Leaf Damage Based Phenotyping Technique and Its Validation Against Fall Armyworm, Spodoptera frugiperda (J. E. Smith), in Maize.
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ABSTRACT:
SUBMITTER: Soujanya PL
PROVIDER: S-EPMC9310382 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Fall armyworm (FAW), one of the most important pests of maize in Latin America, suddenly appeared in Africa in 2016 and spread rapidly. Estimates of crop losses due to FAW are essential in order to compare the impact of these losses with the cost of controlling FAW and advise appropriate technology dissemination and policy. In this study, therefore, crop losses due to FAW in 2017 and 2018 were estimated in all the maize production areas of Kenya. Data were collected during June and July 2018 through 121 group discussions with 1439 farmers, separately with men (697) and women (742), in communities that were randomly selected to represent the major maize growing areas. The results showed that most participants (82%) could correctly identify the FAW from pictures. By 2016, FAW was observed by more than half of the communities (53%), with most of the other half first observing FAW in 2017. The proportion of farmers affected by FAW substantially increased, from the long rains of 2017 (63%) to the long rains of 2018 (83%), and in all zones except for the high tropics and moist mid-altitudes. However, the percentage of loss experienced by affected farmers decreased slightly, from 54% in 2017 to 42% in 2018. In 2017, the low- and medium-potential maize-production areas were the most affected, with losses of >50%, with high-potential areas facing losses of about 30%, resulting in a total loss of 37% for the whole country. In the main 2018 season, losses in the low- and medium-potential areas were less - about 20%, but the high-potential areas were now more affected, leading to a total estimate of 33%. We conclude that FAW has suddenly become a major pest in Kenya, causing losses of about a third of the annual maize production, estimated at about 1 million tonnes.
| S-EPMC7015277 | biostudies-literature
Project description:The fall armyworm (FAW) has recently invaded and become an important pest of maize in Africa causing yield losses reaching up to a third of maize annual production. The present study evaluated different aspects of resistance of six maize cultivars, cropped by farmers in Kenya, to FAW larvae feeding under laboratory and field conditions. We assessed the arrestment and feeding of FAW neonate larvae in no-choice and choice experiments, development of larvae-pupae, food assimilation under laboratory conditions and plant damage in a field experiment. We did not find complete resistance to FAW feeding in the evaluated maize cultivars, but we detected differences in acceptance and preference when FAW larvae were given a choice between certain cultivars. Moreover, the smallest pupal weight and the lowest growth index were found on 'SC Duma 43' leaves, which suggests an effect of antibiosis of this maize hybrid against FAW larvae. In contrast, the highest growth index was recorded on 'Rachar' and the greatest pupal weight was found on 'Nyamula' and 'Rachar'. The density of trichomes on the leaves of these maize cultivars seems not to be directly related to the preference of neonates for feeding. Plant damage scores were not statistically different between cultivars in the field neither under natural nor artificial infestation. However, plant damage scores in 'Nyamula' and 'Jowi' tended to be lower in the two last samplings of the season compared to the two initial samplings under artificial infestation. Our study provides insight into FAW larval preferences and performance on some African maize cultivars, showing that there are differences between cultivars in these variables; but high levels of resistance to larvae feeding were not found.
