Wettable Powder Research Articles

Efficacy of formulation of nematode antagonistic bacterium, <i>Pasteuria penetrans</i> (Thorne) Sayre and Starr, 1985 against root-knot nematode, <i>Meloidogyne incognita</i>

Root-knot nematodes, Meloidogyne spp. are extremely polyphagous pests of both tropical and subtropical crops that cause a great reduction in crop yields and quality. In vegetable production, 10–30% yield loss is caused by root-knot nematode infestation. Pasteuria penetrans is a hyperparasitic bacterium of M. incognita that has a high degree of biocontrol potential. Though, the application of P. penetrans in the form of root powder had been tested by a few scientists in the nurseries, it is highly impractical in the main fields. Commercial formulation of this bacterium is not available in India till date. Based on these facts, four different formulations of P. penetrans viz., kaolinite clay, Emulsifiable Concentrate (EC), wettable talc powder and sodium alginate beads were prepared and tested for its parasitization potential. Among the four, EC formulation showed the highest parasitization potential of 84.6% with a spore load of 11.2/J2 (second stage juvenile). These formulations were stored under room temperature (27±1ºC) to record spore viability. The observation showed that the spores were viable upto 60 days with the highest parasitization of 84.7% in EC formulation. An in-vitro test was carried out in tomato plants to document the infection in M. incognita by endospores released from the formulations. The observation also showed that the spores released from the formulations were multiplied in the female body. Two cell stage and four cell stages of spores were observed in J3 and pre-adult stages of the nematode. The results of this study showed that the EC formulation is highly suitable for field application.

Biosafety evaluation of two Beauveria bassiana products on female albino rats using acute oral test

Application of bio-pesticides in agriculture has been developed as alternative agents to conventional pesticides due to residues accumulating which causing detrimental effects to human and environment. The aim of this investigation is to evaluate biosafety of a bio-insecticide Beauveria bassiana using two products in female rats by single oral dose through hepato- and renal toxicity, hematotoxicity and lipid profile. The two products from B. bassiana (AUMC 9896) were metabolic crude (MC), and wettable powder formulation (WP) of the local isolate. Results showed a significant increase in values of erythrocytes (RBCs), leucocytes (WBCs), platelet count (Plt) and the absolute differential WBC counts. Liver enzymes (AST, ALT, and ALP) and globulin (Glb) content were reduced in the exposed female rats with both types of B. bassiana in comparison to controls. While ratio of AST/ALT and A/G, total protein level (TP) and albumin (Alb) were raised in Beauveria bassiana -treated rats (Bb - treated rats). Urea and creatinine concentrations decreased or increased significantly in treated rats. Moreover, there was a decline in the serum of lipid profiles in WP - treated rats, but LDL levels increased in all treated animal. Additionally, no mortality or toxicity in all treated. All animals treated showed non-significant modifications in body weight gain and a slight change in relative liver weights when compared to controls. These results suggest that both treatments effect markedly on function and somatic index of the liver and slight effects on CBC and lipid profile aspects of treated female rats.

Emission of volatile organic compounds (VOCs) from application of commercial pesticides in China

Applying pesticides can result in emissions of volatile organic compounds (VOCs), but little is known about VOC emission characteristics and the quantities in particular regions. We investigated the use of pesticides in China based on a large-scale survey of 330 counties in 31 provinces and evaluated the national pesticide VOC emission potentials based on thermogravimetric analysis of 1930 commercial pesticides. The results showed that herbicides were the most extensively used pesticide category in China, accounting for 43.47%; emulsifiable concentrate (EC), suspension concentrate, and wettable powder were the dominant pesticide formulations, with proportions of 26.75%, 17.68%, and 17.31%, respectively. The VOC emission potential coefficient (EP) of the liquid formulations was higher than the solid formulations, and the maximum mean EP was 45.59% for EC and the minimum was 0.76% for WP. Among 437 high-VOC pesticide products used in China, EC accounted for 83.52%, and 16.93% of those contained abamectin. The total VOC emissions derived from commercial pesticides in China were 280 kt (kilotons) in 2018, and 65.35% of the contribution was derived from EC. Shandong, Hunan, and Henan were the three provinces with the highest pesticide VOC emissions (>21 kt/y). The emission rate of VOCs from pesticides was 24.80 t/d in China, which was higher than in San Joaquin Valley, California. These findings suggest that some comprehensive measures (e.g., perfecting pesticide management policy, strict supervision for pesticide production and use, and strengthening pesticide reduction publicity) should be taken to reduce VOC emissions from pesticide applications.

