Insect pests are a significant problem in both countries. A field infestation has the potential to cause losses of between 10 to 40 per cent. These can also limit market access domestically and internationally. Pesticides are frequently used, often to excess, prompting concerns relating to pesticide residues. New pests emerging in the Philippines also require that Integrated Pest Management strategies address new threats and excessive pesticide use. In addition improvements in the supply chain are likely to help reduce losses and foster better pre and postharvest practices at all levels. The sustainability of mango industries in the Philippines and Australia will be enhanced through a systems approach to improving pest management and the consistency of supply and quality of mangoes for targeted markets.
Mangoes are a popular fruit in many tropical countries in Asia and in Australia. The Philippines has a mature mango industry based on the Carabao cultivar. A large proportion of this industry is based in Luzon on the southern island of Mindanao and Guimaras in the Visayas. Smallholder production, defined as farms less than three hectares, accounts for 48 per cent of total Philippines production. The Philippines produces around 880,000 tons each year. Of this between 36,000 to 40,000 is exported, making the country the world’s second largest exporter after Mexico, representing around 5.9 per cent of global trade. There is significant scope to increase this production and trade further, as pest and disease losses, production variability, fruit perishability and supply chain management all limit potential. The Australian industry does not have the breadth of problems but does have some pest control and quarantine issues.
Objective 1: To develop improved recommendations for integrated pest management and judicious pesticide use.
Objective 2: To improve control and detection of seed and pulp weevils.
Objective 3: To identify and trial improvements to current practices and conditions for managing mango supply chains.
Integrated Pest Management
In Australia, nine orchard sites producing the main commercial varieties ‘Kensington Pride’ and ‘R2E2’, near Bowen and near Mareeba have been surveyed fortnightly, finding some high fruit spotting bug populations actively feeding on emerging flower panicles at two locations.
Fruit spotting bug is causing reduction in yield because of damage to flowers and by causing premature fruit drop and quality reduction by causing damage to fruit. It is believed that feeding damage caused by fruit spotting bug establishes entry points for the development of anthracnose and the combination of these two factors is a major contributor to the problem.
A DPI&F facility to detect and analyse pheremones is currently being established within other projects. This will be used for the major mango pests when operational.
In the Philippines the project team has set up experimental sites on commercial farms. Two farms in each of the provinces of Guimaras, Davao del Norte and Davao del Sur have been chosen as areas for the IPM and supply chain improvement project. Mangoes grown in Guimaras are exported to the US while fruit from Mindanao are sent to Hongkong and Japan as well as to Manila. In Mindanao the trial sites take in the two distinct climatic condition encountered in the Davao region.
A survey to obtain initial baseline data on farmer production management practices ha been commenced in Guimaras, a, involving both well-managed orchards and backyard-type mango production. The survey is collecting information on farmers’ practice and proposed management intervention at pre-bearing stage. Data is also being obtained on yield and production cost.
The project team also conducted a workshop to familiarize the field staff in Guimaras and Davao with project design and strategies, proposed intervention, commitment/roles and responsibilities, use of pest monitoring sheets, and coordination mechanisms established for the project. Although pest monitoring has now commenced, it has been found that those doing the monitoring do not have adequate resources to perform the task effectively. The development of a pest monitoring kit to assist anyone involved in monitoring to improve effectiveness, is under discussion.
Mango pulp weevil and seed weevil
Planning has been completed and field trials commenced on Palawan on pulp weevil biology and control strategies using chemical and particle films.
A complementary project on mango seed weevil and pulp weevil under the AusAID Asia Public Sector Linkages Program (PSLP) is currently running.
Mango seed weevil, which has been considered a minor pest of Australian mangoes, has over the last year become a significant pest, as it’s presence is now having a substantial detrimental effect on mango export opportunities to China, UAE, Malaysia and South Korea. This project will contribute to a suite of new projects to investigate the problem, which will commence in the coming season.