| S-EPMC7922265 | biostudies-literature
Project description:Switchgrass (Panicum virgatum L.) is a low input, high biomass perennial grass being developed for the bioenergy sector. Upland and lowland cultivars can differ in their responses to insect herbivory. Fall armyworm [FAW; Spodoptera frugiperda JE Smith (Lepidoptera: Noctuidae)] is a generalist pest of many plant species and can feed on switchgrass as well. Here, in two different trials, FAW larval mass were significantly reduced when fed on lowland cultivar Kanlow relative to larvae fed on upland cultivar Summer plants after 10 days. Hormone content of plants indicated elevated levels of the plant defense hormone jasmonic acid (JA) and its bioactive conjugate JA-Ile although significant differences were not observed. Conversely, the precursor to JA, 12-oxo-phytodienoic acid (OPDA) levels were significantly different between FAW fed Summer and Kanlow plants raising the possibility of differential signaling by OPDA in the two cultivars. Global transcriptome analysis revealed a stronger response in Kanlow plant relative to Summer plants. Among these changes were a preferential upregulation of several branches of terpenoid and phenylpropanoid biosynthesis in Kanlow plants suggesting that enhanced biosynthesis or accumulation of antifeedants could have negatively impacted FAW larval mass gain on Kanlow plants relative to Summer plants. A comparison of the switchgrass-FAW RNA-Seq dataset to those from maize-FAW and switchgrass-aphid interactions revealed that key components of plant responses to herbivory, including induction of JA biosynthesis, key transcription factors and JA-inducible genes were apparently conserved in switchgrass and maize. In addition, these data affirm earlier studies with FAW and aphids that the cultivar Kanlow can provide useful genetics for the breeding of switchgrass germplasm with improved insect resistance.
| S-EPMC6564039 | biostudies-literature
Project description:The Yangtze River Delta, located in East China, is an important passage on the eastern pathway of the northward migration of fall armyworm Spodoptera frugiperda (Smith) in China, connecting China's year-round breeding area and the Huang-Huai-Hai summer maize area. Clarifying the migration dynamics of S. frugiperda in the Yangtze River Delta is of great significance for the scientific control and prevention of S. frugiperda in the Yangtze River Delta, even in the Huang-Huai-Hai region and Northeast China. This study is based on the pest investigation data of S. frugiperda in the Yangtze River Delta from 2019 to 2021, combining it with the migration trajectory simulation approach and the synoptic weather analysis. The result showed that S. frugiperda migrated to the Yangtze River Delta in March or April at the earliest, and mainly migrated to the south of the Yangtze River in May, which can be migrated from Guangdong, Guangxi, Fujian, Jiangxi, Hunan and other places. In May and June, S. frugiperda migrated further into the Jiang-Huai region, and its source areas were mainly distributed in Jiangxi, Hunan, Zhejiang, Jiangsu, Anhui and Hubei provinces. In July, it mainly migrated to the north of Huai River, and the source areas of the insects were mainly distributed in Jiangsu, Anhui, Hunan, Hubei and Henan. From the south of the Yangtze River to the north of the Huai River, the source areas of S. frugiperda were constantly moving north. After breeding locally, S. frugiperda can not only migrate to other regions of the Yangtze River Delta, but also to its surrounding provinces of Jiangxi, Hunan, Hubei, Henan, Shandong and Hebei, and even cross the Shandong Peninsula into Northeast China such as Liaoning and Jilin provinces. Trajectory simulation showed that the emigrants of S. frugiperda from the Yangtze River Delta moved northward, westward and eastward as wind direction was quite diverse in June-August. This paper analyzes the migration dynamics of S. frugiperda in the Yangtze River Delta, which has important guiding significance for the monitoring, early warning and the development of scientific prevention and control strategies for whole country.
| S-EPMC9961294 | biostudies-literature
Project description:The alien invasive insect pest Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), commonly referred to as fall armyworm (FAW), is causing significant losses to maize production in Africa since its detection in 2016. As an emergency response, governments in several countries distributed and/or promoted massive use of synthetic insecticides among smallholder farmers to fight FAW. The inappropriate use of synthetic insecticides by non-trained and ill-equipped farmers raises environmental and health concerns. This study aimed to assess the occurrence of native parasitoids of FAW, their parasitism rates, and relative abundance in the central province of Manica, Mozambique. A field collection of FAW egg masses and larvae was conducted from May to August 2019 (dry season of the 2018/2019 cropping season) and in December 2019 and January 2020 (rainy season of 2019/2020 cropping season). A total of 101 egg masses and 1444 larvae of FAW were collected from infested fields. Five larval parasitoids were recorded, but no egg parasitism was observed. Coccygidium luteum Brullé (Hymenoptera: Braconidae) and Drino quadrizonula Thomson (Diptera: Tachinidae) were the primary parasitoids. Maximum parasitism of 23.68% and 8.86% and relative abundance of 100 and 96.3 were recorded for C. luteum and D. quadrizonula, respectively. Total parasitism by different parasitoid species was at 9.49%. Cultural practices favoring the action of these parasitoids should be advocated.
