Locusts and grasshoppers cause extensive damage to crops in many parts of the world, and their control traditionally necessitates the application of large quantities of chemical pesticides over extensive areas (and not always those suffering the crop damage). Emerging concern about the environmental and health impacts of the insecticides led, during the 1990s, to the development of biopesticides for locust control in Africa and Australia. This year, locusts have hit the headlines in both continents, and it seems a good time to examine what contribution the biopesticides are making to locust control.
In Australia, rains in February broke a 2-year drought and also triggered the most serious locust outbreaks since 2000; further outbreaks are expected as overwintering eggs hatch this spring. Meanwhile, Africa is threatened with the worst locust plague for 15 years. FAO (Food and Agriculture Organization of the UN) has described the desert locust (Schistocerca gregaria) situation in northwest Africa as alarming; despite intensive control activities, an upsurge is underway. It warns that a full-scale plague in the region may occur before the end of 2004 and has called for international assistance to help prevent this.
The last desert locust plague in Africa, in 1986–89, took several years, more than US$300 million and some 1.5 million litres of insecticide to bring under control. It was as a consequence of this that the international community, concerned about the nontarget effects of these quantities of pesticides on the environment and human health, initiated the development of alternative control methods. The LUBILOSA (Lutte Biologique contre les Locustes et les Sauteriaux) programme, which began in 1989, developed Green Muscle®, a mycopesticide based on an African strain of the fungus Metarhizium anisopliae var. acridum. In 1993, Australia's CSIRO (Commonwealth Scientific and Industrial Research Organisation) began a project in collaboration with LUBILOSA to undertake parallel development of a mycopesticide for locusts and grasshoppers in Australia, and this led to Green Guard®, based on an Australian strain of the same subspecies.
Green Muscle® was subsequently recommended by the pesticide referee group of FAO for use in environmentally sensitive areas. The product was licensed to Biological Control Products SA (Pty) Ltd (BCP) for the southern and eastern African markets. BCP registered it in South Africa and started commercial production in 1998. A French company was approached for the West African market. It managed to obtain a sales licence (APV) from the Comité Sahélien des Pesticides in 2001 for the CILSS (Comité permanent Inter-etats de Lutte contre la Sécheresse dans le Sahel) zone, but subsequently failed to get commercial production off the ground. Presently, negotiations are under way with the French daughter of an American company. Meanwhile, the pilot production plant at IITA supplies spores at cost price for trials. The national plant protection service in Niger (funded by Lux Development) integrated Green Muscle® in its anti-locust activities in 2000 and 2001, in conjunction with extension activities coordinated by LUBILOSA. However, full integration is not yet possible because of the limited capacity of the IITA plant.
Although projects (see below) continue to demonstrate its efficacy, Green Muscle® has yet to be widely adopted for anti-locust operations. More data are needed to allow it to be optimally targeted, and one group is working at the grassroots level to integrate the technology for smallholder farmers. Many rely wholly on chemical pesticides and the quantities and costs can be enormous. For the current crisis, FAO reported that 4.1 million hectares across five North Africa countries were treated between October 2003 and May 2004 at a cost of more than US$40 million in an attempt to forestall the threatened plague. (By contrast, the total bill for the 12-year LUBILOSA project was about US$17 million). Whereas chemicals may be needed for a quick 'knock-down' to protect adjacent crops, it is becoming increasingly apparent that mycoinsecticides have a clear role in environmentally sound, preventative locust control.
It is a rather different story in Australia, which saw the world's first operational use of a Metarhizium-based mycoinsecticide against locusts in the 2000–01 season. Until earlier this year, a prolonged drought meant locust numbers remained low and there has been limited need for control operations. However, although it has by no means replaced chemical insecticides, Green Guard is on the threshold of becoming an integral part of the Australian anti-locust strategy (alongside fenitrothion and fipronil) and is set for full registration there in September. It is an invaluable technology for areas where chemical insecticides are inappropriate - in conservation areas and the expanding organic agriculture sector.
Control of locusts and grasshoppers in Australia is coordinated by the APLC (Australian Plague Locust Commission), which is responsible for managing outbreaks that constitute an interstate threat, and assisting states to manage intrastate outbreaks. Collaboration between APLC, CSIRO and a commercial partner (initially SGB Pty Ltd, latterly Bio-Care Technology Pty Ltd after their acquisition of SGB) facilitated the progression from research to trials to operational use and integration into the national strategy. In contrast, the locusts and grasshoppers targeted in the LUBILOSA programme affect a large number of countries in Africa and beyond, which creates both regulatory hurdles for the product and additional obstacles in the need to obtain a consensus in the affected countries for a solution. Regulatory procedures (for biopesticides as a whole) are being addressed at national and regional levels, but funding creates a further barrier, with commitment to locust and grasshopper biocontrol needed from international donors as well as national and regional bodies. As the article below demonstrates, scientists and other stakeholders have not been idle. But it needs donors to buy into locust biocontrol in Africa if the Australian story is to have a chance of being repeated. A large consortium of donors contributed to the development of Green Muscle® and funding for research into its use continues. Many donor governments have declared strong commitment to sustainable development and poverty alleviation in Africa. Funding the implementation of the Green Muscle® technology provides an opportunity for donors to contribute towards these goals by supporting a sustainable locust and grasshopper control technology in Africa that not only has proved successful in trials there, but also is being adopted into the national strategy in Australia.
