Way MJ et al Proc S Afr Sug Technol Ass (2011) 84: 84 - 91

REFEREED PAPER BIOSECURITY AGAINST INVASIVE ALIEN PESTS: A CASE STUDY OF SACCHARIPHAGUS (: ) IN THE SOUTHERN AFRICAN REGION

WAY M J1, CONLONG D E1'2 AND RUTHERFORD R Si

1South African Research Institute, Private Bag X02, Mount Edgecombe, 4300, South Africa 2Department of Conservation Ecology and Entomology, University of Stellenbosch, PO Matieland, Stellenbosch, South Africa [email protected] [email protected] [email protected]

Abstract

The spotted stemborer Chilo sacchariphagus poses a major constraint to sugar production in . Current management strategies, in combination with resistant varieties and classical and augmentative biological control tactics, have the potential to combat this serious pest. However, C. sacchariphagus poses a major biosecurity risk to surrounding sugar producing countries in southern Africa. In response to this threat, a comprehensive awareness campaign has been rolled out.It comprises dissemination of illustrative posters, convening of mini-workshops for role players to review phytosanitary measures and regulations, and provision of information on monitoring for the presence of this pest in an attempt to prevent further range expansion. Despite implementing these strategies, there has been limited success in preventing the spread of C. sacchariphagus within Mozambique. This has highlighted the importance of developing a more aggressive biosecurity strategy.

In response, a comprehensive incursion plan has been developed for this pest, and the need for increased engagement of relevant policy-making bodies within this region to streamline legislation and enforcement thereof has been identified. In the longer term, the initiation of research on biosecurity and development of a research presence in Mozambique, funded by SADC countries, is necessary. This would include a plant breeding programme to develop sugarcane varieties resistant to C. sacchariphagus, and research on control tactics such as the Sterile Insect Technique (SIT) and mating disruption. Integration of these with classical and augmentative biocontrol and other more conventional control options into an area-wide integrated pest management plan is proposed. This paper documents the successes to date of the C. sacchariphagus regional biosecurity programme driven by SASRI and sets out a proposed future action plan.

Keywords: Chilo sacchariphagus, sugarcane borer, biosecurity, invasive species, incursion plans, southern African region

Introduction

The problem of invasive alien species continues to pose challenges to agriculture, government, and the community as a whole. Increased trade and global climate change are some factors making it easier for pests and diseases to spread and establish in

84 Way MJ et al Proc S Afr Sug Technol Ass (2011) 84: 84 - 91

previously unaffected areas. Market expansion has increased exchange of contaminated plant material between countries and the numbers of 'stowaways' has increased due to an increase in air traffic. Alien, or naturally occurring phytophagous that invade commercially important agricultural crops are detrimental because of the cost of control and because they may prevent export programmes or cause significant ecological disturbance which results in loss of biodiversity (Westphal et al., 2008).

Global dependence on monocultures of a few crop species has reduced the resilience of agricultural systems to biological invasions. Therefore biosecurity programmes have become critical. These programmes serve to make stakeholders aware of any potential invasive pest or disease problem, and make provision for appropriate structures and mechanisms to handle these invasions. Biosecurity incursion plans have been developed for many agricultural crops in different countries, a good example is the implementation incursion plans for sugarcane in Australia (Sallam and Allsopp, 2008). These provide a way to respond timeously and appropriately to any new invasion by documenting key operational guidelines and activities, and technical tools and procedures, which underpin the necessary decision-making process and subsequent implementation. Coordinated partnerships, at local, national, regional and international level, allow close and frequent collaboration between relevant phytosanitary agencies and involved agencies towards developing and enforcing appropriate policies and procedures.

One of the current major risks to the sugarcane industry in southern Africa is the threat of invasion by the spotted stemborer Chilo sacchariphagus Bojer (Lepidoptera: Crambidae) from Mozambique. The consequence of this pest extending its range through deliberate or inadvertent movement of sugarcane material from one part of Mozambique to another, or across borders into other sugar industries in the southern African region, would be dire.

The South African Sugarcane Research Institute (SASRI) is driving a C. sacchariphagus biosecurity programme to address this potential threat. After presenting the pest and the current situation, this paper documents the actions that have been taken in response, with recommendations for additional initiatives.

