NZPPS pesticide resistance management strategy

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Spider mite resistance management strategy

European red mite eggs
on the calyx of an apple.
(Photo: www.hortnet.co.nz)

R.B. Chapman¹ and N.A. Martin^2
1Soil Plant and Ecology Division, PO Box 94, Lincoln University, Canterbury, New Zealand
²Crop & Food Research, Private Bag 92 169, Auckland, New Zealand

(Revised October 2004)

Reasons for strategy and update

Spider mites are well known for their capacity to develop resistance to many classes of insecticide and miticide. Due to the inherent variation among spider mite populations, it is difficult to generalise about resistance development, cross-resistance patterns and other aspects related to miticide resistance. Resistance management strategies for spider mites may delay the onset of resistance, or suggest alternative management approaches when resistance has developed. However, expert assistance should always be sought when resistance problems arise. Pest management strategies aimed at preventing or minimising resistance will help maintain control and conserve the effectiveness of existing products. This is an update of the earlier resistance management strategy (Insecticide and Miticide Resistance Task Group, 1996).

Background

Spider mites are a group of plant feeding mites that belong to the family Tetranychidae. Some species can be severe pests on fruit trees, greenhouse vegetable and flower crops. Outbreaks of mites are often associated with the use of pesticides used to kill insects, but which also kill the mites' natural enemies.

In New Zealand, the most common spider mite pests belong to two genera, Panonychus and Tetranychus. Pannonychus species produce little webbing, while Tetranychus species often produce much webbing. The species are difficult to distinguish morphologically. Red Tetranychus species are likely to be banana mite or bean mite. The presence of T. cinnabarinus in New Zealand requires confirmation (Zhang 2002). The life cycle of all species comprises an egg stage, larval stage, two nympal stages and adult. Most miticides kill only the active stages (larva, nymphs, and adult mites). However, the relative effectiveness of miticides against immature and adult stages differs between miticides. Some miticides kill only the egg stage or have an ovi-larvicidal action.

¹The presence of this species in New Zealand requires confirmation.

Products with label claims for spider mite control in New Zealand

Products with label claims for control of spider mites can be divided into three broad groups: mineral oils, insecticides (mainly organophosphates) and specific miticides. Many products that previously had label claims may no longer be effective. Products currently available in New Zealand that have label claims for miticidal activity are listed in Table 2.

Table 2: Products with label claims for mite control in New Zealand (revised March 2003). M = mites, CRM = citrus red mite, ERM = European red mite, TSM = two-spotted mite, GH = greenhouses.

	Type of label claim for each crop1
Pesticide category and IRAC chemical group Pesticide common and (product) names
Biological control
Phytoseiulus persimilis (Mite-E, Spidex)	TSM		TSM	TSM	TSM	TSM	TSM	TSM in GH
Fatty acid
Fatty acid - potassium salts (Natrasoap)						ERM TSM
Mineral oil
mineral oil (BP crop oil, Caltex winter spray oil, DC-Tron, Mobil Superior)		CRM			ERM	ERM
Sunspray		CRM	M		ERM	ERM
JMS Stylet Oil			M
Carbamate 1A
oxamyl (Vydate)					ERM
Organo-phosphate 1B
dichlorvos (Nuvos)	M						M	M
Bridged diphenyls 2B
dicofol (Kelthane)	M	M	M		M	M		M
bromopropylate (Neoron)	ERM TSM				ERM TSM	ERM TSM
Pyrethroid 3
tau-fluvalinate (Mavrik Aquaflow)							ERM TSM
bifenthrin (Talstar)							TSM
Avermectin, emamectin 6A
abamectin (Agrimec, Avid)	TSM				ERM TSM		TSM	TSM in GH
Milbemectin (Mit e mec)					ERM TSM
Ovicides 10A
clofentezine (Apollo)	TSM	CRM	TSM in GH	TSM	ERM	ERM
Organotin 12B
azocyclotin (Peropal)	TSM	CRM	TSM		ERM TSM	ERM TSM
fenbutatin oxide (No longer registered)					ERM TSM	ERM TSM
14
propargite (Omite)	TSM	CRM	ERM TSM	TSM	ERM TSM	ERM TSM
Phenoxy-pyrazol 21A
fenpyroximate (Fenamite)					ERM TSM

¹ Label claim may not be for all crops in the crop group. Check label of each product.