Green Muscle®, a mycoinsecticide based on Metarhizium anisopliae var. acridum, was developed by the LUBILOSA programme whose partners included AGRHYMET-CILSS (Centre Régional de Formation et d'Application en Agrométéorologie et Hydrologie Opérationnelle - Comité permanent Inter-états de Lutte contre la Sécheresse dans le Sahel), CABI Bioscience and IITA (International Institute of Tropical Agriculture). The 12-year programme turned a research success (the formulation of fungal spores in oil) into a commercial product by addressing production, storage, formulation and application issues. It demonstrated the practical application of biopesticides in the harshest of environmental conditions (deserts) against an extremely mobile and difficult target pest (the locust). The safety and efficacy of Green Muscle® against the major acridid species in Africa, such as desert locust (Schistocerca gregaria) in West Africa and brown locust (Locustana pardalina) in southern Africa, was demonstrated in field trials in collaboration with African national programmes. Since then, a number of projects have continued with assessing Green Muscle®'s impact on pest species (not just in Africa), and conducting environmental impact studies and ecological research that will allow applications to be timed for optimum efficacy.
As part of a project on environmentally sustainable control of red locust (Nomadacris septemfasciata) in central and southern Africa, funded by the UK Department for International Development (DFID) and led by Imperial College London, several field trials have been conducted with Green Muscle® in Zambia and Tanzania over the last 4 years. These included operational scale treatments against red locust nymphs during the wet season and against adult locusts during the dry season (these large-scale applications were co-funded by FAO [Food and Agriculture Organization of the UN] Technical Cooperation Programme funds). The overall results from the trials indicated that red locust nymphs and adults were susceptible to the fungus and that spray applications caused significant population reductions.
The efficacy studies were accompanied by environmental impact studies to determine the effects of the biopesticide on nontarget invertebrates relative to a chemical pesticide standard. These studies showed the biopesticide to have significantly less impact on nontarget species than the chemical pesticide. Indeed, the only nontarget effects recorded were on nontarget grasshoppers. This result is not unexpected and whilst it should not be dismissed as irrelevant, its significance needs to be placed in context. First, the direct nontarget effects from spray applications of the biopesticide are still far less than with a chemical. Second, long-term effects through establishment and cycling of the pathogen through target and nontarget species are likely to be negligible; studies on persistence and sporulation of cadavers in the field indicated high levels of scavenging and predation such that cadavers could rarely be found, making horizontal transmission extremely unlikely.
Supporting ecological studies were conducted to elucidate the effects of temperature and locust thermoregulatory behaviour on performance of the pathogen. These studies provided valuable insights into the mechanisms employed by locusts to combat infection and into the costs of mounting a defence response. The studies of thermal biology also contributed to the development of a GIS-based model that enables us to predict variability in performance of the biopesticide in time and space, based on measures of ambient temperature. The outputs from the model suggest that the biopesticide should be highly effective against red locust nymphs throughout the species' range during the wet season. It should also be effective against adults in the dry season, although speed of kill is slower and more variable (indicating the need to target adults earlier rather than later in the dry season).
Overall, the assessment of locust control experts who participated in the trials (which included national plant protection officers and representatives from the International Red Locust Control Organisation for Central and Southern Africa [IRLCO-CSA] who have the mandate for locust control in the region), was that the biopesticide provided satisfactory control and, given its limited environmental impact, should be considered for red locust control in the future. A commercial producer in South Africa (BCP) has extended registration for the biopesticide from South Africa to Zambia and Namibia, with registration dossiers currently under review in Tanzania, Mozambique and Sudan.
Locusts and grasshoppers are key pests across extensive parts of southern Europe, North Africa and western Asia; for example, Moroccan locust (Dociostaurus maroccanus) is a pest in the Mediterranean region, eastern Europe and western Asia, and Italian grasshopper (Calliptamus italicus) has pest status in Italy, France, Spain, Russia and the new Central Asian republics. Quite apart from the damage inflicted on agriculture, many affected areas are unique ecosystems and the use of chemical insecticides threatens biodiversity. The ESLOCO (Protecting Biodiversity through Environmentally Sustainable Locust and Grasshopper Control) project, funded by the European Union (EU) and led by CABI Bioscience and Imperial College London, was set up to address the problem of providing control while protecting the environment by adapting Green Muscle® technology for Europe and Asia.
