scholarly journals Differences in Microbiota Between Two Multilocus Lineages of the Sugarcane Aphid (Melanaphis sacchari) in the Continental United States

2020 ◽  
Vol 113 (4) ◽  
pp. 257-265 ◽  
Author(s):  
Jocelyn R Holt ◽  
Alex Styer ◽  
Jennifer A White ◽  
J Scott Armstrong ◽  
Samuel Nibouche ◽  
...  

Abstract The sugarcane aphid (SCA), Melanaphis Sacchari (Zehntner) (Hemiptera: Aphididae), has been considered an invasive pest of sugarcane in the continental United States since 1977. Then, in 2013, SCA abruptly became a serious pest of U.S. sorghum and is now a sorghum pest in 22 states across the continental United States. Changes in insect-associated microbial community composition are known to influence host-plant range in aphids. In this study, we assessed whether changes in microbiota composition may explain the SCA outbreak in U.S. sorghum. We characterized the SCA bacterial microbiota on sugarcane and grain sorghum in four U.S. states, using a metabarcoding approach. In addition, we used taxon-specific polymerase chain reaction (PCR) primers to screen for bacteria commonly reported in aphid species. As anticipated, all SCA harbored the primary aphid endosymbiont Buchnera aphidicola, an obligate mutualistic bacterial symbiont. Interestingly, none of the secondary symbionts, facultative bacteria typically associated with aphids (e.g., Arsenophonus, Hamiltonella, Regiella) were present in either the metabarcoding data or PCR screens (with the exception of Rickettsiella and Serratia, which were detected by metabarcoding at low abundances <1%). However, our metabarcoding detected bacteria not previously identified in aphids (Arcobacter, Bifidobacterium, Citrobacter). Lastly, we found microbial host-associated differentiation in aphids that seems to correspond to genetically distinct aphid lineages that prefer to feed on grain sorghum (MLL-F) versus sugarcane (MLL-D).

2021 ◽  
Vol 22 (13) ◽  
pp. 7129
Author(s):  
Desalegn D. Serba ◽  
Xiaoxi Meng ◽  
James Schnable ◽  
Elfadil Bashir ◽  
J. P. Michaud ◽  
...  

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae) (SCA), has become a major pest of grain sorghum since its appearance in the USA. Several grain sorghum parental lines are moderately resistant to the SCA. However, the molecular and genetic mechanisms underlying this resistance are poorly understood, which has constrained breeding for improved resistance. RNA-Seq was used to conduct transcriptomics analysis on a moderately resistant genotype (TAM428) and a susceptible genotype (Tx2737) to elucidate the molecular mechanisms underlying resistance. Differential expression analysis revealed differences in transcriptomic profile between the two genotypes at multiple time points after infestation by SCA. Six gene clusters had differential expression during SCA infestation. Gene ontology enrichment and cluster analysis of genes differentially expressed after SCA infestation revealed consistent upregulation of genes controlling protein and lipid binding, cellular catabolic processes, transcription initiation, and autophagy in the resistant genotype. Genes regulating responses to external stimuli and stress, cell communication, and transferase activities, were all upregulated in later stages of infestation. On the other hand, expression of genes controlling cell cycle and nuclear division were reduced after SCA infestation in the resistant genotype. These results indicate that different classes of genes, including stress response genes and transcription factors, are responsible for countering the physiological effects of SCA infestation in resistant sorghum plants.


2019 ◽  
Vol 112 (6) ◽  
pp. 2731-2736 ◽  
Author(s):  
Nicholas J Seiter ◽  
Anne D Miskelley ◽  
Gus M Lorenz ◽  
Neelendra K Joshi ◽  
Glenn E Studebaker ◽  
...  

