Soil dissipation of sugarcane billet seed treatment fungicides and insecticide using QuEChERS and HPLC

Complete genome analysis of sugarcane root associated endophytic diazotroph Pseudomonas aeruginosa DJ06 revealing versatile molecular mechanism involved in sugarcane development

Sugarcane is an important sugar and bioenergy source and a significant component of the economy in various countries in arid and semiarid. It requires more synthetic fertilizers and fungicides during growth and development. However, the excess use of synthetic fertilizers and fungicides causes environmental pollution and affects cane quality and productivity. Plant growth-promoting bacteria (PGPB) indirectly or directly promote plant growth in various ways. In this study, 22 PGPB strains were isolated from the roots of the sugarcane variety GT42. After screening of plant growth-promoting (PGP) traits, it was found that the DJ06 strain had the most potent PGP activity, which was identified as Pseudomonas aeruginosa by 16S rRNA gene sequencing. Scanning electron microscopy (SEM) and green fluorescent protein (GFP) labeling technology confirmed that the DJ06 strain successfully colonized sugarcane tissues. The complete genome sequencing of the DJ06 strain was performed using Nanopore and Illumina sequencing platforms. The results showed that the DJ06 strain genome size was 64,90,034 bp with a G+C content of 66.34%, including 5,912 protein-coding genes (CDSs) and 12 rRNA genes. A series of genes related to plant growth promotion was observed, such as nitrogen fixation, ammonia assimilation, siderophore, 1-aminocyclopropane-1-carboxylic acid (ACC), deaminase, indole-3-acetic acid (IAA) production, auxin biosynthesis, phosphate metabolism, hydrolase, biocontrol, and tolerance to abiotic stresses. In addition, the effect of the DJ06 strain was also evaluated by inoculation in two sugarcane varieties GT11 and B8. The length of the plant was increased significantly by 32.43 and 12.66% and fresh weight by 89.87 and 135.71% in sugarcane GT11 and B8 at 60 days after inoculation. The photosynthetic leaf gas exchange also increased significantly compared with the control plants. The content of indole-3-acetic acid (IAA) was enhanced and gibberellins (GA) and abscisic acid (ABA) were reduced in response to inoculation of the DJ06 strain as compared with control in two sugarcane varieties. The enzymatic activities of oxidative, nitrogen metabolism, and hydrolases were also changed dramatically in both sugarcane varieties with inoculation of the DJ06 strain. These findings provide better insights into the interactive action mechanisms of the P. aeruginosa DJ06 strain and sugarcane plant development.

Change-point analysis of lambda-cyhalothrin efficacy against soybean aphid (Aphis glycines Matsumura): identifying practical resistance from field efficacy trials

BACKGROUND

Soybean aphid (Aphis glycines Matsumura) remains the most economically important arthropod pest of soybean in the Upper Midwest Region of the USA. Soybean aphid resistance to the pyrethroid insecticides emerged in 2015; however, the reduction in the efficacy of field applications of pyrethroid insecticides has not been quantified. Based on time-series data from insecticide efficacy trials at two locations, a novel approach of continuous two-phase change point-regression models was used to indicate whether a change in percent control had occurred, and to provide an indication of when and to what degree the percent control had changed.

RESULTS

At both locations examined in this study, a significant change point for percent control of λ-cyhalothrin was detected in 2014, thus marking the onset of practical resistance in the soybean aphid. Percent control decreased at a rate of 4.30% and 19.90% per year at these locations. By contrast, percent control for chlorpyrifos remained high over time with no significant change point.

CONCLUSION

This research demonstrates that retrospective time-series analysis of insecticide efficacy data can identify the onset and magnitude of practical resistance in the field. This further validates and compliments the other lines of evidence related to pyrethroid resistance in soybean aphid. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.