As part of the ESLOCO project, numerous lab, semi-field and field studies were conducted in Spain to evaluate the performance of Green Muscle® against Moroccan locust and Italian grasshopper. Whilst speed of kill was shown to be variable and generally slower in the field than in the lab, the overall results indicate that the biopesticide can provide effective control of these two pest species. In particular, the final large-scale trials in Spain demonstrated significant reductions in field populations with better overall control than that achieved with the chemical pesticide malathion.
Extensive investigations were conducted to evaluate the environmental impacts of the locust biopesticide. These ranged from molecular studies of pathogen stability, through studies on establishment and potential for competition with indigenous pathogens, to field-scale studies monitoring impact on nontarget invertebrates. These comprehensive studies indicate that the M. anisopliae var. acridum isolate used in the biopesticide could potentially establish in Spain, but is unlikely to displace microbial competitors or impact on the majority of nontarget taxa. The one exception is that the exotic pathogen does infect other species of Orthoptera. Once again, this not unexpected result should not be dismissed, but its significance should to be put in context; the host range of the pathogen is considerably narrower than any of the chemical alternatives currently available for use and direct nontarget effects are substantially less with the biopesticide than with a chemical.
To assist in understanding the variability in effectiveness of the biopesticide and develop an appropriate use strategy a pathogen performance model was developed. Based on an understanding of locust thermal biology and the effect of locust body temperature on pathogen growth, the model uses environmental temperature to predict speed of kill of the pathogen. Using historical data and a GIS platform, the model has been used to derive maps which describe likely pathogen performance across the locust season in different years and at different locations in Spain.
The outputs show expected performance of the biopesticide, expressed as number of days for 90% of a locust population to die following treatment. The efficacy maps reveal that there is spatial variation in expected pathogen performance across Spain (and beyond) at different times. In general, the biopesticide is expected to work more quickly during the early part of the season, compared with later. That said, effectiveness varies with age of locusts at time of application; high levels of mortality before 20 days might be important if locusts are 4th instars, but will extend to 30 days if the treatment is against 1st and 2nd instars. Thus, the model reveals three important points with respect to use strategy:
The Green Muscle® dossier has been revised to include results from the efficacy and environmental impact studies and brought in line with the requirements of European Commission Directive EU 91/414 Annexes IIB and IIIB. The relevant parts of the dossier are being translated into Spanish and are due to be submitted to the Spanish regulatory authorities shortly.
DANIDA (Danish International Development Agency) has funded a regional programme for environmentally sound grasshopper control in the Sahel (PRéLISS: Project Régional de Lutte Intégrée contre les Sauteriaux au Sahel), which is being implemented in Niger, Senegal, Burkina Faso and Cape Verde. The partners in this project are IITA, AGRHYMET, the Danish National Environment Research Institute (DMU) and the Danish Heath Society (DDH Environment and Energy A/S). A major focus is the integration of Green Muscle® into a sustainable approach to the management of grasshoppers (notably Senegalese grasshopper, Oedaleus senegalensis) in the Sahel. The decentralization of national plant protection services in many Sahelian countries and new tools, notably microbial biocontrol, create an opportunity to develop environmentally friendly options for grasshopper control in the region by integrating ideas from agricultural research, natural resources management and rural development. The project is working with a range of stakeholders including farmers, village brigades, plant protection officers and national and regional organizations to develop, test and implement this new approach.
Green Muscle® forms the basis of the IPM strategy under development by PRéLISS. Although the LUBILOSA programme has already done most of the research necessary for the development of the product, some questions remain. It is, for example, not yet clear what the optimum dose to apply is under various circumstances. Since the price per kilogram is relatively high, there is considerable pressure to lower the dose as much as possible to be able to compete with chemical insecticides. Field trials conducted in the first 2 years of PRéLISS indicated that the current recommended dose of 50 g/ha for grasshopper control can be reduced to 25 g/ha. This year's trials will hopefully confirm this result. The price per hectare will then be brought into the range of competing products.
Another line of investigation is the mixture of Green Muscle® with low doses of relatively benign chemical insecticides, like pyrethroids. The rationale for this is that farmers do not have much confidence in a product that takes more than a week to yield observable results. For psychological reasons, a fair proportion of grasshoppers should be dead or at least twitching before the end of the day on which they were treated. Initial results of trials in Senegal indicate that the approach could work, but the dose of the chemical product should be further reduced.
One problem with the large-scale application of chemical insecticides is that they often have a more serious effect on natural enemies than on the target insect. This has long been suspected in the case of locust and grasshopper control. For that reason, PRéLISS is studying the impact of natural enemies on grasshopper populations. It has already been established that those attacking egg pods play an extremely important role in regulating populations. In some areas, they often destroy 60–80% of eggs. Another group of natural enemies that turns out to be important is birds. A number of bird species in the Sahel specialize on grasshoppers and others switch to grasshoppers when the latter reach certain densities. The project has found that birds have an important regulatory effect at low to medium grasshopper densities.
