Diatomaceous earth as insecticide: physiological and morphological evidence of its underlying mechanism.

BACKGROUND: Wheat grain containers or silos can be perfect habitats for insects, which generate large economic losses to grain production. Natural alternatives to synthetic insecticides have grown in popularity because of health, economic and ecological issues. Diatomaceous earth is a natural compound that has an insecticide effect by enhancing an insect's dehydration with no toxicity on mammals including humans. The aim of this study is to confirm the effect of diatomaceous earth as an insecticide for the wheat grain pest, the red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae) and demonstrate its underlying mechanisms as an insecticide by open-flow respirometry and scanning electron microscopy. RESULTS: Survival bioassays of T. castaneum revealed a dose-dependent insecticide effect of diatomaceous earth. Gravimetric measurements showed that 2 days exposure to diatomaceous earth produces a significant increase of mass loss. Open-flow respirometry measurements showed an increase of total water emission rate on insects due to an increase of both, respiratory and cuticular water loss. Our study revealed that diatomaceous earth produces an increase of insect's cuticle permeability, which is responsible for elevated cuticular water loss. Scanning electron microscopy images provided visual evidence of the lipid absorbent properties of diatomaceous earth particles, and showed a tendency for higher, although not significant, damaged area of the cuticle's surface from diatomaceous earth treated insects compared to control ones. CONCLUSION: With state-of-the art techniques like open-flow respirometry and scanning electron microscopy, we demonstrated the underlying mechanism of diatomaceous earth as an insecticide and provided new cues for understanding the properties of the cuticle and its ecological importance. © 2024 Society of Chemical Industry.

Integrated Transcriptome Analysis Identified Key Expansin Genes Associated with Wheat Cell Wall, Grain Weight and Yield.

This research elucidates the dynamic expression of expansin genes during the wheat grain (Triticum aestivum L.) development process using comprehensive meta-analysis and experimental validation. We leveraged RNA-seq data from multiple public databases, applying stringent criteria for selection, and identified 60,852 differentially expressed genes across developmental stages. From this pool, 28,558 DEGs were found to exhibit significant temporal regulation in at least two different datasets and were enriched for processes integral to grain development such as carbohydrate metabolism and cell wall organization. Notably, 30% of the 241 known expansin genes showed differential expression during grain growth. Hierarchical clustering and expression level analysis revealed temporal regulation and distinct contributions of expansin subfamilies during the early stages of grain development. Further analysis using co-expression networks underscored the significance of expansin genes, revealing their substantial co-expression with genes involved in cell wall modification. Finally, qPCR validation and grain morphological analysis under field conditions indicated a significant negative correlation between the expression of select expansin genes, and grain size and weight. This study illuminates the potential role of expansin genes in wheat grain development and provides new avenues for targeted genetic improvements in wheat.

Milky Stage Versus Dough Stage of Immature Wheat Grain: Effects on Phytic Acid and Fructan Contents, Antioxidant Activity, Textural Parameters, and Sensory Characteristics of Set-Type Yoghurts

HIGHLIGHTS Yoghurts were supplemented with milky and dough stage wheat grain flours. Total antioxidant capacity was improved by wheat grain flour supplementation. Milky stage wheat provided higher fructan content than that of dough stage wheat. Fermentation reduced phytic acid levels in yoghurts containing wheat grain flours.

Abstract Experimental design was performed by using immature wheat grain (IWG) harvested in two different maturation stages for set-type yoghurt production. IWG was harvested at milky (20 days after anthesis) and dough (30 days after anthesis) stages and was milled. Yoghurt samples were supplemented with milky stage grain flour (MSGF) and dough stage grain flour (DSGF) at 1, 2, and 3% concentrations except for control. All treatments were evaluated with respect to physicochemical, antioxidative, microbiological, textural, and sensorial aspects throughout the 28 days of storage. Phytic acid content of all samples diminished depending on increasing pH values over the storage while it was found higher in MSGF fortified yoghurts. The highest fructan content was determined in yoghurt fortified with 3% MSGF. Antioxidant activity and total phenolic content of yoghurts were improved with IWG fortification. MSGF showed higher antioxidant activity as compared to DSGF. On the other hand, DSGF addition presented better water holding capacity in comparison with MSGF. Likewise, DSGF provided higher firmness and consistency values. Firmness was enhanced with IWG supplementation by reducing syneresis except 1% MSGF added samples. The addition of IWG was found to slightly increase the growth of yoghurt bacteria. Both DSGF and MSGF had adverse effect on the sensory characteristics of yoghurts with their increasing concentrations. Based on the results of this study, to obtain better textural properties and higher antioxidant activity, IWG in different ripening stages can be tried with half combinations (total 3%) in yoghurt. Also, sensorial properties can be improved by flavoring agents.

