Knowledge refresher on Isoclast™ active

Question 1

What are the most common resistance mechanisms observed in the field in neonicotinoid-resistant insects? Is Isoclast™ active affected by those mechanisms?

Answer 1

1. Metabolic resistance - This resistance mechanism does not seem to affect Isoclast™ active.
2. Target-site mutation - Isoclast is less affected by this mechanism compared to any Group 4 insecticide.

Question 2

Isoclast™ active is not very effective on aphids. True or False?

Answer 2

False. Isoclast™ active is known as the “best-in-class aphicide”.

Question 3

Is Isoclast™ active the same as sulfoxaflor?

Answer 3

Yes, Isoclast™ active is the brand name of the active ingredient. Sulfoxaflor is the common name assigned to Isoclast by the International Organization for Standardization (ISO) and the name most commonly used in regulatory documents or industry organizations like IRAC.

Question 4

What features of Isoclast™ active allow it to control sap-feeding insects hidden in the plant canopy feeding from the underside of leaves or out of the direct line of spray?

Answer 4

1. Xylem-systemic activity.
2. Translaminar activity.

Question 5

What is “metabolic resistance” when referring to neonicotinoid-resistant insects? Is Isoclast™ active affected by this mechanism?

Answer 5

Metabolic resistance is the most common mechanism of resistance by which some insect populations develop resistance to neonic insecticides. It occurs when target pests detoxify the insecticide via metabolic processes. However, the mechanism of metabolic resistance that detoxifies neonicotinoids and many other insecticides does not seem to affect Isoclast.

Question 6

Formulated insecticides based on Isoclast™ active are so effective and are the best option for heavy infestations when no other option is available. True or False?

Answer 6

False. Insecticides based on Isoclast™ active should not be used as a last option or a “fire-fighter” option. Use Isoclast™ active early and following local thresholds to prevent build-up of pest populations.

Question 7

What are the symptoms of intoxication from Isoclast™ active on target sap-feeding insect pests?

Answer 7

Muscle tremors, inability to insert mouthparts into plant tissue, and lack of coordination, all of which may become evident within minutes of application. Depending on the target insect species, insect pest mortality in the field may be seen one or two days after application.

Question 8

What attributes of Isoclast™ active allow the control of insect populations resistant to neonicotinoids and to other classes of insecticides?

Answer 8

1. ​Isoclast™ active has a distinct mode of action from those of neonicotinoids or any other class of insecticides currently in the market.
2. The metabolism data thus far suggest that Isoclast is not metabolized by the enzymes that metabolize neonicotinoids.

Question 9

What is IRAC?

Answer 9

IRAC stands for Insecticide Resistance Action Committee. It is the technical group of the industry association CropLife and provides a coordinated response to prevent or delay the development of insecticide resistance in insect and mite pests.

Question 10

The toxicity of Isoclast™ active residues to non-target organisms (NTOs) drops significantly after the product spray has dried. True or False?

Answer 10

True. The drying of residues reduces contact toxicity. In addition, Isoclast™ active quickly degrades into essentially non-toxic metabolites after application, which reduces both contact and oral toxicity. These features allow Isoclast to have a minimum impact on beneficial insects and other NTOs when label recommendations are followed.

Question 11

How quickly can I see the effect of Isoclast™ active in the field?

Answer 11

Isoclast™ active starts acting on target sap-feeding insects immediately and stops their feeding quickly. Mortality in the field may be seen one or two days after application depending on the target insect species.

Question 12

Since Isoclast™ active controls insect pest populations resistant to neonicotinoids, it can be used with confidence over and over because insects cannot develop resistance to it. True or False?

Answer 12

False. Isoclast™ active controls insect pest populations resistant to neonicotinoids. However, if label recommendations are not followed, insects can and will develop resistance to Isoclast. Always follow label recommendations and consult your Corteva Agriscience field specialist for help developing a local IRM plan for your region.

