News 57N General News USA Welcomes Settlers Earlier this year it was reported that popu- Saving Dough lations of the weevils are now well- Two classical biological control pro- established, increasing, and beginning to Russian wheat aphid (Diuraphis noxia) grammes in the USA have reported disperse to other melaleuca infestations. (RWA) arrived in the USA in 1986, and progress with establishment of introduced The promising results show that the weevils since then has cost more than US$1 billion agents this year: one is for an invasive tree are highly effective at defoliating existing in insecticide costs and related losses. Its threatening an important wetland habitat, stands of melaleuca saplings, and it seems North American range now extends the other against an insect causing signifi- likely that they will be able to prevent fur- through 16 US states and two Canadian cant economic damage in key grain crops. ther spread of the invasive tree. Melaleuca provinces. It spends the winter primarily on trees shed 25-33% of their leaves each year, wheat and barley, while several native and but O. vitiosa has a preference for new introduced grass species harbour popula- leaves, and attack these as they are pro- tions during the summer. The most important non-cultivated grass hosts of D. Florida Stripper duced. The weevils in Florida are already consuming enough new foliage that some noxia in North America are the wheat- The broad-leaved paperbark tree, Mela- trees are showing evidence of die-back. In grasses (genus Agropyron; particularly crested wheatgrass, A. cristatum) and wild- leuca quinquenervia, was introduced to time, trees may become completely defoli- Florida at the beginning of the last century. ated. Ultimately, the weevils will ryes (genus Elymus; particularly Canada wildrye, E. canadensis). Hopes of using the tree for timber were not contribute to stopping the problem at its fulfilled, although it did prove economical source, as stressed trees no longer seem to The US government is developing an to grow for ornamental production. Unfor- be producing flowers or seeds. This will arsenal of weapons against the aphid: con- tunately it proved an even bigger success as facilitate control by conventional means, as ventional breeding has produced aphid- an invasive [See: BNI 18(3), 67N ‘Mela- it overcomes the problem that has compli- resistant varieties, which are now available leuca Swamping Florida’ September cated herbicidal or mechanical control to producers; microbial agents are being 1997], and now infests some 200,000 ha of measures so far: the millions of seeds that tested [see BNI 21(1),8N-9N,‘Fungalsolu- the Everglades and is threatening native trees can shed when they die. tion for crop pests?’ March 2000]; and habitat. It thrived in Florida – growing fast, insect parasitoids have also been intro- flowering up to five times a year from 2 Additional agents from Australia are in the duced from the area of the origin of the years old, and producing copious amounts pipeline which target the mature foliage aphid. of seed. A single tree can hold over 60 mil- (Lophyrotoma zonalis, melaleuca sawfly), In 1988, USDA-ARS (US Department of lion seeds in the canopy, releasing them in saplings (Boreioglycaspis melaleucae, Agriculture – Agricultural Research times of stress (fire, frost, herbicide or melaleuca psyllid), and bud growth (Fergu- Service) began work with a consortium of death). sonina sp., melaleuca bud gall fly). Host range studies have been completed with B. federal and state scientists to release 11 spe- The trees were planted as a means of melaleucae, and a proposal for field release cies of exotic RWA parasitoids in the wheat ‘reclaiming’ the Everglades. They grow has been submitted to federal authorities. and barley growing areas of the western densely, forming impenetrable thickets, Psyllids feed on the phloem and heavy USA. They released a staggering 11.8 mil- and spread partly by adventitious roots. The nymphal feeding kills saplings. A proposal lion parasitic wasps, representing more thick mats of roots at the water surface for release of L. zonalis is still pending. than 80 geographic strains collected from cause soil accretion, and this leads to an Concern about possible vertebrate toxins 25 different Eurasian countries where the increase in the elevation of the infested might prevent eventual release of this spe- aphid originated. area. A few centimetres in elevation can cies. Australian host range studies have Key to the success of the project was the cause big differences in the composition of demonstrated the specificity of Fergu- collection of these exotic enemies by staff plant communities here, and the spread of sonina sp. This fly will be tested soon in the of the ARS European Biological Control melaleuca is threatening to transform the Florida quarantine facility with the eight Laboratory in Montpellier, France. Over 60 Everglades from a wet prairie into a closed- native species of Myrtaceae. Both leaf bud exploration