Current status of spider mite resistance in New Zealand

European red mite (ERM) resistance to the organotin miticides, e.g. azocyclotin, has developed at some locations in New Zealand (Bowie et al. 1988). Cross-resistance to fenbutatin oxide has also probably developed. ERM and two-spotted spider mite (TSM) resistance to propargite has also developed at some locations (Bowie et al. 1988; Chapman & Penman 1984; Kabir et al. 1991; Kabir et al. 1993). ERM resistance to dicofol has probably developed at some locations (Collyer & Geldermalsen 1975). While resistance to specific miticides is not thought to be widespread in New Zealand, excessive repeated applications (more than 3 applications per crop, per 12 month period or more than one application per season for ovicides and fenpyroximate) of miticides could lead to resistant populations becoming more prevalent.

Several isolated cases of ERM resistance to the ovicides (clofentezine, hexythiazox) have been detected in New Zealand. Ovicide resistant TSM occur in Australia (Edge et al. 1987) and Spain (B. Ehrke, Schering AG, Agrochemical Division, Berlin, pers. comm.) and USA (Reissig & Hull 1991). Cross-resistance between clofentezine and hexythiazox has been established (Cranham & Helle 1985).

Resistance to bromopropylate, dienochlor, tau-fluvalinate and mineral oils has not been detected in New Zealand.

Citrus red mite (CRM) resistant to the ovicide hexythiazox has been found at single sites in New Zealand, and miticide resistance for this species has also been found overseas (Cranham & Helle 1985).

Although spider mite resistance to newer miticide classes, e.g. mitochondrial electron transport inhibitors (METI) (e.g. tebufenpyrad, fenypyroximate) and chloride channel activators (e.g. avermectin, emamectin) is not known in New Zealand, resistance to miticides in these groups is known overseas (e.g. Beers et al. 1998; Devine et al. 2001; Naeun et al. 2001). Cross-resistance between miticide groups is also known. For example, an Australian TSM strain highly resistant to hexythiazox and clofentezine was more tolerant of fenpyroximate and pyridaben than a susceptible strain (Naeun et al. 2001). A dicofol resistant strain in Korea also showed cross-resistance to tebufenpyrad (Kim et al. 1999). These findings suggest care should be taken when selecting newer miticides to overcome resistance to older miticides.

Abamectin has been used widely by greenhouse flower growers to control TSM. Some growers have reported loss of control with this product. Resistance to this product by TSM is known overseas (Beers et al. 1998).

Resistance management and prevention strategy

Guidelines to reduce the risk of miticide resistance include the following:

• Adopt or continue use of integrated fruit production (IFP), integrated mite control (IMC) or integrated pest management (IPM) programmes using predators.
  Ensure that any pesticides used in pest and disease control programmes are safe to predators.
• Avoid excessive repeated applications of miticides.
  • hexythiazox - Must not be applied more than once per crop, per 12 month period.
  • fenpyroximate - Must not be applied more than once per crop, per 12 month period.
  • abamectin or milbemectin -
    PIPFRUIT Must not be applied more than once per crop, per 12 month period.
    OTHER CROPS Do not make more than 3 applications per crop, per 12 month period.
  • dicofol or bromopropylate - Do not make more than 3 applications per crop, per 12 month period.
  • Other miticides - Do not make more than 3 applications per crop, per 12 month period.
  If more than one mite species needs to be controlled the total number of applications from each group of miticides should not exceed the limits described above.
• If more than two applications are required, use miticides from different chemical groups, including oils where appropriate. Refer to Table 2 for miticides and their chemical groups. Note that cross-resistance can occur between some chemical groups, therefore, seek expert advice before making applications.
• Ensure that miticide applications are correctly timed and that spray coverage is thorough, including the underside of leaves.

Note: Control failure does not always imply resistance.

Implementation

The following recommendations are made:

• Miticide labels should carry the following statement:

  IMPORTANT - RESISTANCE MANAGEMENT
  Resistance to this pesticide could develop from excessive use. To minimise this risk, use strictly in accordance with label instructions. Avoid using this pesticide exclusively all season, and avoid unnecessary spraying. Maintain good cultural and biological control practices.