Molluscicidal effect of 25% wettable powder of pyriclobenzuron sulphate in hilly schistosomiasis-endemic regions

To evaluate the molluscicidal effect of 25% wettable powder of pyriclobenzuron sulphate (WPPS) against Oncomelania snails in hilly schistosomiasis-endemic regions and test its toxicity to fish. In October 2020, a snail-infested setting which had been cleared was selected in Nanjian County, Yunnan Province and divided into several blocks, and the natural snail mortality was estimated. 25% WPPS was prepared into solutions at concentrations of 1 and 2 g/L, and 25% wettable powder of niclosamide ethanolamine salt (WPNES) was prepared into solutions at a concentration of 2 g/L. The different concentrations of drugs were sprayed evenly, and the same amount of water was used as blank control. Snails were surveyed using the systematic sampling method 1, 3 and 7 days post-treatment, and snail survival was observed. A fish pond was selected in Nanjian County, and 2 kg 25% WPPS was evenly sprayed on the water surface to allow the effective concentration of 20 g/L. Fish mortality was estimated 8, 24, 48 and 72 h post-treatment. One-day treatment with 1 and 2 g/L WPPS and 2 g/L WPNES resulted in 97.99%, 97.99% and 94.11% adjusted snail mortality rates (χ2 = 3.509 and 3.509, both P values > 0.05), and the adjusted snail mortality was all 100% 3 d post-treatment with 1 and 2 g/L WPPS and 2 g/L WPNES, while 7-day treatment with 1 and 2 g/L WPPS and 2 g/L WPNES resulted in 91.75%, 86.57% and 57.76% adjusted snail mortality rates (χ2 = 14.893 and 42.284, both P values < 0.05). Treatment with 2 g/L WPPS for 72 h resulted in a 0.67% cumulative mortality rate of fish. 25% WPPS is effective for snail control and highly safe for fish, which is feasible for use in hilly schistosomiasis-endemic regions.

Inhibition of Oomycetes by the Mixture of Maleic Acid and Copper Sulfate.

Since the protective activity of the Bordeaux mixture against plant disease caused by oomycetes was discovered, copper compounds have been used for more than a century as an effective plant protection strategy. However, the application of excessive copper can cause adverse effects through long-term heavy metal accumulation in soils. Therefore, it is necessary to develop new strategies to reduce or replace copper in pesticides based on organic and low-input farming systems. Organic acids are eco-friendly. In this study, we tested the antifungal and anti-oomycete activity of maleic acid (MA) and copper sulfate (CS) against 13 plant pathogens. Treatment with a mixture of MA and CS showed strong anti-oomycetes activity against Phytophthora xcambivora, P. capsici, and P. cinnamomi. Moreover, the concentration of CS in the activated mixture of MA and CS was lower than that in the activated CS only, and the mixture showed synergy or partial synergy effects on the anti-oomycete activity. Application of a wettable powder formulation of MA and CS mixture (MCS 30WP; 26.67% MA and 3.33% CS) had excellent protective activity in pot experiments with control values of 73% Phytophthora blight on red pepper, 91% damping-off on cucumber, and 84% Pythium blight on creeping bentgrass, which are similar to those of the CS wettable powder formulation (6.67% CS) containing two times the CS content of MCS 30WP. These observations suggest that the synergistic effect of the MA and CS combination is a sustainable alternative for effective management of destructive oomycete diseases.

Dissipation and Residues of Pyraclostrobin in Rosa roxburghii and Soil under Filed Conditions.