Given the effect that chemical insecticides have on nontarget insects and even birds, it is easy to see that large-scale applications may be counterproductive. Current grasshopper population upsurges will be suppressed, but the disappearance of many natural enemies will create the conditions for the next upsurge. To get a better idea of this, the project is developing an ecological model that includes grasshoppers, their natural enemies, their impact on crops and the effect of various control methods. Provisional results show that, indeed, applications of chemical insecticides tend to increase the chance of future outbreaks. The important role of various natural enemies is also confirmed.
Two new approaches to grasshopper control are being studied: the potential for releasing an exotic egg parasitoid in the genus Scelio and a pathogenic protozoan, Nosema locustae. Release of the exotic Scelio would create a new parasitoid/host association, because Oedaleus does not occur in its native range. However, the potential effects on indigenous Scelio spp. and on nontarget grasshoppers need to be studied. Nosema locustae is already used to some extent in North America. Although it does not provide significant immediate control, it does become established in the population and causes reduced fitness, especially lower fecundity, over many years. The project is studying the merits of releasing N. locustae in areas of West Africa with recurrent high grasshopper densities.
In order to assist decision makers in selecting the best control method and in targeting their limited resources to areas most likely to experience grasshopper upsurges, the ecological model is being integrated into a GIS-based decision support tool. Ecologically sensitive areas, like national parks and reserves and important bird areas (IBAs), have been mapped into the tool, so that it becomes easier to avoid them when chemical control has to be carried out. The programme will predict areas at risk of high grasshopper populations based on the population densities of the previous year, any control measures taken and the most recent egg pod surveys. It will also show the effects of any of the possible control methods on grasshopper densities, crop yields and populations of natural enemies.
At the end of the present phase of the project, the ecological model and decision support tool will be at an advanced stage. However, several seasons of validation will still be necessary. In addition, end users of the tool need training in its use and agencies collecting meteorological and other data used in the model need to be sensitized and convinced to supply the information either free of charge or for a reasonable fee. The project is presently seeking funding for a second and last phase to achieve its goals.
The principal beneficiaries of the PRéLISS project will be the resource-poor farmers who will gain a grasshopper control technology of minimum risk to themselves, their animals and the environment, yet will enhance agricultural production. At the same time, agricultural and environmental stakeholders will gain a control approach that compromises neither's goals. The project is therefore putting a lot of effort into the sensitization and training of farmers. This is mainly done in close collaboration with local NGOs. A special approach has been developed in Niger in collaboration with the Ministry of Agriculture, FAO and Lux Development (Luxemburg). In villages where farmers have organized themselves, cooperative shops (non-profit) are established and stocked with quality seeds, fertilizers and pest control products, which are provided to the farmers at cost price. Spray equipment and protective clothing can be hired. PRéLISS is supporting the setting up of 16 shops in areas prone to grasshopper outbreaks. Green Muscle® and the pyrethroid Decis® are delivered to the shops at subsidized prices. Special village brigades are trained in monitoring grasshopper populations and proper application techniques. The advantages of an IPM approach are explained to the farmers. During the first 2 years, most of the Green Muscle® delivered to the shops was purchased. Farmers who used it were generally happy about the absence of toxicity, although the slow action of the product caused some anxiety.
The various projects above continue to build on the considerable achievements of the LUBILOSA programme that developed the biopesticide technology. However, challenges still remain to the widespread adoption and implementation of Green Muscle® in Africa. Experience in South Africa, for example, reveals that demonstrating efficacy, achieving registration and establishing production capacity are not sufficient for technology acceptance. Registration remains a serious obstacle because of the time and cost involved in registering the product in all the countries affected by locusts and grasshoppers. This exceeds the resources of the single company presently producing Green Muscle®. In the current projects we have encouraging support from FAO and regional locust control organizations, together with an effective and motivated producer who wish to see the product a commercial success. Nonetheless, given the complexities of locust and grasshopper control (i.e. donor-funded programmes with generally preventive control actions taken in areas/countries far away from the ultimate beneficiaries) and the fact that the benefits of the technology are linked in part to 'non-market' environmental values, we believe that there is still a need for further support to ensure adoption of this promising and innovative technology. Ultimately, widespread adoption rests with donor commitment to purchase the product and pay for protection of the environment as well as controlling locusts and grasshoppers.
Core for Southern African Migrant Pests) News:
Operational Use of Green Guard® for Locust and Grasshopper Control in Australia
Australian farmers, State government authorities and the Australian Plague Locust Commission (APLC) will shortly have a viable alternative to traditional chemical pesticides for control of locust and grasshopper pests threatening grazing pasture and agricultural crops in chemically sensitive areas. Green Guard®, a mycoinsecticide containing conidia of Metarhizium anisopliae var. acridum (isolate FI-985), is now being produced commercially by Bio-Care Technology Pty Ltd following the acquisition of SGB Pty Ltd (the original suppliers) in 2003. Full registration of the product in Australia is expected by October 2004. However, extensive large-scale field testing of various formulations of this product has been undertaken by the APLC since 2000 under a series of special use permits issued by the Australian Pesticide and Veterinary Medicines Authority (APVMA).
