Interference mechanism of Sophora alopecuroides L. alkaloids extract on host finding and selection of the Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

Impacts of Climate Change on the Habitat Suitability and Natural Product Accumulation of the Medicinal Plant Sophora alopecuroides L. Based on the MaxEnt Model

Sophora alopecuroides L., a perennial herb in the arid and semi-arid regions of northwest China, has the ecological functions of windbreaking and sand fixation and high medicinal value. In recent years, global warming and human activities have led to changes in suitable habitats for S. alopecuroides, which may affect the accumulation of natural products. In this study, MaxEnt 3.4 and ArcGIS 10.4 software were used to predict the distribution of potentially suitable habitats for S. alopecuroides in China under climate change. Furthermore, the geographical distribution of S. alopecuroides as affected by human activities, the differences in the content of natural products of S. alopecuroides between different suitable habitats, and the correlation between natural products and environmental factors were analyzed. The results showed that suitable habitats for S. alopecuroides were projected to expand in the future, and the major environmental factors were temperature (Bio1), rainfall (Bio18), and soil pH (pH). When Bio1, Bio18, and pH were 8.4283 °C, 7.1968 mm, and 9.9331, respectively, the distribution probability (P) of S. alopecuroides was the highest. After adding a human activity factor, the accuracy of the model prediction results was improved, and the area of suitable habitats was greatly reduced, showing a fragmented pattern. Meanwhile, habitat suitability had a specific effect on the content of natural products in S. alopecuroides. Specifically, the content of natural products in S. alopecuroides in wild habitats was higher than that in artificial cultivation, and highly suitable habitats showed higher contents than those in non-highly suitable habitats. The contents of total alkaloids and total flavonoids were positively correlated with human activities and negatively correlated with land use types. Among them, total alkaloids were negatively correlated with aspect, and total flavonoids were positively correlated with aspect. In addition, it is suggested that Xinjiang should be the priority planting area for S. alopecuroides in China, and priority should be given to protection measures in the Alashan area. Overall, this study provides an important foundation for the determination of priority planting areas and resource protection for S. alopecuroides.

The Role of Honey Bee Derived Aliphatic Esters in the Host-Finding Behavior of Varroa destructor

Varroa destructor is an obligate ectoparasite of honey bees and shifted from its original host Apis cerana to the new host Apis mellifera in the first half of the twentieth century. The host shift has resulted in a great threat to the health and survival of A. mellifera colonies worldwide. Chemical signals play a crucial role in all aspects of the Varroa life cycle, including host finding. However, the chemical cues that affect the host finding behavior of Varroa mites are still not fully understood. In this study, we systematically profiled the headspace volatiles of both worker and drone larvae of the two honey bee species by using solid phase micro-extraction coupled to gas chromatography-mass spectrometry (SPME-GC-MS), and then used electrophysiological recording and Y-tube olfactometer bioassay to study the potential roles of the selected compounds. The chemical profiling showed that there were four aliphatic esters, ethyl myristate (EM), methyl palmitate (MP), ethyl palmitate (EP), and ethyl oleate (EO) commonly detected from all four types of larval hosts. Among them, EM was a new substance identified from honey bee headspace volatiles. Results from electrophysiological recordings indicated that all the aliphatic esters could elicit significant responses of Varroa pit organs on its forelegs. Moreover, behavioral analyses revealed that EM could significantly attract V. destructor at a medium dosage (10 µg), while MP had no observable effect on the mites and both EP and EO were able to repel the parasites. Our findings suggest an important role of host-derived aliphatic esters in Varroa host finding, and provide new chemicals for Varroa monitoring and control.

