Leaf Damage Based Phenotyping Technique and Its Validation Against Fall Armyworm, Spodoptera frugiperda (J. E. Smith), in Maize

Abstract

Globally, maize is an important cereal food crop with the highest production and productivity. Among the biotic constraints that limit the productivity of maize, the recent invasion of fall armyworm (FAW) in India is a concern. The first line of strategy available for FAW management is to evaluate and exploit resistant genotypes for inclusion in an IPM schedule. Screening for resistant maize genotypes against FAW is in its infancy in India, considering its recent occurrence in the country. The present work attempts to optimize screening techniques suited to Indian conditions, which involve the description of leaf damage rating (LDR) by comparing injury levels among maize genotypes and to validate the result obtained from the optimized screening technique by identification of lines potentially resistant to FAW under artificial infestation. Exposure to 20 neonate FAW larvae at the V5 phenological stage coupled with the adoption of LDR on a 1–9 scale aided in preliminary characterize maize genotypes as potentially resistant, moderately resistant, and susceptible. The LDR varies with genotype, neonate counts, and days after infestation. The genotypes, viz., DMRE 63, DML-163-1, CML 71, CML 141, CML 337, CML 346, and wild ancestor Zea mays ssp. parviglumis recorded lower LDR ratings against FAW and can be exploited for resistance breeding in maize.

Population Dynamics of Fall Armyworm (Lepidoptera: Noctuidae) on Maize Fields in Uganda

“…The lack of significant difference between leaf damage and grain yield in the other cases of this study agrees in part with the results by Britz, [33], who reported that plants with low to moderate damage scores did not suffer significant yield losses. Plant response to damage is influenced not only by the severity of symptoms, but also by factors such as drought conditions [34], soil nutrient status [35], the length of the larval feeding period, and the inherent level of plant resistance to larval feeding damage [36]. These factors, not documented in this study, solely or interactively could have influenced the results of this study.…”

Identification of cassava germplasms resistant to two-spotted spider mite in China: From greenhouse large-scale screening to field validation

“…In addition, the resistance levels of several germplasms were flexible or unstable in different rounds of identification, as one germplasm would shift from one resistance level to another level, while the 12 varieties mentioned above were steadily kept at their fixed resistant levels in any round of identification. The phenomenon of the scarcity of resistant germplasm resource is common in the insect pest resistance identification of other plant species, as cases can be found in the screening of soybean (334 genotypes) resistant to aphid ( Aphis glycines ) ( Bhusal et al., 2013 ), pepper (50 accessions) resistant to green peach aphid ( Myzus persicae ) ( Frantz et al., 2004 ), cotton (over 400 cultivars) resistant to whitefly ( Bemisia tabaci ) ( Li et al., 2016 ), and maize (38 genotypes) resistant to fall armyworm ( Spodoptera frugiperda ) ( Soujanya et al., 2022 ). In those studies, no more than seven resistant genotypes/accessions/cultivars were identified.…”

Variation in Grain Yield Losses Due to Fall Armyworm Infestation among Elite Open-Pollinated Maize Varieties under Different Levels of Insecticide Application

“…Leaf damage rating (LDR) due to FAW was performed on a 1-9 scale, as described by several researchers [18,[30][31][32][33]. The scale was used to categorize the maize genotypes as resistant (1-4), moderately resistant (>4-6), and susceptible (>6-9) [34]. Scoring for LDR was performed four times for the entire plants in the plot, at 42, 49, 56, and 63 days after sowing.…”