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Transform™ Insecticide (sulfoxaflor) for control of aphids in canola

Robert Annetts1, Natalie Elias2 and Ian Corr3

1 Dow AgroSciences Australia. Email rannetts@dow.com
2
Dow AgroSciences Australia. Email icorr@dow.com
3
Dow AgroSciences Australia. Email NElias@dow.com

Abstract

Aphids damage canola crops by direct feeding on sap, by transmitting plant viruses, by injecting toxins and by inducing secondary fungal growth (sooty mould) on honey dew. There are a limited number of insecticides registered for control of aphids in canola, and these often have disadvantages including disruption to beneficial insects and promotion of insecticide resistance. Sulfoxaflor (trade name Transform™ Insecticide 240 SC) is a new insecticide which is effective against a wide range of sap-feeding insects and is being developed for control of aphids in canola in Australia as well as a range of other pests in broadacre and horticultural crops. Data presented here shows that Transform, at rates between 100 -200 mL/ha, is effective on the aphid species which commonly attack canola. Transform is expected to be approved for use in mid 2013 and, once registered, will become a valuable tool for control of aphids in canola.

Key Words

Transform™ Insecticide, sulfoxaflor, aphids, canola

Introduction

The three species of aphids which commonly attack canola are green peach aphid (Myzus persicae), grey cabbage aphid (Brevicoryne brassicae), and turnip aphid (Lipaphis erysimi). Aphids damage canola by direct feeding on growing tips by sucking moisture and nutrients causing wilting, flower abortion and reduced pod set. They may also cover the plants with sticky honeydew, which encourages the growth of black sooty mould, thereby reducing the plants’ ability to photosynthesize and generally decreases plant vigour. Aphids also transmit virus diseases in canola such as beet western yellows virus (BWYV).

Currently only pirimicarb is registered for aphid control in canola by foliar application, although synthetic pyrethroids and organophosphates have been used. Imidacloprid is registered for use as a seed treatment; however, it is unlikely that seed treatments would still be controlling aphid effectively through the key period of crop flowering. The use of foliar insecticides can be disruptive to beneficial insects such as parasitoid wasps, ladybirds, lacewings and hoverflies. Pirimicarb has insect resistance recorded against it and is at a high risk of becoming ineffective as resistance is increasing. There are currently a limited number of options for control of aphids in canola.

Sulfoxaflor was discovered by Dow AgroSciences. It is a member of a new class of insecticides called the sulfoximines and is effective against a wide range of sap-feeding insect pests (Zhu et al., 2011). Previous studies have shown sulfoxaflor to be effective against aphids in cereal crops in Australia (Annetts and Welsh, 2012) and cotton (Annetts and Thomas, 2012). Sulfoxaflor is currently being assessed by the APVMA and may be registered in mid 2013 with the trade name Transform Insecticide. Data presented here shows that Transform is effective on aphids in canola at rates between 100 – 200 mL/ha. When registered it will be a valuable tool for canola growers for control of virus-vectoring aphids in canola.

Methods

Experiments were carried out in 2008 to 2010 across the canola growing areas of eastern Australia. All trials were small-scale randomized complete block trials with four replications and included an untreated control treatment. Plot sizes were adequate to allow accurate treatment application and the assessment of pests (for example 3 m x 10 m plots). Products used and trial details are shown below in Tables 1 and 2 respectively. Treatments were applied using a variety of application set-ups using precision small-plot sprayers (pressurized AgMurf or Azo precision small-plot sprayer) in order to closely simulate commercial practice. Applications targeted high infestations of green peach aphid (M. persicae), grey cabbage aphid (B. brassicae) and turnip aphid (L. erysimi) and were applied under good environmental conditions. All trials were assessed for knockdown 3-4 days after application and residual control at 7 day intervals from 7 to 32 days after application. Exact assessment timing varied at each trial. Aphid numbers were assessed by counting the number of aphids on 10-20 randomly selected leaves or flowers depending on the trial. The maximum manageable numbers of leaves or flowers were counted in order to generate reliable and robust data. All data is presented as aphids per leaf or flower. Data were analyzed using a homogeneity of variance (Bartlett’s test) and normalized as necessary using a log (x+1) transformation. Means were separated using Tukey's HSD (P=.05). Where no transformation symbol exists in the table, no transformation was necessary. Untransformed data are presented, while levels of significance and coefficient of variation are displayed on transformed data. Visual assessments of crop injury were made in each trial. The assessment methods used in these trials provides reliable data.

