Toxicological and molecular adverse effect of Illicium verum fruit constituents toward Bradysia procera

BACKGROUND

Bradysia procera, a ginseng stem fungus gnat, is one of the most serious insect pests of Korean ginseng (Panax ginseng), causing significant damage to plant growth. The goal of this study was to determine the toxicity and mechanism of action of phenylpropanoids (trans-anethole and estragole) isolated from the methanol extract and hydrodistillate of Illicium verum fruit against third-instar larvae and eggs of Bradysia procera.

RESULTS

The filter-paper mortality bioassay revealed that estragole [median lethal concentration (LC₅₀ ) = 4.68 g/cm² ] has a significant fumigant effect, followed by trans-anethole (LC₅₀ = 43.92 g/cm² ). However, estragole had the lowest toxic effect when compared to commercially available insecticides. After 7 days, estragole and trans-anethole at 75 g/cm² inhibited egg hatchability up to 97% and 93%, respectively. At 0.09 g/cm² , insecticides had an inhibitory effect on egg-hatching ability ranging from 88% to 94%. Furthermore, in both closed and open containers, these active constituents were able to consistently induce vapor-phased toxicity. Both estragole and trans-anethole have the ability to inhibit acetylcholinesterase (AChE), which is involved in neurotransmitter function. However, the active constituent estragole from I. verum fruit acted as a potent AChE inhibitor and had a slightly lower effect on cyclic adenosine monophosphate (AMP) than octopamine alone.

CONCLUSION

This finding suggests that estragole may influence Bradysia procera neurotransmitter function via both the AChE and octopaminergic receptors. More research is needed to demonstrate the potential applications of I. verum fruit-derived products as potential larvicides and ovicides for Bradysia procera population control. © 2022 Society of Chemical Industry.

Phenological growth stages of Korean ginseng (Panax ginseng) according to the extended BBCH scale

BACKGROUND

Phenological studies are a prerequisite for accomplishing higher productivity and better crop quality in cultivated plants. However, there are no phenological studies on Panax ginseng that improve its production yield. This study aims to redefine the phenological growth stages of P. ginseng based on the existing Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale and proposes a disease control reference.

METHODS

This study was conducted at the Korea Ginseng Corporation Experiment Station in Gyeonggi province, South Korea. Phenological observations were performed once weekly or twice monthly, based on the developmental stages. The existing BBCH scale with a three-digit code was used to redefine and update P. ginseng's phenological growth codes.

RESULTS

The phenological description is divided into eight principal growth stages: three for vegetative growth (perennating bud, aerial shoot, and root development), four for reproductive growth (reproductive organ development, flowering, fruit development, and fruit maturation), and one for senescence according to the extended BBCH scale. A total of 58 secondary growth stages were described within the eight principal growth stages. Under each secondary growth stage, four mesostages are also taken into account, which contains the distinct patterns of the phenological characteristics in ginseng varieties and the process of transplanting seedlings. A practical management program for disease control was also proposed by using the BBCH code and the phenological data proposed in this work.

CONCLUSION

The study introduces an extended BBCH scale for the phenological research of P. ginseng.

Ovicidal and larvicidal activity and possible mode of action of phenylpropanoids and ketone identified in Syzygium aromaticum bud against Bradysia procera

Bradysia procera is a serious insect pest of Panax ginseng plants. This study was conducted to determine the toxicity and mechanism of action of three phenylpropanoids, three terpenoids, and a ketone from Syzygium aromaticum bud methanol extract and hydrodistillate against third-instar larvae and eggs of B. procera. In a filter-paper mortality bioassay, methyl salicylate (LC₅₀, 5.26μg/cm²) was the most toxic compound, followed by 2-nonanone, eugenol, and eugenyl acetate (8.77-15.40μg/cm²). These compounds were significantly less toxic than either thiamethoxam, clothianidin, or cypermethrin. Egg hatching was inhibited by 97, 85, and 40% at 11.7μg/cm² of methyl salicylate, 2-nonanone, and eugenol, respectively. The egg-hatching inhibition of these insecticides was between 90 and 94% at 0.09μg/cm². These constituents were consistently more toxic in closed versus open containers, indicating that toxicity was achieved mainly through the action of vapor. The mechanism of larvicidal action of methyl salicylate, eugenol, and eugenyl acetate might be primarily due to interference with the octopaminergic system. 2-Heptyl acetate and 2-nonanone might act on both acetylcholinesterase and the octopaminergic receptor. 2-Heptanone might act primarily on acetylcholinesterase. Further studies will warrant possible applications of S. aromaticum bud-derived products as potential larvicides and ovicides for the control of B. procera.

Genetic diversity and population structure analysis in Perilla frutescens from Northern areas of China based on simple sequence repeats

In this study, 21 simple sequence repeat (SSR) markers were used to evaluate the genetic diversity and population structure among 77 Perilla accessions from high-latitude and middle-latitude areas of China. Ninety-five alleles were identified with an average of 4.52 alleles per locus. The average polymorphic information content (PIC) and genetic diversity values were 0.346 and 0.372, respectively. The level of genetic diversity and PIC value for cultivated accessions of Perilla frutescens var. frutescens from middle-latitude areas were higher than accessions from high-latitude areas. Based on the dendrogram of unweighted pair group method with arithmetic mean (UPGMA), all accessions were classified into four major groups with a genetic similarity of 46%. All accessions of the cultivated var. frutescens were discriminated from the cultivated P. frutescens var. crispa. Furthermore, most accessions of the cultivated var. frutescens collected in high-latitude and middle-latitude areas were distinguished depending on their geographical location. However, the geographical locations of several accessions of the cultivated var. frutescens have no relation with their positions in the UPGMA dendrogram and population structure. This result implies that the diffusion of accessions of the cultivated Perilla crop in the northern areas of China might be through multiple routes. On the population structure analysis, 77 Perilla accessions were divided into Group I, Group II, and an admixed group based on a membership probability threshold of 0.8. Finally, the findings in this study can provide useful theoretical knowledge for further study on the population structure and genetic diversity of Perilla and benefit for Perilla crop breeding and germplasm conservation.