| S-EPMC7564170 | biostudies-literature
Project description:Evolution of insect resistance to transgenic crops containing Bacillus thuringiensis (Bt) genes is a serious threat to the sustainability of this technology. However, field resistance related to the reduced efficacy of Bt maize has not been documented in any lepidopteran pest in the mainland U.S. after 18 years of intensive Bt maize planting. Here we report compelling evidence of field resistance in the fall armyworm, Spodoptera frugiperda (J.E. Smith), to Cry1F maize (TC 3507) in the southeastern region of the U.S. An F2 screen showed a surprisingly high (0.293) Cry1F resistance allele frequency in a population collected in 2011 from non-Bt maize in south Florida. Field populations from non-Bt maize in 2012-2013 exhibited 18.8-fold to >85.4-fold resistance to purified Cry1F protein and those collected from unexpectedly damaged Bt maize plants at several locations in Florida and North Carolina had >85.4-fold resistance. In addition, reduced efficacy and control failure of Cry1F maize against natural populations of S. frugiperda were documented in field trials using Cry1F-based and pyramided Bt maize products in south Florida. The Cry1F-resistant S. frugiperda also showed a low level of cross-resistance to Cry1A.105 and related maize products, but not to Cry2Ab2 or Vip3A. The occurrence of Cry1F resistance in the U.S. mainland populations of S. frugiperda likely represents migration of insects from Puerto Rico, indicating the great challenges faced in achieving effective resistance management for long-distance migratory pests like S. frugiperda.
| S-EPMC4234506 | biostudies-literature
Project description:BackgroundThe pyramided genetically modified maize (Zea mays [L.]) event MON 95379, expressing the Cry1B.868 and Cry1Da_7 proteins, was designed to protect against larval feeding damage by the fall armyworm, Spodoptera frugiperda (FAW). Here, we conducted laboratory, greenhouse, and field studies to assess the dose and field efficacy of MON 95379 against FAW and inform the development of insect resistance management plans.ResultsThe Cry1B.868 and Cry1Da_7 proteins were active against susceptible FAW neonates in diet-incorporation bioassays: median lethal concentration [LC50 ] (95% CI) = 62.8 (42.6-87.6) μg/ml diet for Cry1B.868 and 9.4 (5.3-18.6) μg/ml diet for Cry1Da_7. In laboratory leaf disc bioassays, MON 95379 maize and experimental maize lines expressing the individual components were effective in controlling susceptible FAW. In whole-plant assays, MON 95379 controlled FAW resistant to the Cry1A.105 and Cry2Ab2 proteins. Likewise, under field conditions, MON 95379 maize expressing Cry1B.868 and Cry1Da_7 was highly effective at protecting plants against the larval feeding of FAW.ConclusionsThe expression of Cry1B.868 and Cry1Da_7 in MON 95379 consistently protected maize plants against larval feeding by FAW and represents an alternative to manage trait resistance issues in South America. © 2021 Bayer Crop Science-US. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
| S-EPMC8360028 | biostudies-literature
Project description:Fall armyworm (Spodoptera frugiperda Smith), a serious pest of cereals from the Americas, has spread across sub-Saharan Africa and Asia since 2016, threatening the food security and incomes of millions of smallholder farmers. To measure the impact of S. frugiperda under different management approaches, we established on-farm trials across 12 landscapes (615-1,379 mm mean annual rainfall) in Malawi and Zambia during the 2019/2020 and 2020/2021 seasons. Here we present the results from our conventional tillage, monocrop maize, no pesticide treatment, which served to monitor the background S. frugiperda impact in the absence of control measures. Median plot-level S. frugiperda incidence ranged between 0.00 and 0.52 across landscapes. Considering severe leaf damage (Davis score ≥5), the proportion of affected plants varied between 0.00 and 0.30 at the plot scale, but only 3% of plots had ≥10% severely damaged plants. While incidence and damage severity varied substantially among sites and seasons, our models indicate that they were lower in high tree cover landscapes, in the late season scouting, and in the 2020/2021 season. Yield could not be predicted from S. frugiperda incidence or leaf damage. Our results suggest S. frugiperda impacts may have been overestimated at many sites across sub-Saharan Africa. S. frugiperda incidence and damage declined through the cropping season, indicating that natural mortality factors were limiting populations, and none of our plots were heavily impacted. Long-term S. frugiperda management should be based on Integrated Pest Management (IPM) principles, including minimising the use of chemical pesticides to protect natural enemies.