Question 13

What attribute(s) of Isoclast™ active make it an excellent tool in an Insecticide Resistance Management (IRM) program and therefore, an excellent rotation partner with other chemistries?

Answer 13

1. It belongs to a unique class of insecticides, the sulfoximines.
2. It has a robust lack of cross-resistance with other products.

Question 14

What features of Isoclast™ active contribute to its lack of metabolism in neonicotinoid-resistant insects and why is this important?

Answer 14

There is lack of metabolism in neonicotinoid-resistant insects thanks to the novelty of Isoclast’s chemical class (sulfoximines) and to its distinct molecule structure - Isoclast does not contain amine nitrogen in its structure as other insecticides from Group 4 like neonicotinoids do. This is important because it allows Isoclast™ active a broad lack of cross-resistance with other chemistries currently in the market.

Question 15

Which two attributes of Isoclast™ active contributed to its placement in subgroup 4C mode of action classification, separate from neonicotinoids which are in subgroup 4A?

Answer 15

1. ​Isoclast™ active has a novel chemical structure and thus, it was placed in a new and different chemical class of insecticides called sulfoximines.
2. There is a lack of metabolism of Isoclast™ active in neonicotinoid-resistant insects that translates in a lack of cross-resistance in insects that possess a metabolic resistant mechanism.

Question 16

Isoclast™ active has translaminar and xylem-systemic activities. Therefore, good application coverage is not necessary. True or False?

Answer 16

False. The systemic properties of Isoclast do not replace the need for good application coverage on crop foliage.

Question 17

Isoclast™ active helps reduce the transmission of plant viruses because it kills both the insect vector and the virus. True or False?

Answer 17

False. Isoclast™ active causes the insect to stop feeding, which reduces their potential to transmit the virus to non-infected plants. Isoclast does not kill the virus already present in plants. Plants already infected will not recover.

Question 18

What is the classification of Isoclast™ active based on its mode of action?

Answer 18

Isoclast™ active is classified in subgroup 4C of IRAC’s Mode of Action Classification.

Question 19

What does it mean to have a “lack of metabolism in neonicotinoid-resistant insects” and why is this an important Isoclast attribute?

Answer 19

One way insects can become resistant to an insecticide is by developing the ability to detoxify the insecticide to less toxic or non-toxic substances via metabolism. Lack of metabolism of Isoclast in neonicotinoid-resistant insects means these insects cannot detoxify Isoclast via metabolism and therefore they will be controlled.

Question 20

Are there more commercial insecticides within subgroup 4C Mode of Action Classification?

Answer 20

No, Isoclast™ active is currently the only commercial member classified within subgroup 4C based on its mode of action.

Question 21

What is the term that describes the movement of Isoclast™ active from the surface of the leaf into the leaf tissue?

Answer 21

Translaminar activity.

Question 22

What are some of the environmental benefits of Isoclast™ active?

Answer 22

1. Effective at low use rates – thus, low environmental load.
2. Degrades rapidly in the environment – It does not persist in the environment.
3. Degrades rapidly to metabolites that exhibit low toxicity to non-target organisms (NTOs) including bees.
4. The toxicity of its residues to NTOs is significantly reduced after the product spray has dried.

Question 23

Isoclast™ active is sold under different formulations across the globe. What are some advantages of Isoclast-formulated products?

Answer 23

1. ​Stable under UV light.
2. Excellent rainfastness.
3. Stable within a wide pH range of spray diluents.
4. Dissolves easily within broad ranges of water temperatures and water pH used in agriculture.

Question 24

What is “target-site mutation” when referring to neonicotinoid-resistant insects? Is Isoclast™ active affected by this mechanism?

Answer 24

Target-site mutation is a resistance mechanism to some IRAC Group 4 insecticides and has been observed in some field populations of the green peach aphids and cotton aphids. It is less common than metabolic resistance and results from a point mutation in the acetylcholine binding site. Isoclast™ active is less affected by it compared to any other Group 4 insecticide. Studies on target-site resistant green peach aphid populations indicate that they continue to be controlled with Isoclast at field-use rates.

