Baseline Response, Monitoring, and Cross-Resistance of Spodoptera frugiperda (Lepidoptera: Noctuidae) to Sodium Channel Blocker Insecticides in Brazil

Abstract

Spodoptera frugiperda (J.E. Smith) is one of the key cross-crop pests in Brazilian agroecosystems. Field-evolved resistance of S. frugiperda to some conventional insecticides and Bt proteins has already been reported. Thus, the use of insecticides with new mode of action such as sodium channel blockers (indoxacarb and metaflumizone) could be an important tool in insecticide resistance management (IRM) programs. To implement a proactive IRM, we conducted baseline response and monitoring to indoxacarb and metaflumizone in 87 field populations of S. frugiperda collected from major maize-growing regions of Brazil from 2017 to 2020, estimated the frequency of resistance alleles to indoxacarb, and evaluated cross-resistance of indoxacarb and metaflumizone to some selected insecticides and Bt proteins. Low variation in susceptibility to indoxacarb (4.6-fold) and metaflumizone (2.6-fold) was detected in populations of S. frugiperda in 2017. The frequency of the resistance allele to indoxacarb was 0.0452 (0.0382–0.0527 CI 95%), by using F2 screen method. The mean survival at diagnostic concentration, based on CL99, varied from 0.2 to 12.2% for indoxacarb and from 0.0 to 12.7% for metaflumizone, confirming high susceptibility of S. frugiperda to these insecticides in Brazil. No cross-resistance was detected between sodium channel blocker insecticides and other insecticides (organophosphate, pyrethroid, benzoylurea, spinosyn, and diamide) and Bt proteins. These findings showed that sodium channel blocker insecticides are important candidates to be exploited in IRM strategies of S. frugiperda in Brazil.

Invasiveness, biology, ecology, and management of the fall armyworm, Spodoptera frugiperda

“…The prevailing use of organophosphate and carbamate insecticides before the 1980´s was succeeded by pyrethroids (Diez-Rodríguez & Omoto 2001;Wood et al 1981;Yu, 1991;1992;Yu et al 2003). Starting in about 2000, spinosyns, avermectins, oxadiazines, insect growth regulators (chitin synthesis inhibitors and ecdysteroid agonists) and diamides have been used intensively in the Americas (Bolzan et al 2019;Kaiser et al 2021;Lira et al 2020;do Nascimento et al 2016;Okuma et al 2018). Bt-based insecticide formulations have also been used in the region (Blanco et al 2014;Gutierrez-Moreno et al 2020).…”

Susceptibility Evaluation of Fall Armyworm (Spodoptera frugiperda) Infesting Maize in Kenya against a Range of Insecticides

“…Nevertheless, the resistance of the pest populations to this compound was found to be very low (1- to 2-fold). Low variation in the susceptibility (4.6-fold) to indoxacarb was reported by Kaiser et al [ 27 ]. Deshmukh et al [ 28 ] reported low potency (2-fold) of indoxacarb against FAW collected from unsprayed maize farms in India using a similar bioassay method.…”

Safety Evaluation of Chemical Insecticides to Tetrastichus howardi (Hymenoptera: Eulophidae), a Pupal Parasitoid of Spodoptera frugiperda (Lepidoptera: Noctuidae) Using Three Exposure Routes

“…nubilale (Hymenoptera: Trichogrammatidae) [ 29 ]. This finding may be connected to the unique mechanism of indoxacarb, which is a sodium-channel-blocking insecticide that blocks the flow of sodium ions to nerve cells, preventing the transmission of nerve impulses that could lead to paralysis and insect death [ 30 , 31 ]. Therefore, it is recommended to consider indoxacarb as a field insecticide to prevent and control S. frugiperda .…”