Search

In the present work, laboratory assays were performed to appraise the biocontrol potential of Metarhabditis amsactae, a Rhabditid nematode, against fifth instar larvae of Corcyra cephalonica. Virulence was tested at four different doses, i.e. 20, 40, 80 and 160 IJs/L (infective juveniles per larva) and mortality was documented from 24 up to 96 h of nematode treatment. Concentration and time-based enhancement in larval mortality was observed with 100% mortality recorded at 160 IJs/L after 96 h. Even at 20 IJs/L concentration, 60% and 76.7% larval mortality was recorded after 72 and 96 h, respectively. At 80 IJs/L, the mortality increased from 33.3% at 48 h to more than 90% at 96 h of nematode inoculation. Whereas, at 40 IJs/L, it enhanced from 16.7% at 48 h to 83.3% at 96 h. The effect of M. amsactae infection on the immune system of C. cephalonica was also evaluated at a dose of 100 IJs/L after 12, 24, 36 and 48 h time intervals. Insect larvae displayed augmented levels of antioxidant and detoxifying enzymes. The peak activities of superoxide dismutase, catalase, ascorbate peroxidase, phenol oxidase and glutathione-S-transferase in infected larvae were observed after 36 h, whereas acetylcholine esterase levels peaked after 48 h, as compared to control. Malondialdehyde content was also increased post nematode infection. Thus the current study is the first report that depicts the significant bioefficacy and immunomodulatory effects of M. amsactae against C. cephalonica under laboratory conditions. However, further research to assess its efficiency under field conditions is required. [ABSTRACT FROM AUTHOR]

Fungal diseases form perforated disease spots in tobacco plants, resulting in a decline in tobacco yield and quality. The present study investigated the antagonistic effect of Bacillus subtilis CTXW 7-6-2 against Rhizoctonia solani, its ability to promote the growth of tobacco seedlings, and the expression of disease resistance-related genes for efficient and eco-friendly plant disease control. Our results showed that CTXW 7-6-2 had the most vigorous growth after being cultured for 96 h, and its rate of inhibition of R. solani growth in vitro was 94.02%. The volatile compounds produced by CTXW 7-6-2 inhibited the growth of R. solani significantly (by 96.62%). The fungal growthinhibition rate of the B. subtilis CTXW 7-6-2 broth obtained after high-temperature and no-high-temperature sterile fermentation was low, at 50.88% and 54.63%, respectively. The lipopeptides extracted from the B. subtilis CTXW 7-6-2 fermentation broth showed a 74.88% fungal growth inhibition rate at a concentration of 100 mg/l. Scanning and transmission electron microscopy showed some organelle structural abnormalities, collapse, shrinkage, blurring, and dissolution in the R. solani mycelia. In addition, CTXW 7-6-2 increased tobacco seedling growth and improved leaf and root weight compared to the control. After CTXW 7-6-2 inoculation, tobacco leaves showed the upregulation of the PDF1.2, PPO, and PAL genes, which are closely related to target spot disease resistance. In conclusion, B. subtilis CTXW 7-6-2 may be an efficient biological control agent in tobacco agriculture and enhance plant growth potential.

Introduction: Southern blight, caused by Sclerotium rolfsii, poses a serious threat to the cultivation of Coptis chinensis, a plant with significant medicinal value. The overreliance on fungicides for controlling this pathogen has led to environmental concerns and resistance issues. There is an urgent need for alternative, sustainable disease management strategies. Methods: In this study, Bacillus velezensis LT1 was isolated from the rhizosphere soil of diseased C. chinensis plants. Its biocontrol efficacy against S. rolfsii LC1 was evaluated through a confrontation assay. The antimicrobial lipopeptides in the fermentation liquid of B. velezensis LT1 were identified using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOFMS). The effects of B. velezensis LT1 on the mycelial morphology of S. rolfsii LC1 were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results: The confrontation assay indicated that B. velezensis LT1 significantly inhibited the growth of S. rolfsii LC1, with an inhibition efficiency of 78.41%. MALDI-TOF-MS analysis detected the presence of bacillomycin, surfactin, iturin, and fengycin in the fermentation liquid, all known for their antifungal properties. SEM and TEM observations revealed that the mycelial and cellular structures of S. rolfsii LC1 were markedly distorted when exposed to B. velezensis LT1. Discussion: The findings demonstrate that B. velezensis LT1 has considerable potential as a biocontrol agent against S. rolfsii LC1. The identified lipopeptides likely contribute to the antifungal activity, and the morphological damage to S. rolfsii LC1 suggests a mechanism of action. This study underscores the importance of exploring microbial biocontrol agents as a sustainable alternative to chemical fungicides in the management of plant diseases. Further research into the genetic and functional aspects of B. velezensis LT1 could provide deeper insights into its biocontrol mechanisms and facilitate its application in agriculture. [ABSTRACT FROM AUTHOR]

Aims: Sabah's red algae, Kappaphycus alvarezii is facing a problem whereby the production of seaweed is declining over the years due to a disease called ice-ice disease caused by Vibrio spp. Endophytic Bacillus strains have been widely studied for their potential as biocontrol agents against harmful pathogens. This study reports the genome sequence of the beneficial endophytic Bacillus strain VUMS1 isolated from the healthy K. alvarezii at Semporna Island in Sabah, attempting to determine its full biocontrol potential. Methodology and results: The whole genome sequence showed that VUMS1 genome size is 3,754,982 bp with 3,854 protein-coding where 2,535 are genes with assigned functions. The analysis revealed the presence of genes that are involved in antimicrobial and antifungal activity such as fengycin, bacillibactin, bacilysin and lichenysin. The biocontrol potential of VUMS1 was evaluated against Vibrio parahaemolyticus isolated from the diseased K. alvarezii. Results showed that the inhibition zone of VUMS1 by cross-streaking method against V. parahaemolyticus was 21 ± 0.71 mm and the growth of V. parahaemolyticus treated with VUMS1 in a co-culture experiment decreased by 98% on day 5 of treatment. Conclusion, significance and impact of study: The results of this work indicate that VUMS1 is affiliated as Bacillus altitudinis and it may contribute to the biocontrol activity against Vibrio spp. infection in K. alvarezii. This is the first report of endophytic Bacillus altitudinis from K. alvarezii with biocontrol properties. Future studies will determine the potential application of the B. altitudinis VUMS1 strain in biological control and growth promotion for sustainable seaweed farming. [ABSTRACT FROM AUTHOR]