Abstract The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), has become a major pest of grain sorghum, Sorghum bicolor (L.) Moench, in the United States in recent years. Feeding by large densities of sugarcane aphids causes severe damage, which can lead to a total loss of yield in extreme cases. Our objective was to determine the effect of grain sorghum planting date on sugarcane aphid population dynamics and their potential to reduce yields. We conducted field experiments from 2015 to 2017 in which an aphid-susceptible grain sorghum hybrid was planted at four different dates, which encompassed the typical range of planting dates used in Arkansas production systems. Plots were either protected from sugarcane aphid feeding using foliar insecticide sprays, or left untreated to allow natural populations of sugarcane aphids to colonize and reproduce freely. Planting date impacted both the magnitude and severity of sugarcane aphid infestations, with the highest population densities (and subsequent reductions in sorghum yield) generally occurring on plots that were planted in May or June. Sugarcane aphid feeding reduced yields in the untreated plots in two of the four planting date categories we tested. Earlier planting generally resulted in less sugarcane aphid damage and improved yields compared with later planting dates. While the effect of planting date on sugarcane aphid populations is likely to vary by region, sorghum producers should consider grain sorghum planting date as a potential cultural tactic to reduce the impact of sugarcane aphid.


2020 ◽  
Vol 113 (4) ◽  
pp. 1990-1998 ◽  
Author(s):  
Jessica C Lindenmayer ◽  
Kristopher L Giles ◽  
Norman C Elliott ◽  
Allen E Knutson ◽  
Robert Bowling ◽  
...  

Abstract The sugarcane aphid (Melanaphis sacchari Zehntner) is a significant economic pest of grain sorghum (Sorghum bicolor (L.) Moench) in the Southern United States. Current nominal and research-based economic thresholds are based on estimates of mean aphids per leaf. Because enumerating aphids per leaf is potentially time consuming, binomial sequential sampling plans for M. sacchari were developed that allow users to quickly classify the economic status of field populations and determine when an economic threshold has been exceeded. During 2016 and 2017, counts of M. sacchari were recorded from 281 sampling events in 140 sorghum fields located in six states (Oklahoma, Kansas, Texas, Arkansas, Louisiana, Mississippi) . Regression analysis was used to describe the relationships between the mean M. sacchari density per two-leaf sample and proportion of plants infested with one or more aphids. Tally thresholds of T50 and T100 aphids per two-leaf sample were selected based on goodness of fit and practicality. Stop lines for both tally thresholds were developed for selected economic thresholds using Wald’s sequential probability ratio test. Model validations using an additional 48 fields demonstrated that reliable classification decisions could be made with an average of 11 samples regardless of location. This sampling system, when adopted, can allow users to easily and rapidly determine when M. sacchari infestations need to be treated.


2019 ◽  
Vol 112 (6) ◽  
pp. 2719-2730 ◽  
Author(s):  
Phillip J Haar ◽  
G David Buntin ◽  
Alana Jacobson ◽  
Adrian Pekarcik ◽  
M O Way ◽  
...  

Abstract The invasive sugarcane aphid, Melanaphis sacchari (Zehntner), is a devastating new pest of grain sorghum. Studies were conducted utilizing an integrated approach of four management tactics: planting date, insecticidal seed treatment, a foliar-applied insecticide, and plant resistance. Experiments were conducted in 2016 and 2017 at Griffin, Tifton, and Plains Georgia, and in 2016 in Texas, Alabama, and Oklahoma, United States. Early planting was effective in reducing damage and increasing yields when compared to the late planting. Use of a resistant variety reduced cumulative aphid-days, plant injury and usually prevented significant yield loss. Foliar application of flupyradifurone when aphids reached an economic threshold, was an effective management tactic preventing aphid injury and yield loss. Use of clothianidin seed treatment also reduced aphid injury and yield loss of the susceptible hybrid but generally did not prevent injury and yield loss of the resistant hybrid. We conclude that an earlier planting date coupled with a resistant variety and judicious use of an efficacious foliar-applied insecticide can effectively manage sugarcane aphid on grain sorghum. An insecticide seed treatment also may be useful to reduce the risk of sugarcane aphid damage to seedlings of susceptible hybrids.


2020 ◽  
Vol 113 (4) ◽  
pp. 1850-1857
Author(s):  
B E Wilson ◽  
F P F Reay-Jones ◽  
L Lama ◽  
M Mulcahy ◽  
T E Reagan ◽  
...  