Plasticity in Chemical Host Plant Recognition in Herbivorous Insects and Its Implication for Pest Control

Chemical communication is very important in herbivorous insects, with many species being important agricultural pests. They often use olfactory cues to find their host plants at a distance and evaluate their suitability upon contact with non-volatile cues. Responses to such cues are modulated through interactions between various stimuli of biotic and abiotic origin. In addition, the response to the same stimulus can vary as a function of, for example, previous experience, age, mating state, sex, and morph. Here we summarize recent advances in the understanding of plant localization and recognition in herbivorous insects with a focus on the interplay between long- and short-range signals in a complex environment. We then describe recent findings illustrating different types of plasticity in insect plant choice behavior and the underlying neuronal mechanisms at different levels of the chemosensory pathway. In the context of strong efforts to replace synthetic insecticides with alternative pest control methods, understanding combined effects between long- and close-range chemical cues in herbivore-plant interactions and their complex environment in host choice are crucial to develop effective plant protection methods. Furthermore, plasticity of behavioral and neuronal responses to chemical cues needs to be taken into account to develop effective sustainable pest insect control through behavioral manipulation.

Genus Sophora: a comprehensive review on secondary chemical metabolites and their biological aspects from past achievements to future perspectives

Sophora is deemed as one of the most remarkable genera of Fabaceae, and the third largest family of flowering plants. The genus Sophora comprises approximately 52 species, 19 varieties, and 7 forms that are widely distributed in Asia and mildly in Africa. Sophora species are recognized to be substantial sources of broad spectrum biopertinent secondary metabolites namely flavonoids, isoflavonoids, chalcones, chromones, pterocarpans, coumarins, benzofuran derivatives, sterols, saponins (mainly triterpene glycosides), oligostilbenes, and mainly alkaloids. Meanwhile, extracts and isolated compounds from Sophora have been identified to possess several health-promising effects including anti-inflammatory, anti-arthritic, antiplatelets, antipyretic, anticancer, antiviral, antimicrobial, antioxidant, anti-osteoporosis, anti-ulcerative colitis, antidiabetic, anti-obesity, antidiarrheal, and insecticidal activities. Herein, the present review aims to provide comprehensive details about the phytochemicals and biological effects of Sophora species. The review spotlighted on the promising phytonutrients extracted from Sophora and their plethora of bioactivities. The review also clarifies the remaining gaps and thus qualifies and supplies a platform for further investigations of these compounds.

Unraveling the Biosynthesis of Quinolizidine Alkaloids Using the Genetic and Chemical Diversity of Mexican Lupins

Quinolizidine alkaloids (QAs) are synthesized by the genus Lupinus as a defense against herbivores. Synthesis of QAs in lupins is species- and organ-specific. Knowledge about their biosynthesis and their corresponding pathways are still fragmentary, in part because lupins of commercial importance were mainly investigated, representing a small sample of the chemodiversity of the genus. Here, we explore the use of three Mexican lupins: Lupinus aschenbornii, Lupinus montanus, and Lupinus bilineatus as a model to study the physiology of QA biosynthesis. The corresponding QA patterns cover widely and narrowly distributed tetracyclic QAs. Quinolizidine alkaloid patterns of seeds and plantlets at different developmental stages were determined by GLC–MS and compared to identify the onset of de novo QA synthesis and to gain insight into specific and common biosynthesis trends. Onset of de novo QA biosynthesis occurred after the metabolization of seed QA during germination and was species-specific, as expected. A common QA pattern, from which the diversity of QA observed in these species is generated, was not found; however, lupanine and 3β-lupanine were found in the three specieswhile sparteine was not found in Lupinus bilineatus, suggesting that this simplest tetracyclic QA is not the precursor of more complex QAs. Similar patterns of metabolization and biosynthesis of structurally related QAs were observed, suggesting a common regulation.

Proteome profiling reveals the efficacy and targets of sophocarpine against asthma

Sophocarpine (SPC) as a quinolizidine alkaloid displays powerful effects on inflammatory diseases through regulating multiple targets. Asthma is a complex heterogeneous and inflammatory disease with an increasing incidence worldwide. Here we established a mice asthma model and investigated the effect of SPC. Mice induced by ovalbumin (OVA) exhibits exacerbated Th1/Th2 immune imbalance and allergic lung inflammation. SPC treatment regulated Th1/Th2 cytokines production (IL-4, IL-5 and INF-γ) in BALF, reduced IgE level in serum, inhibited inflammatory cell infiltration, and improved the lung tissue pathology. Proteomic results showed that 5064 proteins in lung tissue were detected and among them 223 preliminary therapeutic targets of SPC were selected. Subsequently, excluding non-human genes, 109 targets with established crystal structures were harvested. Meanwhile, the molecular docking results showed that the binding energy of 87 targets with SPC was varied from -9.72 kcal/mol to 227.16 kcal/mol. Further, SPC suppressed arrb2, anxa1, myd88 and sphk1 expression and activated p-stat1. All of the five targets based on the screened results of proteomics and molecular docking are critical in allergic asthma. Thus, our data revealed that SPC alleviated bronchial asthma via targeting multi-targets.