Knowledge base

C. sacchariphagus is oriental in origin, and has spread west across the globe into many sugar industries including and Reunion (Williams, 1983) and, since 1998, Mozambique (Way and Turner, 1999). This stemborer has been a major constraint on sugar productionin Mozambique inthenorth on Acucareira de Mozambique (Mafambisse) estate and Companhia de Sena (Marromeu or Sena) sugar estates. Infestations at Mafambisse, where damage appears to increase during below-average rainfall seasons, have generally increased each year, which is partly attributable to changes in variety disposition. The other two main sugar estates in the south part of Mozambique, namely Maragra situated in the southern Mozambican district and Acucaeira de Xinavane (Xinavane), have never been invaded by C. sacchariphagus. Stem boring damage caused by C. sacchariphagus larvae leads to substantial loss (Goebel and Way, 2009). This borer is restricted largely to sugarcane, with a few unsubstantiated other host records (Williams, 1983). Despite the presence of the natural enemies preying on all

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life stages in infested crops, populations are frequently insufficiently controlled (Conlong, 2000; Conlong and Goebel, 2002).

Invasion of South African sugarcane

So far, C. sacchariphagus has not invaded South Africa, but climatic suitability studies show that the KwaZulu-Natal coastline of South Africa and adjacent deep river valleys, especially in the north, are the most vulnerable parts to its establishment in the region (Goebel, 2006; Bezuidenhout et. al., 2008). Escape from specialist natural enemies is a further factor favouring the establishment of thisexotic pest in South Africa. Management options in the areas of origin comprise a combination of planting clean seedcane, hot water treatment (HWT) of seed cane at 50 °C for 30 minutes, annual harvest, resistant varieties and releases of natural enemies.

Research completed in Mozambique

A concerted control effort employing multiple tactics arguably has the potential to eradicate C. sacchariphagus from Mozambique. Managing the insect through classical and augmentative biological control within an integrated pest management (IPM) plan is also an option. For example in 2001, Xanthopimpla stemmator Thunberg (Hymenoptera: Ichneumonidae) was released in Mozambican sugarcane, and within a year 60% reductions of C. sacchariphagus populations were measured, with parasitoid recoveries two years after releases ended (Conlong and Goebel, 2002). An effective indigenous egg parasitoid, Trichogramma bournieri Pintureau and Babault (Hymenoptera: Trichogrammatidae), is present in sugarcane in Mozambique (Conlong and Goebel, 2006). Differences in relative varietal resistances have been found (Conlong et. al., 2004) and older carry-over crops reportedly support higher C. sacchariphagus infestations.

Monitoring options available

Natural spread of this stem borer from Mozambique is unlikely, because the sugar estates are remote and are surrounded by natural vegetation, across which these are unlikely to fly. However, moving sugarcane material infested by C. sacchariphagus from the source location poses a serious problem due to recent expansions and traffic between sugar industries. Border towns such as Komatipoort in South Africa are probable high risk entry points, and transport in this instance will be primarily by private vehicles that do not get adequately inspected for plant material. The situation is further exacerbated by the fact that travelers naively, or deliberately, frequently bring across the border fresh sugarcane stalks that might be infested.

C. sacchariphagusdistributionismonitored usingtrappingsystemsemploying pheromone lures (Nesbitt et. al., 1980) to attract individuals into the trapping device. A grid of traps has been deployed along a strategically important area with the view of using this surveillance to increase the likelihood of detecting the pest should it invade South Africa. It is important to note in this regard that eradication cost is directly proportional to the period between invasion and detection (latent period) of any pest species; hence the importance of establishing such intensive surveillance systems. Once detected, the communication networks among relevant role players,organisations and bodies, includingfarmers,crop protection workers,industry managers, government and agricultural policy makers, are used to report an invasion.

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Visual scouting is also used to search for stem borer damage symptoms, which are shot holes on leaves -Id side-shooting of stalks. It is important to positively identify any specimens found e field due to possible confusion with the maize stemborer C. partellus (Swinhoe) (Lcpidoptera: Pyralidae) (Way and Kfir, 1997).

Scouting and trapping monitoring techniques have been used to determineie presence of C. sacchariphagus at Mafambisse and la (Way and Turner,' Conlong 7000). r- visits have shown that this absent from the soue----n estates ° = MoL (Way and Goebel, 2003), Mal--vi (Rutherford and Way, 2003), Swaziland (Way and Kfir, 1997) and Massingir in Mozambique (Way and Erasmus, 2009).