Abstract The sugarcane aphid, Melanaphis sacchari Zehntner, is an economically damaging pest of sorghum, Sorghum bicolor (L.), across the southern United States. Field experiments investigated impacts of sorghum cultivar, nitrogen fertilization, and insecticides on M. sacchari infestations and sorghum yields in Louisiana and South Carolina in 2017 and 2018. In South Carolina, M. sacchari densities in unprotected plots peaked on 30–31 July of both years before declining by early- to mid-August. In Louisiana, infestations peaked on 26 and 12 July for 2017 and 2018, respectively, and declined by mid-August. Nitrogen fertilization influenced M. sacchari densities in Louisiana in 2018 with the highest-level infestations recorded from plots that received high N rates. Densities of M. sacchari on susceptible sorghum cultivar, DKS 38-88, were 1.5- to 2.3-fold greater than on DKS 37-07 in both years in Louisiana and in 2018 in South Carolina. Nitrogen fertilization was associated with improved sorghum yields in Louisiana experiments. Sorghum yields across experiments were 2- to 4-fold greater in plots protected with multiple insecticide applications than in unprotected plots. Yield from plots with insecticides sprayed once at currently used action thresholds differed from unprotected plots only in the 2018 Louisiana experiment. Results from these experiments indicate insecticidal protection of susceptible sorghum cultivars remains critical throughout much of the southern United States. Further research is needed to develop integrated management programs that incorporate fertilization manipulation, cultivar resistance, and insecticidal control.


1995 ◽  
Vol 20 (1) ◽  
pp. 230-230
Author(s):  
R. M. Anderson ◽  
G. L. Teetes

Abstract Foliar treatments of 2 organophosphates and imidachloprid (Confidor) were evaluated for yellow sugarcane aphid (YSA) and greenbug (GB) control in a research greenhouse at Texas A&M University. Hybrid grain sorghum seedlings (ATx399 × RTx430) were grown in 110-mm germination pots containing a prepared soil mixture composed of peat, vermiculite, and periite in a 2:1:1 ratio, respectively. Four days after plant emergence and 3 d prior to insecticide applications, each seedling plant was infested with 10-20 YSA or GB. There were 5 singleseedling replications for each treatment. Insecticides were applied by using a CO2-pressurized backpack sprayer, through TX-3 hollow-cone nozzles at 35 psi, producing a finished spray volume of 5.6 gpa. Pre-treatment counts of YSA and GB were made the day of insecticide application; post-treatment counts of aphids were made 1, 2, and 3 DAT. Percent control was calculated by using Abbott’s (1925) formula. Data were statistically analyzed by using ANOVA and LSD.


Author(s):  
Liliana Aguilar Marcelino ◽  
Jesús Antonio Pineda Alegría ◽  
David Osvaldo Salinas-Sánchez ◽  
Víctor Manuel Hernández Velázquez ◽  
Gonzalo Iván Silva Aguayo ◽  
...  

The sugarcane aphid, Melanaphis sacchari Zehntner (Hemiptera: Aphididae), is the main pest of sorghum, Sorghum bicolor L. Moench (Poaceae), in Mexico. To control this insect, farmers currently use synthetic chemical insecticides, which are toxic to humans and biodiversity. However, natural products are a promising potential source of safer alternative means to control different agricultural pests. The main objective of this study was to evaluate the insecticidal effect of contact by fumigation of pure molecules of four commercial fatty acids (palmitic, stearic, pentadecanoic and linoleic acids), the phytosterol ß -sitosterol, and the flavonoid rutin. The results showed that fatty acids were the most effective against M. sacchari ; the highest mortality rate (85%) was produced by linoleic acid and the LC 50 was 1,181 ppm, followed by stearic and palmitic acids with mortality percentages of 74 and 63%, respectively, at a concentration of 2,500 ppm at 72 h. The positive control, imidacloprid, had 100% mortality in 24 h and the tween 20 negative control exhibited 4% mortality in 72 h. Our results show that commercial fatty acids are effective against adults of M. sacchari , and can be considered an environmentally friendly alternative to the frequent use of synthetic chemical insecticides.


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