Table 1. Insecticides and formulation used in the trials

Trade Name /Formulation

Active Ingredient

Concentration (g a.i./L or kg)

Transform™ Insecticide

Sulfoxaflor

240 SC

Dimethoate 400

Dimethoate

400 EC

Pirimor WG

Pirimicarb

500 WG

BS-1000

nonionic surfactant

 

Agral 600

nonionic surfactant

 

Table 2. Trial details (Crop=Canola Brassica rapa cv. 'Canola')

Trial Number

082044IC

104007RA

084023RA

104003RA

Year

2008

2010

2008

2009

Author

I. Corr

T. Butler, & D. Kohler

R. Annetts

M. Sumner

Location

Tamworth,
NSW

Latrobe,
Tasmania

Gatton,
Queensland

Badgingarra,
Western Australia

Variety

4GC78

K9198

N/R

Rottnest

Crop Stage

Early flowering

Full flowering

Full flowering

Early flowering

Aphid stage assessed

Wingless nymphs

Total aphids

Wingless nymphs

Total aphids

Water rate (L/ha)

100

100

100

100

Pressure (kPa)

200

150

210

200

Nozzle type

Flat fan

Flat fan

Flat fan

Flat fan

Nozzle Tip

110015DG

XR80015VS

110015DG

11002

N/R = not recorded.

Results

This report describes four trials carried out in the field in Australia. Transform Insecticide (240 g/L suspension concentrate) was safe to all crops.

All trials were completed on large populations of aphids. Transform gave very good control of all aphid species in all the trials (see Table 3.). Transform gave quick knock down of aphids 3 days after application and was significantly superior (P<0.05) to the untreated in all trials. Residual control provided by Transform was not observed to “break” in any trial, even when assessed to 32 days after application, with aphid populations tending to decline naturally in the untreated plots during the trials. It is unlikely that Transform is giving residual control for such a length of time, rather it is more likely to be a reflection of lack of reinvasion by aphids; however, previous studies have shown that residual control of aphids could be expected for between 14 and 21 days, which is confirmed in these trials. These data do however show that Transform at 100 to 200 mL/ha gave reliable and robust control of aphids in canola on all species in all trials.

Conclusion

Data from these four field trials demonstrates the excellent activity of Transform on aphids in canola. Transform at 100 to 200 mL/ha will provide robust control of green peach aphid, grey cabbage aphid and turnip aphid in canola. Insecticides should be targeted against low populations of aphids wherever possible; however, this isn’t always possible, and the higher rate of Transform will provide improved control in these situations. Extensive field testing globally has demonstrated that all formulations of sulfoxaflor, including Transform Insecticide, are safe to all crops when applied according to label directions.

Table 3. The number of aphids counted per leaf or inflorescent.

Treatment

Rate mL/ha

Mean (SE)

Mean (SE)

Mean (SE)

Mean (SE)

Mean (SE)

Grey cabbage aphid (B. brassicae)

082044IC

3 DAA (12/09/2008)†

7 DAA (16/09/2008)†

15 DAA (24/09/2008)†

20 DAA (29/09/2008)

 

Untreated

 

13.2 2.13 a

12.4 1.02 a

5.5 0.88 a

0.55 0.09 a

 

Transform*

100

0 0.03 b

0 0.03 b

0.9 0.09 b

0.79 0.11 a

 

Transform*

200

0 0 b

0 0 b

0.6 0.17 b

0.51 0.09 a

 

Pirimor WG*

1 Kg/ha

0 0 b

0 0 b

0.9 0.24 b

0.51 0.12 a

 

CV

 

20.2

13.62

27.78

28.72

 

104007RA

3 DAA (4/02/2010)†

7 DAA (8/02/2010)†

14 DAA (15/02/2010)†

   

Untreated

 

2.80 0.07 a

2.70 0.07 a

1.03 0.04 a

   

Transform

100

0.05 0.01 b

0.30 0.03 b

0.08 0.01 a

   

Transform

200

0.08 0.01 b

0.68 0.04 ab

0.03 0.01 a

   

Pirimor WG

1 Kg/ha

0.08 0.01 b

0.50 0.04 b

0.05 0.01 a

   

CV

 

75.62

58.1

153.07

   

Green peach aphid (M. persicae)

084023RA

3 DAA (24/10/2008)

7 DAA (28/10/2008)

     

Untreated

 

1.15 0.13 a

1.23 0.09 a

     

Transform

100

0.10 0.04 b

0.03 0.03 b

     

Transform

200

0 0 b

0.05 0.03 b

     

Dimethoate 400

375

0 0 b

0 0 b

     

CV

 

45.57

28.76

     

Turnip aphid (L. erysimi)

104003RA

3 DAA (2/09/2009)†

8 DAA (7/09/2009)†

15 DAA (14/09/2009)†

22 DAA (21/09/2009)†

32 DAA (1/10/2009)†

Untreated

 