The development of Green Guard® to this stage was driven in part by an increasing trend towards organic farming in Australia during the late 1990s and a reaction by many farmers to overuse of chemical pesticides. Produce grown under the 'clean and green' banner promised higher returns for farmers from domestic and international markets. The development of a major organic beef industry in the remote grasslands of western Queensland and South Australia, considered to be a significant breeding and 'outbreak' area for the Australian plague locust, Chortoicetes terminifera, also forced the APLC to rethink its strategy of early intervention with chemical control to reduce locust populations and migrations into the intensive cropping areas of eastern and southern Australia. A survey of cattle producers in this area in 1999 determined that at least 50% of suitable locust habitat could become inaccessible to the APLC for future control operations if there was no acceptable alternative to chemical pesticides (primarily fenitrothion) available. A range of options was explored and of these, use of the fungus Metarhizium anisopliae var. acridum, applied as a biopesticide registered as Green Guard® (a CSIRO [Commonwealth Scientific and Industrial Research Organisation] initiative), showed the most promise. To further develop the product and coordinate research opportunities and funding, the Locust and Grasshopper Biocontrol Committee was formed with representatives from CSIRO, State departments of agriculture (Queensland and New South Wales), the APLC and landholder groups. Funding from each of these groups assisted with important lab and field efficacy studies on each of the major locust and grasshopper pest species affecting agriculture in different areas and crops, e.g. APLC - Australian plague locust, (pasture and cereals); Queensland - spur-throated locust, Austracris guttulosa, and migratory locust, Locusta migratoria, (pasture and sorghum); New South Wales and landholders - wingless grasshopper, Phaulacridium vittatum, (orchards, vegetables, lucerne and pasture).
During 1999/2000, a series of aerial trials (total of ca. 4000 ha treated) applying ultra low volume (ULV) formulations of Green Guard® determined that effective control (>90%) of Australian plague locust nymphs could be achieved at a dose of 25 g (1 ∞ 1012) conidia per hectare applied at rates of 500 ml to 1 litre/ha of carrier oil (Caltex Summer Spray oil) through Micronair AU5000 rotary atomizers. Previously rates as high as 50–125 g/ha had been tested. Based on the efficacy of this lower rate the APLC entered into an agreement with the commercial producer (SGB) to purchase a minimum of 500 kg of conidia annually (equivalent to treatment of 20,000 ha at the 25 g/ha dose) for a period of 3 years. This guaranteed 'market', whilst small, enabled small-scale commercial production and provided a degree of financial certainty that allowed SGB to plan longer term, scale up production, build better facilities to improve output and tackle problems associated with quality of product, drying of conidia, stability of formulations and long-term storage of large quantities of conidia. In short the production progressed from the scale needed to support a small research programme to a commercial operation.
The nature of the product formulation was critical to the successful development of Green Guard® as an operational ULV pesticide. The CSIRO team under Richard Milner (firstname.lastname@example.org) worked closely with the APLC to develop a formulation that could be easily transported and mixed in the field while not causing blockages in aircraft spraying equipment. The result was an oil concentrate containing 300 g of dry conidia per litre of corn oil. This was then diluted in a low viscosity mineral oil (Caltex Summer Spray oil) to give the required concentration for ULV application. Corn oil was chosen as its viscosity assisted in keeping the conidia in suspension and it mixed readily with the mineral spray oil. The oil concentrate was supplied in 20-litre heavy-duty plastic buckets (allowing easy access for remixing) each containing 14 litres of oil and 4.2 kg of conidia. The choice of Summer Spray oil as the diluent was made following advice from National Association for Sustainable Agriculture Australia (NASAA), the main organic farming certifying organization, that this oil could be applied with the Green Guard® ULV concentrate to certified organic properties.
Using this ULV formulation the APLC developed and refined a standard 'incremental drift spraying' application technique for blanket aerial treatments with Green Guard® based on field trial results and wind tunnel tests. In the wind tunnel evaluations the formulation was run at operational flow rates through a Micronair AU5000 atomizer using various blade settings (to vary cage rpm [revolutions per minute] and droplet size) with an air velocity of 200 km/h (to duplicate aircraft flying speed). The spray droplet spectrum produced at each blade setting was determined using a Malvern laser analyser and the results were used to model down-wind deposition patterns under varying wind speed conditions using the Gaussian Diffusion Model (GDM) developed by Ian Craig and Nicholas Woods (Centre for Pesticide Application & Safety, University of Queensland, www.aghort.uq.edu.au/cpas/). The final spraying technique (still in use by APLC today) employed a 100 m spacing between spray runs made at right angles to the prevailing wind, a VAR (volume application rate) of 500 ml/ha, 45° blade setting with Micronair AU5000 (cage rpm - 6100, VMD [volume median diameter] - 96 microns, span - 1.24), a release height of 10 m and a flying speed of about 200 km/h.
