7. PROTECTING AND FACILITATING MARKET ACCESS FOR HORTICULTURAL PRODUCTS

7.1 Enhancing Horticultural Security

While the GATT outcome has given New Zealand more secure market access, there are a number of issues that require research as a result. MAF needs to ensure that non-tariff trade barriers, such as placing treatment conditions on imports or refusal of imports, are scientifically justifiable. This requires gathering information on pest and diseases of proposed imports.

Operational research in this area supports the activities of the Chief Plants Officer, Richard Ivess, and his operation which seeks to enhance agricultural and horticulture security and facilitate market access for New Zealand's horticultural products. Research priorities are set by Richard Ivess, Dr Godwin Balasingam and Dr Ruth Frampton.

7.1.1

Programme Title: Identification of vascular plants which should be prohibited from entering New Zealand.

Programme Leader:Dr P Williams

Institution:Landcare Research

Summary

MAF Regulatory Authority is required by the Biosecurity Act to ensure that all plant taxa proposed to be brought into New Zealand which are not prohibited or already here must be evaluated for their potential weediness. A computer-based weed risk assessment model developed in Australia was tested to see how it would classify plant taxa (plant species, sub-species or genus) for their potential weediness if imported into New Zealand. It was found that the model has the ability to detect virtually all major weeds in New Zealand, whether of agriculture/forestry, the environment, or just nuisance weeds.

Description

To evaluate a computer-based weed risk assessment model (WRA) developed in Australia with the assistance of New Zealand scientists, and adapt it for use as a potential border control tool in New Zealand.

Approach & Outcomes

MAF Regulartory Authority is required by the Biosecurity Act to ensure that all plant taxa proposed to be brought into New Zealand which are not prohibited or already here must be evaluated for their potential weediness.

The WRA system works according to the principles that weeds from countries of origin with similar climate to New Zealand should be rejected; otherwise taxa with biological attributes suggestive of invasive plants or weeds should be subjected to evaluation; otherwise taxa should be accepted. The model produces a recommendation to accept, reject or evaluate the plant. It is considered better to erroneously reject a plant taxon that would confer a net benefit than to erroneously admit one that would cause a loss or damage.

Requirements for the model included that it be:

  • effective in discriminating weeds from non-weeds;
  • fully transparent and based on sound scientific principles as international agreements require that prohibited taxa fit the definition of a quarantine pest;
  • able to identify environmental weeds as well as agricultural and horticultural ones; and
  • be capable of dealing with species at the genus or sub-species level.

The model was tested on 370 plant taxa in Australia, where it was concluded that the model is an objective, credible, and relatively quick risk assessment system able to screen large numbers of potential new entries.

The model was then altered slightly for New Zealand conditions to produce the NZWRA model. The score sheets were modified as if it were proposed to import the taxa into New Zealand. The model scores were compared with scores for weediness provided by 11 people.

Virtually all plants (98%) ranked as major weeds were rejected, including all taxa currently classed as noxious plants in New Zealand, and the majority of minor weeds were either rejected (65%) or required further evaluation (27%). Most non-weeds (64%) were accepted. The variance for the weediness classification from the respondents was predictably high, and related largely to perceived usefulness.

Researchers concluded that the NZWRA has the ability to detect virtually all major weeds in New Zealand, whether of agriculture/forestry or the environment, or just nuisance weeds. The system has some ability to indicate which sector is likely to be affected and, as Pheloung (1995) concluded, could be modified to show this more clearly.

The fact that some useful plants may be potentially rejected in this process, and that many taxa will require evaluation on the basis of the information available, means that ancillary procedures should be in place to gather more information about a taxon's biology, ecology, and potential for control, and to undertake cost/benefit analysis once this information has been obtained.

A major benefit of the NZWRA system is that it is transparent, with clear assumptions regarding weed attributes. In contrast, expert opinion as to the weediness of a plant in New Zealand, just as in Britain (Perrins et al. 1992), will always be variable and biased towards particular environments.

Progress in determining weediness will be gained mainly from a greater understanding of the factors that make specific habitats prone to invasion, and the particular attributes of the invading taxa that enable them to exploit these habitats. In the absence of such detailed information for many land use systems, the NZWRA appears to do an excellent job of predicting which plants could become major weeds in New Zealand.

Reports

The results were recorded in a paper - Landcare 9596/080.

References

Pheloung (1995)

Perrins et al 1992

7.1.2

Programme Title: Enhancement and further development of the economic impact assessment modules

Programme Leader:Dr H Bigsby

Institution:Lincoln University

Summary

A cost-benefit analysis model for pest risk analysis to be used in developing quarantine standards was developed further. The model provides a methodology for quantifying technical trade barriers that contain elements of risk and economic impacts, in ways in which they can be dealt with in a trade forum. The important change is that barriers can be treated on the basis of expected outcome rather than the technical characteristics of the barrier. As such, it is possible to step beyond only considering whether the barrier involves an insect or a bacteria, and instead focus on whether a potential event behind the barrier is above, below or within an expected dollar value.

Description

To further develop and refine the several modules of the cost-benefit analysis model for pest risk analysis including:

  • ensuring that modelling capabilities or data strategies can be put into the module based on case studies to allow the module to address a full range of economic impacts;
  • making further identification of critical variables in the economic impact assessment and developing procedures for rapid screening of pest economic impacts;
  • validating the Partial Equilibrium Module based on complete case studies of 2 fruit fly species to ensure that the structure of the module contains the necessary modelling capabilities to estimate welfare effects of pest introduction on consumers and producers, and making changes if necessary;
  • developing procedures for incorporating economic variables into a risk management process;
  • developing the model so that economic criteria can be used for selection of appropriate risk management options and practices; and
  • assisting HortResearch in developing a generic pest and disease risk model for export systems.

Approach & Outcomes

The purpose of this objective was to develop procedures for incorporating economic variables into a risk management process. A secondary purpose was to develop the modules so that economic criteria can be used for selection of appropriate risk management options and practices.

The means by which this was to be done was originally to develop case studies for alternative risk management options and practices. Participation in the development of the Draft Pest Risk Analysis Standards for New Zealand led to a concerted effort to develop the methodological approach to pest risk management. While the methodology needs to be developed with data, there is only limited data availability so far. The existing data is useful in providing a basis for a methodology but not in developing risk management options. The analysis is described in a report to MAF.

The research has introduced a methodology (Iso-risk) for quantifying technical trade barriers that contain elements of risk and economic impacts in ways in which they can be dealt with in a trade forum. The important change is that barriers can be treated on the basis of expected outcome rather than the technical characteristics of the barrier. As such, it is possible to step beyond only considering whether the barrier involves an insect or a bacteria, and instead focus on whether a potential event behind the barrier is above, below or within an expected dollar value.

This provides the basis for even treatment of technical barriers in a trade environment. Any two events which fall above or below a particular benchmark should be expected to be subject to Technical Barriers Trade (TBT) or Sanitary/Phytosanitary Standards (SPS) which have similar effects. An important point is that two exporters can now be subject to different technical standards but in a way in which the GATT rules on equal treatment should not be violated. This is because the outcome of the trade barrier must be similar.

Values derived from an Iso-Risk analysis can also be expressed as a per unit tariff equivalent to make them comparable to other non-tariff barriers. All that is required is for the expected value, or Pest Risk, to be spread over the volume of the commodity which is subject to the TBT. The development of international standards and the use of tools such as Iso-Risk should make the SPS interchange less conservative and trade-offs more possible.

Conferences

Bigsby, H. and Crequer, J. (1996): Quantifying Technical Trade Barriers: Phytosanitary Measures. A paper presented at the NZAES Conference, Blenheim, July 5-6.

Bigsby, H. and Crequer, J. (1996): A Conceptual Model for the Management of Pest Risk. A paper presented at the SEEM 2 Conference, Dunedin, June 24-2.

7.1.3

Programme Title: Enhancement of Pacific Island database and the establishment of a database of plant species known to be present in mainland New Zealand

Programme Leaders:Dr T Crosby and Dr E Nicol

Institution:Landcare Research

Summary

The Pacific Island database has been developed to provide information to MAF Regulatory Authority on the pests and diseases associated with particular Pacific Island plant hosts of horticultural importance to New Zealand. This information is needed for carrying out quarantine assessment of imported products. The database was updated, audited and installed.

The database of exotic plants in New Zealand is a useful resource for MAF in developing importation standards. The revised 1996 version of the Reference Index contains 10091 entries, mostly at the species level, that have an import status allocated. Electronic and hard copy versions of the revised 1996 MAF Reference Index for Importation of Seed for Sowing, along with an electronic copy of the database of vascular plants used for its preparation, were sent to MAF Regulatory Authority.

Objective 1:
Enhancement of Pacific Island database
Research Leader: Dr T Crosby

Objective 2:
Database of exotic plants in New Zealand
Research Leader: Dr E Nicol

Description - Objective 1: Enhancement of Pacific Island database

To undertake a scientific audit of the taxonomic accuracy of the host, pathogen, and insect names entered into the database, and ensure as far as possible the names used correspond to currently accepted names:

  • updating pest distribution as new information comes available;
  • providing further host-pathogen association information for up to 200 host plants of commercial importance; and
  • maintaining the integrity of the data in the database.

Approach & Outcomes

The Pacific Island database has been developed to provide information to MAF Regulatory Authority on the pathogens associated with particular Pacific Island plant hosts of horticultural importance to New Zealand. This information is needed for carrying out quarantine assessment of imported products. Many exporting countries compile such information themselves, but New Zealand has undertaken the database establishment for the Pacific Islands.

The update and installation of the database was carried out.

Description - Objective 2: Database of exotic plants in New Zealand

  • To establish a comprehensive database of vascular plant genera and species present in New Zealand, using records from as many sources as are available e.g. published and unpublished species lists, data from the Woody Plants in Cultivation database, MAF-RA Reference Index, taxonomic checklists and scientific publications); and
  • to undertake a scientific audit of the information entered into the database to ensure taxonomic accuracy as far as possible.

Approach & Outcomes

The database of exotic plants in New Zealand is a useful resource for MAF in developing importation standards and for MAF. The information provided on location and contents of exotic plant collections in New Zealand assists with consideration of plant import applications, as there may be no justification for restricting importation of a plant already widespread in New Zealand. The database is also useful for MAF and regional authorities in planning weed control programmes and for providing information useful to horticulturalists, plant breeders and environmentalists.

Electronic and hard copy versions of the revised 1996 MAF Reference Index for Importation of Seed for Sowing, along with an electronic copy of the database of vascular plants used for its preparation were sent to MAF Regulatory Authority.

The revised 1996 version of the Reference Index contains 10091 entries, mostly at the species level, that have an import status allocated. This compares with ca. 6802 entries (including 3884 species or cultivar names) in the previous (1995) version of the Reference Index, which was largely genus-based. Additionally, we have supplied a copy of an extended version of the Reference Index containing 15796 entries that includes a number of species for which we have records in New Zealand, but for which there is, as yet, insufficient information to allow importation of seed without further evaluation. The extended version of the Reference Index is effectively a list of all vascular plant species recorded on the "AllNZspp.db" database at 30 June 1996.

7.1.4

Programme Title: Validation of pest-host associations

Programme Leader:Dr J Cowley

Institution:MAF Quality Management

Summary

The objectives were to validate and publish information concerning major pests on crops such as tomato cucurbits grape, avocado and other subtropicals, and to add unpublished and published information for cutflowers and cereal crops (or other crops of priority importance) to data from surveys carried out previously by MAF Quality Management.

Considerable progress was made in retrieval of Plant Protection Centre records and their scientific validation, quality checking against data entry standards and clarification where necessary, and entry of completed records into the Plant Protection Information Network database (PPIN). The work on stonefruit, cereal and cutflowers was moved into 1996/97 because in several instances completion of data entry for a particular crop was delayed while quality problems relating to the data were investigated and solutions developed. These problems usually related to recording of host cultivar or rootstock names. The researchers plan to complete validation of citrus, grapes and subtropicals within the first quarter of 1996-1997; retrieval and validation of tomatoes and cucurbits by the end of the second quarter; and progressive completion of all data entry within the same period.

Objective 1:
Priority pest-host associations information
Research Leader: Dr F Hill

Objective 2:
Horticultural survey information analysis
Research Leader: Mr P Holder

Description - Objective 1: Priority pest-host associations information

To validate and publish information concerning major pests on crops such as tomato, cucurbits, grape, avocado and other subtropicals by:

  • researching information from unpublished and published sources;
  • emphasising Lepidoptera, Acari, Homoptera, Coleoptera, Thysanoptera, Heteroptera, Diptera, Nematoda and Plant Pathology information for the above crops;
  • reviewing recent new record information;
  • validating distributions, species determinations and host identifications;
  • highlighting areas for research such as follow-up surveys where records appear incomplete for particular species;
  • commenting on the significance of the pest-host association; and
  • publishing data from the Objective 1 currently underway.

Approach & Outcomes

Considerable progress was made in retrieval of Plant Protection Centre records and their scientific validation, quality checking against data entry standards and clarification where necessary, and entry of completed records into the Plant Protection Information Network database (PPIN).

The estimated total number of records which will be available on PPIN from this source is 8500 records, of which 2961 (35%) are now on PPIN. Retrieval and validation of records is completed for stonefruit, pipfruit, citrus, and kiwifruit. Retrieval is completed for grapes and subtropical. Tomato and cucurbit records are still being retrieved. The status of this work for each priority crop is further described in Table 1.