Rosa roxburghii has been widely planted in China. Powdery mildew is the most serious disease of R. roxburghii cultivation. Pyraclostrobin was widely used as a novel fungicide to control powdery mildew of R. roxburghii. To assess the safety of pyraclostrobin for use on R. roxburghii fruits, its residue rapid analysis as well as an investigation on its dissipation behaviors and terminal residues in R. roxburghii and soil under field conditions were carried out. The QuEChERS method was simplified using LC–MS/MS detection and combined with liquid–liquid extraction purification to allow determination of pyraclostrobin levels in R. roxburghii fruits and the soil. The fortified recoveries at 0.1~5.0 mg/kg were 93.48~102.48%, with the relative standard deviation of 0.64~3.21%. The limit of detection of the analytical method was 0.16 and 0.15 µg/kg for R. roxburghii fruit and soil, respectively. The effects of different spray equipment and formulations on the persistence of pyraclostrobin in R. roxburghii were as follows: gaston gasoline piggyback agricultural sprayer (5.38 d) > manual agricultural backpack sprayer (3.37 d) > knapsack multi-function electric sprayer (2.91 d), suspension concentrate (SC) (6.78 d) > wettable powder (WP) (5.64 d) > water dispersible granule (WG) (4.69 d). The degradation of pyraclostrobin followed the first-order kinetics and its half-lives in R. roxburghii and soil were 6.20~7.79 days and 3.86~5.95 days, respectively. The terminal residues of pyraclostrobin in R. roxburghii and soil were 0.169~1.236 mg/kg and 0.105~3.153 mg/kg, respectively. This study provides data for the establishment of the maximum residue limit (MRL) as well as the safe and rational use of pyraclostrobin in R. roxburghii production.

Large-scale (Phase III) evaluation of broflanilide 50WP (VECTRON\u2122 T500) for indoor residual spraying for malaria vector control in Northeast Tanzania: study protocol for a two-arm, non-inferiority, cluster-randomised community trial

BackgroundIndoor residual spraying (IRS) is a major method of malaria vector control across sub-Saharan Africa. Effective control is being undermined by the rapid spread of insecticide resistance. There is major investment in development of new insecticides for IRS that possess novel modes of action, long residual activity, low mammalian toxicity and minimal cross-resistance. VECTRON™ T500, a new IRS product containing the active ingredient broflanilide as a 50% wettable powder (WP), has been shown to be efficacious against pyrethroid susceptible and resistant vector species on mud and concrete substrates in experimental hut (Phase II) trials.MethodsA two-arm non-inferiority cluster randomized controlled trial (Phase III) will be undertaken in Muheza District, Tanga Region, Tanzania. VECTRON™ T500 will be compared to the IRS product Fludora® Fusion (clothianidin 50% WP + deltamethrin 6.25% WP). The predominant malaria vectors in the study area are pyrethroid-resistant Anopheles gambiae s.s., An. arabiensis and An. funestus s.s. Sixteen village clusters will be pair-matched on baseline vector densities and allocated to reference and intervention arms. Consenting households in the intervention arm will be sprayed with VECTRON™ T500 and those in the reference arm will be sprayed with Fludora® Fusion. Each month, CDC light traps will collect mosquitoes to estimate changes in vector density, indoor biting, sporozoite and entomological inoculation rates (EIR). Susceptibility to IRS active ingredients will be assessed using World Health Organisation (WHO) bottle bioassays. Target site and metabolic resistance mechanisms will be characterised among Anopheles field populations from both trial arms. Residual efficacy of both IRS products will be monitored for 12 months post intervention. Questionnaire and focus group discussions will explore factors that influence adherence, adverse effects and benefits of IRS.DiscussionThis protocol describes a large-scale non-inferiority evaluation of a novel IRS product to reduce the density and EIR of pyrethroid-resistant Anopheles vectors. If VECTRON™ T500 proves non-inferior to Fludora® Fusion, it will be considered as an additional vector control product for malaria prevention and insecticide resistance management.Trial registration: ClinicalTrials.gov, NCT05150808, registered on 26 November 2021. Retrospectively registered.

