Host plant-mediated effects on Buchnera symbiont: implications for biological characteristics and nutritional metabolism of pea aphids (Acyrthosiphon pisum).

Introduction: The pea aphid, Acyrthosiphon pisum, is a typical sap-feeding insect and an important worldwide pest. There is a primary symbiont-Buchnera aphidicola, which can synthesize and provide some essential nutrients for its host. At the same time, the hosts also can actively adjust the density of bacterial symbiosis to cope with the changes in environmental and physiological factors. However, it is still unclear how symbionts mediate the interaction between herbivorous insects' nutrient metabolism and host plants. Methods: The current study has studied the effects of different host plants on the biological characteristics, Buchnera titer, and nutritional metabolism of pea aphids. This study investigated the influence of different host plants on biological characteristics, Buchnera titer, and nutritional metabolism of pea aphids. Results and discussion: The titer of Buchnera was significantly higher on T. Pretense and M. officinalis, and the relative expression levels were 1.966±0.104 and 1.621±0.167, respectively. The content of soluble sugar (53.46±1.97µg/mg), glycogen (1.12±0.07µg/mg) and total energy (1341.51±39.37µg/mg) of the pea aphid on V. faba were significantly higher and showed high fecundity (143.86±11.31) and weight (10.46±0.77µg/mg). The content of total lipids was higher on P. sativum and T. pretense, which were 2.82±0.03µg/mg and 2.92±0.07µg/mg, respectively. Correlation analysis found that the difference in Buchnera titer was positively correlated with the protein content in M. officinalis and the content of total energy in T. pratense (P < 0.05). This study confirmed that host plants not only affected the biological characteristics and nutritional metabolism of pea aphids but also regulated the symbiotic density, thus interfering with the nutritional function of Buchnera. The results can provide a theoretical basis for further studies on the influence of different host plants on the development of pea aphids and other insects.

Visual and Electrochemical Detection of let-7a: A Tumor Suppressor and Biomarker.

Let-7a, a type of low-expressed microRNAs in cancer cells, has been investigated as a promising biomarker and therapeutic target for tumor suppression. Developing simple and sensitive detection methods for let-7a is important for cancer diagnosis and treatment. In this work, the hybridization chain reaction (HCR) was initiated by let-7a via two hairpin primers (H1 and H2). After the HCR, the remaining hairpin H1 was further detected by lateral flow assay (LFA) and electrochemical impedance spectroscopy. For LFA, biotin-modified H1(bio-H1) and free H2 were used for HCR. With the decrease of let-7a concentration, the color of T line gradually increased. As for electrochemical methods, the H1'-AuNP-modified electrode was used for detection of bio-H1 based on the difference of impedance (ΔRct) detected without and with different concentrations of let-7a participating in the HCR. This method could detect let-7a in the range of 10.0 fM and 1.0 nM with detection limits of 4.2 fM.

Oviposition Preference and Age-Stage, Two-Sex Life Table Analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Different Maize Varieties.

Host plants play an important role in the growth, development, and reproduction of insects. However, only a few studies have reported the effects of maize varieties on the growth and reproduction of S. frugiperda. In this study, a free-choice test was used to evaluate the oviposition preferences of female adults on ten common maize varieties and ten special maize varieties. The population fitness of S. frugiperda on six different maize varieties was also examined using the age-stage, two-sex life table method. The results showed that S. frugiperda oviposited and completed its life cycle across all maize cultivars. Moreover, the S. frugiperda females exhibited a significantly higher oviposition preference on the special maize varieties than on the common maize varieties. The highest number of eggs and egg masses occurred on Baitiannuo and the lowest on Zhengdan 958. The egg + larval stage, preadult, pupal stage, adult, APOP, TPOP, and total longevity of S. frugiperda were significantly shorter on the special maize varieties than on the common maize varieties. The fecundity, oviposition days, pupal weight, and hatching rate of S. frugiperda were significantly higher on the special maize varieties than on the common maize varieties. Specifically, S. frugiperda had the highest fecundity, female, and male pupal weight on Baitiannuo. Moreover, the net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of S. frugiperda were the greatest on Baitiannuo, whereas the shortest mean generation time (T) occurred on Zaocuiwang. The lowest R0, r, and λ, and longest T occurred on Zhengdan 958, suggesting that Zhengdan 958 is a non-preferred host plant compared to the other tested maize varieties. The findings of this study can provide a reference for the rational planting of maize and provide basic scientific information for the management of S. frugiperda.

Responses of Six Wheat Cultivars (Triticum aestivum) to Wheat Aphid (Sitobion avenae) Infestation.

Resistant variety screening is widely recommended for the management of Sitobion avenae. The purpose of this study was to assess responses of six wheat varieties (lines) to S. avenae. The aphid quantity ratio (AQR) was used to assess S. avenae resistance. Pearson's correlation coefficient was used to perform a correlation analysis between AQR, biological parameters, and the accumulation of total phenolic and flavonoid content. When compared to the other cultivars, the results showed that two cultivars, Yongliang No.15 and Ganchun No.18, had high resistance against S. avenae. The correlation analysis revealed a positive relationship between total phenol and flavonoid content accumulation and developmental duration (DD), and a negative relationship between accumulation and weight gain (WG) and mean relative growth rate (MRGR). The correlation between flavonoid and biological parameters was statistically stronger than the correlation between total phenol and biological parameters. This research provides critical cues for screening and improving aphid-resistant wheat varieties in the field and will aid in our understanding of the resistance mechanism of wheat varieties against S. avenae.