Owen Jones, Suterra, Treforest Industrial Estate, Pontypridd, South Wales CF37 5SU

Transcription

1 III JORNADAS INTERNACIONALES SOBRE FEROMONAS, ATRAYENTES, TRAMPAS Y CONTROL BIOLOGICO: HERRAMIENTAS PARA LA GESTIÓN INTEGRADA MURCIA, 19 Y 20 DE NOVIEMBRE DE 2013 Pheromones: a basic tool in IPM Owen Jones, Suterra, Treforest Industrial Estate, Pontypridd, South Wales CF37 5SU ojones@suterra.com Introduction Nearly 55 years have now passed since the discovery of the first insect pheromone by researchers in Germany and much progress has been made in their development and use in insect pest management over the last three decades. The concept of IPM is based on the recognition that no single approach to pest control offers a universal solution and that the best and most sustainable crop protection can be provided by a combination of various tactics and practices based on sound ecological principles. Pheromones are a commonly used component of many insect IPM programs. The two primary uses of pheromones in IPM programmes are for detection / monitoring and for mating disruption. Detection and Monitoring It is estimated that the sale of traps and semiochemical-based lures account for over $55million worldwide per annum at the manufacturer s level. Witzgall et al. (2010) estimated that there were over 20 million monitoring lures sold worldwide per annum covering over 10 million hectares. Sex pheromone-based lures account for the majority of attractant dispensers sold although, increasingly, attractants from other sources are also being used, such as food, host plantderived and oviposition attractants. Major insect species being widely monitored include the forestry pests (Lymantria dispar and many bark-beetle species of the genus Ips), top-fruit moth pests, (Cydia pomonella, Grapholitha molesta, Anarsia lineatella), grape pests (Lobesia botrana, Eupoecilia ambiguella), cotton pests (Pectinophora gossypiella, Anthonomus grandis) and many fruit fly species (Ceratitis capitata, Bactrocera dorsalis, Bactrocera oleae). In IPM there is a need to do regular scouting for targeted pest species, and especially so with biological pest management products. Therefore the availability of reliable and generally inexpensive semiochemical-based monitoring systems has been a very valuable tool for pest management advisers, farmers and growers, alike. It is undoubtedly also the case that the use of semiochemical-based monitoring systems has led to a much more rational and cost-effective use of conventional insecticides over the last 25 years. There are still a number of limitations in the use of semiochemical-based monitoring systems and factors such as the following need to be kept in mind when these systems are being used:

2 1. The traps are a measure of the behaviour of the insect and are not an absolute representative sample of the population. For instance an insect may not respond to a pheromone lure if it is immature, migrating or aestivating. 2. It is usually the adult stage of the pest species that is being monitored and the correlation between adult numbers and the subsequent immature stages can be affected by many factors both biotic, such as predation and disease, and a-biotic, such as temperature and stage of development of the host crop. 3. Traps and lures offered for sale for monitoring purposes are generally not regulated by government agencies and therefore there are no external checks on the quality of the materials. It is down to the manufacturers to establish and maintain their own quality standards. While there is little that can be done about the first factor mentioned above other than to bear it in mind when analysing data, many ecological studies are being carried out by academics, extension personnel and private companies to provide the end users with a better interpretation of trap catches by taking into account environmental and biological factors to determine the need or the timing of control interventions. As for the third factor, there have been calls for some form of minimum standards in the manufacture of monitoring traps and lures. If such guidelines were established, then manufacturers could ensure that their products meet those standards and would have an audit trail to demonstrate that, should it ever be required. There would need to be agreement between the scientific community and the pheromone industry for such standards to be established but it is eminently achievable if there is consensus and willingness from all stakeholders for this to happen. So what is new in the field of insect monitoring with semiochemicals? GPS mapping and remote sensing have advanced significantly during the last decade and there are many examples of both that are operational today. Spatial information regarding pest distribution in an orchard provides the grower with valuable information for pest management decisions leading to savings in labour and products as required in good IPM practices (Fig. 1).

3 Figure 1 Spatial density of insects based on pheromone trap catches Similarly, pheromone traps that have cameras incorporated into their structure can send images of catches from remote locations to central observatories where again pest management decisions can be made by trained personnel without them having to visit the trap (Fig 2). Figure 2 Remote observations of trap catches in pheromone baited traps As legislation in the future will demand the adoption of IPM practices within the European Union (Directive 2009/128/EC the Sustainable Use of Pesticides) and elsewhere, the use of such diagnostic devices will continue to increase over the next decade. Mating Disruption Market demand, legislative pressures and significant technological advances in pheromone manufacture and controlled release have all contributed to a substantial increase in the use of sex pheromones for mating disruption in recent years. It is estimated that over one million hectares of crops and forestry are now treated per annum with sex pheromones for control of insect pests by mating disruption. This has a market value of nearly $300 million at the