Host plant odours and their recognition by the odourant-binding proteins of Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

BACKGROUND

The Asian citrus psyllid (ACP), Diaphorina citri, is one of the major pests in citrus production because it transmits huanglongbing, a devastating disease of citrus plants. Odourant-binding proteins (OBPs) play an important role in the olfactory perception of insects. Revealing the function of DcitOBPs is beneficial to the development of new ACP management strategies.

RESULTS

An analysis of the components of volatiles from the new shoots of six host plant species showed that β-caryophyllene was the characteristic volatile compound in flushing shoots and the most abundant volatile compound in three of the six tested ACP host plant species. The tissue expression profiles of nine known DcitOBPs were analyzed based on a transcriptome database, and DcitOBP3 and DcitOBP6 exhibited high expression in the antennae of both sexes and the ovipositor of females. The binding ability of two recombinant proteins with eight ligands was studied through competitive binding analysis; the results showed that DcitOBP6 exhibited stronger binding to β-caryophyllene. Behavioural trials indicated that sexually mature female adults of D. citri were significantly attracted to β-caryophyllene at concentrations of 0.1 μL mL^-1 and 10 μL mL^-1 . RNAi analysis in female D. citri showed that the reduction of DcitOBP6 transcript abundance led to a decrease in antennae EAG activity and behavioural responses to β-caryophyllene.

CONCLUSION

The results demonstrate that DcitOBP6 is involved in the perception of an important host plant volatile, β-caryophyllene, in the ACP, and provide a theoretical foundation for behavioural interference in ACP management.

Larvicidal, Ovicidal, Synergistic, and Repellent Activities of Sophora alopecuroides and Its Dominant Constituents Against Aedes albopictus

In the current study, to combat insecticide resistance, we explored larvicidal, ovicidal, synergistic, and repellent activities of Sophora alopecuroides extract and its dominant constituents against Aedes albopictus. The results of the toxicity bioassays demonstrated that the extract of S. alopecuroides exerted significant larvicidal activity (16.66-86.66%) against the third-instar larvae of Ae. albopictus at different concentrations (5-50 ug/mL) and low hatchability of eggs (2.32-75%) at 5-50 ug/mL. The constituents of S. alopecuroides showed a synergistic effect when applied as a mixture (LC30 + LC30) against larvae, while no synergistic effect was observed against the eggs of Ae. albopictus. S. alopecuroides extract provided 93.11% repellency in the first 90 min and gradually decreased to 53.14% after 240 min, while the positive control DEET (N,N-diethyl-3-methylbenzamide) showed 94.18% in the first 90 min and 55.33% after 240 min. All of the results exhibited a concentration-dependent effect. To the best of our knowledge, this is the first time that a study has identified a highly effective extract of S. alopecuroides, which could be used as an alternative agent to control larvae and eggs and to repel adults of Ae. albopictus.

Effects of botanical pesticide itol A against the tobacco cutworm, Spodoptera litura (Fab.)