Supply Chain Improvement.
In the Philippines, fruit damage caused by poor packaging and handling practices have been identified as major causes of quality loss. Changing practices will require some parts of the industry to adopt significant changes. Strategies to facilitate this are being developed.
In Australia, the mango industry is undertaking a major review of its export strategy. When this is complete in mid-2006, the export supply chain work within this project will commence.
To develop improved recommendations for integrated pest management and judicious pesticide use. (This objective has been expanded to include the additional outputs of providing pest monitoring kits and training workshops for Philippines project personnel and industry stakeholders).
To improve control and detection of seed and pulp weevils.
To identify and trial improvements to current practices and conditions for managing mango supply chains.
Integrated Pest Management. In the Philippines field infestation by insects cause losses and damage levels ranging from 10 to 40 percent, or limit market access, particularly for small-scale farmers. Systems approaches that integrate field control with postharvest treatments will reduce costs and the risk of quarantine failures and other regulatory penalties.
Using sites in Davao del Norte, Davao del Sur and Guimaras as pilot demonstration areas, collection of baseline data on farmer pest management as well as reviews of existing cultural management practices were conducted. Current yield and problems encountered by farmers were identified, to develop specific interventions. In each demonstration site, cooperators were identified and backyard and orchard mango trees were chosen. The pre-bearing activities include pruning, sanitation, fertilization and flush management. Interventions for bearing trees were flower induction, foliar fertilization, insecticide/fungicidal sprays, flower brisking, tagging and proper harvesting and postharvest handling. Familiarization of stakeholders with the major insect pests per site, damage symptoms and pest monitoring has also been done.
In Australia, for the second season, populations of fruit spotting bugs have been found to increase from mid- flowering through to early fruit-set in both the Atherton Tablelands and Burdekin regions. This season also experienced a high population of green vegetable bugs (Nezara viridula) during the flowering and fruit set period.
Mean orchard infestation levels of fruit spotting bugs began rising in August in the Burdekin and peaked at 13% in September for R2E2’s and 10% for KP’s. On the Tablelands fruit spotting bug populations began rising in mid September and peaked at 17% for R2E2’s and 13% for KP’s. Population levels were lower on all farms then the previous season.
The level of fruit drop and damaged fruit caused by fruit spotting bugs were lower on the Tablelands then the previous season being 17% and 15% for Oct and Nov for R2E2’s and 21% and 10% for KP’s of all collected fruit drop samples. The fruit damage results may have also been skewed higher then normal because of the similar feeding style of the green vegetable bugs that were active during the same sampling periods.
Pulp weevil and seed weevil. An IPM work plan for pulp weevil has been developed for Palawan to reduce usage of insecticides by 40% and to improve control of leafhoppers, pulp weevil and fruit fly. Field studies on pulp weevil have just been conducted and the data is being summarized. The method of fruit volatiles collection will be modified as initial analysis did not yield good results. Crude extracts from fruits, flowers, and weevils were collected and will be used in bioassays to determine attractancy and synergistic effects of blends.
Insect semiochemistry. Following earlier work in collaboration with the USDA Beltsville Laboratory, a trial pheromone blend for Amblypelta nitida was deployed in sticky plastic traps. However this proved unsuccessful. Further work is required to refine the formulation with respect to constituents and the ratios required. For Amblypelta lutescens, a particular isomer of one of the identified substances is required and this will be supplied by the Belysville laboratory when available.
SPME sampling of volatile emissions of major tropical fruits is continuing to investigate attractancy. Preliminary analysis has been commenced and identification of key components will be completed when resources become available.
Compounds released by both mango seed weevil (Australia) and mango pulp weevil (Philippines) have been collected by solid-phase microextraction (SPME) field collectors to analyse for possible pheromones. They are being analysed by DPI&F.