• This resistance management strategy should be included:
  i. in industry-wide spray programmes for export horticultural crops.
  ii. on product labels for all miticides.
• Where clofentezine has been used regularly over the past few seasons, advice should be sought from a specialist advisor. If the performance of this miticide is suspect at a site where there has been repeated use in the past, then this miticide should not be used again and products from a different chemical group introduced. Clofentezine resistance may confer cross-resistance to some miticides from other groups.

Crop recommendations

The following options are available for the design of spray programmes.

Note: All products listed may not be suitable for crops being exported to certain markets. Check with your export agency before applying any pesticide on export crops. Observe withholding periods.

Pipfruit: apples, pears and nashi.
An integrated fruit production programme is available for apples using Typhlodromus pyri and Phytoseiulus persimilis.

• Late dormant: mineral oil for ERM eggs.
• Greentip: either clofentezine and/or mineral oil.
• Mid-November: either azocyclotin (or fenbutatin oxide), or propargite (not pears or nashi), or dicofol, or clofentezine (only 1 application per season), or abamectin (only one application per season).
• Early-late December: fenpyroximate (only one application per season).
  Follow recommendations for correct timing of applications for ERM control.
• Early December to mid January: milbemectin (only one application per season, do not use if abamectin has been applied)
• Early-January onwards: either azocyclotin (or fenbutatin oxide), or propargite (not pears or nashi), or dicofol.
  Where possible, use a product from a different chemical group to that used in December.
  All purpose spraying oil can be used throughout the summer at 1% except on russet-prone varieties.

Summerfruit (Stonefruit)
An integrated mite control programme is available for apples using Typhlodromus pyri and Phytoseiulus persimilis.

• Green tip: either clofentezine or mineral oil.
• Petal fall onwards: either azocyclotin, or bromopropylate, or dicofol, or fenbutatin oxide, or propargite.
  All purpose spraying oil can be used throughout the summer at 1% except on russet-prone varieties.
  Ensure thorough coverage and avoid excessive repeated applications (no more than one (of clofentezine) or three (of azocyclotin, bromopropylate, dicofol, fenbutatin oxide, propargite) spray(s) per crop, per 12 month period).

Strawberry

• Runner beds: introduce Phytoseiulus persimilis.
• Production beds: introduce P. persimilis..
• If predators are not present in adequate numbers, or after planting and prebloom, apply miticides according to label instructions. Use either abamectin, or dicofol, or propargite, or clofentezine (prebloom only).
  Ensure thorough coverage and avoid excessive repeated applications (no more than one (of clofentezine or three (of abamectin, dicofol, propargite) spray(s) per crop, per 12 month period).

Other berryfruit
Check labels as not all products have label claims for all crops.
Use either azocyclotin, or bromopropylate, or clofentezine, or propargite.
Ensure thorough coverage and avoid excessive repeated applications (no more than one clofentezine or no more than three azocyclotin, bromopropylate, or propargite spray(s) per crop, per 12 month period).

Grapes
Use either azocyclotin, or clofentezine, or dicofol, or propargite.
Ensure thorough coverage and avoid excessive repeated applications (no more than one clofentezine and no more than three azocyclotin, dicofol and propargite spray(s) per crop, per 12 month period).

Hops
Use either clofentezine or propargite.
Ensure thorough coverage and avoid excessive repeated applications (no more than one clofentezine and no more than three propargite spray(s) per crop, per 12 month period).

Ornamentals
Integrated pest management (IPM) programmes using Phytoseiulus persimilis are available for some flower crops.
If predators cannot be used apply miticides according to label instructions. Use either abamectin, or tau-fluvalinate.
Ensure thorough coverage and avoid excessive repeated applications (no more than three sprays per crop, per 12 month period).

Glasshouse vegetable crops
Integrated pest management programmes using Phytoseiulus persimilis are available for most vegetable crops.
Use abamectin or dicofol.
Ensure thorough coverage and avoid excessive repeated application (no more than three sprays per crop, per 12 month period).

Acknowledgements

Thanks for help from G. McLaren, HortResarch.

References

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