In South Africa, it will be critically important to have a harmonised approach to IRM for FAW across the industry and across technologies. This approach should combine a clear and simple structured refuge policy which does not confuse growers between the requirements for FAW and maize stalk borers in South Africa, and which enables a high grower compliance. There are several commercialised Bt-products in South Africa which are very similar. This approach is in the best interests of the seed industry, growers and South African consumers. The new guidelines have now been published on the IRAC website.
Fall armyworm (FAW) (Spodoptera frugiperda) is a serious pest in corn, if uncontrolled; this pest can cause a severe damage of the breeding materials of the seed industry at Puerto Rico. One of the tools to manage FAW is the use of insecticides of different modes of action. However, FAW has a tremendous ability to develop resistance. Therefore, monitoring the susceptibility or resistance of FAW to insecticides is critical to establish a successful insecticide resistance management plan (IRM). Monitoring of resistance requires the knowledge of specific methods of insecticide bioassays and analysis of data. Consequently, Michigan State University, IRAC International, and Corteva Agriscience in partnership with PRABIA offered a training course in methods of bioassays for FAW.
The training consisted of classroom training and hands-on laboratory and field experience and reviewed concepts associated with insecticide mode of action and resistance to synthetic compounds. A review of the theory and practice of laboratory bioassays methods for detection of insecticide resistance including leaf disc (IRAC Method No. 007) and insecticide incorporated diet (IRAC Method No. 020) was performed by the participants. In addition, evaluation of the larval mortality was performed by the participants of this training. Probit procedure from SAS and/or POLO program were used to analyze mortality data of the laboratory bioassays, and results of the data analysis were discussed.
On April 4, 2019, IRAC-BR and the Copacol cooperative (Cafelândia-PR) organized the I WORKSHOP ON INSET RESISTANCE MANAGEMENT (MRI) to discuss the validation of regional MRI recommendations. The event brought together experts on insect resistance and the staff of Copacol.
Initially the process of evolution of insect resistance to insecticides and Bt plants and MRI strategies was presented and discussed. The IRAC-BR representatives presented the current susceptibility data to insecticides in the main pest species that attack soybean and corn crops, such as: Spodoptera frugiperda, Chrysodeixis includens, Helicoverpa armigera, Euschistus heros and Bemisia tabaci.
For the practical part of the Workshop, the participants were divided into working groups for case studies looking for solutions to regional problems, with a view to MRI. Among the pest insects of regional importance are the management of the brown bug (Euschistus heros), the belly-green bug (Dichelops melacanthus) and the carpiaceous caterpillar (Spodoptera frugiperda). The current management of these species was discussed and how it could be improved, taking into account the production system of the region, in order to delay the evolution of resistance. The possibility of implementing MRI strategies at regional level and monitoring the susceptibility of populations of these sites in partnership with IRAC-BR consultants was also discussed, since Copacol has a large area of coverage in the western region of Paraná. The I Workshop on MRI was very productive, as it allowed discussion on the approach of IRAC-BR with the technical staff of Copacol. on the current management practices of the main soybean and corn pest insects in the western region of Paraná, as well as, what MRI strategies can be put into practice at the regional level to delay the evolution of resistance. IRAC-BR thanks Copacol for the reception and organization of this Workshop.