trips (throughout the endemic canopy swamp. and flower bud galls are produced by the fly range of D. noxia) were made between and its symbiotic nematode, Fergusobia sp. 1988 and 1994. Seventeen different coun- A USDA-ARS (US Department of Agri- This will further help stem flower produc- tries were visited by more than 40 federal culture – Agricultural Research Service) tion and enhance traditional control and state scientists and technicians, and that project based at its Australian Biological measures. resulted in the collection (mostly from D. Control Laboratory identified some 400 noxia-infested wheat and barley fields) of species attacking this and other related Contact: Ted Center, at least 29 species of natural enemies for Melaleuca species in its native range in Invasive Plant Research Laboratory, release in North America to combat the Australia. It identified, amongst others, a USDA, Agricultural Research Service, pest. leaf-feeding weevil, Oxyops vitiosa,asa 3205 College Ave., promising potential biocontrol agent. The Fort Lauderdale, FL 33314, USA From 1991 to 1993, ARS scientists at the weevils were first released in Florida in Email: [email protected] Plant Sciences and Water Conservation March 1997, and between then and June Fax: +1 954 476 9169 Research Laboratory in Stillwater, Okla- 1998, some 1500 adults and 6700 larvae homa released seven parasitoid species in were released at 13 sites in six counties. wheatfields in eastern Colorado, with the Are we on your mailing list? BiocontrolNews and Information is always pleased to receive news of research, conferences, new products or patents, changes in personnel, collaborative agreements or any other information of interest to other readers. If your organization sends out press releases or newsletters, please let us have a copy. In addition, the editors welcome proposals for review topics. 58N BiocontrolNews and Information 2000 Vol. 21 No. 3 aim of establishing natural enemies in the The weevils and the mite were reared in a an increase was observed, and no additional grain-growing areas there. Seven years glasshouse under quarantine conditions. releases were necessary. later, John Burd (ARS) reports that four of Detailed host-specificity tests, involving 76 the species have become established species of plants belonging to 42 families Studies in Bangalore indicated that N. eich- throughout a six-state area: Colorado, for the weevils and 88 species of plants horniae and N. bruchi could be successful Kansas, Montana, Nebraska, Oklahoma belonging to 42 families for the mite, con- even in tanks that dry during the summer. and Wyoming. Three of the species were firmed their safety to cultivated plants in In the laboratory they survived without also found parasitizing related greenbugs India. Limited field trials were then con- food for as long as 48 and 28 days, respec- (Schizaphis graminum) on sorghum, and ducted with permits issued by the Plant tively, in 95% humidity, and much longer two species successfully parasitized RWA Protection Adviser to the Government of inthepresenceoffreewater.Theycan on summer wild grass hosts. India (PPA). Based on the results obtained probably survive periods of drought by during these studies the PPA gave permis- remaining below plant debris or within Contact: John D. Burd, USDA, sion for open field releases throughout the crevices in the soil and water may be avail- ARS, PSWCRL, 1301 N. Western Road, country. able to them in the form of dew. Stillwater, OK 74075, USA Email: [email protected] Neochetina eichhorniae and N. bruchi More than 150,000 weevils were released at Fax: +1 405 624 4142 established readily under field conditions in different locations in 15 states elsewhere in India after large-scale releases were initi- India. Spectacular biological control of ated in 1983. Field studies indicated that water hyacinth was achieved in the 286 km² release of a breeding population of about Loktak Lake in Manipur, 75% of which was Biological Control of 1000-5000 adults, depending on the area of covered by the weed. Control was achieved Water Hyacinth: the Indian weed coverage, invariably resulted in within 3 years of release of some 18,500 Experience establishment, irrespective of whether the adult weevils during 1987-88. Besides the initial releases were made at one spot or lake’s importance to the local community Water hyacinth (Eichhornia crassipes), over a wide area. During the first year the for fishing, a hydroelectric power project set which entered the country as an orna- insects were observed to multiply and up at Loktak Lake in 1983 has an installed mental, is the most serious aquatic weed in spread throughout the weed mat on which capacity to generate 105 MW of power and India, creating a large number of problems they had been released. Thereafter, an irrigate 23,000 ha of land. Control of water in the management and utilization of fresh- increase was seen in the number of adults hyacinth by release of weevils has brought water resources.