at a small seed production. However, safely allow 5000 to be number of sites so far and it this agent did not establish harvested for other areas. is not yet known whether it well in dry areas. Studies One year later and the has survived. 5 What's New in Biological Control of Weeds? Number 18 May 2001

Desperately Seeking Agents Areas surveyed so far Potential survey areas remaining Californian thistle is not proving to be an easy biological control target by any means. So far only one of the released to attack the plant in New Zealand is showing any promise (see Table 1). More agents are urgently needed to add pressure to the plant and researchers are leaving no stone unturned in their search for suitable candidates.

Table 1. biological control agents released against Californian Over the 40 years that thistle in New Zealand researchers have been looking, quite an array of insects have Altica carduorum Failed to establish despite numerous been found to hang out on Foliage-feeding beetle releases Californian thistle. Lema cyanella Established at low levels at a few sites, Unfortunately, the vast Foliage-feeding beetle probably not capable of having a majority have turned out significant impact to be not sufficiently host specific, not damaging Rhinocyllus conicus Prefers nodding thistle but will also attack enough, or difficult to work Seed-feeding weevil Californian thistle (and other thistles) to a with. Specificity is lesser extent particularly critical for agents Urophora cardui Appears to be establishing in New Zealand. intended for areas like North Gall-forming fly Capable of stunting plant growth, but no America that have native impact seen yet thistles to contend with. Urophora stylata Appears to be establishing on Scotch thistle, Experience has also shown Seed-feeding fly may attack Californian thistle slightly that, with its extensive underground rhizomes the Casting the net widely many of these places have plant is quite hard to knock Californian thistle occurs not until recently been (or back and is not too troubled naturally in Europe, western still aren’t) safe or easy to by a bit of damage to its Asia, and northern Africa. It visit. The best places still leaves. Researchers are now also grows under a wide left to look for agents for focussing their attention on range of environmental New Zealand (eastern finding potentially more conditions, which means Turkey and the Caucasus harmful root and stem feeders there are lots of places out Mountains) will be some of that may have the added there where potential the most difficult tackled so bonus of allowing naturally biological control agents far, if they can be surveyed at occuring pathogens to gain might be lurking. However, all (see Map). entry to the plant. 6 What's New in Biological Control of Weeds? Number 18 May 2001

Table 2. Where have researchers looked so far? the insect fauna seemed to be slightly impoverished here. The 1960–65 southern England, France, southern Germany, most likely centre of origin for Switzerland, Austria, northern Italy, northern Californian thistle (and where part of former Yugoslavia you might expect to find the 1972 north-eastern Iran, northern Pakistan, Japan richest associated fauna) is now 1990–93 Germany, Austria, Poland believed to be in the Caucasus. 1997 northern Germany, Poland, Czech Republic, Nine species of insects Slovakia currently feature on the list of 1999 southern Russia possibilities requiring further 2000 Uzbekistan research (Table 3). If none come to fruition, then it may be André Gassmann, of CABI or exciting so far in southern necessary to fall back on a Bioscience, Switzerland, is Russia or more recently in mycoherbicide approach. leading a team of researchers Uzbekistan. Almost 85% of There are a number of different who are currently searching Uzbekistan is desert or semi- pathogens being studied for new agents on our behalf. desert and the thistle tends to around the world with this Unfortunately André’s team have grow in cultivated, irrigated end in mind (see Issue Number not unearthed anything special areas. Compared to other areas 15 of this newsletter).

Table 3. Potentially useful insects that warrant further investigation

Aceria anthocoptes Potentially very specific and damaging, common in the Balkans Gall-forming mite Altica carduorum May be better strains available in China Foliage-feeding beetle Apion onopordi Can vector the fungus Puccinia punctiformis, Root-feeding weevil but the weevil is uncommon in native range Cheilosia sp. Potentially host specific, but may not be especially damaging Stem/root-boring fly and is difficult to rear Corythuca disticta Insect native to the USA, where it has been distributed to a Sap-sucking lace bug small extent as a biological control agent Dyaphis lappae Recorded from Denmark, warrants further study Root-feeding aphid Euhagena palariformis Potentially very host specific, but proving difficult to collect Root-boring moth in Turkey Lixus elongatus May not be particularly damaging, but a close relative, Stem-boring weevil Lixus cardui, has proved useful against Onopordum in Australia Thamnurgus sp. Potentially damaging, but is uncertain and Root-boring beetle proving difficult to collect in southern Russia 7 What's New in Biological Control of Weeds? Number 18 May 2001

Lessons learned The only agent showing any promise in New Zealand, the Californian thistle gall fly, has only been released in a few places and there is still a lot of scope for increasing its distribution. Last year eight farmers/regional council staff in the Otago/ Southland area again attempted to rear gall flies in special cages outdoors. The idea was that they could bulk up the number of flies and get them more widely Jason Miller, farmer; Simon Fowler; and Grant Catto, Californian Thistle Action established faster than if the flies Group chairman, assess the success of this year's Californian thistle gull fly were left to their own devices. rearing. Photo: The Southland Times. Even with a tried and true recipe to follow, and a year’s experience a lot of traps for young players the cage rearing has not yet under their belts, there were still (Table 4). This has meant that realised its true potential.