Toxicity of Kaempferia galanga rhizome constituents to Meloidogyne incognita juveniles and eggs

Abstract

The toxicity of Kaempferia galanga rhizome constituents to second-stage juveniles (J2) and eggs of Meloidogyne incognita was examined in vitro and in container experiments. Results were compared with those of three nematicides: carbofuran, fosthiazate and metam sodium. Ethyl cinnamate (EC) and ethyl p-methoxycinnamate (EMC) were the nematicidal and hatch inhibitory principles. In direct-contact mortality bioassays, EC 0.037 mg ml–1) and EMC (0.041 mg ml–1) were more toxic than carbofuran (0.092 mg ml–1) but less toxic than fosthiazate (0.002 mg ml–1) towards J2 based upon 48 h LC50 values. EC and EMC treatments resulted in 100% and 93 and 81% inhibition of hatch at 125.0 and 62.5 μg ml–1, respectively. Inhibition of these compounds was higher than carbofuran and metam sodium but significantly lower than fosthiazate. In contact +fumigant mortality bioassays with J2, EC and EMC applied at 0.25 and 0.125 mg (g soil)–1resulted in 81 and 80% and 77 and 73% mortality, respectively, while carbofuran and metam sodium treatments resulted in 86 and 96% and 57 and 73% mortality, respectively. Fosthiazate resulted in 92% mortality at 0.063 mg (g soil)–1. In vapour-phase mortality bioassays with J2, EC and EMC were more effective in a closed container than in an open one, indicating that mode of delivery was, in part, a result of vapour action. Global efforts to reduce the level of highly toxic synthetic nematicides in the agricultural environment justify further studies on K. galanga rhizome-derived materials, particularly ethyl cinnamate and ethyl p-methoxycinnamate, as potential nematicides and hatching inhibitors for the control of M. incognita as fumigants with contact action.

Toxicity of Kaempferia galanga rhizome-derived extract and steam distillate to Meloidogyne incognita juveniles and eggs, and their effects on Lycopersicon esculentum germination and growth

Abstract

The toxicity of Kaempferia galanga rhizome-derived methanol extract (RME), powder (RP) and steam distillate (RSD) to Meloidogyne incognita second-stage juveniles (J2) and eggs, and their effects on Lycopersicon esculentum germination and growth were examined in vitro and in pot experiments. Results were compared with those of three nematicides: carbofuran, fosthiazate and metam sodium. In contact + fumigant bioassays with J2, RME applied at 1, 0.5 and 0.25 mg (g soil)–1 resulted in 92, 88 and 73% mortality, respectively. The lethality of RME was almost the same as carbofuran but lower than that of either fosthiazate or metam sodium. RSD and RP were less active than RME. In vapour-phase mortality bioassays with J2, the test materials were more effective in a closed container than in an open one, indicating that mode of delivery was, in part, a result of vapour action. In direct-contact mortality bioassays with M. incognita eggs, RME, RSD and fosthiazate treatments resulted in 91, 100 and 95% inhibition of hatch at 250 μg ml–1 and 82, 88 and 81% inhibition of hatch at 100 μg ml–1, respectively. In filter paper bioassays with L. esculentum seed, 8.8 μg cm–2 RME and RP did not cause germination inhibition, while RSD and fosthiazate treatments resulted in 84 and 13% germination inhibition. In pot tests, RME and RSD applied at 8 mg (g soil)–1 reduced galling caused by M. incognita significantly, and fosthiazate at 0.02 mg (g soil)–1 stopped galling completely. Kaempferia galanga rhizome-derived materials, particularly a methanol extract, merit further study as potential nematicides and hatching inhibitors for the control of M. incognita as fumigants with contact action.

The behavior of a poly(aniline) solid contact pH selective electrode based on N,N,N',N'-tetrabenzylethanediamine ionophore

A hydrogen ion-selective solid-contact electrode based on N,N,N',N'-tetrabenzylethanediamine has shown the best Nernstian slope and selectivity and the widest response range in a Tris buffered pH sample solution. Its linear dynamic range was pH 3.50-11.94, and the Nernstian slope showed 52.1 mV/pH (at 20 +/- 0.2 degrees C). When it was directly applied to human whole blood (in pH range 6.0-8.5) we could obtain the same satisfying results. This electrode continuously contacted a Tris 7.47 buffered solution, human whole blood and a hydrofluoric acid solution for one month without any loss of performance. Also, hydrofluoric acid did not influence the surface of this electrode, and thus it was maintained without showing any changes in potentials after being used in a hydrofluoric acid solution. The standard deviation in the determined e.m.f. differences was 1.5 mV (N = 5) for Tris buffer solutions of pH 6.5 and 1.1 mV at a Tris buffer solutions of pH 8.5. The 90% response time of the electrodes obtained by injecting of hydrochloric acid into the Tris buffer sample solution was less than 10 s. Especially, in the this paper, with these potential response characteristics of hydrogen ion selective poly(aniline) solid contact electrode, we have also presented the pH response mechanism of this electrode and the role of poly(aniline) and a doped anion in a poly(aniline) layer.