| S-EPMC9748589 | biostudies-literature
Project description:The relationship between plants and insects is continuously evolving, and many insects rely on biochemical strategies to mitigate the effects of toxic chemicals in their food plants, allowing them to feed on well-defended plants. Spodoptera frugiperda, the fall armyworm (FAW), accepts a number of plants as hosts, and has particular success on plants of the Poaceae family such as maize, despite their benzoxazinoid (BXD) defenses. BXDs stored as inert glucosides are converted into toxic aglucones by plant glucosidases upon herbivory. DIMBOA, the main BXD aglucone released by maize leaves, can be stereoselectively re-glucosylated by UDP-glycosyltransferases (UGTs) in the insect gut, rendering it non-toxic. Here, we identify UGTs involved in BXD detoxification by FAW larvae and examine how RNAi-mediated manipulation of the larval glucosylation capacity toward the major maize BXD, DIMBOA, affects larval growth. Our findings highlight the involvement of members of two major UGT families, UGT33 and UGT40, in the glycosylation of BXDs. Most of the BXD excretion in the frass occurs in the form of glucosylated products. Furthermore, the DIMBOA-associated activity was enriched in the gut tissue, with a single conserved UGT33 enzyme (SfUGT33F28) being dedicated to DIMBOA re-glucosylation in the FAW gut. The knock-down of its encoding gene reduces larval performance in a strain-specific manner. This study thus reveals that a single UGT enzyme is responsible for detoxification of the major maize-defensive BXD in this pest insect.
| S-EPMC7781194 | biostudies-literature
Project description:BackgroundThe fall armyworm, Spodoptera frugiperda, is an agricultural pest of significant economic concern globally, known for its adaptability, pesticide resistance, and damage to key crops such as maize. Conventional chemical pesticides pose challenges, including the development of resistance and environmental pollution. The study aims to investigate an alternative solution: the application of soluble silicon (Si) sources to enhance plant resistance against the fall armyworm.MethodsSilicon dioxide (SiO2) and potassium silicate (K2SiO3) were applied to maize plants via foliar spray. Transcriptomic and biochemical analyses were performed to study the gene expression changes in the fall armyworm feeding on Si-treated maize.ResultsResults indicated a significant impact on gene expression, with a large number of differentially expressed genes (DEGs) identified in both SiO2 and K2SiO3 treatments. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis identified critical DEGs involved in specific pathways, including amino acid, carbohydrate, lipid, energy, xenobiotics metabolisms, signal transduction, and posttranslational modification, significantly altered at both Si sources. Biochemical analyses further revealed that Si treatments inhibited several enzyme activities (glutamate dehydrogenase, trehalase, glucose-6-phosphate dehydrogenase, chitinase, juvenile hormone esterase, and cyclooxygenase while simultaneously inducing others (total protein, lipopolysaccharide, fatty acid synthase, ATPase, and cytochrome P450), thus suggesting a toxic effect on the fall armyworm. In conclusion, Si applications on maize influence the gene expression and biochemical activities of the fall armyworm, potentially offering a sustainable pest management strategy.
| S-EPMC10896081 | biostudies-literature