Itol A, an isoryanodane diterpene derived from Itoa orientalis Hemsl. (Flacourtiaceae), is a potential plant-based insecticide. However, the effect of itol A on the tobacco cutworm [Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)], an important and widely distributed insect pest, remains unclear. In this study, the toxicity and inhibitory potency of itol A on S. litura were evaluated. The results indicated that itol A exhibited larvicidal activity against the third instar larvae in a concentration-dependent manner (LC50 875.48 mg/L at 96 h). Antifeedant activity also was observed, and the 24-h AFC50 values were 562.05 and 81.47 mg/L in the no-choice and choice experiments, respectively. The insect growth was inhibited after treatment of itol A, as reflected by long developmental periods, low-quality pupae, and various abnormalities. Itol A exerted ovicidal effect on S. litura, with an estimated LC50 of 759.30 mg/L. Itol A deterred oviposition in the choice experiment (ODI50 909.60 mg/L). Besides, the activities of α-amylase, general protease, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were inhibited after itol A treatment over time compared to controls, which may be a relevant mechanism underlying the toxicity of itol A toward S. litura. However, the activities of lipase, carboxylesterase (CarE), glutathione S-transferase (GST), and cytochrome P450 monooxygenase (P450) were increased. Taken together, these results suggest that itol A could be a good botanical pesticide to reduce the population of S. litura in integrated pest management programs.

Assessment of Lethal, Sublethal, and Transgenerational Effects of Beauveria Bassiana on the Demography of Aedes Albopictus (Culicidae: Diptera)

Dengue fever is one of the most rapidly spreading arthropod-borne diseases. Diurnal vectorial properties of Aedes albopictus contribute to the dispersion of the dengue viruses. Frequent and injudicious use of synthetic insecticides led to the evolution of resistant phenotypes in Ae. albopictus which necessitates the search for an alternative of current control strategies. Developing a long-lasting and environmentally safe tactic based on knowledge of ecology and population dynamics of Ae. albopictus is critical. Therefore, with a view towards biological control and ecology, the effect of entomopathogenic fungi (EPF) Beauveria bassiana on filial and first filial generations of Ae. albopictus were studied. Investigations showed 87.5% adulticidal activity leading to altered fecundity and adult longevity in a filial generation. The lethal (LC50) and sublethal (LC20) concentrations of B. bassiana were applied to filial generation (F0) to study demographic parameters in the first filial generation (F1). Results showed reduced net reproductive rates (Ro) intrinsic rate of increase (r), and mean generation time (T) compared to uninfected controls. Prolonged larval and pupal duration were observed followed by reduced longevity of male and female adults. Fecundity in the first filial generation was significantly changed with the lethal and sublethal concentrations of B. bassiana. Thus, it is concluded that B. bassiana has the potential to play a vital role in integrated mosquito management strategies.

Sophora alopecuroides L.: An ethnopharmacological, phytochemical, and pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora alopecuroides L., which is called Kudouzi in China, is a medicinal plant distributed in Western and Central Asia, especially in China, and has been used for decades to treat fever, bacterial infection, heart disease, rheumatism, and gastrointestinal diseases.

AIM OF THE REVIEW

This review aims to provide up-to-date information on S. alopecuroides, including its botanical characterization, medicinal resources, traditional uses, phytochemistry, pharmacological research, and toxicology, in exploring future therapeutic and scientific potentials.

MATERIALS AND METHODS

The information related to this article was systematically collected from the scientific literature databases including PubMed, Google Scholar, Web of Science, Science Direct, Springer, China National Knowledge Infrastructure, published books, PhD and MS dissertations, and other web sources, such as the official website of Flora of China and Yao Zhi website (https://db.yaozh.com/).

RESULTS

A total of 128 compounds, such as alkaloids, flavonoids, steroids, and polysaccharides, were isolated from S. alopecuroides. Among these compounds, the effects of alkaloids, such as matrine and oxymatrine, were extensively studied and developed into new drugs. S. alopecuroides and its active components had a wide range of pharmacological activities, such as anticancer, antiviral, anti-inflammatory, antimicrobial, analgesic, and neuroprotective functions, as well as protective properties against pulmonary fibrosis and cardiac fibroblast proliferation.

CONCLUSIONS

As an important traditional Chinese medicine, modern pharmacological studies have demonstrated that S. alopecuroides has prominent bioactivities, especially on gynecological inflammation and hepatitis B, and anticancer activities. These activities provide prospects for novel drug development for cancer and some chronic diseases. Nevertheless, the comprehensive evaluation, quality control, understanding of the multitarget network pharmacology, long-term in vivo toxicity, and clinical efficacy of S. alopecuroides require further detailed research.