Closer 240SC is powered by IsoclastTM active (sulfoxaflor), discovered by and proprietary to Dow AgroSciences, currently is the sole member of a new chemical class of insecticides, the sulfoximines in the chemical class 4C. Isoclast has been developed globally for use in major crop groups, including Roses, Carnations, Cotton, leafy and fruiting vegetables, apples, soybeans, rice (outside of the U.S.), cereals, citrus, cole crops, grapes, and other crops. Isoclast controls economically important and difficult-to control sap-feeding insect pests including most species of aphids, jassids, leafhoppers, mealybugs, plant bugs, plant hoppers, stink bugs, and whiteflies, and certain species of psyllids and scales.
Noteworthy Features
- Effective at low use rates
- Excellent knockdown and residual control
- Excellent translaminar and systemic activity
- Effective against insect pest populations resistant to other insecticides
- Valuable rotation partner with other chemistries i.e. Neonicotinoids.
- Minimal impact on beneficial insects, including bees and natural enemies, when applicators follow label directions for use.
Mode of Action and Resistance
Management
Available data indicate Isoclast™ active exhibits complex and unique interactions with insect nicotinic acetylcholine receptors (nAChR) that are distinct from those observed with neonicotinoids.
Isoclast is a high efficacy nAChR agonist with low affinity for the imidacloprid binding site. Numerous studies have been conducted to determine whether insects resistant to other insecticides are cross resistant to Isoclast. Available data for Isoclast indicate a broad lack of cross-resistance in many sap-feeding insect strains resistant to other insecticides. In several field studies, Isoclast controlled insect populations known to be resistant to neonicotinoids and to insecticides with other modes of action (e.g., carbamates, organophosphates, pyrethroids).
The broad lack of cross-resistance between Isoclast and neonicotinoids is due primarily to differences in metabolism by monooxygenase enzymes, which are the predominant mechanism of insecticide resistance in the field. Laboratory studies have demonstrated a monooxygenase that degrades neonicotinoids has no effect on Isoclast.
The novel chemistry of Isoclast and the lack of cross-resistance suggest that efficacy of Isoclast will be retained even in the presence of sap-feeding insect strains that are resistant to other insecticides, including neonicotinoids. For reasons indicated in the preceding paragraphs, sulfoxaflorTM was classified as a Group 4, Subgroup 4C insecticide in the Insecticide Resistance Action Committee Mode of Action Classification Scheme (Version 7.2, April 2012, http://www.irac-online. org). Sulfoxaflor is the sole member of this subgroup. Neonicotinoids insecticides are classified in Group 4, Subgroup 4A in the IRAC Mode of Action Classification Scheme.
Because of its unique properties and broad lack of cross-resistance, Isoclast will be a useful rotation partner with other insecticide chemistries, enhancing insect resistance management (IRM) strategies.
How Isoclast™ Active Kills Insect Pests Isoclast™ active kills insect pests both on contact and through ingestion to provide both knockdown and residual control. Isoclast displays translaminar movement (moves to the opposite leaf surface) when applied to foliage and is xylem-mobile.
Biological Activity
Background
Sap-feeding insects, especially those in the sub-orders Hemiptera and Homoptera, are among the most destructive insect pests in the world, annually causing economic losses in both row crops and horticultural crops. Management of sap-feeding insects often requires diverse and intensive control tactics, including the use of insecticides. Consequently, populations of sap-feeding insects have developed resistance to many insecticides representing a wide range of insecticide modes of action. Isoclast’s efficacy and unique mode of action suggest that it will be a key tool for controlling economically important pests and a useful rotation partner in IRM programs.
Efficacy of Isoclast Against Insect Pests
Isoclast provides excellent efficacy against target pests at low use rates. Proposed application rates of Isoclast range from approximately 100 to 200 millilitres of product per hectare depending on the target pest and the crop. Field efficacy trials with Isoclast have been conducted worldwide on many crops against a wide range of sap feeding insects. Results from these trials have revealed that Isoclast provides excellent control of many species of sap-feeding insects, including mealybugs, whiteflies and aphids.
Impact of Isoclast™ Active on Natural Enemies of Insect Pests
Field studies have been conducted to measure the impact of Isoclast™ active on several predatory and parasitic arthropods (natural enemies): assassin bugs, big-eyed bugs, braconid wasps, green lacewings, lady beetles, minute pirate bugs (including Orius insidious ), and spiders.
When applied at field-use rates in these studies, Isoclast had no significant impact on population levels of any of the natural enemies measured. In addition, Isoclast has had no impact on beneficial mite species. Based on the results from these studies, as well as on observations from other field trials, use of Isoclast is not expected to cause outbreaks of secondary insect pests (often referred to as “flaring”).
Crop Tolerance
Tolerance of formulations of Isoclast is high for the many major crop species that have been tested. At labelled use rates, Isoclast exhibited no phytotoxicity in seedling emergence and vegetative vigor tests in ten crop species. No crop injury has been observed in any field trials over a range of environmental conditions, and no differences in varietal sensitivity have been observed. Since being registered in multiple countries, Dow AgroSciences has received no reports of any negative plant responses or phytotoxicity from application of Isoclast.
Isoclast™ Active and Non-Target Organisms
Isoclast™ active does not persist in the terrestrial environment and degrades rapidly to products that exhibit low toxicity to non-target organisms. Consequently, when Isoclast is used according to label directions, exposure of non-target organisms to Isoclast is expected to be minimal. Based on available data, use of Isoclast in the manner consistent with label directions will not cause any unreasonable adverse effects in the environment.
Isoclast and Bees
The effects of Isoclast on honey bees (Apismellifera) and bumble bees have been studied in laboratory experiments and in tunnel tests that simulate field conditions. In laboratory studies, Isoclast exhibits acute toxicity to bees when consumed by or applied directly to bees. However, in tests designed to mimic use conditions, toxicity of Isoclast to bees was significantly reduced after the spray droplets had dried.
Acute Toxicity (Laboratory Studies). Under laboratory conditions, Isoclast exhibited acute toxicity to bees when the bees were exposed by oral or contact routes of administration. Isoclast technical and formulated products had similar toxicities to honey bees. The primary metabolite was not toxic to honey bees. The following table shows available acute toxicity data.
Summary
At the time of publication of this bulletin, the findings from all of the completed studies suggest that although Isoclast is acutely toxic to bees in laboratory studies, the risk of adverse effects on bees should be low under field conditions when applicators follow label directions for use. Because potential exposures to honey bees may vary among crops and field conditions at the time of application, it is important to read and follow all label directions regarding honey bees.