Question 25

What attribute(s) of Isoclast™ active make it an excellent tool in an Integrated Pest Management (IPM) program?

Answer 25

1. ​High compatibility with natural enemies.
2. Low impact on pollinators.
3. No evidence of outbreaks of secondary pests.
4. High selectivity on sap-feeding pests.
5. Effective at low rates, which means low environmental load.

Question 26

What are the features of Isoclast™ active that reduce the potential for plant virus transmission?

Answer 26

1. Quick knockdown activity on target pests.
2. Fast feeding cessation: Demonstrated ability to stop insect feeding quickly.

Question 27

Only one statement below is correct about the Insecticide Resistance Action Committee (IRAC). Which one?

1. IRAC assigned sulfoxaflor the commercial brand name of Isoclast™ active.
2. IRAC classified Isoclast™ active into the sulfoximines class.
3. IRAC placed the sulfoximines such as Isoclast™ active into subgroup 4C of the Mode of Action (MoA) classification. Sulfoximines are the sole member of subgroup 4C.
4. IRAC approved the registration of Isoclast™ active.

Answer 27

Only # 3 is correct. IRAC placed sulfoxaflor (Isoclast™ active) in subgroup 4C of the MoA classification. Sulfoximines are the sole member of subgroup 4C.

Question 28

Are there more commercial insecticides in the sulfoximines class?

Answer 28

No, Isoclast™ active was the first and is currently the only commercial member of the sulfoximines class.

Question 29

Isoclast™ active is a new generation neonicotinoid insecticide. True or False?

Answer 29

False. Isoclast™ active is not a neonicotinoid. Isoclast, 1) has a different chemical structure; 2) belongs to a different chemical class; 3) belongs to a different mode of action classification subgroup and 4) has a different metabolism compared to neonicotinoid insecticides.

Question 30

When used according to label recommendatios, Isoclast™ active does not pose an unacceptable risk to bees and pollinators. True or False?

Answer 30

True. Isoclast™ active has excellent attributes (such as low residual toxicity, low environmental persistence, and degrades quickly into essentially non-toxic metabolites), which make risks to honey bees easier to manage by farmers when following all label directions.

Question 31

What attributes of Isoclast™ active allow for the immediate and long-lasting control of target pests?

Answer 31

Fast activity (also referred to as quick knockdown activity) and extended residual control (enabled by its xylem systemicity within the plant).

Question 32

What are some key features of Isoclast™ active?

Answer 32

1. Distinct mode of action.
2. Effective at low rates.
3. Excellent contact and ingestion activities.
4. Excellent translaminar and xylem-systemic activities.
5. Controls a broad-spectrum of sap-feeding insect pests.
6. Fast acting with excellent knockdown and residual control.
7. Effective against insect pest populations resistant to other insecticides.

Question 33

What is Isoclast™ active?

Answer 33

Isoclast™ active (common name sulfoxaflor) is an award-winning insecticidal active ingredient with a distinct mode of action, discovered by and proprietary to Dow AgroSciences (now Corteva Agriscience) developed to manage a broad range of economically important sap-feeding insect pests in major crops worldwide.

Question 34

Isoclast™ active belongs to this chemical class:

Answer 34

Sulfoximines.

Question 35

Insect populations resistant to other chemistries, including neonicotinoids, will always be controlled with Isoclast™ active. These insects will not develop resistance to Isoclast. True or False?

Answer 35

False. Insects have a demonstrated ability to develop resistance to old and new chemistries. Although Isoclast currently controls resistant insect populations, strict adherence to the product label and product use recommendations is of extreme importance to make Isoclast benefits sustainable and continue to offer growers an important tool to control resistant pest populations.

Question 36

Name two awards received by Isoclast™ active in 2014?

