ReferencesChapman B 2010. A review of insecticide use on pasture and forage crops in New Zealand. Unpublished report, AgResearch, Lincoln. 76 pp.Manktelow D, Stevens D, Walker J, Gurnsey S, Park N, Zabkiewicz J, Teulon D, Rahman A 2005. Trends in pesticide use in New Zealand: 2004. Report to the Ministry for the Environment, Project SMF4193.

AcknowledgementsThe authors wish to thank the New Zealand Foundation for Research, Science and Technology (Contract LINX0804) for funding this study.

Implications of registered insecticide Implications of registered insecticide reassessment for pasture pest management

R. Bruce Chapman - Insect Science Solutions, 830 Selwyn Road, RD 8, Christchurch 7678 bruce.chapman@insectscience.co.nzTrevor A. Jackson - AgResearch Ltd, Private Bag 4749, Christchurch 8140 trevor.jackson@agresearch.co.nz

SummaryAs part of an assessment of the risks, costs and benefi ts of substances approved under the HSNO Act, ERMA has established a list of potentially harmful materials for reassessment. The initial “Chief Executive Initiated Reassessment List” contains 20 potentially hazardous substances of which 12 are insecticides. This study identifi es the implications of the ERMA reviews on the possible ongoing availability of insecticides registered for use on pasture and forage crops. Organophosphate insecticides registrations are at most risk of withdrawal following the review process.

Insecticide use on pasturesInsecticides have traditionally been used to control insect pests of pasture and forage crops in New Zealand. Around 80 tonnes of insecticide active ingredient is applied annually to pastures (Manketelow 2004), however, most currently-registered insecticides are regarded as ‘old chemistry’.

In New Zealand and other parts of the world older insecticides have progressively been withdrawn. There is concern that new insecticides will not be available to the pastoral sector to replace older withdrawn products.

This study reviewed the current insecticide registrations for insect pests of pasture and forage crops, and considered the implications of the Environmental Risk Management Authority’s (ERMA) hazardous substance reassessment process and commercial factors on their continued availability.

MethodsAll insecticides currently registered for use on insect pests of pasture and forage crops were identifi ed from the ACVM registration database (https://eatsafe.nzfsa.govt.nz/web/public/21) and the New Zealand Novachem Agrichemical Manual (http://www.agrichemical.co.nz). Registered uses for each insecticide were summarized.

The ERMA Chief Executive Initiated Reassessment List for hazardous substances was accessed (http://www.ermanz.govt.nz/hs/reassessment/ceo.html) to identify insecticides scheduled for review.

Views were sought from some New Zealand agrichemical industry representatives in relation to insecticide product withdrawal and prospects for new active ingredients.

Conclusions• A range of registered insecticides is available for the control of key pests of pasture and forage crops• Organophosphate insecticides dominate the available registered products• Organophosphate insecticides are potentially at the greatest risk of being withdrawn following the ERMA

reassessment process• Technical and commercial factors could also contribute to the withdrawal of insecticides in the future• The prospects for new replacement insecticides for pasture and forage crop pests are uncertain

Trevor Jackson Bruce Chapman

Table 1: Insecticide active ingredients registered (Y) for key pasture and forage crop insect pests in New Zealand, and the status of ERMA review.

ResultsRegistered uses of insecticides on pasture and forage crops:• 26 active ingredients from 5 insecticide chemical groups, and one microbial product are registered • Registered active ingredients are: organophosphates (10), pyrethroids (5), carbamates (5), neonicotinoids

(3), with one benzoyl phenyl urea and two combination insecticides• Organophosphates are registered for a broad range of pests on pasture and forage crops• Most registered uses of pyrethroid insecticides are for lepidopteran pests on forage crops• Neonicotinoid insecticides are only applied as seed dressings against seedling pests • For individual insect pests, most insecticides are registered for aphids (16), springtails (11), armyworms (9),

and Argentine stem weevil (8), diamondback moth (8).

ERMA review status:• 9 insecticide active ingredients registered for use on pasture or forage crops pests are currently on the ERMA

review list• 8 of those 9 active ingredients are organophosphate insecticides

Other factors that might contribute to the withdrawal of older insecticides include:• product withdrawal in other countries• reduced technical support and supply• declining sales leading to voluntary withdrawal• competition with new application technologies, e.g. seed treatments

Prospects for the registration of new active ingredients in New Zealand may be limited by:• small agrichemical market size for pasture and forage crop pest insecticides• availability and cost of new insecticide active ingredients, registration costs

Grass Grub Larvae

Argentine Stem WeevilPorina Caterpillars

Springtail