Diamide insecticides: chlorantraniliprole and cyantraniliprole compared, with resistance management

IRAC, the Insecticide Resistance Action Committee, classifies diamides as Group 28, ryanodine receptor modulators, a group that currently contains chlorantraniliprole, cyantraniliprole, cyclaniliprole, flubendiamide and tetraniliprole [1]. Because every member shares one target site, IRAC asks that resistance management treat all Group 28 insecticides as one group [2]. This guide explains the mode of action, compares the two most common anthranilic diamides, summarises documented resistance and sets out the IRAC rotation rules.

1. Mode of action

Ryanodine receptors control the release of calcium from internal stores in muscle. Group 28 insecticides bind to these receptors and cause uncontrolled release and depletion of internal calcium, preventing further muscle contraction [2]. IRAC describes the result as activation of muscle ryanodine receptors leading to contraction and paralysis [1]. Treated insects show rapid cessation of feeding, lethargy, regurgitation, muscle paralysis and finally death [2].

Structural work shows that phthalic and anthranilic diamides bind the same site in the transmembrane region of the receptor, with different poses [3]. The binding site is not conserved between insects and mammals, and diamides are about 100 to 1,000 times more selective for insect receptors than for mammalian ones [3].

2. Chlorantraniliprole and cyantraniliprole compared

Both are anthranilic diamides. Chlorantraniliprole was the first of them and is particularly effective against Lepidoptera [4]. Cyantraniliprole is chemically similar but has a broader spectrum and controls sucking insects such as aphids and whiteflies [4]; it has been described as the first diamide to target piercing sucking pests effectively [5].

The practical difference is the target list, not a way around resistance: both belong to the same mode of action group [1], and the cross resistance described below has extended across the diamides [7][11].

3. Documented resistance

Resistance has developed quickly in some pests [4][7]. Sources differ on the mechanism in diamondback moth: IRAC's 2012 poster described it as believed to be metabolic and cross resistant to all diamide products [7], while later work identified target site mutations in the ryanodine receptor; the G4946E mutation has been reported in diamondback moth in at least nine countries on three continents [4].

Diamondback moth (Plutella xylostella)

Resistance appeared within 18 months of the launch of flubendiamide in Thailand in 2009, with cross resistance to chlorantraniliprole; the following year it was observed in the Philippines, and in 2011 in Taiwan and the Guangzhou area of southeast China [4][7]. In China's 2024 national monitoring, diamondback moth showed mostly moderate to high resistance to chlorantraniliprole, rising compared with 2023 [9].

Spodoptera

In China's 2024 monitoring, beet armyworm (Spodoptera exigua) showed mostly high resistance to chlorantraniliprole, above 140 fold in populations from Shanghai, Zhejiang and Hubei [9]. In the United States, beet armyworm resistance to chlorantraniliprole was first reported in 2020; in the laboratory it declined when exposure stopped, which the authors see as manageable by removing the selection pressure [12]. In fall armyworm (Spodoptera frugiperda), diamide resistance was until 2022 known from laboratory selected strains, with an I4734M/K mutation identified in strains selected from Brazilian field populations [10]; susceptibility of Brazilian field populations to cyantraniliprole then fell from 2017 to 2023, and a selected strain showed high cross resistance to flubendiamide, chlorantraniliprole and cyclaniliprole [11].

Tomato leafminer (Tuta absoluta)

IRAC lists diamide resistance in Tuta absoluta in Italy and Greece and in Israel [8].

Whiteflies

China's 2024 monitoring found moderate to high resistance to cyantraniliprole in Bemisia tabaci eggs, with high resistance in populations from Shanghai, Hainan and Shanxi [9]. Higher expression of UDP glycosyltransferases, detoxification enzymes, is a key metabolic mechanism of cyantraniliprole resistance in B. tabaci, and these enzymes also mediated cross resistance to chlorantraniliprole [5].

4. IRAC resistance management guidance

IRAC's general rule is that successive generations of a pest should not be treated with insecticides from the same mode of action group, and that applications are arranged into spray windows defined by crop stage and pest biology [1]. For Group 28, the diamide working group gives these rules [2][7]:

• Treat all Group 28 products as one group; do not rotate one diamide with another [2].
• Use a window approach so that consecutive pest generations are not exposed to Group 28 [2][7].
• A treatment window lasts about 30 days, 15 to 45 days depending on the local generation time, and should approximate one generation of the target pest; several applications are acceptable within one window or against one generation [7].
• After a Group 28 window, rotate to a window of effective insecticides with a different mode of action [2].
• For crops shorter than 50 days, treat the whole crop cycle as one Group 28 window and use other modes of action in the next planting at the same site [7].
• Group 28 windows should cover no more than about 50% of the crop cycle, from seedling to harvest [2][7].
• Do not reduce label rates, target the most susceptible life stages and monitor field performance [2].
• Do not use tank mixtures or premixtures where resistance to either component is known in the target population [2].

IRAC also stresses that rotation partners must control the pest well: rotating with products that give poor control increases the risk of diamide resistance [7].

5. Examples from the catalogue

The table lists Huasheng catalogue ingredients that belong to Group 28 or are named as rotation options in the sources. Groups were checked against IRAC version 11.5 [1].

The table describes IRAC groups and what the cited sources say. It is not a list of registered uses. Which products may be used, on which crops, at what rate and interval is set by each country's registration and by the product label.

6. Regional notes

China

For areas with high resistance, the 2024 national monitoring report advises stopping chlorantraniliprole against diamondback moth, suspending chlorantraniliprole and indoxacarb against beet armyworm, and suspending cyantraniliprole against whiteflies, preferring biological products and rotating other modes of action, with each product used no more than once per vegetable season [9]. In cotton bollworm in the Yangtze River cotton region, chlorantraniliprole resistance was still susceptible to low, but rising [9].

Latin America

In Brazil, cyantraniliprole is widely used against sucking and defoliating pests, including fall armyworm, and field susceptibility declined from 2017 to 2023, especially in intensive systems of the Cerrado [11]. Large scale screening of Brazilian field populations for ryanodine receptor resistance mutations has been carried out to support resistance management [10].

Other regions

In Europe and the Middle East, diamide resistant Tuta absoluta is listed for Italy, Greece and Israel [8]. In the United States, beet armyworm resistance to chlorantraniliprole was first reported in 2020 [12].

7. A practical sequence

• List the Group 28 products used on the farm, including seed treatments and premixtures, and count them as one group [2].
• Check local monitoring for diamide resistance in the key pests [9].
• Plan the season in windows of about one pest generation [7].
• Use Group 28 in no more than about half of the crop cycle, and never on consecutive generations [2][7].
• Fill the other windows with effective insecticides from other IRAC groups, and biologicals where advised [1][9].
• Keep full label rates and target young larvae [2].
• Monitor insect populations for loss of field efficacy [2].

Frequently asked questions