Supply chain. In the Philippines, deficiencies in the supply chain severely affect fruit quality and market opportunities. Accurate analysis will provide a ‘road map’ from which technical or business priorities can be identified and strategies implemented to bring about improvements. The detailed methodology for the Philippine mango supply chain has been developed, as well as a preliminary outline describing in general term the country’s mango industry and information relevant to the development of specific supply chain maps were also initiated. The supply chain reviews marketing information more specific to focus areas in Davao del Norte, Davao del Sur, and Guiamaras.. The initial supply chain map is being validated during the series of field visits to the production areas. This component is providing an overview of the major technical postharvest problems
With the support of the Australian mango industry, a Queensland Government initiative and commercial exporters, several major supply chains were monitored from farm to retail in Singapore and Hong Kong. A range of problems have been identified including unsatisfactory product handling before export, unsuitable facilities for product handling in target markets as well as unfamiliarity with Australian fruit. Preliminary training activities have been commenced in both markets to address some of the issues. As a result of the monitoring activities in Australia, deficiencies in handling and preparing fruit for export were identified. Procedures to improve practices have been discussed with supply chain members and training has been provided to their staff.
Field studies were conducted to develop improved recommendations for integrated pest management and judicious pesticide use. Baseline data were taken as the basis for the recommendations. Pest identification and monitoring provided the indices of knowing the insect population and its degree of damage for the different control methods employed.
Data collected from the baseline surveys showed that mango growers/cooperators were dependent solely on chemical control as their method of suppressing pests and diseases, having an average of 13 chemical spraying cycles. Almost none of the cooperators practiced insect pest monitoring as their basis for employing control measures. There was only minor pruning or none at all, sanitation and even a fertilisation scheme were given scant attention, and no soil analysis conducted.
Five insect pests (cecid fly, mango leafhoppers, blossom blight, mango seedborer and mango fruit fly) were identified and found to damage mango leaves, flowers and fruits. Cecid fly damages both new and old leaves, while mango leafhopper and blossom thrips damage flowers. On fruits, mango seed borer contributed much of the damage (average fruit damage around 20%) followed by mango fruit fly (11%) and cecid fly (3.5%).
Integrated pest management interventions such as regular sanitation, pruning, balanced fertilisation, pest monitoring as a basis for need-based chemical application, yellow/white sticky and light traps, early bagging, insect pheromone and use of lorsban-impregnated plastic successfully reduced the percentage of fruit damage to 4.8% from six spraying cycles applied 8, 15, 21, 35, 42 and 55 days after flower induction, and gave significant yield increase to around 140 kilos per tree as compared to farmer’s practice with 7.5% damage and yield of 50 kilos per tree. On the cost and return analysis IPM gave the highest return of investment (164%) with an increment of 99.5% over that of farmer’s practice (chemical spray alone).
Observations on field populations of mango pulp weevil adults at quiescent stage were made. An IPM work plan was developed against three pests - leafhopper, mango pulp weevil (MPW) and fruit fly. This work plan was anchored on four IPM strategies - cultural control, pest monitoring, chemical control and physical control.
Crude extracts were collected from mango fruits, male and female weevils (virgin and mated) and male and female weevil frass (virgin and mated) to determine attractancy to virgin female weevils. The components of mated male weevil frass were determined by gas chromatography/mass spectrometry (GC-MS) and standard chemicals were used to determine attractancy to virgin female weevils.
Data on the survey conducted in northern and southern Palawan were accessed as well as data from mango x-ray examination for MPW infestation. Adult weevils were found to stay up on the main branches of mango trees at quiescent stage. The IPM work plan consisting of cultural, physical and chemical control and pest monitoring was able to reduce MPW population to 2%. Physical control (bagging) enabled the reduction of spray application to 5 times throughout the fruit production period.
Mated male frass at 3 frass equivalents elicited the highest attraction (73.3%) to virgin female weevils. Twenty-four components were identified by GC-MS from mated male frass; one component, acetic acid, elicited the same percentage attraction. A survey in northern Palawan showed that the area is still free of MPW.