Development of an incursion plan

Since 1999, SASRI has driven a regional biosecurity programme between and within SADC countries that includes all biological threats, including the immediate threat from C. sacchariphagus.Dedicatedbiosecurityworkshopshavebeenorganisedin Mpumalanga, Swaziland and Mozambique. These workshops have raised awareness about pest threats, highlighted tools (revised C. sacchariphagus poster), discussed scouting and the refined trapping technique, and reviewed C. sacchariphagus control tactics and future research projects, including the need for a balanced variety disposition to reduce the pest risk, with emphasis on the C. sacchariphagus susceptible variety N25.

Shortcomings

Resilience to imminent incursions may be achieved by developing phytosanitary regulations and associated legislation for enforcement, effective surveillance systems to allow rapid detection, awareness propaganda about potential incursions, and contingency incursion plans as a means to respond timeously and appropriately to any new invasion. Although these actions will certainly reduce the risk of pest threat, unfortunately, recent observations in Mozambique (Way, 2010) have shown that, despite the best efforts by SASRI to contain this pest, C. sacchariphagus has spread out of the delimitation zone in Mozambique, and it thus poses a greater biosecurity threat than previously. The response to this development has been to alter the focus of the C. sacchariphagus biosecurity plan by placing more emphasis on the need to control the pest at its source in Mozambique. The spread of the pest within Mozambique has clearly illustrated the need for more stringent control on the sugarcane estates at the source in Mozambique.

New biosecurity initiative

Following the successes and shortcomings experienced with the C. sacchariphagus biosecurity programme, a revised and more direct approach has been used to strongly promote legislative processes because the recommendations are invariably not being adhered to. Some of the following recommendations are:

There is a need for the National Department of Agriculture in South Africa (NDA) to declare C. sacchariphagus a quarantine pest. This will allow control measures to be applied throughout South Africa.

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Movement of all sugarcane material across the border between Mozambique and South Africa needs to be prohibited. Further engagement with the NDA is required to review the policy document that allows a limited number of sugarcane stalks to be transported from Mozambique through the Komatipoort border post into South Africa. Phytosanitary cross border control between South Africa and Mozambique requires attention which can be improved through engagement between the South African Sugar Association (SASA) executive and the NDA. To achieve the goals of theC. sacchariphagus biosecurity programme crop protection, workers in South Africa need to continue visiting Mozambique fields for borer inspections. The C. sacchariphagus awareness programme needs to be promoted by the SASRI Extension Officers and Local Pest, Disease and Variety Control Committee (LPD&VCC) officers in strategic regions close to the border with Mozambique (Mpumalanga, Pongola) in South Africa. Continued collaboration is required between specialist researchers (entomologists and pathologists) from SASRI, administrative staff from SASRI including the Director of the Institute, the recently appointed Biorisk Manager and the Knowledge Manager, field managers and senior policy makers from the major sugar producing companies in Mozambique. The LPD&VCC need to clarify rules pertaining to financial compensation to growers issued with plough-out orders due to newly emerging hazardous pests or diseases in South Africa. Associacao dos Produtores de Acucar de Mocambique (APAMO) should be approached with a framework document detailing strategy, local infrastructure, networking systems, research priorities,individual, corporate and government responsibility, phytosanitary regulations and compliance therewith. Engagement with APAMO on issues of infrastructure in Mozambique developed to regulate the phytosanitary component of agricultural activities is required. There is a need to determine which parties or bodies are responsible for regulating seedcane movement in Mozambique. There should be a moratorium on moving material from the northern sugar estates (Sena and Mafambisse) to the southern ones (Xinavane and Maragra). The possible introduction of a 'cordon sanitaire' around the infested sugar estates, possibly using the Zambezi River in the north and the Save River in the south, requires urgent consideration. Action must be taken to degazette the susceptible variety N25 in Mozambique. Continued and more aggressive communication is needed to inform the Mozambique authorities about the risk posed by this borer. Engagement between affected countries and the relevant policy-making bodies that are responsible for enforcement of phytosanitary measures must be increased.

Development of regional biosecurity research centre in area of invasion

Another facet of the new biosecurity initiative revolves around increasing the ability to control the pest in the areas of origin in Mozambique, which in turn will restrict range expansion within Mozambique and further afield and automatically reduce the level of this pest threat in the southern African region. The following recommendations set out by SASRI need to be adopted with a minimum of delay:

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Only clean seed that is not infested with C. sacchariphagus must be used for new estate plantings. Where necessary, seedcane schemes such as those operating in South Africa with hot water treatment (HWT) at 50 °C for 30 minutes must be established. Where possible, the area planted to the C. sacchariphagus susceptible N25 variety (Conlong et al., 2004) should be limited, and a balanced variety disposition with less than 30% per variety is recommended. Carry-over cane must be avoided since infestations cannot be easily controlled in crops older than 12 months.