3.76 1.06 a

6.28 1.01 a

13.96 2.56 a

8.89 0.95 a

7.73 1.38 a

Transform**

100

0.01 0 b

0 0 b

0.05 0.03 b

0.26 0.16 b

0.30 0.05 b

Transform**

200

0.15 0.14 b

0 0 b

0.08 0.06 b

0.19 0.11 b

0.79 0.48 b

Pirimor WG***

500 g/ha

0.09 0.03 b

0.06 0.05 b

0.47 0.19 b

1.62 0.87 b

0.85 0.44 b

CV

 

54.19

30.07

25.89

39.35

42.55

Means followed by same letter do not significantly differ (P=.05, Tukey's HSD)
† Log (x+1) transformation
DAA= days after application
CV= coefficient of variation
*BS-1000 0.25 %v/v
**BS-1000 100 mL/100 L
***Agral 600 18 mL/100 L

Trial work carried out by Dow AgroSciences (unpublished report: Welsh, 2009) has demonstrated a significant reduction in the transmission of the plant virus barley yellow dwarf virus (BYDV) when Transform was applied for aphid control in a cereal crop. It is likely that Transform will provide protection from certain plant viruses by controlling virus-vectoring aphids, this subject is currently being investigated.

Aphid resistance to the neonicotinoids, carbamates, synthetic pyrethroids and organophosphates is well recorded. Many aphid species are prone to developing resistance as they reproduce asexually. Studies carried out by Dow AgroSciences have demonstrated that sulfoxaflor interacts at the nicotinic acetylcholine receptor (nAchR) site (Watson et al., 2011). Extensive testing has demonstrated no cross-resistance between sulfoxaflor and neonicotinoids or other insecticide classes (Zhu et al., 2010, Babcock et al., 2011). As a result; Transform will be a valuable tool as a new and additional mode of action, as reliance on limited modes of action leads quickly to resistance.

The selectivity of Transform to beneficial insects has been studied extensively in Australia. This unpublished work shows that Transform has a favourable beneficial insect profile. Transform at 100 mL/ha had a very low effect on spiders, a low effect on wasps, predatory beetles, lacewings and ants and a moderate effect on thrips, predatory bugs and Trichogrammatids. Transform had a major effect on apple dimpling bugs, which can be both a beneficial and pest depending on the crop. Integrated pest management (IPM) is gaining momentum in broadacre cropping. The introduction of insecticides such as Transform which are safe to beneficial insects will facilitate the adoption of IPM in Australia and contribute to the sustainability of canola growing.

Transform has an excellent fit in IPM programmes because of its spectrum of activity and low impact on many key beneficial insects. It has low mammalian toxicity, and has minimal effect on non-target organisms such as fish, birds, and aquatic invertebrates. Transform will have a broad label in broadacre and horticulture and will be registered for control of all major species of aphids known to damage canola, cereals and cotton.

™ Transform is a trademark of Dow AgroSciences LLC.
Agral 600
is a registered Trademark
BS-1000 is a registered Trademark
Pirimor is a registered Trademark

Acknowledgment

Thanks to T. Butler, D. Kohler and M. Sumner (Peracto) who carried out trial work reported in this paper. The authors would like to acknowledge their contribution. Thanks to Paul Downard and Matthew Cahill who reviewed this paper and provided advice.

References

Annetts, R. and J., Thomas (2012). Sulfoxaflor for Management of Cotton Pests in Australia. 2012 Beltwide Cotton Conferences, Orlando, Florida, January 3-6, 2012. 1067-1075

Annetts, R. and M., Welsh (2012). Sulfoxaflor control of oat aphid (Rhopalosiphum padi) in Western Australian cereals. 2012 WA Agribusiness Crop Updates, 28-29 February, Pan Pacific Hotel. 13-17

Babcock, J.M., C.B. Gerwick, J.X. Huang, M.R. Loso, G. Nakamura, S.P. Nolting, R.B. Rogers, T.C. Sparks, J. Thomas, G.B. Watson and Y. Zhu (2011). Biological characterization of sulfoxaflor, a novel insecticide. Pest Manag. Sci. 67: 328–334

Watson, G.B., M.R. Loso, J.M. Babcock, J.M. Hasler, T.J. Letherer, C.D. Young, Y. Zhu, J.E. Casida, and T.C. Sparks (2011). Novel nicotinic action of the sulfoximine insecticide sulfoxaflor. Insect Biochemistry and Molecular Biology, doi:10.1016/j.ibmb.2011.01.009

Zhu, Y, M.R. Loso, G.B. Watson, T.C. Sparks, R.B. Rogers, J.X. Huang, B.C. Gerwick, J.M. Babcock, D. Kelley, V.B. Hegde, B.M. Nugent, J.M. Renga, I. Denholm, K. Gorman, G.J. DeBoer, J. Hasler, T. Meade and J.D. Thomas (2011). Discovery and characterization of sulfoxaflor, a novel insecticide targeting sap-feeding pests. J. Agric. Food Chem. 59: 2950-2957.

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