Introduction: Tea is one of the most widely consumed beverages around the world. Larvae of the moth, Ectropis obliqua Prout (Geometridae, Lepidoptera), are one of the most destructive insect pests of tea in China. E. obliqua is a polyphagus insect that is of increasing concern due to the development of populations resistant to certain chemical insecticides. Microbial biological control agents offer an environmentally friendly and effective means for insect control that can be compatible with "green" and organic farming practices. Methods: To identify novel E. obliqua biological control agents, soil and inset cadaver samples were collected from tea growing regions in the Fujian province, China. Isolates were analyzed morphologically and via molecular characterization to identity them at the species level. Laboratory and greenhouse insect bioassays were used to determine the effectiveness of the isolates for E. obliqua control. Results: Eleven isolates corresponding to ten different species of Metarhizium were identified according to morphological and molecular analyses from soil and/or insect cadavers found on tea plants and/or in the surrounding soil sampled from eight different regions within the Fujian province, China. Four species of Metarhizium including M. clavatum, M. indigoticum, M. pemphigi, and M. phasmatodeae were documented for the first time in China, and the other species were identified as M. anisopliae, M. brunneum, M. lepidiotae, M. majus, M. pinghaense, and M. robertsii. Insect bioassays of the eleven isolates of Metarhizium revealed significant variation in the efficacy of each isolate to infect and kill E. obliqua. Metarhizium pingshaense (MaFZ-13) showed the highest virulence reaching a host target mortality rate of 93% in laboratory bioassays. The median lethal concentration (LC50) and median lethal time (LT50) values of M. pingshaense MaFZ-13 were 9.6 × 104 conidia/mL and 4.8 days, respectively. Greenhouse experiments and a time-dose-mortality (TDM) models were used to further evaluate and confirm the fungal pathogenic potential of M. pingshaense MaFZ-13 against E. obliqua larvae. Discussion: Isolation of indigenous microbial biological control agents targeting specific pests is an effective approach for collecting resources that can be exploited for pest control with lowered obstacles to approval and commercialization. Our data show the presence of four different previously unreported Metarhizium species in China. Bioassays of the eleven different Metarhizium strains isolated revealed that each could infect and kill E. obliqua to different degrees with the newly isolated M. pingshaense MaFZ-13 strain representing a particularly highly virulent isolate potentially applicable for the control of E. obliqua larvae. [ABSTRACT FROM AUTHOR]

Introduction: Bipolaris sorokiniana is the popular pathogenic fungi fungus which lead to common root rot and leaf spot on wheat. Generally, chemical fungicides are used to control diseases. However, the environmental pollution resulting from fungicides should not be ignored. It is important to study the mode of antagonistic action between biocontrol microbes and plant pathogens to design efficient biocontrol strategies. Results: An antagonistic bacterium DB2 was isolated and identified as Bacillus amyloliquefaciens. The inhibition rate of cell-free culture filtrate (CF, 20%, v/v) of DB2 against B. sorokiniana reached 92.67%. Light microscopy and scanning electron microscopy (SEM) showed that the CF significantly altered the mycelial morphology of B. sorokiniana and disrupted cellular integrity. Fluorescence microscopy showed that culture filtrate destroyed mycelial cell membrane integrity, decreased the mitochondrial transmembrane potential, induced reactive oxygen species (ROS) accumulation, and nuclear damage which caused cell death in B. sorokiniana. Moreover, the strain exhibited considerable production of protease and amylase, and showed a significant siderophore and indole-3-acetic acid (IAA) production. In the detached leaves and potted plants control assay, B. amyloliquefacien DB2 had remarkable inhibition activity against B. sorokiniana and the pot control efficacy was 75.22%. Furthermore, DB2 suspension had a significant promotion for wheat seedlings growth. Conclusion: B. amyloliquefaciens DB2 can be taken as a potential biocontrol agent to inhibit B. sorokiniana on wheat and promote wheat growth. [ABSTRACT FROM AUTHOR]

• Rare arable plant cover can reduce the total number of aphids. • Cereal aphids decreased through predation of active hunting spiders. • Direct effects of rare arable plants only on active hunting spiders. In agricultural landscapes, arable plants are negatively affected by management intensification. These species can fulfill various ecosystem functions, such as biological pest control, by supporting predators. The ecosystem functions of common plant species are widely known. By contrast, the contribution of rare arable plants (RAPs) to biocontrol in cereal fields remains poorly understood. This study investigated the effect of RAPs on biocontrol potential. We compared cropped plots with and without sowing of rare and threatened arable plant species and investigated the effects on cereal aphids and their antagonistic predators, active hunting, and web-building spiders, as well as carnivorous/omnivorous carabids. We counted the total number of aphids on cereal shoots and trapped ground-dwelling arthropods on an experimental field and on 10 agricultural farms in the vicinity of Munich, Germany, in 2018 and 2019. The effects of the presence of RAPs were analyzed using linear mixed-effect models, whereas cover of RAPs was analyzed using structural equation models. Linear models revealed that the presence of RAPs did not significantly affect the aphid density and the activity densities of spiders and carabids. Structural equation models revealed direct negative effects of RAP cover on aphid density. However, no indirect effects via the predators of aphids were detected. Direct negative effects of active hunting spiders on aphids were determined, but not of the other potential predators. Our results suggest that RAPs may impact aphid infestation, however, the activity density of spiders and carabids were unsuitable indicators for such interactions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Both arrhenotoky (sexual reproduction of females and asexual reproduction of males) and thelytoky (asexual reproduction of females) occur within the order Hymenoptera. The existence of both thelytokous and arrhenotokous strains within one species provides an opportunity to compare the biocontrol efficiency between two reproductive modes. The parasitoid Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae) has thelytokous and arrhenotokous strains with sympatric distributions. This parasitoid is used to control invasive leafminers through feeding, stinging, and parasitization. To compare the biocontrol efficiency of the two strains, we analyzed life tables and host-killing parameters of these two strains reared on the leafminer Liriomyza sativae Blanchard using the age-stage, two-sex life table and the CONSUME-MSChart software. RESULTS: Our results showed that the intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0) of the thelytokous strain were significantly higher than those of the arrhenotokous strain. The thelytokous females also performed better than the arrhenotokous females for the net host-feeding rate, net host-stinging rate, and net host-killing rate, but not the finite parasitism rate. Conclusively, the finite host-killing rate of the thelytokous strain (0.8720 ± 0.0516) was significantly higher than that of the arrhenotokous strain (0.5914 ± 0.0832). CONCLUSION: We concluded that thelytokous N. formosa is a better candidate as a biocontrol agent than arrhenotokous N. formosa to control leafminers. Our results shed light on how to choose a better biocontrol agent for integrated pest management (IPM) based on biological control, especially for co-occurring thelytokous and arrhenotokous parasitoids. [ABSTRACT FROM AUTHOR]

The bacterial wilt of common bean, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) is one of the most severe diseases affecting Phaseolus vulgaris production worldwide. This study aimed at evaluating the biocontrol potential of strains of rhizobacteria against bacterial wilt of common bean. Sequence analysis of the 16S rRNA gene was used to identify Cff isolates and also the bacterial antagonists. A soft agar overlay assay was used to select three biocontrol isolates based on their antagonistic activity against Cff. Our findings demonstrate that seed treatment using rhizobacterial P. fluorescens, Bacillus cereus , and Paenibacillus polymyxa species coupled with foliar application significantly reduced Cff disease incidence and disease severity. Therefore, biocontrol methods are potentially a safe, effective, and sustainable alternative to chemicals for controlling bacterial wilt of beans. [ABSTRACT FROM AUTHOR]

In addition to rhizospheric soil, Bacillus may be found worldwide. Root-associated Bacillus spp. are known as plant growth-promoting rhizobacteria for various reasons, including the formation of in dole acetic acid (IAA-auxin), phosphate solubilization, and siderophore production (PGPR). One of the most beneficial interactions between plants and microbes is plant growth-promoting rhizobacteria (PGPR). Rhizobacteria of the genus Bacillus may produce spores that persist in the soil for long periods, even in the harshest environments. PGPR enhances plant growth by inducing systemic resistance, antibiosis, and competitive omission. It is possible to use this genus to augment or improve soil fertility with other biocompatible bacteria, such as nitrogen-fixing species Azospirillum and Azotobacter. Based on this chapter's emphasis on the use of Bacillus on various commercially significant crops. [ABSTRACT FROM AUTHOR]

Potato is constantly exposed to various kinds of phytopathogens which cause diseases during the developmental stage and post-harvest storage. This investigation was designed to assay the anti-phytopathogen activity of bacterial endophytes and their suppressive effects on rot disease in potato. The study also aimed to screen isolates for their plant growth-promoting traits and establish GC–MS-based metabolite profile of the potent isolate. Endophytes were isolated from Rumex dentatus and identified based on 16S rRNA gene. They were screened in dual culture assay against fungal phytopathogens and the potent isolate was tested for its capability to suppress Fusarium rot disease in potato tubers. The mechanism of action of endophytes on the phytopathogens was assessed using scanning electron microcopy. Isolates were also screened in vitro to assay their capability to produce phytohormones, hydrolytic enzymes, and to solubilize phosphates. Endophytic isolates produced proteases with a diameter of halo zone ranging from 7 to 32 mm. Bacillus sp. KL5 exhibited the highest production of indole acetic acid (IAA) with the amount of 104.28 µg/mL and was the most potent antagonist of Fusarium oxysporum and Verticillium dahliae with an inhibitory percentage of 61.53 and 100%, respectively. It showed a reduction of potato rot disease severity by more than 50%. GC–MS of active fractions of KL5 showed the presence of dibutylphthalate and 2,4-di-tert-butylphenol as major metabolites. From this study, it is evident that endophytic Bacillus species from R. dentatus are potent antagonists of F. oxysporum and V. dahliae. Bacillus sp. KL5 is a potent inhibitor of pathogenic F. oxysporum in potato tubers and can be developed as a biocontrol agent. [ABSTRACT FROM AUTHOR]

Chitosan-based film with and without antagonistic yeast was prepared and its effect against Penicillium italicum was evaluated. The biocompatibility of yeast cells in the developed films was assessed in terms of population dynamics. Furthermore, the impact on physicochemical properties of the prepared films with and without yeast cells incorporated were evaluated in terms of thickness, mechanical properties, color and opacity. Chitosan films with the antagonistic yeast entrapped exhibited strong antifungal activity by inhibiting the mycelial development (55%), germination (45%) and reducing the sporulation process (87%). Chitosan matrix at 0.5% and 1.0% was maintained over 9 days of cell viability. However, at 1.5% of chitosan the population dynamics was strongly affected. The addition of yeast cells only impacted color values such as a*, b*, chroma and hue angle when 1.0% of chitosan concentration was used. Conversely, luminosity was not affected in the presence of yeast cells as well as the opacity. Besides, the addition of antagonistic yeast improved the mechanical resistance of the films. The addition of D. hansenii in chitosan films improve their efficacy for controlling P. italicum, and besides showed desirable characteristics for future use as packaging for citrus products. [ABSTRACT FROM AUTHOR]

Agrobacterium salinitolerans DG3-1 is an endophytic bacterium isolated from cotton root tissue. Our previous work has shown that it can inhibit the growth of Fusarium and Verticillium wilt pathogens as well as increase the chlorophyll content of cotton leaves. Here, we reported the complete genome sequence of strain DG3-1, which was analyzed by sequence reads generated from Nanopore PromethION and Illumina NovaSeq PE150 platforms. This genome sequence could be used to clarify the possible mechanism of DG3-1 at the gene level.[Graphic: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

This research was executed to select beneficial antagonists from digestive organ of Allomyrina dichotoma larva that can be put on environment friendly control against phytopathogenic fungi. We screened 38 bacterial strains inhibiting mycelial growth against eight plant pathogens through dual culture assay. The 10 strains among 38 bacterial strains were selected as beneficial microbes showing antifungal activity against Botrytis cinerea, Plasmodiophora brassicae, Colletotrichum acutatum and Phytophthora capsici through under greenhouse pot trials. The 10 bacterial strains that shown strongest antifungal activity were classified into 3 genera and 10 species, and identified as the genus Bacillus (DM146, DM152, DH2, and DH16), Paenibacillus (DF30, DH14, and DM142) and Streptomyces (DF137, DM48, and DH92) by morphological characteristics and 16s rRNA gene sequence. The 10 bacterial strains had solubilizing activity of insoluble phosphates, production of IAA (indole-3-acetic acid), ö-1,3-glucanase and protease. Among the 10 bacterial strains, DM152 strain was produced significant enhancement of all growth parameters of chili pepper and tomato seedlings under greenhouse condition. Thus, this study demonstrated that gut microbes of Allomyrina dichotoma larva will be useful as a potential biocontrol agent against plant pathogens and biofertilizer.

In agroecosystems, crop diversification plays a fundamental role in maintaining and regenerating biodiversity and ecosystem services, such as natural pest control. Temporal diversification of cropping systems can affect the presence and activity of natural enemies by providing alternative hosts and prey, food, and refuges for overwintering. However, we still lack studies on the effects of temporal diversification on generalist predators and their biocontrol potential conducted at field scale in commercial agricultural settings. Here, we measured proxies of ecosystem functions related with biological pest control in 29 commercial agricultural fields characterized by cereal-based cropping system in Lower-Saxony, northern Germany. The fields differed in the number of crops and cover crops cultivated during the previous 12 years. Using the Rapid Ecosystem Function Assessment approach, we measured invertebrate predation, seed predation and activity density of generalist predators. We aimed at testing whether the differences in the crop rotations from the previous years would affect activity of predators and their predation rates in the current growing season. We found that the length of the crop rotation had neutral effects on the proxies measured. Furthermore, predation rates were generally lower if the rotation comprised a higher number of cover crops compared to rotation with less cover crops. The activity density of respective taxa of predatory arthropods responded differently to the number of cover crops in the crop rotation. Our results suggest that temporal crop diversity may not benefit the activity and efficiency of generalist predators when diversification strategies involve crops of very similar functional traits. Adding different resources and traits to the agroecosystems through a wider range of cultivated crops and the integration of semi-natural habitats are aspects that need to be considered when developing more diverse cropping systems aiming to provide a more efficient natural pest control.

Natural enemies of mustard aphid play vital role in checking the population of L. erysimi below the threshold level. Study revealed that Betasyrphus sp. grubs are potential aphidophagus predetor. Feeding potential increases with the age of larva. Ist instar grub consumed on an average 6.10-6.80 aphids per day, second instar devoured 60.90-66.50 aphids and third instar consumed 84.3-85.5 aphids per day. Betasyrphus sp can be used in field as potential bio control agent of musterd aphid L. erysmi. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• hg18 is a new endophytic strain of Paenibacillus polymyxa isolated from cucumber plants. • hg18 can manufacture antimicrobial compounds, such as iturin, fengycin, and non-ribosomal polypeptide synthase. • hg18 has good potential for use as a biofertilizer and as a biocontrol agent against cucumber Fusarium wilt. Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum is a serious fungal, soil-borne disease that has a dramtic negative impact on the yield and quality of cucumber. In this study, isolates of endophytic bacteria isolated from healthy cucumber plants were evaluated for their ability to inhibit Fusarium wilt. Results indicated that 6 out of 100 of the obtained endophytic bacterial isolates exhibited significant inhibitory activity against mycelial development of F. oxysporum f. sp. cucumerinum , with an inhibition rate > 60 % in dual culture assays. Among the active isolates, strain hg18 exhibited the strongest activity with a 69.57 % rate of inhibition. Strain hg18 was identified as Paenibacillus polymyxa based on morphological, physiological, and biochemical traits, as well as a phylogenetic tree that was constructed using 16S rRNA and rpoB gene sequences. Biological and PCR assays demonstrated that strain hg18 can secrete IAA, a siderophore, hydrolytic enzymes, including protease, cellulase and glucanase, and antimicrobial compounds, such as iturin, fengycin, and non-ribosomal polypeptide synthase, as well as fix nitrogen. Strain hg18 decreased the disease index of cucumber Fusarium wilt and promoted cucumber growth in non-diseased plants in greenhouse experiments, compared to a water treatment. These findings demonstrate the potential of using P. polymyxa hg18 as a biocontrol agent for controlling Fusarium wilt in cucumber. [ABSTRACT FROM AUTHOR]

Chitosan-based film with and without antagonistic yeast was prepared and its effect against Penicillium italicum was evaluated. The biocompatibility of yeast cells in the developed films was assessed in terms of population dynamics. Furthermore, the impact on physicochemical properties of the prepared films with and without yeast cells incorporated were evaluated in terms of thickness, mechanical properties, color and opacity. Chitosan films with the antagonistic yeast entrapped exhibited strong antifungal activity by inhibiting the mycelial development (55%), germination (45%) and reducing the sporulation process (87%). Chitosan matrix at 0.5% and 1.0% was maintained over 9 days of cell viability. However, at 1.5% of chitosan the population dynamics was strongly affected. The addition of yeast cells only impacted color values such as a*, b*, chroma and hue angle when 1.0% of chitosan concentration was used. Conversely, luminosity was not affected in the presence of yeast cells as well as the opacity. Besides, the addition of antagonistic yeast improved the mechanical resistance of the films. The addition of D. hansenii in chitosan films improve their efficacy for controlling P. italicum, and besides showed desirable characteristics for future use as packaging for citrus products.

Introduction: Southern blight, caused by Sclerotium rolfsii , poses a serious threat to the cultivation of Coptis chinensis , a plant with significant medicinal value. The overreliance on fungicides for controlling this pathogen has led to environmental concerns and resistance issues. There is an urgent need for alternative, sustainable disease management strategies., Methods: In this study, Bacillus velezensis LT1 was isolated from the rhizosphere soil of diseased C. chinensis plants. Its biocontrol efficacy against S. rolfsii LC1 was evaluated through a confrontation assay. The antimicrobial lipopeptides in the fermentation liquid of B. velezensis LT1 were identified using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS). The effects of B. velezensis LT1 on the mycelial morphology of S. rolfsii LC1 were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM)., Results: The confrontation assay indicated that B. velezensis LT1 significantly inhibited the growth of S. rolfsii LC1, with an inhibition efficiency of 78.41%. MALDI-TOF-MS analysis detected the presence of bacillomycin, surfactin, iturin, and fengycin in the fermentation liquid, all known for their antifungal properties. SEM and TEM observations revealed that the mycelial and cellular structures of S. rolfsii LC1 were markedly distorted when exposed to B. velezensis LT1., Discussion: The findings demonstrate that B. velezensis LT1 has considerable potential as a biocontrol agent against S. rolfsii LC1. The identified lipopeptides likely contribute to the antifungal activity, and the morphological damage to S. rolfsii LC1 suggests a mechanism of action. This study underscores the importance of exploring microbial biocontrol agents as a sustainable alternative to chemical fungicides in the management of plant diseases. Further research into the genetic and functional aspects of B. velezensis LT1 could provide deeper insights into its biocontrol mechanisms and facilitate its application in agriculture., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tang, Wang, Huang, Guo, Guo, Duan, Wang, Wang and You.)

We isolated a new Trichoderma harzianum strain, named T-A66. Potato dextrose agar (PDA) was the best medium for both mycelium growth and sporulation of T-A66 strain, while sucrose and potassium nitrate were the best source of carbon and nitrate, respectively. T-A66 strain and its culture filtrate significantly antagonized the growth of the pathogen Fusarium oxysporum in in vitro tests. An experiment using potted plants showed that the T-A66 strain promoted growth and induced disease resistance of bitter gourd seedlings to bitter gourd wilt caused by F. oxysporum, by inducing quick H2 O2 burst and callose deposition, as well as increasing antioxidant enzymes activities and phenolic compounds content. Indole acetic acid (IAA) was involved in the beneficial effects of T-A66. Ultimately, T-A66 strain diminished membrane lipid peroxidation and cell death, and controlled successfully bitter gourd wilt in greenhouse with a biocontrol efficiency of 90.32% after 15 days of F. oxysporum inoculation. The results suggested a good biocontrol potential of T-A66 strain against bitter gourd wilt. [ABSTRACT FROM AUTHOR]

Spiders (Araneae) form abundant and diverse assemblages in agroecosystems such as fruit orchards, and thus might have an important role as natural enemies of orchard pests. Although spiders are polyphagous and opportunistic predators in general, limited information exists on their natural prey at both species and community levels. Thus, the aim of this study was to assess the natural prey (realized trophic niche) of arboreal hunting spiders, their role in trophic webs and their biological control potential with direct observation of predation events in apple orchards. Hunting spiders with prey in their chelicerae were collected in the canopy of apple trees in organic apple orchards in Hungary during the growing seasons between 2013 and 2019 and both spiders and their prey were identified and measured. Among others, the composition of the actual (captured by spiders) and the potential (available in the canopy) prey was compared, trophic niche and food web metrics were calculated, and some morphological, dimensional data of the spider-prey pairs were analyzed. Species-specific differences in prey composition or pest control ability were also discussed. By analyzing a total of 878 prey items captured by spiders, we concluded that arboreal hunting spiders forage selectively and consume a large number of apple pests; however, spiders' beneficial effects are greatly reduced by their high levels of intraguild predation and by a propensity to switch from pests to alternative prey. In this study, arboreal hunting spiders showed negative selectivity for pests, no selectivity for natural enemies and positive selectivity for neutral species. In the trophic web, the dominant hunting spider taxa/groups (Carrhotus xanthogramma, Philodromus cespitum, Clubiona spp., Ebrechtella tricuspidata, Xysticus spp. and 'Other salticids') exhibit different levels of predation on different prey groups and the trophic web's structure changes depending on the time of year. Hunting spiders show a high functional redundancy in their predation, but contrary to their polyphagous nature, the examined spider taxa showed differences in their natural diet, exhibited a certain degree of prey specialization and selected prey by size and taxonomic identity. Guilds (such as stalkers, ambushers and foliage runners) did not consistently predict either prey composition or predation selectivity of arboreal hunting spider species. From the economic standpoint, Ph. cespitum and Clubiona spp. were found to be the most effective natural enemies of apple pests, especially of aphids. Finally, the trophic niche width of C. xanthogramma and Ph. cespitum increased during ontogeny, resulting in a shift in their predation. These results demonstrate how specific generalist predators can differ from each other in aspects of their predation ecology even within a relatively narrow taxonomic group. [ABSTRACT FROM AUTHOR]

Plants encounter many biotic agents, such as viruses, bacteria, nematodes, weeds, and arachnids. These entities induce biotic stress in their hosts by disrupting normal metabolism, and as a result, limit plant growth and/or are the cause of plant mortality. Some biotic agents, however, interact symbiotically or synergistically with their host plants. Some microbes can be beneficial to plants and perform the same role as chemical fertilizers and pesticides, acting as a biofertilizer and/or biopesticide. Plant growth promoting rhizobacteria (PGPR) can significantly enhance plant growth and represent a mutually helpful plant-microbe interaction. Bacillus species are a major type of rhizobacteria that can form spores that can survive in the soil for long period of time under harsh environmental conditions. Plant growth is enhanced by PGPR through the induction of systemic resistance, antibiosis, and competitive omission. Thus, the application of microbes can be used to induce systemic resistance in plants against biotic agents and enhance environmental stress tolerance. Bacillus subtilis exhibits both a direct and indirect biocontrol mechanism to suppress disease caused by pathogens. The direct mechanism includes the synthesis of many secondary metabolites, hormones, cell-wall-degrading enzymes, and antioxidants that assist the plant in its defense against pathogen attack. The indirect mechanism includes the stimulation of plant growth and the induction of acquired systemic resistance. Bacillus subtilis can also solubilize soil P, enhance nitrogen fixation, and produce siderophores that promote its growth and suppresses the growth of pathogens. Bacillus subtilis enhances stress tolerance in their plant hosts by inducing the expression of stress-response genes, phytohormones, and stress-related metabolites. The present review discusses the activity of B. subtilis in the rhizosphere, its role as a root colonizer, its biocontrol potential, the associated mechanisms of biocontrol and the ability of B. subtilis to increase crop productivity under conditions of biotic and abiotic stress. [ABSTRACT FROM AUTHOR]

Leptus sp. of mite larvae are ectoparasite of Kusum plant bug, L.augur. It parasitizes the adults and nymphs of host bug throughout the year, maximum being during rainy season July to September and minimum during winter months December to February. The parasite brings physical and anatomical changes in host. Percent of parasitization in field varied from 2 to 18% and 50 to 77.7% in laboratory.The parasite is able to check the multiplication of bug population upto some extent and can be used as biocontrol agent. [ABSTRACT FROM AUTHOR]

Two strains representing a yeast species of Metschnikowia were isolated from the surface of citrus leaves collected in Chongqing Province, China. Preliminary tests showed that this species has a biocontrol potential for inhibiting citrus green mold. This yeast species is most closely related to Metschnikowia koreensis based on the phylogenetic tree derived from neighbour-joining analysis of 26S rRNA gene D1/D2 domain. However, M. koreensis differs from this species by seven (1.5%) substitutions in the 26S rRNA gene D1/D2 domain and by >100 (>25%) mismatches in the internal transcribed spacer (ITS) region. The name Metschnikowia citriensis sp. nov. (type strain FL01 T  = CICC 33213 T  = KCTC 27796 T , strain FL02 = CICC 33214) is proposed for the novel species because of morphological, physiological and biochemical characteristics and the sequence comparisons of the 26S rRNA gene D1/D2 domain and ITS region. [ABSTRACT FROM AUTHOR]

One of the most destructive diseases affecting potato production globally is bacterial wilt, caused by Ralstonia solanacearum. Options for controlling this pathogen are currently limited. Therefore, in this study, whole genome sequence was used to assess the potential of phage Reminis as biocontrol agent. No sequences related to undesirable genes including virulence factors, antibiotic resistance, or lysogenic mediated or toxin-coding genes were found in phage genome, this suggests that phage Reminis may be a potential candidate for future R. solanacearum control strategies. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: The use of thelytokous Wolbachia‐infected Trichogramma (parasitic wasps) has long been considered as a way to enhance the efficacy of biocontrol. However, Wolbachia can affect the host physiology. We compared decision‐making between bisexual and thelytokous Wolbachia‐infected lines of Trichogramma dendrolimi Matsumura regarding behavior toward fresh and old eggs of Corcyra cephalonica at 25 ± 1 °C and 70 ± 5% relative humidity. RESULTS: The behavioral patterns and sequences of the two lines were basically the same. The durations of various behavioral patterns and values of fitness indicators of the bisexual line on fresh eggs were generally significantly shorter and better, respectively, than on old eggs, whereas the thelytokous line behaved similarly toward the two types of eggs, and differences in most fitness indicators between fresh and old eggs were not significant. On fresh eggs, the durations of various behaviors in the bisexual line were generally significantly shorter than in the thelytokous line and the fitness indicators were generally significantly better. CONCLUSION: Wolbachia affected the fitness of T. dendrolimi negatively. The potential of the thelytokous line as a biocontrol agent would not be as good as that of the bisexual line when decision‐making only is considered. Therefore, further evaluations need to be carried out before the thelytokous line can be used in practical biocontrol. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Grey mould of tomato caused by Botrytis cinerea is a highly damaging disease worldwide. This study was aimed at identifying fungal strain QF05, which was isolated from the sandy soil collected in the Qinghai-Tibet Plateau in China and to evaluate its biocontrol potential on grey mould and growth promotion effect on tomato plants. On the basis of morphological observation and a multigene phylogeny based on the ITS, β-tubulin and calmodulin genes, QF05 was identified as Aspergillus tubingensis. An in vitro dual culture test indicated obvious antagonistic activity by strain QF05 against B. cinerea. Strain QF05 distinctly reduced grey mould in assays on tomato fruits and plants. Treatments with the culture filtrate of strain QF05 and a tenfold dilution of the filtrate gave disease biocontrol efficacy of 34.5 and 31.0% on tomato plants, respectively. QF05 also promoted seed germination and plant growth of tomato. Length and total fresh and dry mass of tomato plants were all significantly increased by 17.8, 25.7 and 56.8%, respectively, after treatment with the tenfold dilution of the culture filtrate. QF05 also had positive biocontrol attributes such as indoleacetic acid and siderophore production, phosphate solubilization, and rhizosphere colonization. All these results indicated the good performance of A. tubingensis QF05 for the biocontrol of tomato grey mould and growth promotion of tomato plants. [ABSTRACT FROM AUTHOR]

Spiders are important natural enemies of pests in many agroecosystems. Spiders' diversity and abundance-and therefore their biological control potential-often increases with the presence of non-crop habitats adjacent to the agroecosystem and/or the abundance of such habitats in the landscape. This research aims to determine whether spider communities dwelling on vine plant trunks are richer and more abundant in terraced vineyards than in plain vineyards. We found that spiders' abundance and species richness were significantly greater during part of the season in the plain than the terraced types of vineyards. The abundance of spiders on the vine plants in the terraced vineyards decreased gradually from the field margins to the centre while no such pattern was observed in the plain vineyards. Subsequent experiments will be needed in order to elucidate the role of the individual mechanisms and parameters that underpin our findings. For example, the air flow (direction and intensity), the presence of the predators, heterogeneity and the presence of shrubs on the slopes of terraces should be studied further. Particularly, because our findings contradict the general assumption that terraced vineyards should host richer spider communities. [ABSTRACT FROM AUTHOR]

The study investigated potential microRNA-like small RNAs (milRNAs) from multi-stress-tolerant Tricho- fusants and parental strains (P1- Trichoderma virens NBAIITvs12 and P2- Trichoderma koningii MTCC796) for antagonistic activity during interaction with phytopathogen Sclerotium rolfsii. The Trichoderma was cultured in-vitro , with and without antagonism, against the pathogen and total RNA was extracted followed by small RNA library construction and sequencing. The milRNAs were identified by mapping high-quality unique reads against a reference genome. The milRNAs were recognized higher in antagonist Trichoderma during interaction with test pathogen compared to normal growth. The novel milRNAs candidates were found to vary during interaction with the pathogen and normal growth. The gene ontology and functional analysis illustrated that a total of 5828 potential targeted genes were recognized for 93 milRNAs of potent Fu21_IB and 3053 genes for 62 milRNAs of least fusant Fu28_IL. Functional annotation of milRNA-predicted genes integrating KEGG pathways indicates new insights into regulatory mechanisms, by interfering with milRNAs, associated with signal transduction, amino sugar metabolism, benzoate degradation, amino acid metabolism, and steroid and alkaloid metabolism for potential biocontrol of stress-tolerant Tricho -fusant FU21 during interaction with S. rolfsii. The present investigation is the first report of conserved and novel milRNAs from Tricho- fusants and parental strains interacting with S. rolfsii. [Display omitted] • Study is the first report of conserved and novel milRNAs from stress tolerant Tricho- fusants interacting S. rolfsii. • Conserved 93 milRNA identified in potent Fu21_IB and predicted 5828 targeted genes. • Fold change analysis recognized significantly up/down regulated milRNAs in FU21_IB/FU28_IL. • Functional annotations of milRNAs-predicted genes acknowledged pathways for stress tolerance and biocontrol mechanism. • The study might be useful for antagonists mechanism to restrain of phytopathogen by interfering milRNAs during interaction. [ABSTRACT FROM AUTHOR]

Glyphosate is an herbicide that is used worldwide with potential environmental risks to nontarget organisms. We applied an age-stage, two-sex life table approach to assess the sublethal effects of short-term oral exposure to a glyphosate-based herbicide on the life table parameters and biocontrol potential of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Aphids (Metopolophium dirhodum (Walker) (Sternorrhyncha: Aphididae)) treated with herbicide (an isopropylamine-salt of glyphosate) at low recommended, maximum recommended, and double the maximum recommended concentration for agricultural situations, and untreated controls were offered to the fourth instar of H. axyridis for 24 h. Development, consumption, and fecundity were measured daily until death. We detected minor differences in the hatching rate and mean generation time, whereas the longevity, fecundity, net reproductive rate, intrinsic rate of increase, finite rate of increase, and consumption were unaffected across treatments. We conclude that biocontrol potential of H. axyridis was not affected by acute oral intoxication by a glyphosate-based herbicide during the larval stage for 24 h under the study design. [ABSTRACT FROM AUTHOR]

Enterobacter hormaechei is an opportunistic pathogen and is found in a large variety of food including animal-derived food. In recent years, bacteria present a severe clinical challenge due to their increasing resistance to antibiotics. Bacteriophages have gained attention as a new antibacterial strategy. In this study, we isolated a novel E. hormaechei bacteriophage IME278 from hospital sewage in Beijing, China. Bacteriophage IME278 had a double-stranded linear DNA genome with 40,164 bp and 51.99% GC content. Whole-genome alignments showed IME278 shared 87% homology with other phages in the National Center for Biotechnology Information (NCBI) database. And phylogenetic analysis demonstrated that IME278 was highly similar to bacteriophages belonging to the genus Kayfunavirus , family Autographiviridae, indicating IME278 can be classified as a new member of the Autographiviridae family. Transmission electron microscopy revealed that IME278 had an icosahedral head 51.72 nm in diameter and a tail 151.28 nm in length. Bacteriophage IME278 was able to survive under high temperature (50 °C–70 °C) and its activity decreased significantly above 70 °C and almost completely inactivated at 80 °C. Bacteriophage IME278 could survive in a wide pH range (4.0–11.0) and it was stable in chloroform (up to 5%). The phage was sensitive to UV irradiation. Bacteriophage IME278 had a latent period of 40 min and reached a plateau stage at 150 min and its cleavage was approximately 8.21 × 108/3.66 × 108 = 2.24. The biocontrol potential of bacteriophage IME278 was evaluated in a model that artificially contaminated pork with E. hormaechei 529 and the result revealed that IME278 could effectively control bacterial contamination on pork. The in-depth analysis of the biological characteristics, whole genome sequencing, and bioinformatics of IME278 has laid the foundation for the biocontrol application and the treatment of bacteria using bacteriophages. • The discovery of E. hormaechei bacteriophage IME278 expand our knowledge of the diversity of phage contingent. • E. hormaechei bacteriophage IME278 shared 87% homology with other phages, indicating IME278 can be classified as a new genus. • E. hormaechei bacteriophage IME278 was similar to bacteriophages belonging to the genus Kayfunavirus , family Autographiviridae. • The biocontrol potential of bacteriophage IME278 revealed that IME278 could effectively control bacterial contamination on pork. [ABSTRACT FROM AUTHOR]

Introduction: Tea is one of the most widely consumed beverages around the world. Larvae of the moth, Ectropis obliqua Prout (Geometridae, Lepidoptera), are one of the most destructive insect pests of tea in China. E. obliqua is a polyphagus insect that is of increasing concern due to the development of populations resistant to certain chemical insecticides. Microbial biological control agents offer an environmentally friendly and effective means for insect control that can be compatible with "green" and organic farming practices., Methods: To identify novel E. obliqua biological control agents, soil and inset cadaver samples were collected from tea growing regions in the Fujian province, China. Isolates were analyzed morphologically and via molecular characterization to identity them at the species level. Laboratory and greenhouse insect bioassays were used to determine the effectiveness of the isolates for E. obliqua control., Results: Eleven isolates corresponding to ten different species of Metarhizium were identified according to morphological and molecular analyses from soil and/or insect cadavers found on tea plants and/or in the surrounding soil sampled from eight different regions within the Fujian province, China. Four species of Metarhizium including M. clavatum, M. indigoticum, M. pemphigi , and M. phasmatodeae were documented for the first time in China, and the other species were identified as M. anisopliae, M. brunneum, M. lepidiotae, M. majus, M. pinghaense , and M. robertsii . Insect bioassays of the eleven isolates of Metarhizium revealed significant variation in the efficacy of each isolate to infect and kill E. obliqua . Metarhizium pingshaense (MaFZ-13) showed the highest virulence reaching a host target mortality rate of 93% in laboratory bioassays. The median lethal concentration (LC 50 ) and median lethal time (LT 50 ) values of M. pingshaense MaFZ-13 were 9.6 × 10 4 conidia/mL and 4.8 days, respectively. Greenhouse experiments and a time-dose-mortality (TDM) models were used to further evaluate and confirm the fungal pathogenic potential of M. pingshaense MaFZ-13 against E. obliqua larvae., Discussion: Isolation of indigenous microbial biological control agents targeting specific pests is an effective approach for collecting resources that can be exploited for pest control with lowered obstacles to approval and commercialization. Our data show the presence of four different previously unreported Metarhizium species in China. Bioassays of the eleven different Metarhizium strains isolated revealed that each could infect and kill E. obliqua to different degrees with the newly isolated M. pingshaense MaFZ-13 strain representing a particularly highly virulent isolate potentially applicable for the control of E. obliqua larvae., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhao, Chen, Keyhani, Wang, Li, Pu, Li, Liu, Lai, Zhu, He, Cai, Guan and Qiu.)

Introduction: Bipolaris sorokiniana is the popular pathogenic fungi fungus which lead to common root rot and leaf spot on wheat. Generally, chemical fungicides are used to control diseases. However, the environmental pollution resulting from fungicides should not be ignored. It is important to study the mode of antagonistic action between biocontrol microbes and plant pathogens to design efficient biocontrol strategies., Results: An antagonistic bacterium DB2 was isolated and identified as Bacillus amyloliquefaciens . The inhibition rate of cell-free culture filtrate ( CF , 20%, v/v) of DB2 against B. sorokiniana reached 92.67%. Light microscopy and scanning electron microscopy (SEM) showed that the CF significantly altered the mycelial morphology of B. sorokiniana and disrupted cellular integrity. Fluorescence microscopy showed that culture filtrate destroyed mycelial cell membrane integrity, decreased the mitochondrial transmembrane potential, induced reactive oxygen species (ROS) accumulation, and nuclear damage which caused cell death in B. sorokiniana . Moreover, the strain exhibited considerable production of protease and amylase, and showed a significant siderophore and indole-3-acetic acid (IAA) production. In the detached leaves and potted plants control assay, B. amyloliquefacien DB2 had remarkable inhibition activity against B. sorokiniana and the pot control efficacy was 75.22%. Furthermore, DB2 suspension had a significant promotion for wheat seedlings growth., Conclusion: B. amyloliquefaciens DB2 can be taken as a potential biocontrol agent to inhibit B. sorokiniana on wheat and promote wheat growth., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Luan, Yi, Huang, Cui, Hou, Zhu, Ren, Jia and Liu.)

Aphid parasitoids are important components in biological control of aphid populations in a variety of crop systems. Aphidius avenae Haliday and Aphidius gifuensis Ashmead (Hymenoptera: Braconidae) are key biological control agents for Sitobion avenae (F.) (Hemiptera: Aphididae), which causes serious damage to wheat worldwide. This study aimed to evaluate their parasitic potentials focusing on their thermal biological characteristics in a temperate area. Based on supercooling temperature recording techniques, the freezing point, minimum temperature for walking, and the temperature for activity recovery after chill coma of A. gifuensis females (−19.8, −5.1, and 5.9 °C, respectively) were significantly lower than those of A. avenae (−18.1, −3.3, and 7.8 °C, respectively) . The results showed that A. gifuensis had lower temperature tolerance compared with A. avenae, illuminating that it could take precedence in suppressing population growth of S. avenae when aphid colonies were still small in early spring. [ABSTRACT FROM AUTHOR]

Background: Both arrhenotoky (sexual reproduction of females and asexual reproduction of males) and thelytoky (asexual reproduction of females) occur within the order Hymenoptera. The existence of both thelytokous and arrhenotokous strains within one species provides an opportunity to compare the biocontrol efficiency between two reproductive modes. The parasitoid Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae) has thelytokous and arrhenotokous strains with sympatric distributions. This parasitoid is used to control invasive leafminers through feeding, stinging, and parasitization. To compare the biocontrol efficiency of the two strains, we analyzed life tables and host-killing parameters of these two strains reared on the leafminer Liriomyza sativae Blanchard using the age-stage, two-sex life table and the CONSUME-MSChart software., Results: Our results showed that the intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R 0 ) of the thelytokous strain were significantly higher than those of the arrhenotokous strain. The thelytokous females also performed better than the arrhenotokous females for the net host-feeding rate, net host-stinging rate, and net host-killing rate, but not the finite parasitism rate. Conclusively, the finite host-killing rate of the thelytokous strain (0.8720 ± 0.0516) was significantly higher than that of the arrhenotokous strain (0.5914 ± 0.0832)., Conclusion: We concluded that thelytokous N. formosa is a better candidate as a biocontrol agent than arrhenotokous N. formosa to control leafminers. Our results shed light on how to choose a better biocontrol agent for integrated pest management (IPM) based on biological control, especially for co-occurring thelytokous and arrhenotokous parasitoids. © 2022 Society of Chemical Industry., (© 2022 Society of Chemical Industry.)

Ssk1-type response regulator proteins are the core elements of histidine-to-aspartate systems that mediate fungal stress tolerance, a determinant to the biocontrol potential of fungal entomopathogens. We characterized the functions of Beauveria bassiana Ssk1 (Bbssk1) by analyzing multi-phenotypic changes in Δ Bbssk1 and differentially expressed genes in the digital gene expression (DGE) libraries of Δ Bbssk1 and wild-type constructed under osmotic stress. The Bbssk1 disruption caused 25 % reductions in conidial yield and virulence to Spodoptera litura larvae and significant defects in tolerances to two osmotic salts (81-84 %), HO oxidation (23 %), two fungicides (21-58 %), three cell wall biosynthesis inhibitors (25-36 %), and three metal ions (~8 %) during colony growth, respectively, but little changes in cell sensitivity to menadione oxidation and in conidial thermotolerance and UV-B resistance. RNA-seq analysis with the DGE libraries revealed differential expressions of 1,003 genes in the Δ Bbssk1 genome. Of those, many associated with conidiation, stress response, xenobiotic transport, cell wall integrity, and protein/carbohydrate metabolism were remarkably down-regulated, including the genes involved in mitogen-activated protein kinase (MAPK) signal pathway that downstream of Bbssk1. Our results indicate that Bbssk1 regulates positively the expressions of the MAPK cascade in the pathway of B. bassiana and many more downstream genes associated with conidiation, multi-stress tolerance, and virulence. [ABSTRACT FROM AUTHOR]

Abstract: Adenylate cyclase (AC) is a core element of cAMP signalling network. Here we show functional diversity and differentiation of Beauveria bassiana AC (BbAC) and Metarhizium robertsii AC (MrAC). Severe growth defects occurred in ΔBbAC and ΔMrAC grown on nutrition-rich SDAY and several minimal media but were largely alleviated by adding cAMP to SDAY. Conidial yield increased greatly in ΔBbAC but decreased in ΔMrAC. During colony growth, ΔBbAC was highly sensitive to oxidation, high osmolarity, cell wall perturbation, carbendazim fungicide, Mn2+, Zn2+, Fe3+, and EDTA but more tolerant to Cu2+ while ΔMrAC showed higher osmotolerance, decreased sensitivity to Fe3+, and null response to carbendazim or cell wall stress despite similar responses to oxidation and other metal ions. Conidial UV-B resistance decreased by 32 % in ΔBbAC and 22 % in ΔMrAC despite little change in their theromotolerance. Median lethal time (LT50) estimates of ΔBbAC and ΔMrAC against susceptible insects were 10.9 and 1.4 d longer than those from wild-type strains respectively. All the phenotypic changes were restored to wild-type levels by each gene complementation. Taken together, BbAC and MrAC regulated differentially conidiation, pathogenicity, and multistress responses in B. bassiana and M. robertsii, thereby making different contributions to their biocontrol potential. [Copyright &y& Elsevier]

The aphid endoparasitoid Diaeretiella rapae (McIntosh), parasitizing green peach aphid Myzus persicae (Sulzer), mustard aphid Lipaphis erysimi (Kaltenbach) and cabbage aphid Brevicoryne brassicae (L.) in Kangra, Kullu, Mandi, Shimla, Hamirpur, Sirmaur, Una and Bilaspur districts of north Indian Himalayan state, Himachal Pradesh was studied. At different locations, parasitism by D. rapae in December, January, February and March ranged from 0.00 to 5.30, 0.00 to 16.40, 19.30 to 31.20 and 0.00 to 49.80%. Under field conditions, experiments were conducted to evaluate the side effect of some commonly used chemical insecticides and biopesticides on D. rapae. Percent parasitism by D. rapae in dimethoate treated plots was negatively affected, and it reduced from 11.85 to 0.01%, whereas biopesticides didn't affect the parasitism. Further laboratory investigations assessed the suitability of aphids viz. M. persicae, B. brassicae and L. erysimi as hosts for mass rearing of D. rapae. Among the aphid hosts, second nymphal instar of M. persicae was found to be the larger in size, followed by B. brassicae and L. e rysimi. D. rapae reared on M. persicae were larger in size compared to those reared on B. brassicae and L. erysimi. Further, M. persicae reared on Capsicum annuum proved to be the best aphid host for D. rapae based on high percent parasitism (58.60%) and high fertility (76 eggs/female). The current research advises that D. rapae can be mass reared on aphid hosts in a laboratory that would supplement augmentative biological control in rapeseed-mustard. Our results also demonstrate that biopesticides can be used against aphids infesting rapeseed-mustard, with limited risk to the parasitoid, D. rapae and can be a fruitful option to chemical-based insecticides. • The percent parasitism by D. rapae was maximum during later stage of the crop growth. • Dimethoate and neonicotinoids reduced the percent parasitism by the parasitoid. • Biopesticides did not affect the parasitism by D. rapae and proved safer. • Myzus persicae being the largest aphid host produced larger adult parasitoids. • Biological parameters of D. rapae were best when M. persicae was reared on C. annuum. [ABSTRACT FROM AUTHOR]

Abstract: South African citrus thrips (Scirtothrips aurantii) established adventitiously in Australia. Although it is a major horticultural pest in Africa, it is now advocated as a possible biological control agent against Bryophyllum delagoense Eckl. & Zeyh. (Crassulaceae). To evaluate the biocontrol potential of S. aurantii a two year field study was conducted on the western Darling Downs of southern Queensland. Imidacloprid insecticide was applied to two quadrats at each of 18 field sites to assess, in the absence of S. aurantii, the persistence of individual plants and to quantify propagule production and recruitment by this declared weed. A third quadrat was left, as a control, to be infested naturally by S. aurantii. When released from herbivory by thrips in the field, plants grew significantly more, flowered more, and were significantly more fecund than plants in the quadrats with S. aurantii. Increases in growth and fecundity translated into significantly increased plant numbers but not increased recruitment. Recruitment even declined in experimental quadrats, through the indirect effects of releasing plants from herbivory. Field sampling also revealed that S. aurantii may be sensitive to seasonal climatic fluctuations. These and other local climatic influences may limit the biological control potential of the insect. [Copyright &y& Elsevier]

A naturally-occurring fungus called Entomophthora grylli was for the first time isolated from two species of grasshopper Oxya velox and Oxya vicinia in Jammu and Kashmir, India. The epizootic was confined along Indo-Pak border between 74 degrees 24' and 75 degrees 18', East longitude and 32 degrees 50' and 33 degrees 30' North latitude. The fungus proved to be highly pathogenic and the natural mortality was significantly influenced by the population density which increased from 26.00 to 73.60 over the period of epizootics. On the basis of the available literature this appears to be the first record from the Indian sub-continent. While many infected grasshoppers apparently produced neither conidia nor resting spores, the cadavers were found to be full of hyphal bodies and resting spores towards the end of epizootics. These resting spores or their germ tubes were not invasive as such but if provided a saturated environment for a week, they start germinating, resulting in germ conidia which were able to induce dermal pathogencity. Further, it was observed that the disease could not be transmitted to healthy individuals by ingestion. However, the intra-haemocoel infectivity of fresh resting spores, germinated resting spores, and germ conidia proved to be highly pathogenic as they resulted in 81.4% grasshopper mortality. Although E. grylli is fastidious, it is possible to multiply it on a large scale as protoplasts which are infective upon injection in their hosts. However, the lack of a cell wall renders them very fragile, and they are neither infective upon application to the insect's cuticle nor upon ingestion. In the present study, a method on delivery of pathogen through 'sticky molasses pan trap' was developed for inducing infection in grasshoppers in a paddy nursery which would facilitate its use as a bioinsecticide, analogous to other entomopathogenic fungi. [ABSTRACT FROM AUTHOR]

Gluconacetobacter diazotrophicus, an endophytic diazotroph also encountered as rhizosphere bacterium, is reported to possess different plant growth promoting characteristics. In this study, we assessed the biocontrol potential of G. diazotrophicus under in vitro conditions with soil-borne plant pathogenic Fusarium oxysporum. The possible compounds involved in the biocontrol involves 2,4-diacetylphloroglucinol, Pyrrolnitrin and Pyoluteorin. Thin layer chromatography analysis revealed that G. diazotrophicus produced the antibiotic, Pyoluteorin which helped in the suppression of soil-borne pathogenic. The volatile compounds of G. diazotrophicus also inhibited the growth of F. oxysporum. Tests for the production of hydrogen cyanide indicated that G. diazotrophicus does not produced HCN. [ABSTRACT FROM AUTHOR]

Abstract: Predatory nematodes feed on soil microorganisms including plant parasitic nematodes. They reduce populations of plant parasitic nematodes in virtually all soils because of their constant association with plant parasitic nematodes in the rhizosphere, and also release nutrients in plant-available forms, which may enable plants to better withstand nematode burden on their roots. Predation by nematodes of the orders Mononchida, Diplogasterida, Dorylaimida and Aphelenchida, has been studied but the data available in field/natural conditions are insufficient to conclude whether they are effective biocontrol agents of plant parasitic nematodes. However, among the different types of predators, diplogasterids are the most suited for biocontrol of nematodes, because of their short life cycles, easy culture, prey-specificity, chemotaxis sense and resistance to adverse conditions. This article summarizes progress to date and suggests ways to encourage the use of predatory nematodes as biocontrol agents in the management of plant parasitic nematodes. [Copyright &y& Elsevier]

Agrobacterium salinitolerans DG3-1 is an endophytic bacterium isolated from cotton root tissue. Our previous work has shown that it can inhibit the growth of Fusarium and Verticillium wilt pathogens as well as increase the chlorophyll content of cotton leaves. Here, we reported the complete genome sequence of strain DG3-1, which was analyzed by sequence reads generated from Nanopore PromethION and Illumina NovaSeq PE150 platforms. This genome sequence could be used to clarify the possible mechanism of DG3-1 at the gene level.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.