4 manufacturer s level. Many of the Lepidopteran species mentioned above under detection / monitoring are also controlled using mating disruption techniques. Demand for environmentally benign technologies for pest management is increasing generally on a global basis. The growth in the bio-pesticide market of which the semiochemicals form a part, has been substantial over the last decade with a compound growth rate of over 15% per annum. This has been driven in turn by three factors: Regulation, Residues and Resistance (the three Rs). Regulation: In Europe the principal piece of legislation that regulates crop protection products is the EC Regulation 1107/2009 which replaced the EC Directive 91/414/EEC which entered legislation in July The Regulation and the preceding Directive attempts to provide a pan-european harmonisation of plant protection product registration. In practice, it has reduced the number of conventional pesticide active ingredients by over 60% leaving many minor use crops with few or no products for pest control. The cost of bringing a new conventional agrochemical active ingredient onto the market is measured in hundreds of millions of Euros while the equivalent cost for bio-pesticides rarely reaches 5 million and in the case of semiochemicals is often below 1 million. In some member states there are schemes that help and encourage the registration of biopesticides such as those in the UK and in Denmark. Residues: Supermarkets and consumer groups are also driving the change. Multiple outlet stores and supermarkets are increasingly being more demanding in terms of pesticide residue levels in fruit and vegetables. Some have established target dates by which they want to be able to say that all the fruits and vegetables on sale in their shops are residue-free. They are therefore making demands of their suppliers that growers adopt production methods that will achieve this goal. Like most bio-pesticides, semiochemical-based products are exempt from residue limits on fresh and processed foods around the world. Semiochemical-based products are therefore ideal components of integrated pest management practices that help in achieving this objective of zero residues. Resistance: Pest resistance to conventional chemical pesticides is a significant grower and industry concern. Scientific research has repeatedly demonstrated that continuous use of the same class of pesticides (especially those reliant on a single mode of action) will result in the emergence of a pest population resistant to those products. As semiochemicals have an entirely different mode of action they are ideal candidates in resistance management practices. As for the technological advances that have helped in the growth of the mating disruption market, the two main factors relate to the availability of the active ingredients at economic costs and the range of controlled release technologies now available to suit most agronomic situations. Active Ingredients: The cost per kilogram of pheromone active ingredients has slowly been reducing as volume demand has increased and as synthetic chemistry processes have improved. As the number of steps in a particular

5 pheromone synthetic route is reduced and less expensive intermediates are found, the costs of active ingredients have come down significantly over the last couple of decades and has undoubtedly allowed the industry to develop. Controlled Release Technologies: There is now a very wide range of controlled release technologies for deployment in different crops. Table 1. Deployment strategies for different pheromone dispensers Controlled release device Microencapsulated pheromones Hand-Applied Number of point Weight of active sources per ha ingredient per dispenser device million 350 mg per capsule Weight of active ingredient per ha About 40 g per application 250 to mg g Dispensers Meso Emitters g g Puffers g g Table 1 shows the controlled release devices currently in use, the number of point sources associated with each, the weight of active ingredient in each and the total weight of active ingredient per hectare. It is interesting that the number of point sources can vary enormously together with the weight of active ingredient per dispenser while the amount of active ingredient used per hectare remains strictly within a fairly limited range. The rapid expansion of the use of Puffers / Misters has been notable during the last decade despite some early scepticism. The underlying work by Casado et al. (2011) (Fig 3) has now clearly shown that within the downwind plume emitting from a puffer that the area covered by the puffer s plume is easily one acre (0.4 hectares). Figure 3. Trap catch suppression down-wind of a puffer in a fruit orchard (Casado et al., 2011)

6 What are the recent developments therefore in mating disruption? New insect orders are now being controlled using sex pheromones. The vine mealy bug, Planococcus ficus, and the California red scale, Aonidiella aurantii, are two which have received a lot of attention in recent years. Both have been successfully controlled with sex pheromones and hopefully this will extend to other pests from the same order and possible new pests from other orders such as midge species or ants where it has been shown that this is possible but where the challenge of pheromone synthesis has first to be overcome. Mass Trapping and Lure and Kill Mass trapping has been very successful in the case of Tephritid fruit fly pests such as the Mediterranean Fruit Fly, Ceratitis capitata. Many thousands of hectares are now using traps baited with ammonium salts and amines for managing populations of this pest. An extension of the mass trapping approach is to do away with the trap and replace it with an insecticide coated killing device so that trap catch saturation is avoided. Both mass trapping and lure and kill approaches have a very promising future provided there are powerful attractants for the females of the species as well as the males. More research into female fruit fly attractants is needed as this is the main determining factor influencing the development of these two techniques. A Case Study of the use of Pheromones in the Integrated Pest Management of Chilo suppressalis Chilo suppresalis is a serious pest of rice in Spain and in many other countries. With the identification of the sex pheromone of this species in the late 1980s, a new tool became available for monitoring and control of this pest. Twenty years of mating disruption efforts against it have shown that an area wide programme, such as the one developed in the Valencia rice growing area, is highly effective and sustainable over many years. A carry over effect of population reduction was observed from one year to the next allowing a reduction in the amount of pheromone required for successful control. In another rice-growing area of Spain, the Delta of the river Ebro, mass trapping using the sex pheromone has been practiced for a number of years in combination with selective insecticide applications. This has also been very effective in reducing the environmental impact of insecticide applications in ecologically important habitats. Conclusion Pheromones and other semiochemicals are gradually gaining their rightful place as important components of integrated pest management practices. It has taken many years to achieve this goal. There are many strong driving forces related to residue management, regulatory pressures and residue management of conventional pesticides, that will further encourage the use of pheromones and semiochemicals in IPM programmes. Mating disruption has become very well established in fruit tree crops and vines but as yet has not been exploited much in vegetables and broad-acre crops. It has also been restricted so far to Lepidopteran pests these are future challenges for the pheromone industry and the research community to work on together.

7 References Casado, D., Cave, F. and Welter, S (2011) Effect of Pheromone Dose Reduction on the Plume of Aerosol Puffers: Preliminary Studies. Western Orchard Pest & Disease Management Conference 2011 Witzgall, P., Kirsch, P. and Cork, A. (2010) Sex pheromones and their impact on pest management. J.Chem Ecol. 36: