Comparative genome analysis of Bacillus thuringiensis strain HD521 and HS18-1

Bacillus thuringiensis (Bt) is an important biological insecticide used to management of different agricultural pests by producing toxic parasporal crystals proteins. Strain HD521 has an antagonistic effect against Rhizoctonia solani AG1IA, the causal agent of rice sheath blight. This strain with three cry7 genes can the formation of bipyramidal parasporal crystals (BPCs). BPCs are used for insecticidal activities against Henosepilachna vigintioctomaculata larva (Coleoptera). Strain HS18-1 contains different types of BPCs encoding genes and has effective toxicity for Lepidoptera and Diptera insects. Here we report the whole genome sequencing and assembly of HD521 and HS18-1 strains and analyzed the genome constitution covering virulence factors, types of plasmid, insertion sequences, and prophage sequences. The results showed that the genome of strain HD521 contains a circular chromosome and six circular plasmids, encoding eight types of virulence protein factors [Immune Inhibitor A, Hemolytic Enterotoxin, S-layer protein, Phospholipase C, Zwittermicin A-resistance protein, Metalloprotease, Chitinase, and N-acyl homoserine lactonase (AiiA)], four families of insertion sequence, and comprises six pro-phage sequences. The genome of strain HS18-1 contains one circular chromosome and nine circular plasmids, encoding five types of virulence protein factors [Hemolytic Enterotoxin, S-layer protein, Phospholipase C, Chitinase, and N-acyl homoserine lactonase (AiiA)] and four families of insertion sequence, and comprises of three pro-phage sequences. The obtained results will contribute to deeply understand the B. thuringiensis strain HD521 and HS18-1 at the genomic level.

The First Report on the Transovarial Transmission of Microsporidian Nosema bombycis in Lepidopteran Crop Pests Spodoptera litura and Helicoverpa armigera

Microsporidia are ubiquitous fungi-related parasites infecting nearly all vertebrates and invertebrates. Microsporidian Nosema bombycis is a natural pathogen of multiple insects, including the silkworm and many agricultural and forest pests. N. bombycis can transovarially transmit in silkworm and cause huge economic losses to the sericulture. However, it remains unclear whether N. bombycis vertically transmits in the crop pests Spodoptera litura and Helicoverpa armigera. Here, we investigated the infection of N. bombycis in S. litura and H. armigera to illuminate its infectivity and transovarial transmission. In result, tissue examination with light microscopy revealed that the fat body, midgut, malpighian tubules, hemolymph, testis, and ovary were all infected in both pest pupae. Immunohistochemical analysis (IHA) of the ovariole showed that a large number of parasites in maturation and proliferation presented in follicle cell, nurse cell, and oocyte, suggesting that N. bombycis can infect and multiply in these cells and probably transovarially transmit to the next generations in both pests. Microscopic examination on the egg infection rate demonstrated that 50% and 38% of the S. litura and H. armigera eggs were congenitally infected, respectively. IHA of both eggs manifested numerous spores and proliferative pathogens in the oocyte, confirming that N. bombycis can invade into the female germ cell from the parent body. After hatching of the infected eggs, we detected the infection in offspring larvae and found large quantities of proliferative pathogens, confirming that N. bombycis can transovarially transmit in S. litura and H. armigera, and probably persists in both pest populations via congenital infection. In summary, our work, for the first time, proved that N. bombycis is able to vertically transmit in S. litura and H. armigera via infecting the oocyte in the parent, suggesting that N. bombycis could be a biological insecticide for controlling the population of crop pests.

How Does Bacillus thuringiensis Crystallize Such a Large Diversity of Toxins?

Bacillus thuringiensis (Bt) is a natural crystal-making bacterium. Bt diversified into many subspecies that have evolved to produce crystals of hundreds of pesticidal proteins with radically different structures. Their crystalline form ensures stability and controlled release of these major virulence factors. They are responsible for the toxicity and host specificity of Bt, explaining its worldwide use as a biological insecticide. Most research has been devoted to understanding the mechanisms of toxicity of these toxins while the features driving their crystallization have long remained elusive, essentially due to technical limitations. The evolution of methods in structural biology, pushing back the limits of the resolution attainable, now allows access to be gained to structural information hidden within natural crystals of such toxins. In this review, I present the main parameters that have been identified as key drivers of toxin crystallization in Bt, notably in the light of recent discoveries driven by structural biology studies. Then, I develop how the future evolution of structural biology will hopefully unveil new mechanisms of Bt toxin crystallization, opening the door to their hijacking with the aim of developing a versatile in vivo crystallization platform of high academic and industrial interest.