The following longer term recommendations need to be pursued:

Overall, a more concerted IPM approach combined with research and implementation of novel insect control tactics in the longer term needs to be implemented. A programme for breeding C. sacchariphagus resistant varieties is warranted. Such an initiative would have to be established and staffed on estates in Mozambique. SASRI could then provide released, pre-release and parental genotype material (Nibouche and Tibere, 2008). Consideration should be given to the export and planting of tissue cultured material (Anon, 2009). Additional biologicalcontrol options that require research include augmenting populations of the egg parasitoid Trichogramma bournieri Pintureau and Babault (Hymenoptera: Trichogrammatidae). The monitoring programme needs to be extended, with vigilance and monitoring on Malawi sugar estates that, being immediately across the Zambezi River, are at high risk of invasion by C. sacchariphagus from Sena Sugar Estate in Mozambique. To assess the effectiveness of control measures and also the current status of this pest, there is a need for regular scouting programmes in infested fields on sugar estates in Mozambique and on estates in Mozambique where the pest has not been recorded. The C. sacchariphagus scouting and trapping programme needs to be sustained and moreover extended to cover a larger area within the southern African region. The surveillance systems along the South African/Mozambique border should be increased, with permanent monitoring using pheromone-baited traps along the Malawi/Mozambique and Mozambique/Makatini Flats corridors. Sterile Insect Technique (SIT) and mating disruption are novel control tactics that could be researched in Mozambique. The mating disruption technique involves saturating sugarcane crops with a synthetic form of the scent (pheromone) released by moths to attract mates; this will disrupt normal functioning of communication which in turn will reduce numbers of fertile eggs laid by females. SIT involves irradiating moths with sub-lethal doses of radiation or x-rays and releasing these individuals into the field to mate with the wild moths, resulting in sterile offspring. These are complementary techniques particularly appropriate for use in Mozambique where, because sugar estates are surrounded by natural vegetation and since the pest apparently only feeds on sugarcane plants, there is little or no re-infestation from surrounding vegetation. It is important to conduct surveys in wild host plants in Mozambique to confirm the host specificity of C. sacchariphagus.

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There is value in determining the economic loss caused by C. sacchariphagus in Mozambique so that cost-benefit evaluations are possible for any control measures implemented. A regional C. sacchariphagus research initiative in Mozambique that is being promoted by SASRI researchers could establish variety screening trials, conduct mating disruption trials, assess parasitoids and monitor pest levels and movement. This regional initiative would need to consolidate collaboration between relevant networks of people in the SADC region towards a coordinated and co-funded biosecurity programme that could deal with any future biosecurity threat facing the region as a whole. Inter-industry contact needs to be maintained through mini-workshops and relevant forums to disseminate information about the status of C. sacchariphagus in the region. Finally, the biosecurity programme needs periodical review in order to match objectives, needs, capacity and goals.

Conclusion

SASRI, recognising the significance of this particular pest threat, has taken a leading role in the development and implementation of a regional biosecurity programme. The approach has been to control the pest in the area of origin while reducing the chance of range expansion through raising awareness levels. Despite these actions, the stemborer has increased its range in Mozambique and thereby the level of risk in the southern African region. This has necessitated a re-focus with more emphasis on the control of the pest in Mozambique, requiring the development of a regional biosecurity initiative in that country.

Building resilience in neighbouring sugar industries remains important through a greater degree of adherence to phytosanitary regulations and enforcement in Mozambique and across country borders.

Additional mobilisation of working collaborative alliances with regulatory personnel in the SADC sugarcane countries is needed, as are further and ongoing implementation of additional comprehensive public information programmes, education and training of specialist pest diagnostic systems, pest interception programmes, pest eradication programmes and management. Greater coordination of existing infrastructure by the recently appointed Biorisk Manager at SASRI will strengthen capacity building in the arena of biosecurity within the southern African region.