Fortuitously, the development of a robust ULV formulation and increased production coincided with a major outbreak of Australian plague locust in eastern Australia. Working under an emergency use permit issued by the NRA, between October 2000 and January 2001 the APLC treated 71 blocks covering some 23,000 ha with Green Guard®. This area comprised approximately 12% of the total area treated during the outbreak, the remainder being treated with fenitrothion or fipronil. Green Guard® was used in areas where chemical pesticides could not (organic properties, national parks, endangered vertebrate species habitat and areas bordering wetlands). Field assessments demonstrated that effective control of nymphs (>90% mortality) was achieved at a dose of 25 g/ha in 500 ml/ha of spray oil over a range of vegetation types and densities. Depending on temperature (both day and night) the time taken to reach this level of mortality varied from 10 to 12 days when maximum day temperatures reached 34–42°C (minimum night temperature of 20–25°C, summer conditions) to 14 to 18 days at 22–30°C (minimum night temperature of 10–15°C, spring conditions). Continuing development of the fungal infection in locusts on warm nights proved to be an important factor that enhanced the usefulness of Green Guard® for control operations in the hot conditions often encountered during the summer plague locust season in Australia.
Following this successful demonstration of Green Guard® as a viable alternative pesticide, work progressed towards implementing it on a fully operational scale. Steps in this programme included improving production and storage procedures, determining effective rates for the control of other locust and grasshopper species, development of a formulation that could be used by farmers with high-volume ground control application equipment (e.g. boom and nozzle) and a complete data package, including toxicology and nontarget effects, to support the registration of Green Guard® for commercial use in Australia. Progress to date has been steady.
A suspension concentrate (SC) formulation was developed and tested (15 trials over 230 ha) on a variety of high value, organic horticultural crops threatened by wingless grasshopper (fruit trees, olives, vineyards, pine trees and lucerne) and Australian plague locust nymphs (improved pasture). Various forms of high-volume water application equipment commonly used by farmers were used to apply this formulation to check for problems with mixing, coverage or blockages. It performed well and at a dose of 50 g conidia per hectare gave farmers effective and economic control. Farmers can currently choose between 1 and 3 ha pack sizes. An emulsifiable concentrate (EC) formulation is under development and should be available by late 2004.
The APLC maintains a supply contract with the new commercial producer, Bio-Care Technology Pty Ltd who is also investigating an expansion of production to include a growing market in China. If successful this arrangement would increase the long-term viability of Green Guard® production in Australia. Current production yields using self-aerating culture bags are about 90 g of FI-985 conidia per kilogram of growing substrate (boiled rice). The dry spores (<5% moisture) are stored as a dry powder or as formulated product at 4°C. Long-term storage tests have shown that the material stores well for a least 18 months under either condition. Current costs for Green Guard® ULV are AU$ 12/ha (using 25 g/ha dose) with an additional AU$ 0.80/litre for the Summer Spray oil. The Green Guard® SC costs farmers AU$ 36/ha.
The APLC also developed a mechanical system for premixing the Green Guard® ULV and Summer Spray oil at airstrips prior to loading into spray aircraft. This had been a major problem during past control operations due to the time consuming and labour intensive nature of the manual mixing process. This new system proved highly efficient during major control operations in February 2004 when 12,500 ha with very high densities of Australian plague locust nymphs were successfully treated on several organic beef production properties in southwest Queensland.
A submission for the commercial registration of Green Guard® has been with the APVMA since mid 2002. As well as the usual problems associated with the registration of a new pesticide, the long review process has concentrated heavily on the possible effects that large-scale aerial use of Green Guard® may have on the environment and nontarget species. Questions from the reviewing authorities have largely been answered and the APLC and Bio-Care Technology Pty Ltd are confident that the product will be registered by October 2004.
It is also worth noting that in the current registration submission, the application rates are based on vegetation cover rather than on locust species. Modelling studies by Joe Scanlan (Queensland Department of Natural Resources, email@example.com) and field data collected by the APLC indicated that locusts and grasshoppers in tall, thick vegetation pick up most of their lethal dose of spores from the vegetation and require a high dose per hectare, while locusts in short or sparse vegetation require a much lower dose per hectare. Low vegetation is a common feature of Australian plague locust and wingless grasshopper habitats. Therefore a dose of 25 g/ha would usually prove effective against these two pests, although situations do occur where locusts are present in tall or thicker grasses or crops and a 50 g/ha dose would be more effective. Tall, dense vegetation is common in migratory locust habitats so a 50 g/ha dose will be used against this species. The spur-throated locust is almost always found roosting in tall, dense grass or in trees. Many more spores are required to cover the high surface area of this habitat so a higher dose of 75 g/ha is required for this species.
The use of Green Guard® technology in Australia by the APLC and other groups involved in the control of locust and grasshopper pests is likely to increase in the future as widespread use of traditional chemical pesticides in specific areas becomes harder to justify due to economic, environmental or social constraints. Increased production of Green Guard® funded by the APLC and the groups represented by the Locust and Grasshopper Biocontrol Committee provided an impetus for continuing commercial production and registration of the product. It also provided the APLC with the quantities of material required to investigate and ultimately demonstrate efficacy of Green Guard® at an operational level.
Australian efforts to bring the environmental weed bridal creeper, Asparagus asparagoides, under control are continuing. A concerted effort by the CSIRO (Commonwealth Scientific and Industrial Research Organisation) and the Cooperative Research Centre (CRC) for Australian Weed Management, in collaboration with community groups, schools and landholders, has led to one of the most successful biological control programmes in Australia.
This South African plant was introduced into Australia as an ornamental in the mid 1800s, but soon naturalized and invaded natural bushland. It is now a major environmental weed across the whole of southern Australia and is one of Australia's 20 'Weeds of National Significance'. Bridal creeper is a climber that can smother vegetation and take over large areas of land. In dense infestations, the underground tubers, representing up to 90% of the weed's biomass, form 'mats' under the soil surface that prevent native plants from growing. Birds that feed on bridal creeper's bright red berries spread the seeds and are responsible for the establishment of satellite populations kilometres away from the main infestations.
Three biological control agents of bridal creeper have been released in Australia: the leafhopper, Zygina sp. in 1999, the rust fungus, Puccinia myrsiphylli in 2000 and the leaf beetle, Crioceris sp. in 2002. A national redistribution programme was set up in 2002, with financial assistance from the Australian Government's Natural Heritage Trust, to fast track the release and spread of the first two agents across the entire range of bridal creeper infestations.
Since then, CSIRO staff have taught on-ground groups and landholders the basic skills needed to identify, release and monitor the impact of the agents. A website (www.ento.csiro.au/bridalcreeper) has been developed to provide detailed information about the programme and various protocols. A national database of release sites linked to a web-based interactive map has facilitated keeping track of the releases. According to database entries, the leafhopper and rust fungus have now been released at a total of 827 and 1031 sites, respectively, across southern Australia. These are, however, an underestimate of numbers because not all collaborators have provided details about their releases.
Both the leafhopper and the rust fungus damage bridal creeper by attacking the leaves. The leafhoppers feed on mesophyll cells and their damage is seen as white variegations on the leaf surface. The rust fungus infects stems and leaves and is easily recognizable as yellow circular areas on the upper sides of leaves and by corresponding orange sporulating pustules on the under side. Severe infestations of both agents result in reduced photosynthesis, premature defoliation and reduced tuber production.
Last year, reports of natural spread of the rust fungus of up to 1 km from release sites after one year were very encouraging. In 2003, the rust was also seen to cause severe defoliation of plants in the middle of the weed's growing season. This was particularly apparent in Western Australia, New South Wales and Kangaroo Island in South Australia. This extensive damage prevented bridal creeper from flowering and producing fruits in spring and also severely diminished the underground reserves. These are exciting outcomes which will make a significant contribution towards reducing the spread of this weed and the density of existing populations.
It is still early days for the Crioceris sp. leaf beetle, the third agent released against bridal creeper. Establishment has only been confirmed at a few sites in Western Australia, and more work is required to determine the best time and number of insects to release. The leaf beetle has one to two generations per year, consumes young expanding leaves and shoots, and only lays eggs on shooting tips. Both adults and larvae are difficult to handle and consequently this agent will be unsuitable for mass rearing by community groups and schools. However, once the beetles are established at release sites, community groups could become involved in redistributing them to new sites.
The invasive and destructive blackberry, Rubus fruticosus aggregate, is one of southern Australia's most important 'Weeds of National Significance'. Its impenetrable thickets reduce the production, recreational or aesthetic value of land and block access to waterways. It is now estimated that blackberry occupies 8.8 million hectares of Australia, an area larger than Tasmania.
A new attempt towards the biological control of blackberry began in April 2004 with the first release of additional strains of the rust fungus, Phragmidium violaceum, from Europe. There had been two earlier introductions of this rust fungus into Australia - an illegal one in 1984 and, in 1991, an official release of another strain of the fungus. These introductions had mixed results. In some areas they had practically no effect on blackberry while in others they severely defoliated bushes.
Work in the 1990s by the Cooperative Research Centre (CRC) for Australian Weed Management led to a much better understanding of the genetic variation in blackberry and provided the basis to improve the biological control of this troublesome weed. Eight additional European rust strains were selected because together they can affect a wider range of Australian weedy blackberries. Results from specificity tests showed that these rust strains do not pose a threat to commercial blackberry cultivars and Australian native Rubus species. After the required consultation process, Biosecurity Australia cleared the strains for release on blackberry.
