Insecticide resistance management and industry: the origins and evolution of the Insecticide Resistance Action Committee (IRAC) and the mode of action classification scheme

Abstract

Insecticide resistance is a long-standing problem affecting the efficacy and utility of crop protection compounds. Insecticide resistance also impacts the ability and willingness of companies around the world to invest in new crop protection compounds and traits. The Insecticide Resistance Action Committee (IRAC) was formed in 1984 to provide a coordinated response by the crop protection industry to the problem of insecticide resistance. Since its inception, participation in IRAC has grown from a few agrochemical companies in Europe and the US to a much larger group of companies with global representation and an active presence (IRAC Country Groups) involving an even wider array of companies in more than 20 countries. The focus of IRAC has also evolved from that of defining and documenting cases of insecticide resistance to a pro-active role in addressing insecticide resistance management (IRM) providing an array of informational and educational tools (videos, posters, pamphlets) on insect pests, bioassay methods, insecticide mode of action and resistance management, all publicly available through its website (https://irac-online.org/). A key tool developed by IRAC is the Insecticide Mode of Action (MoA) Classification Scheme, which has evolved from a relatively simple acaricide classification started in 1998 to the far broader scheme that now includes biologics as well as insecticides and acaricides. A separate MoA Classification Scheme has also been recently developed for nematicides. The IRAC MoA Classification Scheme coupled with expanding use of MoA labeling on insecticide and acaricide product labels provides a straightforward means to implement IRM. An overview of the history of IRAC along with some of its notable accomplishments and future directions are reviewed. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Keywords: crop protection; insecticide mode of action; insecticide resistance; resistance management; sustainable agriculture.

Figure 1

(A) Number of cases of insecticide resistance per decade and approximate dates of introduction for selected major classes of insecticides and acaricides. (B) Cumulative number of cases of resistance to selected insecticides/classes 1940–1980. Resistance cases based on data from the ARPD. ⁶⁵ (Mota‐Sanchez and Wise 2020).

Figure 2

Initial IRAC organization (1984) versus current (2020) including working groups (WG). Information from Jackson 1986, IRAC 2020. ³¹ , ⁴⁴ Dotted lines indicate informal linkages between IRAC and other external organizations. MSU APRD – Michigan State University, Arthropod Pesticide Resistance Database. ⁶⁵ EPPO, European and Mediterranean Plant Protection Organization; FRAC, Fungicide Resistance Action Committee (1981); HRAC, Herbicide Resistance Action Committee (1989); RRAC, Rodenticide Resistance Action Committee (1990).

Figure 3

Company numbers and composition of IRAC as a function of time.

Figure 4

The global expansion of IRAC country groups as a function of time. 1998 (Brazil, US, Australia*), 2008 (addition of India, South Africa, Spain), 2020 ‐ all countries currently listed. Two other IRAC regional groups (not shown) are IRAC Asia and IRAC Europe. *IRAC Australia is linked to CropLife Australia, and not directly to IRAC international ‐ included here for informational purposes.

Figure 5

Number of different MoA classes or Groups as a function of time. 1988 to 1998 the classification was focused on acaricides. From 2001 onwards the MoA Classification Scheme included insecticides and acaricides but excluded nematicides, which are now addressed in a separate MoA Classification scheme. ⁵ Between 2005 ⁴⁸ and 2010 ⁵⁰ continued refinement of the MoA Classification Scheme led to the removal/reclassification of some Groups resulting in a reduction in the number of Groups. Data derived, in part, from. ⁵ , ⁴⁸ , ⁴⁹ , ⁵⁰ , ⁵¹ , ⁵² , ⁵⁶ , ⁶⁷