REFERENCES

Anon (2009). NovaCane® Planting guide. Published by the South African Sugarcane Research Institute, Mount Edgecombe, South Africa. Bezuidenhout CN, Goebel R, Hull PJ, Schultze RE and Maharaj M (2008). Assessing the potential of Chilo sacchariphagus (Lepidoptera: Crambidae) as a pest in South Africa and Swaziland: realistic scenarios based on climatic indices. Afr Entomology 16(1): 86-90. Conlong DE (2000). Eldana saccharina parasitoid searches, Mozambique and Zimbabwe: March 2000. SA Sugarcane Research Institute, Overseas and Local Report Backs, Vol. 10, May to July 2000. 17 pp.

90 Way MJ et al Proc S Afr Sug Technol Ass (2011) 84: 84 - 91

Conlong DE and Goebel R (2002). Biological control of Chilo sacchariphagus (Lepidoptera: Crambidae) in Mozambique: The first steps. Proc. S Afr Sug Technol Ass 76: 310-320. Conlong DE and Goebel FR (2006).Trichogramma bournieri Pintureau and Babault (Hymenoptera:Trichogrammatidae)andChilosacchariphagusBojer(Lepidoptera: Crambidae) in sugarcane in Mozambique: A new association. Ann Soc Entomol (ns). 42(3-4): 417-422. Conlong DE, Sweet P and Piwalo J (2004). Resistance of southern African varieties of sugarcane to Chilo sacchariphagus (Lepidoptera: Crambidae) in Mozambique, and development of a non-destructive field resistance rating system. Proc S Afr Sug Technol Ass 78: 297-306. Goebel FR (2006). The effect of temperature on development and reproduction of the sugarcane stalk borer, Chilo sacchariphagus (Bojer 1856) (Lepidoptera: Crambidae). Afr Entomology 14(1): 103-111. Goebel FR and Way M (2009). Crop losses due to two sugarcane stem borers in Reunion and South Africa. Sugar Cane International 27(3): 107-111. Nesbitt BF, Beevor PS, Hall DR, Lester R and Williams JR (1980). Components of the sex pheromone of the female sugar cane borer, Chilo sacchariphagus (Bojer) (Lepidoptera: Pyralidae). Identification and field trials. J Chem Ecol 6: 385-394. Nibouche S and Tibere R (2008). Damage assessment for selection of resistance to the spotted stalk borer and genetic correlations for resistance and yield components in sugarcane. Blackwell Publishing, Berlin, Germany, Plant Breeding, 127(1): 38-42. Rutherford RS and Way MJ (2003). Reports on visits to Dwangwa and Nchalo, Sucoma sugar estates in Malawi, 14-20 September 2003, 1-14. Internal Report. South African Sugar Association Research Institute, Mount Edgecombe, 4300, South Africa. 28 pp. Sallam MS and Allsopp (2008). PG Bureau of Sugar Experiment Stations, Queensland, Australia. Preparedness for borer incursion, Chilo Incursion Management Plan, version 1, 50 pp. Way MJ (2010). Chilo Workshop at Acucaeira de Mozambique (Mafambisse) Sugarcane Estate, Mozambique, 25 February 2010. SA Sugarcane Research Institute, Overseas and Local Report Backs, Vol. 42, Sept 2009 to March 2010, pp 49-51. Way MJ and Erasmus J (2009). Report on a visit to Massingir sugar estate (ProCana) Mozambique, May 2009. SA Sugarcane Research Institute, Overseas and Local Report Backs Vol. 39. March to June 2009. pp 53-57. Way MJ and Goebel R (2003). Report on visits to Xinavane and Maragra sugar estates in Mozambique, 5-9 May 2003, SA Sugarcane Research Institute, Overseas and Local Report Backs, Vol. 21, January 2003 to May 2003, 2 pp. Way MJ and Kfir R (1997). The stem borer Chilo partellus (Swinhoe) ( Lepidoptera: Pyralidae) in sugarcane in southern Africa. Afr Ento 5(1): 170-172. Way MJ and Turner PET (1999). The spotted borer Chilo sacchariphagus (Lepidoptera: Pyralidae: Crambidae), in Mozambique. Proc S Afr Sug Technol Ass 73: 112-113. Westphal MI, Browne M, MacKinnon K and Noble I (2008). The link between international trade and the global distribution of invasive alien species. Biol Invasions 10: 391-398. Williams JR (1983). The sugar cane stem borer (Chilo sacchariphagus) in Mauritius. Revue Agricole et Sucriere de File Maurice 62: 5-23.

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