The current strategy is to release the additional rust strains at different time of the year at a few experimental release sites in the Manjimup region in Western Australia and the Tumut region in New South Wales and the first releases were made in April 2004. All eight rust strains were released at each site to maximize the chance of at least one type finding local blackberries to its liking.
Outcomes from this work will assist in determining the best season for releasing the rust strains in order to increase their chance of establishment before large-scale releases are undertaken across Australia. Molecular tools will be used to determine establishment rates of the rust strains, as they can not be distinguished morphologically from the existing populations of the rust in Australia. The long-term effectiveness of the additional rust strains released will be assessed in future years by monitoring changes in blackberry biomass along permanent transect lines set up at the sites.
Other partners in this research include the Western Australian Department of Conservation and Land Management, the Western Australian Department of Agriculture, and the Australian Government's Department of Agriculture, Fisheries and Forestry.
By: Louise Morin,
New Florida Home for Biocontrol
On 9 July 2004 a dedication ceremony was held for a new purpose-built quarantine facility dedicated to the biological control of invasive plants and arthropods in Florida. On this date the University of Florida's Institute of Food and Agricultural Sciences officially began operations in its Biological Control Research & Containment Laboratory (BCRCL) as part of its Indian River Research & Education Center in Ft. Pierce. The 17,000 square foot (1580 m2) facility, funded by the Florida Legislature, will be used by entomologists to contain, evaluate, rear and release host-specific insects for biological control of invasive plants and arthropods. Work will be conducted in a cooperative environment with the Florida Department of Agriculture and Consumer Services. The BCRCL features two sections, one for containment and another for non-containment. The containment section includes two laboratories, one for research on biological control of arthropods and another for research on biological control of invasive plants. Also in the containment area are a maximum security laboratory, a fumigation room, a pass-through autoclave, a fume hood room, six climate-controlled rearing rooms, a diet preparation room and six spacious greenhouses. Within the non-containment area are two additional laboratories, a conference room, a camera room and seven offices. Maintenance and operation of the facility is funded annually by a grant from the Florida Legislature.
In Florida, more nature is lost annually to invasive plants than to development. An estimated 1.5 million acres [over 600,000 ha] in central and south Florida are consumed by three of the most well-known invasive plants: Brazilian peppertree (Schinus terebinthifolius), melaleuca (Melaleuca quinquenervia) and Australian pine (Casuarina equisetifolia). The Mexican bromeliad weevil (Metamasius callizona) is endangering populations of Florida's native bromeliads, or 'airplants'. The cycad aulacaspis scale (Aulacaspis yasumatsui) is devastating one of the area's most popular landscape plants, the king sago (Cycas revoluta). Research for the biological control of these invasive pests is currently being conducted by BCRCL scientists.
Parasitoids of Mealybugs on Coffee in Cuba
The 1990s in Cuba were important years for researching and introducing new phytosanitary strategies with a view to converting an agriculture dependent on chemical products towards a sustainable one. This transformation has involved the development of integrated pest management (IPM) and, in particular, one of its most effective tactics: biological control. Coffee has been one of the crops that recently received the benefits of the new strategies, but species lists and biological and demographic studies remain inadequate. This article records the results of surveys for mealybug (pseudococcid) natural enemies carried out in Cuba's coffee-growing regions.
Mealybugs are among the main pests of coffee. They attack different parts of the plant and are very difficult to control with chemical products. Before effective biological control strategies can be developed, more effort must be devoted to aspects of basic research such as taxonomy. This includes the characterization of the indigenous beneficial fauna, information which can be used in the development of an appropriate control strategy.
Surveys were conducted in different seasons in the central and eastern regions of the country, where there are important coffee-producing areas. Samples of leaves, branches, fruits and roots infested with mealybugs were taken to the laboratory, where the natural enemies were reared out.
The following encyrtid primary parasitoid species and genera were reared from mealybugs on coffee during the surveys, most of which have been used successfully in biological control programmes in other countries:
Also found was Diadiplosis cocci Felton, a small cecidomyiid fly whose larva develops under the ventral surface of its mealybug host. The larvae can live in either the aerial parts of the plant or the roots, feeding on the body contents of their hosts and acting as ectoparasites.
The search for new and promising natural enemies associated with pseudococcids needs to continue. Nevertheless, the knowledge acquired from these recent surveys allows us to begin work on methods for improving the conservation of the beneficial biota in the crop. It is also important to have identified the indigenous natural enemies in case it becomes necessary to develop strategies of mass propagation and augmentative release of these potential agents in order to maintain control of mealybug populations on coffee.
By: Margarita Ceballos
Vazquez* and María de los Angeles Martínez,