Table 1: Summary of Progress of Objective 1 as at 30 June 1996

Crop Retrieval Validation Data Management
Stonefruit Completed Completed (773) 522 (67%) records in PPIN
Pipfruit Completed Completed (1171) 760 (65%) records in PPINl
Citrus Completed Completed (699) 592 (84%) records in PPIN
Kiwifruit Completed Completed (885) 427 (48%) records in PPINl
Tomatoes 1416 (55%) records retrieved 371 (26 % of retrieved) records validated 38 (10%) of validated records in PPINl
Cucurbits 526 (61%) records retrieved 107 (20% of retrieved) records validated 63 (59 %) of validated records in PPINl
Grapes Completed (592) 474 (80%) records validated 217 (45%) of validated records in PPIN
Subtropical Completed (1381) 597 (43%) records validated 342 (57%) of validated records in PPTN

Note:The process of quality control reduces the number of records eligible for entry into PPIN. Hence the tabulated figures may be smaller than in previous reports.

Description - Objective 2: Horticultural survey information analysis

To add unpublished and published information for cutflowers and cereal crops (or other crops of priority importance) to data from surveys carried out by MAF Quality Management in 1994-1995 and 1995-1996 by:

  • researching information from unpublished and published sources;
  • emphasising Lepidoptera, Acari, Homoptera, Coleoptera, Thysanoptera, Heteroptera, Diptera, Nematoda and Plant Pathology information for the above crops;
  • validating distributions, species determinations and host identifications;
  • highlighting areas for research such as follow-up surveys where records appear incomplete for particular species;
  • commenting on the significance of the pest-host association; and
  • publishing data from the Objective 2 currently underway.

Approach & Outcomes

The estimated total number of records which will be available on PPIN from Plant Protection Centre sources is in excess of 3000 records, of which 1432 (47%) are now on PPIN.

Retrieval and validation of records from earlier crop surveys is completed for pipfruit, tomatoes, and cucurbits. Retrieval is completed for grapes and citrus. No new to New Zealand records resulted from the stonefruit survey, but possible extension to distributions and new host records within the survey results have yet to be assessed.

Supplementation of the cereal and cutflower surveys by retrieval of historical Plant Protection Centre records is proceeding.

Compilation of pest-host associations from the literature to augment PPIN base data has begun, with the retrieval of stonefruit records completed.

The status of this work for each priority crop is further described in Table 2.

Table 2: Summary of Progress of Objective 2 as at 30 June 1996

Crop Retrieval Validation Data Management
Stonefruit No new to NZ records; retrieval of other survey records of interest not begun. Completed retrieval from Pennycook (215) Not begun
Pipfruit Completed Completed (235) 172 (73%) records in PPIN
Citrus Completed 713 (97%) records validated 586 (82%) of validated records in PPIN
Tomatoes Completed Completed (215) 199 (93%) records in PPIN
Cucurbits Completed Completed (456) 367 (80%) records in PPIN
Grapes Completed (461) 228 (49%) records validated 108 (47%) of validated records in PPIN
Cereal 432 records retrieved Not begun
Cutflower 186 records retrieved Not begun

Note:The process of quality control reduces the number of records eligible for entry into PPIN. Hence the tabulated figures may be smaller than in previous reports.

Landcare Research NZ Ltd was sub-contracted to carry out a pilot programme to test its data retrieval and validation procedures for delivery of specific host-pest association information from the national collections. The first part of this was the extraction of information on thrips from the National Arthropod Collection, and 510 records of thrips of 31 species on the crops of interest were supplied for assessment before validation. The delivery format is being developed jointly. A similar process will be carried out for delivery of validated host-pest association records from other disciplines.

In several instances completion of data entry for a particular crop was delayed while quality problems relating to the data were investigated and solutions developed. These problems usually related to recording of host cultivar or rootstock names.

The work on stonefruit, cereal and cutflowers was moved into the 1996/97 year. The researchers plan to complete validation of citrus, grapes and subtropicals within the first quarter of 1996-1997; retrieval and validation of tomatoes and cucurbits by the end of the second quarter; and progressive completion of all data entry within the same period.

7.1.5

Programme Title: Development of new and rapid techniques for identifying fruit fly immature stages (Tephritidae) to the species level

Research Leader: Dr K Armstrong

Institution:Lincoln University

Summary

The ribosomal DNA (rDNA) technique has been developed for use by quarantine inspectors in preventing the accidental introduction to New Zealand of fruit fly - a major exotic fruit pest. The technique rapidly identifies the immature stages of the various species of fruit fly.

The research confirmed that the rDNA technique is an appropriate and efficient means of identification down to the subgenus level, and beyond for many species. The pilot study demonstrated the quarantine application of the technique by enabling identification of more specimens than otherwise could have been achieved, and rapid, on-call diagnoses when necessary. The technique is available for use in the current form, but could be modified to distinguish a greater number of species and to improve success rates with poor quality/complex DNA samples.

Other methods were also investigated, with the intention that they may be complementary to, or ultimately used instead of, the rDNA technique. Some gene fragments were found which may be suitable targets for analysis. This objective was not pursued further due to the continued success of the first objective.

It was concluded that a diagnostic kit can be constructed, for the majority of species, using the rDNA technique in its current form. This work is being undertaken in the 1996/97 programme.

Objective 1:Diagnostic protocol for subgenus identification of fruit flies (Tephritidae)

Objective 2:Alternative PCR-based method for the identification of fruit flies (Tephritidae)

Description - Objective 1: Diagnostic protocol for subgenus identification of fruit flies

To complete the assessment of this technique by screening additional selected species.

Approach & Outcomes

Quarantine inspectors need a working protocol that can rapidly identify the immature stages and discriminate species of fruit fly at least to the subgeneric level, to prevent the accidental introduction to New Zealand of this major exotic fruit pest. DNA-based diagnostic protocols for the identification of fruit fly species have, to date, been developed on a very limited scale. Research has largely been at the population level, focusing on geographic quarantine issues.

Previous work indicated that the robustness of the rDNA technique with respect to quality and quantity of the sample DNA and the speed of diagnosis (<12 h) made it a promising prospect for a diagnostic technique.

The method for PCR-RFLP analysis of ribosomal DNA from larvae was optimised and the DNA extraction and PCR methods successfully adapted for use with eggs. Clarity of diagnostic profiles was significantly improved. Twenty two species, across three genera and in both high and low risk quarantine categories, were analysed. A multiple restriction enzyme approach increased the number of species with diagnostic profiles to 13, compared to the eight using Rsa I alone. This included the medfly (Ceratitis capitata), four Anastrepha species (A. lindens, A. obliqua, A. serpentina and A. grandis), species in three Bactrocera subgenera (the cucumber fruit fly B. (Aus.) cucumis, the melon fly B. (Z.) cucurbitae and B. (N.) xanthodes) and five out of the 13 B. (Bactrocera) species (the true oriental fruit fly B. (B.) dorsalis, the banana fruit fly B. (B.) musae, the solanum fruit fly B. (B.) latifrons, B. (B.) melanotus and B. (B.) curvipennis). Five other species can be identified down to one out of two or threespecies separated by subtle restriction variation that may not be adequate for diagnostic purposes. Four species form two pairs with identical restriction haplotypes (B. (B.) neohumeralis and B. (B.) tryoni; B. (B.) passiflorae and B. (B.) facialis). Diagnostic patterns were extremely reproducible within and between populations. A preliminary sequence analysis of the 18S identified possible tephritid-specific PCR priming sites. The protocol was trialed in a pilot study using specimens from air passenger interceptions and the Auckland medfly infestation. Thirteen out of 18 air passenger samples were positively identified, six of which were subsequently confirmed by rearing of samples by MAF. The Auckland samples (n=66) were all identified as medfly. A subset of these was analysed by Dr. R. Mangan (Pennsylvania State University) who determined their mitochondrial DNA haplotype to be BBB, suggesting the likely origin of the infestation to be Hawaii or South America.

Researchers in a DNA sequence project concluded that molecular protocol continues to be an efficient means of identification down to the subgenus level, and beyond for many species. The pilot study demonstrated the quarantine application of the technique by enabling identification of more specimens than otherwise could have been achieved and a rapid, on-call diagnoses when necessary. The technique is available for use in the current form, but could be modified to distinguish a greater number of species and to improve success rates with poor quality/complex DNA samples. Work on this modification and construction of a DNA test kit for quarantine use are included in the 1996/97 programme.

Description - Objective 2: Alternative PCR-based method for the identification of fruit flies

To consider other polymerase chain reaction (PCR) methods, with the intention that they may be complementary to, or ultimately used instead of, the rDNA technique by:

  • screening of rDNA - using other universal primers designed to amplify more variable regions;
  • continuing to investigate randomly amplified polymorphic DNA (RAPD), and if this technique shows promise, screen all available species and PCR primers;
  • transferring mitochondrial RNA (mtRNA) genes - using different universal primers and procedures similar to those for rDNA; and
  • screening of mitochondrial DNA (mtDNA) - using different universal primers and procedures similar to those for rDNA.

Approach & Outcomes

Fifteen PCS primer pair combinations were screened for the PCR amplification of an appropriate mitochondrial DNA target. Eight of these produced single fragments of 2-12 kb, 2 of which are likely to encompass useful gene regions and therefore may be suitable targets for RFLP analysis. This objective was not pursued further due to the continued success of Objective 1. Technology transfer of this work has included publication in the Bulletin of Entomological Research, participation in a Fruit Fly DNA Workshop held in Brisbane and an invitation to attend the Working Group 011 Fruit Flies of the Western Hemisphere meeting in Chile later this year.

Conferences

Technology transfer of this work has included publication in the Bulletin of Entomological Research, participation in a Fruit Fly DNA Workshop held in Brisbane and an invitation to attend the Working Group 011 Fruit Flies of the Western Hemisphere meeting in Chile later this year.

7.1.6

Programme Title: Development of a fruit monitoring system for surveillance and evaluation of the environmental impact of bait trapping for non-lure responsive species of fruit flies

Programme Leader:Dr J Cowley

Institution:MAF Quality Management

Summary

Researchers aimed to develop a fruit monitoring system for fruit fly species that are non-lure responsive, to provide early warning of exotic fruit flies, and information necessary in the development of a National Pest Management Strategy. As it is considered most likely that early fruit fly infestation would occur in a domestic garden or a park, which may not be sprayed with insecticides, fruit from home gardens throughout Auckland was monitored. The predominant insects reared from this fruit were vinegar flies, dried fruit beetles and mould mites. Some codling moths were also reared from apples. No pests new to New Zealand were detected in the fruit samples. No fruit flies were reared from the fruit collected.

It was concluded that a total of 3328 sites would need to be surveyed over the entire country, to have 95% confidence that an infestation level of 0.1% would be detected. This would cost approximately $900,000 (excluding overheads, set-up costs), which is 4.5 times higher than bait trapping (based on 1,000 traps). Fruit monitoring may not prove cost effective for all fruit fly species across a wide range of hosts. However, compared with pheromone trapping, fruit collection and incubation will monitor for all fruit fly species. It may therefore prove cost effective to at least target relatively host-specific flies. Alternatively, surveys of specific crops, which would include incubation of fruit, could be undertaken on a regular basis (e.g., once every 5 years).

Trials to establish whether the use of liquid protein bait would affect native dipteran populations led to conclusions that individual species have their own seasonal abundance patterns which need to be investigated further and to better understand trapping effects on a seasonal and population basis. Overall, results of this study did not show a detrimental impact on fly populations as a result of bait trapping. However, it was impossible to determine whether bait traps were having a significant impact on the population of a particular species in a particular area without increasing the number of traps per treatment and the number of replicates. Trapping would have to continue for a number of months in succession to determine whether populations in certain areas were depressed relative to others, or whether the disappearance or decline of a particular species was due to seasonal fluctuations. In addition, the ageing of bait seems to affect the trap response of some species.

Objective 1: Fruit monitoring programme design
Research Leader: Dr C White

Objective 2: Fruit monitoring field trials
Research Leader: Dr J Dymock

Objective 3: Bait trapping trial design
Research Leader: Dr C White

Objective 4: Bait trapping field trials
Research Leader: Dr J Dymock

Description - Objective 1: Fruit monitoring programme design

To develop a protocol for a fruit monitoring programme by:

  • evaluating and selecting target fruit crops to be monitored;
  • evaluating a selection of the months in which the target fruit crops should be monitored;
  • designing trials in a manner that ensures the data collected is suitable for statistical analysis;
  • developing a sampling calendar, listing fruit types and numbers to be collected from locality over time;
  • developing and documenting procedures for the implementation of the trials; and
  • preparing a preliminary report on trial design.

Description - Objective 2: Fruit monitoring field trials

To begin trials according to the trial design developed in Objective 1 by:

  • assembling equipment for the trials;
  • liaising with property owners for access to properties;
  • preparing for and carrying out training of staff involved in the trials;
  • regular collection of samples;
  • examining fruit samples and recording of data;
  • quarterly reporting progress;
  • analysis of data; and
  • preparing a final report in a form suitable for publication.

Approach & Outcomes - Fruit Monitoring

The goal was to develop a fruit monitoring system for fruit fly species that are non-lure responsive, to provide early warning of exotic fruit flies (Tephritidae), and information necessary in the development of a National Pest Management Strategy.

It is considered most likely that early fruit fly infestation would occur in a domestic garden or a park, which may not be sprayed with insecticides. A monitoring trial, sampling fruit from home gardens throughout Auckland, was therefore carried out. Fruit was left in incubators to allow development of any fruit fly larvae present. Throughout the monitoring programme, 27 types of fruit were collected, comprising 11,077 individual fruit from 689 samples.

The predominant insects reared were vinegar flies (Drosophila sp.), dried fruit beetles (Nitidulidae) and mould mites (Tyrophagus sp.). Some codling moths were also reared from apples. No pests new to New Zealand were detected in the fruit samples.

No fruit flies (Tephritidae) were reared from the fruit collected. As no fruit flies were found in 11,077 pieces of fruit taken from 440 sites, the upper 95% confidence bound to the proportion of sites infested with fruit flies is 0.7%. Since most fruit fly species do not breed in all fruit types, but may concentrate on particular families or types of fruit, the upper 95% confidence bounds were calculated for host groupings. Rosaceae, for instance, are the primary hosts for R. pomonella, and citrus (Rutaceae) and subtropical fruits are hosts for A. widens.

The upper 95% confidence bound for the percentage of properties infested each month ranged from 3.4% in November 1995 to 5% in April 1996. Collection of fruit was terminated in mid-May, resulting in fewer fruit being collected in that month. No Mediterranean fruit fly were detected in Mt Roskill despite collecting fruit from one of the infested properties two weeks prior to the date that the first flies were trapped.

It was concluded that a total of 3328 sites would need to be surveyed to have 95% confidence that an infestation level of 0.1% would be detected. Conversely, only 44 sites would need to be surveyed to have 85% confidence in detecting an infestation level of 5%.

The approximate annual direct cost of fruit monitoring, based on 95% confidence in detecting a fruit fly infestation of 0.1% over the entire country was estimated. Incubation facilities would have to be provided at the main centres to reduce the risk in transporting fruit around the country. Purchase and permanent installation of portacoms to accommodate the fruit incubation would decrease this cost on a long term basis. Travel time would increase in some of the provincial areas because of the distances between populated areas and in Auckland for the more distant suburbs. The resources needed would also increase if cucurbit and solanaceous crops were included.

In 1992, the cost of bait trapping was estimated as at least $200,000 per 1,000 traps. This includes the time involved in servicing traps, preparation of the bait mixture, sorting and identifying specimens but excludes travel costs. The main disadvantage of bait trapping is the poor efficacy of the bait which denatures quickly, often within 24 hours.

The approximate cost of fruit monitoring to detect a fruit fly infestation level of 0.1% (over the entire country) with 95% confidence was calculated to be $900,000 (excluding overheads, set-up costs), which is 4.5 times higher than bait trapping (based on 1,000 traps). Fruit monitoring may not prove cost effective for all fruit fly species across a wide range of hosts. However, compared with pheromone trapping, fruit collection and incubation will monitor for all fruit fly species. It may therefore prove cost effective to at least target relatively host-specific flies such as R.pomonella in Rosaceae. Alternatively, surveys of specific crops (e.g., Cucurbitaceae), which would include incubation of fruit, could be undertaken on a regular basis (e.g., once every 5 years).

Description - Objective 3: Bait trapping trial design

To develop a bait trapping system which will provide an early warning of the arrival of exotic non-lure responsive fruit fly in this country and help, if necessary, in an eradication strategy by:

  • reviewing results of previous bait trap catches for selection of sites;
  • selecting the months in which to trap;
  • designing the trials in a manner that ensures the data collected is suitable for statistical analysis
  • developing and documenting procedures for the implementation of the trials; and
  • preparing a preliminary report on trial design.

Description - Objective 4: Bait trapping field trials

To begin field trials to trial design of Objective 1 by:

  • liaising with property owners for access to properties;
  • carrying out training of staff involved in the trials;
  • assembling equipment for the trials and establishing traps on sites;
  • collecting regular samples;
  • examining and recording of trap catches;
  • reporting progress quarterly;
  • analysing data;
  • preparing a final report and recommendations relevant to the development of the National Pest Management Strategy; and
  • preparing data for publication.

Approach & Outcomes - Bait Trapping

Protein bait may be used in the future for surveillance of those fruit flies which do not respond to synthetic pheromone lures. It will also be needed if any of these flies become established. At present, protein bait is used in traps during outbreak responses to fruit fly incursions to attract female flies. The aim of the trials was to establish whether the use of liquid protein bait will affect native dipteran populations, as the Biosecurity Act requires that any detrimental effects of control measures must be considered. The trials also aimed to determinethe effect of bait ageing on the numbers of flies caught; and ascertain individual species’ population fluctuations over a defined period.

A pilot trial was conducted during September 1995. Large site to site variations due to species-site interaction masked any possible changes in fly numbers as a result of trapping.

For the second trapping round the procedure used in the pilot trial was modified. Trapping commenced in the western suburbs of the Auckland isthmus (Mt Roskill, Mt Albert, Mt Eden, One Tree Hill, Hillsborough) on 15 November and ran until 15 December 1995. Three trapping regimes were implemented. In each case the traps were placed 1.2 km apart with replicate sets of different trapping regimes being at least 2.4 km apart. There was again large site to site variation.

During a surveillance programme, trapping would continue throughout an entire season. This means that the fly population(s) in an area with a trap would be subjected to the influences of trapping throughout the entire season, possibly affecting multiple generations. To determine late summer trends in fly populations further trapping was done during summer/autumn 1996 at six sites in urban Auckland where the highest numbers of flies had previously been trapped. Overall number of flies showed a downward trend throughout this period, probably due to the onset of cool temperatures.

It was concluded that individual species have their own seasonal abundance patterns which need to be investigated further. This is essential to a better understanding of trapping effects on a seasonal and population basis. Overall, results of this study did not show a detrimental impact on fly populations as a result of bait trapping. However, it was concluded that it would be impossible to determine whether bait traps were having a significant impact on the population of a particular species in a particular area without increasing the number of traps per treatment and the number of replicates. In addition, trapping would have to continue for a number of months in succession to determine whether populations in certain areas were depressed relative to others, or whether the disappearance or decline of a particular species was due to seasonal fluctuations. In addition the ageing of bait seems to affect the trap response of some species.

Reports

Anon. (1994a): Pest Risk Assessment. Apple Maggot (Rhagoletis pomonella). Report of the Lynfield Plant Protection Centre to MAF Regulatory Authority, p.15.

Anon. (1994b): Pest Risk Assessment. Mexican Fruit Fly (Anastrepha ludens). Report of the Lynfield Plant Protection Centre to MAF Regulatory Authority, p.13.

Anon. (1994c): Pest Risk Assessment. Walnut Husk Fly (Rhagoletis completa). Report of the Lynfield Plant Protection Centre to MAF Regulatory Authority, p.12.

Anon. (1994d): Pest Risk Assessment. West Indian Fruit Fly (Anastrepha obliqua). Report of the Lynfield Plant Protection Centre to MAF Regulatory Authority, p.12.

7.1.7

Programme Title: Development of rapid diagnostic techniques to determine alive/dead status of scale insects and mealybugs

Research Leader:Dr R T Baker

Institution:MAF Quality Management

Summary

Mealy bugs and scale insects are pests of various fruit and other horticultural crops. To find a way for quarantine officers to distinguish between live and dead scale insects and mealy bugs on imported products, a technique involving staining with biological dyes was tested to see if it was effective.

It was concluded that none of the four biological stains used could be suitably employed as a technique to distinguish between live and dead mealy bug eggs or scale insects and scale eggs because mealy bug eggs, dead or alive; live scale insects, both adults and eggs, and heat-killed adult scales did not stain in any of the test dyes. Although some freeze-killed adult scale insects and scale eggs were stained, it was with such variability and inconsistency as to be unsuitable for making reliable distinctions between live and dead specimens.

Description

A technique which works well for nematodes was tested to distinguish between live and dead scale insects (adults and eggs) and mealybugs (eggs) by:

  • collecting scale insects and mealybugs;
  • setting up and maintaining colonies of live scales and mealybugs of as many different species as possible from New Zealand and from intercepted specimens on imported produce and plants; and
  • examining stained specimens by binocular microscopy.

Approach & Outcomes

Mealy bugs and scale insects are pests of various fruit and other horticultural crops which look the same whether alive or dead. Quarantine officers need to be able to distinguish between live and dead adults and eggs of these pests on imported products.

Various mealy bug and scale insects and their eggs were obtained and stained as described above.

The results for mealy bugs was that for all stains, at all concentrations and time periods, no staining was observed in any of the eggs of P .affinis, P. calceolariae and P. simians. Live crawlers of P. longispinus did not become stained. Similarly, none of the dead crawlers were stained by KMnO4, Meldola Blue or Nile Blue A. However, in 0.5% phloxine B. 20% of dead crawlers of P. Iongispinus were stained pink after 48 hours in the stain.

Live scale insects did not take up any of the stains. In the case of dead scales there was a different outcome for those specimens that were killed by heat and those killed by freezing. Adult scales killed by heat did not take up any of the test stains. Staining of scales killed by freezing was observed in each of the test stains; specimens staining brown in KMnO4, blue in Nile Blue A, purple/ black in Meldola Blue and pink in phloxine B. However, the degree of staining was not consistent, with between 20-80% of specimens being stained. The degree of staining was also variable with some specimens completely stained, others partially and some remaining unstained even after 48 hours.

Live scale eggs of H. lataniae and H. rapax did not take up any of the test stains. Dead eggs did not become stained by either KMnO4 or by phloxine B. but between 25-40% were stained by both Nile Blue A and Meldola Blue.

It was concluded that of the four biological stains used in this project, none could be suitably employed as a technique to distinguish between live and dead mealy bug eggs or scale insects and scale eggs because:

  • mealy bug eggs did not stain in any of the test dyes, whether they were dead or alive;
  • similarly, live scale insects, both adults and eggs, and heat-killed adult scales were unaffected by these dyes; and
  • although some freeze killed adult scale insects and scale eggs were stained, it was with such variability and inconsistency as to be unsuitable for making reliable distinctions between live and dead specimens. Also, the different outcome between heat-killed and frozen specimens indicates that the means by which specimens have died influences the uptake of the dye.

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Farm Monitoring Programme Manager
Monitoring and Evaluation
MAF Policy
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0623
Fax: +64 4 894 0741
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