Research and Development / 31/03/1999
Final Project Report
(Not to be used for LINK projects)
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Section 1 : Identification sheet
1. / (a) / MAFF Project Code / PN0801
(b) / Project Title / Quantification of the effects of pesticides on the population dynamics of beneficial arthropods
?????
(c) / MAFF Project Officer
(d) / Name and address
of contractor / IACR-Rothamsted
Harpenden
Herts. AL5 2JQ
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????? Postcode ?????
(e) / Contractor’s Project Officer
(f) / Project start date / 01/04/1993 / Project end date / 31/03/1999
(g) / Final year costs: / approved expenditure / £272,000
actual expenditure
Project end date / £248,697
(h) / Total project costs / total staff input: / approved project expenditure / £1,304,000
actual project expenditure
Project end date / £1,265,223
*approved staff input / 20
*actual staff input / £20
(i) / Date report sent to MAFF / 23/08/1999
(j) / Is there any Intellectual Property arising from this project (enter YES or NO) ? / NO
*staff years of direct science effort
Section 2 : Scientific objectives / Milestones
2. / Please list the scientific objectives as set out in CSG 7 (ROAME B). If necessary these can be expressed in an abbreviated form. Indicate where amendments have been agreed with the MAFF Project Officer, giving the date of amendment. You may enter a maximum of 12 lines in this box. Press the DOWN arrow twice to move to the next question.
CSG 13 (1/97) 2
1. To develop appropriate laboratory bioassays for key beneficial arthropod species.2. To develop appropriate laboratory bioassays for key beneficial arthropod species.
3. To obtain baseline toxicological data for representative chemicals and species.
4. To explore the utility of multiple dose testing for non-target arthropods.
5. To generate extended laboratory tests to assist with the extrapolation of bioassay data to field situations.
6. To investigate interactions between pesticides, parasitoids and aphids under simulated field conditions.
7. To undertake fundamental studies of the life histories and population dynamics of key species.
8. To investigate spatial dispersion and dispersal movements of beneficial arthropods.
9. To investigate short-term and year-to-year effects of pesticides on key species, comparing the relative merits of small, barriered plots and large, unbarriered plots. (In collaboration with PN 0802)
10. To predict the long-term effects of pesticides on key natural enemy species.
CSG 13 (1/97) 2
3. / List the primary milestones for the final year.It is the responsibility of the contractor to check fully that ALL primary milestones have been met and to provide a detailed explanation if this has not proved possible
Milestones / Target
date / Milestones met?
(enter YES or NO)
Number / Title / in full / on time
If any milestones have not been met in the final year,
an explanation should be included in Section 5.
Section 3 : Declaration
4. / I declare that the information I have given in this report is correct to the best of my knowledge and belief. I understand that the information contained in this form may be held on a computer system.
Signature / Date
Name
Position in Organistation
You should now complete Sections 4 and 5 of this report
CSG 13 (1/97) 2
Section 4 : Executive summaryYou may enter a maximum of 58 lines of text in this box. Press the DOWN arrow twice to move on.
CSG 13 (1/97) 2
This report describes work conducted at IACR-Rothamsted to support the development of a conditional, tiered scheme for assessing risks posed by pesticides to non-target arthropods in agricultural environments. Our research addressed the design, execution and interpretation of all stages in a testing hierarchy from first-tier ‘worst-case’ laboratory bioassays, through extended laboratory and semi-field experiments, to large-scale field trials. The organisms investigated were ground-dwelling predators (carabid beetles and lycosid spiders) and aphid parasitoids: two ecologically functional groups of beneficial non-targets at risk from exposure to pesticides and used as standard test groups in assessment schemes.With laboratory bioassays, emphasis was on the utility and advantages of testing organisms at multiple rather than single doses, as currently practised. Extensive testing of carabids and lycosids with organophosphates and pyrethroids demonstrated the feasibility of obtaining repeatable dose-response relationships, and the influence of biological variables including rearing history, sex and body size on the precision of such bioassays. However, some aspects of bioassay design (e.g. assessment criteria and holding period), and the ability to extrapolate results across taxa, were strongly dependent on the insecticide group under consideration. Results for aphid parasitoids were often more erratic and difficult to replicate, highlighting a need for further work to fine-tune and standardise bioassay conditions.
Extended laboratory tests investigated sublethal effects of pesticides on biology and behaviour, which are impossible to assess in first-tier bioassays. Exposure of the parasitoid Diaeretiella rapae to pirimicarb residues significantly affected the foraging behaviour of females when searching for aphid hosts (Myzus persicae). The sex-ratio of parasitoids produced by parents that had developed in pesticide-treated hosts was also affected, becoming highly male-biased. Pesticide effects on egg-laying by carabids were slight and unlikely to be of practical significance. However, marked effects on the diurnal activity, causing nocturnal species to become active during the day, do have potential implications for population dynamics (e.g. by increasing predation by birds).
‘Semi-field’ experiments were conducted on aphid parasitoids under simulated field conditions in the laboratory, and on carabids in small enclosures in the field. In field simulators, there were clear cut differences in host:parasitoid ratios for one and two generations after insecticide exposure. One notable innovation in our work on parasitoids was the use of pesticide-resistant hosts to avoid or minimise host depletion by insecticides. Another innovation in work on carabids was the use of mark-release-recapture techniques to estimate pre- and post-treatment population densities, and to distinguish between effects on trap catches of direct mortality, post-treatment recruitment and changes in locomotory activity. Failure to do this is a serious constraint on the interpretation of data from pitfall traps.
A four year field trial conducted in conjunction with PN 0802 was the first direct and large-scale investigation of how plot size and the use of insect-proof barriers affects the efficiency and consistency of pitfall trapping. Trap catches were significantly higher and less variable in the larger, open plots than in small, barriered ones. Results of a subsequent large-scale experiment investigating whether pesticides affect the year-to-year population dynamics of carabid species are still being analysed in detail, but do indicate a reduction in adult numbers in insecticide-treated plots in the second year, compared to the previous year in which chemicals were applied.
These and other results presented have several important implications for the design and conduct of a tiered risk assessment scheme, some of which are already embodied in new recommendations from the European Plant Protection Organisation (EPPO) and Council of Europe (CoE). Throughout the project, results were disseminated through publications and presentations at scientific conferences, and meetings with other researchers, advisors, industrialists and policy-makers (including PSD personnel). Key findings and recommendations are emboldened in the project report that follows.
CSG 13 (1/97) 2
Section 5 : Scientific reportCSG 13 (1/97) 2
File reference: RSCYour scientific report should be no longer than 16 PAGES long
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7
File reference: RSC1. INTRODUCTION
1.1. Background
Pesticides are still essential to prevent loss in yield and quality from diseases, pests and weeds in agricultural food production in the UK and throughout the EU. However, widespread pesticide use is potentially detrimental to the environment, partly through effects on non-target organisms, and there is particular concern about effects on beneficial arthropods. In the early 90’s, the European and Mediterranean Plant Protection Organisation (EPPO) and the Council of Europe (CoE) formed an Expert Panel to develop guidelines for the risk assessment of the effects of pesticides on the environment, including effects on beneficial arthropods. Around the same time, the European Chemical Industry formed a Beneficial Arthropod Testing Group (BART) to develop testing procedures to assess the side-effects of pesticides on the natural enemies of pests. The testing procedure advocated by both bodies was a conditional, step-wise scheme, starting with ‘worst-case’ laboratory bioassays and progressing through extended laboratory and semi-field tests to full scale field trials, with the decision to progress to the next tier of tests being dependent upon the results of the previous one.The proposed, tiered, risk assessment scheme required development and validation and the registration authorities required further information, particularly on potential long-term and sublethal effects of pesticides on non-target arthropods, to help them to interpret the data generated by the testing procedures. The purpose of this project was to address these two issues.
1.2. External developments during the project
In March 1994, a non-target arthropod specialist workshop was organised, partly funded by the EC, to draft proposals for non-target arthropod regulatory testing to be included in Annexes II and III of the new EC Plant Protection Product Directive 91/414/EEC. The workshop, which was called ESCORT (European Standard Characteristics Of Beneficials Regulatory Testing), involved representatives from research, industry and regulatory authorities throughout the EC. The recommendations arising from the workshop were published later that year by the Society of Environmental Toxicology and Chemistry (SETAC) - Europe:K.L. Barrett, N. Grandy, E.G. Harrison, S. Hassan & P. Oomen (eds.) Guidance document on regulatory testing procedures for pesticides with non-target arthropods.
This document presented proposals for the selection of standard test species, implementation of laboratory, extended laboratory, semi-field and field tests and the interpretation of data for risk assessment and management. This meeting also led to the formation of a Beneficial Arthropod Field Studies Working Group which met in August 1995 to produce a guidance document for the execution of regulatory field studies. One of the managers of PN 0801 (WP) participated in both the ESCORT workshop and the field studies working group.
As a result of the ESCORT workshop and a number of follow-up activities, EPPO/CoE have recently drafted a series of proposed amendments to their risk assessment scheme. Some of these amendments are in line with recommendations arising from the research done in PN 0801 and the associated project PN 0802, but others give rise for concern. These recommendations and concerns are addressed in this report.
2. OVERVIEW OF THE STUDIES DONE IN PN 0801
2.1. Laboratory Bioassays
Testing protocols, based on methods used by the International Organisation for Biological Control (IOBC) Working Group on Pesticides and Beneficial Organisms, were developed for ground-dwelling predators (carabid beetles and spiders) and adult parasitic wasps (aphid parasitoids). Multiple dose tests, to generate dose-response data, were conducted using the following species and insecticides:
INSECTA - COLEOPTERACarabidae
Pterostichus cupreus (dimethoate; l-cyhalothrin)
Pterostichus madidus (dimethoate; l-cyhalothrin)
Pterostichus melanarius (dimethoate; l-cyhalothrin)
Harpalus rufipes (dimethoate; pirimicarb; l-cyhalothrin; chlorpyrifos)
Nebria brevicollis (dimethoate)
Bembidion lampros (dimethoate)
INSECTA - HYMENOPTERA
Braconidae
Diaeretiella rapae (dimethoate; l-cyhalothrin, pirimicarb)
ARACHNIDA - ARANEAE
Lycosidae
Trochosa ruricola (dimethoate, l-cyhalothrin)
Trochosa terricola (dimethoate, l-cyhalothrin)
Pardosa prativaga (dimethoate)
Pardosa palustris (dimethoate)
Pardosa nigriceps (dimethoate)
Pardosa purbekiensis (dimethoate)
Alopecosa spp. (dimethoate)
Linyphiidae
Erigone spp. (dimethoate)
In the case of Pterostichus cupreus, which is one of the standard first tier test species recommended by the ESCORT workshop, field caught insects were tested alongside ones reared in the laboratory to investigate any possible differences in response to insecticides. In the case of P. melanarius and P. madidus, males and females were tested separately to investigate any consistent differences in response of the two sexes. Other species of carabid were included largely to determine the effect of body size on tolerance of pesticides.
2.2. Extended laboratory studies
Extended laboratory tests were principally designed to detect and measure sublethal effects of pesticides on beneficial biology and behaviour which are impossible to assess in the initial tier bioassays.The effects of residues of the insecticides pirimicarb and dimethoate on the searching behaviour of the aphid parasitoid Diaeretiella rapae whilst foraging for hosts on potted oilseed rape plants were investigated using observational bioassays. The length of time parasitoids stayed on the plant, the proportion of time on the plant spent searching for hosts, as opposed to resting and grooming, and the parts of the plant searched were recorded in the presence and absence of residues and the presence and absence of aphid hosts.
The effects of exposing pesticide-resistant aphids (Myzus persicae) to pirimicarb, using a dipping technique, on the development and reproduction of D. rapae parasitoids subsequently attacking and developing in those aphids were investigated.
Attempts were made to detect and measure any effects of exposure to primicarb or dimethoate on the fecundity (egg production) and fertility (egg hatch) of the beetle Pterostichus melanarius using field-collected individuals. Adult females were treated with the maximum recommended field rates and subsequent survival, egg production and egg hatch rate were measured over 8 weeks.
Infra-red video recording equipment was used to monitor the effects of dimethoate on the diurnal activity and movement patterns of P. melanarius. Groups of beetles were released on treated and untreated sand substrates within arenas constructed in a controlled environment room and monitored for 3-4 days. Rates of movement and the timing and frequency of activity periods were measured.