Simultaneous Biofortification of Wheat with Zinc, Iodine, Selenium, and Iron through Foliar Treatment of a Micronutrient Cocktail in Six Countries.

Field experiments were conducted on wheat to study the effects of foliar-applied iodine(I) alone, Zn (zinc) alone, and a micronutrient cocktail solution containing I, Zn, Se (selenium), and Fe (iron) on grain yield and grain concentrations of micronutrients. Plants were grown over 2 years in China, India, Mexico, Pakistan, South Africa, and Turkey. Grain-Zn was increased from 28.6 mg kg-1 to 46.0 mg-1 kg with Zn-spray and 47.1 mg-1 kg with micronutrient cocktail spray. Foliar-applied I and micronutrient cocktail increased grain I from 24 µg kg-1 to 361 µg kg-1 and 249 µg kg-1, respectively. Micronutrient cocktail also increased grain-Se from 90 µg kg-1 to 338 µg kg-1 in all countries. Average increase in grain-Fe by micronutrient cocktail solution was about 12%. The results obtained demonstrated that foliar application of a cocktail micronutrient solution represents an effective strategy to biofortify wheat simultaneously with Zn, I, Se and partly with Fe without yield trade-off in wheat.

Prestimulation of wheat seedlings with gibberellic acid followed by application of an agitated high dilution of the same hormone

In previous multicentre studies, the influence of a homeopathic ultra-high dilution of gibberellic acid on wheat growth was scrutinized. Data showed that this test dilution slowed down stalk growth when experiments were performed in the autumn season. The aim of this work was to test the hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth-inhibiting effect of the ultra-high dilution of the plant hormone. Grains of winter wheat (Triticum aestivum, 500 or 1000 per group) were pretreated with (non-agitated) gibberellic acid 10-5, 10-4 and 10-3 parts by weight (Ge-5, Ge-4, Ge-3) or with water (?W0?) for control prior to further treatment. Grains were then observed under the influence of extremely diluted gibberellic acid (10-30 parts by weigth) prepared by stepwise dilution and agitation according to a protocol derived from homeopathy (?G30x?). Analogously prepared water was used for control (?W30x?). Seedlings were allowed to develop under standardized conditions for 7 days; plants were harvested and stalk lengths were measured. Of the four pretreatment variants under study, Ge-3 yielded most growth, followed by Ge-4 , Ge-5 and finally W. This outcome was modulated by the application of G30x in that the inhibition obtained with G30x as compared to W30x was the greater the lower the pretreatment concentration of G had been. The hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth inhibiting effect of G30x had to be rejected. Rather, G30x slowed down stalk growth most in the W0 group with p < 0.001, only moderately in the Ge-5 and Ge-4 group and not at all in the Ge-3 group.(AU)

Prestimulation of wheat seedlings with gibberellic acid followed by application of an agitated high dilution of the same hormone

In previous multicentre studies, the influence of a homeopathic ultra-high dilution of gibberellic acid on wheat growth was scrutinized. Data showed that this test dilution slowed down stalk growth when experiments were performed in the autumn season. The aim of this work was to test the hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth-inhibiting effect of the ultra-high dilution of the plant hormone. Grains of winter wheat (Triticum aestivum, 500 or 1000 per group) were pretreated with (non-agitated) gibberellic acid 10-5, 10-4 and 10-3 parts by weight (Ge-5, Ge-4, Ge-3) or with water (?W0?) for control prior to further treatment. Grains were then observed under the influence of extremely diluted gibberellic acid (10-30 parts by weigth) prepared by stepwise dilution and agitation according to a protocol derived from homeopathy (?G30x?). Analogously prepared water was used for control (?W30x?). Seedlings were allowed to develop under standardized conditions for 7 days; plants were harvested and stalk lengths were measured. Of the four pretreatment variants under study, Ge-3 yielded most growth, followed by Ge-4 , Ge-5 and finally W. This outcome was modulated by the application of G30x in that the inhibition obtained with G30x as compared to W30x was the greater the lower the pretreatment concentration of G had been. The hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth inhibiting effect of G30x had to be rejected. Rather, G30x slowed down stalk growth most in the W0 group with p < 0.001, only moderately in the Ge-5 and Ge-4 group and not at all in the Ge-3 group.