Table 4. Difficulties experienced rearing Californian thistle gall flies in field cages and how to overcome them

Problem experienced Solution

Galls kept in the fridge over winter were not kept Hang galls in wire cages in the shade outside moist enough (it doesn’t matter if they go (close to their host plant) to allow the galls to mouldy), which meant that the flies emerged too break down sufficiently and the maggots to late in the season complete development

Wind damage to cages allowed some flies to Design and build stronger cages. Also fence off a escape corner of a paddock for the rearing cages so any flies that escape can attack plants outside the cages (as happened at one site)

Stock ate galls Use fine wire mesh to protect the galls once the rearing cages are removed Extreme drought may have affected plant (and Try watering thistles if the season is drier than hence insect) development in some areas usual

These lessons, learned the hard out and it will be third time lucky Californian Thistle Action way, remind us that rearing for these dedicated souls and they Group which successfully insects is often not easy — even will be amply rewarded for their gained a 3- year grant from the trained entomologists find it hard perseverance in years to come! Agricultural and Marketing at times! Hopefully, most of the Research and Development difficulties have now been ironed This project is funded by The Trust (AGMARDT) in 1999. 8 What's New in Biological Control of Weeds? Number 18 May 2001

Posters Galore!

Recently we have been busy preparing some new display material and revamping some of our older stuff. This means that a selection of colourful new posters are now available to brighten up your office or pull in the crowds at field days (see below).

Contact Lynley Hayes ([email protected] or Ph 03 3256 701 ext 3808) if you wish to place an order. Don’t forget that the video “Natural Born Weed Killers”, featuring a cast of millions, is also still available to help you to wow audiences and educate people about biological control of weeds.

Poster A0* A1* A2* A3*

What’s Eating Gorse? $100 $75 $50 $25

What’s Eating Nodding Thistle? $100 $75 $50 $25

What’s Eating Old Man’s Beard? $100 $75 $50 $25

What’s Eating Ragwort? $100 $75 $50 $25

Snakes and Ladders (a humorous yet realistic insight into what’s involved in developing biological control programmes) $100 $75 $50 $25

* A0 = 840 x 1190 mm, A1 = 594 x 841 mm, A2 = 420 x 594 mm, and A3 = 297 x 420 mm All prices include GST. 9 What's New in Biological Control of Weeds? Number 18 May 2001

Winter Activities

Winter is the time when many black waste substance (frass), coming spring, and get up to people can have a bit of a and the ribs of the surrounding date on the paperwork. If you breather on the biological leaves take on a reddish-brown have any outstanding release control front. The end of May colour at the base. The leaves or recovery forms, then please is often the cut-off time for of damaged rosettes become send them in without delay so harvesting ragwort flea beetles less prickly and start to look a we can ensure our nationwide (Longitarsus jacobaeae), bit like dandelion leaves. You databases remain as up to date although it may still be may see rosettes that look like as possible. Also start possible to collect them in good this at any time of the year, but thinking about suitable release numbers in warmer areas the damage is usually most sites for any new agents that throughout winter. Nodding obvious later in the winter and you may be receiving from us, thistle crown weevils in early spring. If you dig a and planning harvesting (Trichosirocalus horridus) can damaged rosette out of the operations for broom seed usually be shifted around as ground and cut it in half with beetles (Bruchidius villosus), late as June. Winter can be a a pocket knife, you should be gorse pod moths (Cydia good time to check nodding able to see the white grubs succedana), and gorse thrips thistle crown weevil release feeding inside. The weevil also (Sericothrips staphylinus). sites. Some weevils lay eggs all attacks cotton, marsh, year round, but the bulk of plumeless, Scotch, slender- them begin to lay in the winged and winged thistles so autumn and the damage to the look out for damage to these rosettes becomes more plants too. noticeable as the winter progresses. As the grubs feed Remember to use the winter in the crown, they produce a time to make plans for the

This newsletter is produced three times a year by: Manaaki Whenua – Landcare Research NZ Ltd PO Box 69 Editor: Lynley Hayes Lincoln 8152 Email: [email protected] New Zealand Layout: Judy Camden & Kirsty Cullen Ph +64 3 3256 700 Cartoons: Anouk Wanrooy Fax +64 3 3252 418 Website: www.landcare.cri.nz ISSN 1173-762X

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