Answer 36

1. R&D 100 Award. Known as the “Oscars of Invention”, this award honors excellence in innovation for top technology products of the year.
2. AGROW Award for “Best New Crop Protection Product or Trait”. This is one of agriculture’s top product honors.

Question 37

Isoclast™ active has a different mode of action. True or False?

Answer 37

False. Isoclast™ active has a distinct mode of action.

Question 38

Isoclast™ active is not affected by the insect metabolism responsible for conferring resistance to other insecticides such as neonicotinoids. True or False?

Answer 38

True, Isoclast™ active is distinct in that it is not affected by the metabolism responsible for causing resistance to other insecticides such as neonicotinoids.

Question 39

The Insecticide Resistance Action Committee (IRAC) classified Isoclast™ active in a chemical class called sulfoximines, True or False?

Answer 39

False. IRAC classified Isoclast™ active in subgroup 4C of the Mode of Action Classification. Sulfoximines is the name of the chemical class and was not assigned by IRAC.

Question 40

What type of insects are controlled by Isoclast™ active?

Answer 40

Sap-feeding insect pests.

Question 41

Both Isoclast™ active and neonicotinoids belong to Group 4 and therefore they both have the same mode of action. True or False?

Answer 41

False. There are several subgroups within Group 4 mode of action classification. Neonicotinoids belong to subgroup 4A and Isoclast™ active (a sulfoximine) belongs to subgroup 4C. Being in Group 4 means they share the same target site. However, Isoclast has complex and unique interactions with the target site, resulting in a different metabolism compared to neonicotinoids. Therefore, the mode of action of Isoclast is distinct from that of neonicotinoids.

Question 42

What is xylem-systemic activity?

Answer 42

Xylem-systemic activity or xylem-systemicity is a feature that allows Isoclast™ active to be absorbed through the plant tissue and move upwards to the terminal growth, transported via the plant’s xylem vascular system.

Question 43

Which of the two lists of insect pests below is controlled by Isoclast™ active?

1. Aphids, whiteflies, jassids, leafhoppers, planthoppers, stink bugs, plant bugs, mealybugs and some psyllid and scale insect species.
2. Caterpillars and other lepidopterous pests, beetles, termites, fruit flies, leafminers, maggots, mites.

Answer 43

List # 1 is correct. Isoclast™ active has proven efficacy on a broad-spectrum of sap-feeding insect pests.

Question 44

Only one statement below is correct about the routes of exposure of target insect pests to Isoclast™ active. Which one?

1. Contact only.
2. Contact and inhalation.
3. Ingestion and inhalation.
4. Contact and ingestion.

Answer 44

Only # 4 is correct. Isoclast™ active has a dual mode of exposure: Contact and ingestion.

Question 45

Isoclast™ active and neonicotinoids have several differences in the chemical structures of their molecules. Describe two of them.

Answer 45

To illustrate this, we will use the imidacloprid molecule to represent neonicotinoids:

1. See red arrow labeled 1 in figure below: All neonicotinoids have an amine nitrogen (N). Isoclast does not have an amine nitrogen.
2. See blue arrow labeled 2 in figure below: Except for dinotefuran, neonicotinoids have chlorine (Cl). In contrast, Isoclast has a trifluoromethyl group (F3C).

Question 46

Regarding the mode of action (MoA) of Isoclast™ active (the manner in which Isoclast interacts at the insect’s target site), only one statement below is true. Which one?

1. It has a different mode of action.
2. It has a distinct mode of action.
3. It has an extended mode of action.
4. It has a systemic mode of action.

Answer 46

Only # 2 is correct. Isoclast™ active has a distinct mode of action.

Question 47

Which of the two statements below is true?

1. Isoclast™ active applied to the leaf is absorbed by the leaf (via translaminar activity) and stays in the leaf.
2. Isoclast™ active applied to the stem travels upwards (via xylem-systemic activity) to the leaves present in that stem at the time of application.

Answer 47

Both statements are true.