An evaluation of the use of sideral precursors and biologics in the cultivation of long-legged flax

The paper presents data on the study of the effectiveness of new biological drugs-the biofungicides Trichozan and Vitariz and biological insecticide against the background of the action and aftereffect of the sideral precursors of long-legged flax. The research was conducted in the Scientific Research Center of the Ivanovo State Agricultural Academy in 2018-2020. The positive effect of the action and aftereffect of the sideral precursors on the productivity of plants and the yield of flax was established. The greatest increases in the yield of straw and seeds were obtained in 2019-2020 when flax was placed after the sideral precursors and the complex use of the biological products Trichozan, Vitariz, and Bioinsecticide. The quality of flax straw improved by 0.5-0,25 sortonomer with the interaction of the complex of biological products and the action of siderates and by 0.25 sortonomer-with the use of biological products for the treatment of seeds and plants against the background of the aftereffect of siderates. The level of profitability for the years increased by 41.9-11.7%, respectively.

Effects of a Prototype Pneumatic Machine to Control the Colorado Potato Beetle on Potato Plant Growth and Tuber Yield

HighlightsA prototype pneumatic machine used to control the Colorado potato beetle (CPB) had no effect on potato plant growth.Yields in pneumatic treatment plots were comparable to those of control plots treated with a biological insecticide.Pneumatic control of the CPB could be an alternative to reduce reliance on chemical insecticides in potato fields.Abstract. The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is the major insect pest of potato plants. Currently, the most effective method for controlling the CPB is to apply chemical insecticides throughout its lifecycle. However, the CPB has the ability to resist most chemical insecticides. Control of this insect pest has therefore become extremely difficult, prompting researchers to explore effective alternatives. The use of pneumatic methods to control the CPB is a promising alternative to chemical means. The objective of this study was to develop an effective pneumatic control method for the CPB to reduce the reliance on chemical insecticides in potato fields. In this context, a prototype pneumatic machine was designed and built. The prototype uses positive air pressure to dislodge CPBs from potato foliage, deposit them on the ground between the rows, and crush them. The effects of three airflow velocities (45, 50, and 55 m s-1) and two tractor travel speeds (5 and 6 km h-1) on CPB control, plant growth, and tuber yield were investigated in potato plots. Overall, the results showed no significant differences in yield between treatments (p = 0.3268), indicating that the yield of potato plants treated with the prototype was comparable to that of plants treated with a biological insecticide (Entrust). In addition, the prototype did not have any negative effects on plant growth. This suggests that the prototype could be safely and efficiently used in potato fields to control the CPB. The success of this innovative control method could greatly contribute to reducing the use of chemical insecticides to control the CPB. Keywords: Airflow velocity, Leptinotarsa decemlineata (Say), Pneumatic control, Potato, Travel speed.

Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides

Despite its benefits as biological insecticide, Bacillus thuringiensis bears enterotoxins, which can be responsible for a diarrhoeal type of food poisoning. Thus, all 24 isolates from foodstuffs, animals, soil and commercially used biopesticides tested in this study showed the genetic prerequisites necessary to provoke the disease. Moreover, though highly strain-specific, various isolates were able to germinate and also to actively move, which are further requirements for the onset of the disease. Most importantly, all isolates could grow under simulated intestinal conditions and produce significant amounts of enterotoxins. Cytotoxicity assays classified 14 isolates as highly, eight as medium and only two as low toxic. Additionally, growth inhibition by essential oils (EOs) was investigated as preventive measure against putatively enteropathogenic B. thuringiensis. Cinnamon Chinese cassia showed the highest antimicrobial activity, followed by citral, oregano and winter savory. In all tests, high strain-specific variations appeared and must be taken into account when evaluating the hazardous potential of B. thuringiensis and using EOs as antimicrobials. Altogether, the present study shows a non-negligible pathogenic potential of B. thuringiensis, independently from the origin of isolation. Generally, biopesticide strains were indistinguishable from other isolates. Thus, the use of these pesticides might indeed increase the risk for consumers’ health. Until complete information about the safety of the applied strains and formulations is available, consumers or manufacturers might benefit from the antimicrobial activity of EOs to reduce the level of contamination.

Aplikasi Insektisida Nabati Berbahan Utama Tumbuhan Rawa Dalam Mengendalikan Hama Utama Padi Di Lahan Rawa Pasang Surut

Based on integrated pest control, the use of toxic chemicals or chemical pesticides/insecticides is the last alternative if other components are no longer able to control, then pesticides/insecticides can be used. Currently, plant-based insecticides are being developed in controlling plant pests. Unwise and continuous use of chemical pesticides/insecticides will cause environmental pollution problems that result in pest outbreaks, pest resistance, and resurgence, ridding of non-targeted pests and natural enemies of plant pests and bad effects on consumers and pets. About 350-500 species of plants have the potentials to become sources of plant-based insecticides, from that number around 90-100 species of swamp plants have the potentials to be used as biological insecticides in controlling rice and vegetable/horticulture pests. Some of the plant species that extracts were used in this study were ‘jingah’, ‘tapak liman’, ‘simpur’ and ‘kamandrah’. This study was arranged in an experiment using a randomized block design (RBD) with 5 replications. The treatments given included extracts of 4 types of swamp plants plus 3 control treatments, namely control 1 (without pest control), control 2 (BGA plant-based insecticide treatment), and control 3 ('Dimehipo' chemical insecticide). From the results of the study it could be concluded that extracts for ‘jingah’, ‘tapak liman’, ‘simpur’ and ‘kamandrah’ were effective in controlling the main rice pests in the tidal swamp land. As for the yield of dried grain harvest in the swamp, plant extracts 4.54-4.62 and control of chemical insecticides 4.63 t/ha, BGA biological insecticide. For convenience for use, Jingahextracts need to be considered because this jingah plant extract can cause allergies and itching when exposed to the skin and is very disturbing for the user. Keywords: application, rice pest, tidal swamp, vegetable insecticide ABSTRAK Berdasarkan pengendalian hama terpadu, penggunaan bahan kimia beracun atau pestisida/insektisida kimiawi merupakan alternatif terakhir apabila komponen lainnya tidak mampu lagi, baru pestisida/insektisida dapat digunakan. Bahkan sekarang ini mulai dikembangkan pestisida/insektisida nabati dalam mengendalikan hama tanaman. Penggunaan pestisida/insektisida kimiawi yang kurang bijak dan terus-menerus akan menyebabkan masalah pencemaran lingkungan yang berakibat terjadinya ledakan hama, terjadinya resistensi dan resurgensi hama, terbunuhnya hama bukan sasaran dan musuh alami hama tanaman, serta pengaruh buruk bagi konsumen dan hewan peliharaan. Di lahan rawa ditemukan sekitar 350-500 jenis tumbuhan/tanaman yang berpotensi sebagai insektisida nabati, dari jumlah tersebut sekitar 90-100 jenis tumbuhan rawa berpotensi sebagai bahan pembuatan insektisida nabati dalam mengendalikan hama padi, hama sayuran/hortikultura. Beberapa jenis tumbuhan tersebut yang ekstraknya digunakan pada penelitian ini adalah jingah, tapak liman, kamandrah dan pulai. Penelitian dilakukan dengan percobaan yang menggunakan rancangan acak kelompok dengan lima ulangan. Perlakuan yang diberikan meliputi ekstrak empat macam tumbuhan rawa dan ditambah dengan 3 perlakuan kontrol, yaitu kontrol 1 (tanpa pengendalian), kontrol 2 (perlakuan insektisida nabati BGA) dan kontrol 3 (insektisida kimiawi Dimehipo). Dari hasil penelitian dapat disimpulkan bahwa tumbuhan-tumbuhan jingah, tapak liman, simpur dan tumbuhan kamandrah efektif dalam mengendalikan hama utama padi di lahan rawa pasang surut. Hasil gabah kering panen dengan aplikasi ekstrak tumbuhan rawa adalah sebesar 4,54-4,62 t/ha dan kontrol insektisida kimia 4,63 t/ha, insektisida nabati BGA. Untuk kenyamanan bagi penggunakan maka ekstrak tumbuhan jingah perlu dipertimbangkan karena ekstrak tumbuhan jingah ini dapat menimbulkan alergi dan gatal-gatal kalau terkena kulit dan sangat mengganggu bagi pengguna. Kata kunci: hama padi, insektisida nabati, rawa pasang surut

Efficacité d’une lutte mécanique associée au biopesticide Neco 50 EC dans le contrôle des adultes de Diastocera trifasciata (Coleoptera : Cerambycidae), ciseleur des branches d’anacardier en Côte d’Ivoire

En Côte d’Ivoire, les vergers d’anacardiers du centre, centre-ouest et de l’est sont constamment attaqués par le Cerambycidae Diastocera trifasciata. Ces attaques, sans méthodes de contrôle efficaces s’amplifient au fil des années. Cette étude a été réalisée en vue d’évaluer d’une part l’efficacité d’une lutte mécanique contre les larves de D. trifasciata et d’autre part l’efficacité d’un biopesticide Neco 50 EC en comparaison avec un insecticide de synthèse Acétamipride 32 g/l + Lambdacyhalothrine 30 g/l. Les expérimentations ont été effectuées en mars 2017 et en septembre 2018 dans la localité de Brobo (centre de la Côte d’Ivoire). La lutte mécanique a consisté à retirer systématiquement toutes les branches infestées de larves de l’espèce et à les incinérer. Quant aux tests d’efficacité, 10 concentrations, à raison de 5 par produit ont été pulvérisées directement sur les adultes de D. trifasciata en conditions semi naturelles. Les résultats ont montré que la lutte mécanique a fait baisser le niveau des attaques de 100% à 35%. Concernant les insecticides, l’association Acétamipride 32 g/l + Lambdacyhalothrine 30 g/l a occasionné des taux de mortalité compris entre 70 et 100% à toutes les concentrations testées. Avec le biopesticide Neco 50 EC, des taux de mortalité supérieurs à 70% ont été enregistrés avec les concentrations de 3,3.10-4 g/ml et 2,5.10-4 g/ml en 24 h. Ces résultats ont permis de montrer l’efficacité de la lutte mécanique et des produits contre D. trifasciata. La méthode mécanique pourrait être vulgarisée pour permettre une bonne gestion préventive des attaques du ravageur dans les vergers d’anacardier. Quant à la lutte par l’insecticide biologique, des tests de confirmation devront être faits en plein champ pour mieux apprécier son efficacité.Mots clés : Analeptes trifasciata, attaques, Acétamipride, Lambdacyhalothrine, lutte intégrée, Côte d’Ivoire. English Title: Efficacy of mechanical control associated with the biopesticide Neco 50 EC in the control of adults of Diastocera trifasciata (Coleoptera: Cerambycidae), a cashew tree branch girdler in Côte d'IvoireIn Côte d'Ivoire, cashew orchards in the central, western central and eastern parts of the country are constantly attacked by Cerambycidae Diastocera trifasciata. These attacks, without effective methods of control, have been increasing over the years. This study was carried out in order to evaluate on the one hand the efficacy of mechanical control of D. trifasciata larvae and on the other hand the efficacy of a biopesticide Neco 50 EC compared to a synthetic insecticide Acetamiprid 32 g/l + Lambdacyhalothrin 30 g/l. Experiments were carried out on March 2017 and to September 2018 in the locality of Brobo (central Côte d'Ivoire). Mechanical control consisted in systematically removing all branches infested with larvae of the species and incinerating them. As for efficacy tests, 10 concentrations, at a rate of 5 per product, were sprayed directly on adults of D. trifasciata under semi-natural conditions. Results showed that mechanical control reduced the level of attacks from 100% to 35%. The synthetic insecticide caused mortality rates between 70 and 100% at all concentrations tested. With biopesticide Neco 50 EC, mortality rates higher than 70% were recorded with concentrations of 3.3.10-4 g/ml and 2.5.10-4 g/ml after 24 h. These results demonstrated the effectiveness of mechanical control against D. trifasciata. The mechanical method could be extended to allow good preventive management of pest attacks in cashew orchards. As for control by biological insecticide, confirmatory tests will have to be carried out in the field to better assess its effectiveness.Keywords: Analeptes trifasciata, attacks, Acetamiprid, Lambdacyhalothrin, Integrated Pest Management, Côte d'Ivoire