Efficacy of Bacillus subtilis XZ18-3 as a Biocontrol Agent against Rhizoctonia cerealis on Wheat

Rhizoctonia cerealis is a major fungal pathogen of wheat that causes great yield losses in all wheat-growing regions of the world. The biocontrol agent Bacillus subtilis XZ18-3 was investigated for inhibiting R. cerealis growth in wheat. The results of the mycelial growth test showed that the sterile filtrate of B. subtilis XZ18-3 could significantly inhibit the mycelial growth of R. cerealis and cause swelling and rupture of the mycelium. Observation by transmission electron microscopy indicated that the sterile filtrate could penetrate the cellular membrane of Rhizoctoniacerealis, resulting in organelle destruction. The effect of the sterile filtrates on the pathogen cells, shown through fluorescent microscopy using different stains, revealed the mechanism by which the sterile filtrate caused DNA fragmentation, accumulation of ROS and changes in cell membrane permeability. To reach a better treatment of the soil-borne fungi, the components of a wettable powder were screened and an optimised formula determined (30.0% kaolin, 4.0% polyvinyl alcohol, 8.0% Tween-80, 2.0% polyethylene glycol and 100% fermentation broth). A quality index analysis revealed that the wetting powder reached acceptable biological pesticide standards. Pot control experiments showed that the wettable powder of B. subtilis XZ18-3 effectively controlled the pathogens with an efficacy of 88.28%. This study has provided the potential biocontrol agents (BCAs) for wheat sharp eyespot disease.

Behavioural impairment and oxidative stress by acute exposure of zebrafish to a commercial formulation of tebuconazole

Tebuconazole is a systemic follicular fungicide known to cause diverse problems in non-target organisms namely associated to the pure active ingredient. As such, the objective of this work was to evaluate developmental changes induced by a tebuconazole commercial formulation to a non-target animal model. Zebrafish embryos at ± 2 h post-fertilization were exposed to tebuconazole wettable powder concentrations (0.05, 0.5 and 5 mg L-1) for 96 h with developmental toxicity assessed throughout the exposure period and biochemical parameters evaluated at the end of the exposure. Behavioural assessment (spatial exploration and response to stimuli) was conducted 24 h after the end of the exposure. While no developmental and physiological alterations were observed, exposure to tebuconazole resulted in an increased generation of reactive oxidative species at the 0.05 and 0.5 mg L-1 concentrations and a decreased GPx activity at the 0.5 mg L-1 concentration suggesting a potential protection mechanism. There was also a change in the avoidance-escape behaviour supporting an anxiolytic effect suggesting possible alterations in the central nervous system development demanding further studies.

Applying different infective structures of Beauveria bassiana to Coffea arabica infested with Hypothenemus hampei (Coleoptera: Curculionidae) under field

Coffee is the most appreciated beverage in worldwide; Brazil is the largest producer and exporter of this commodity. Organochlorine endosulfan was banned from the country in 2013 due to its teratogenic agent-related features. Since then, coffee plantations have experienced increased Hypothenemus hampei infestation rates. The aim of the current study is to assess variations in the rates of Coffea arabica fruits brocaded by H. hampei after the application of entomopathogenic fungal species Beauveria bassiana IBCB66. Experiments were carried out with ‘Catuaí’ and ‘Mundo Novo’ cultivars between 2018 and 2020, during the borer transit period. Three experiments were carried out based on the application of the aforementioned fungal species on the investigated coffee plant species, both by spraying and sprinkling, at 30-day intervals; 10 fruits were collected per face of each useful plant in each repetition. The experiment has followed a randomized blocks design with five treatments, including the control, and five repetitions, each. Beauveria bassiana Ecobass (IBCB66) wettable powder spray, at the concentration of 2 × 1013·ha–1, was used in experiments I and II. On the other hand, the mix used in experiment III was prepared with blastospores at concentration of 5 × 1012·ha–1 blastospores + 0.1% Silwet. The sprinkling process in all three experiments has used dry aerial conidia at concentration of 2 × 1013·ha–1. Collected data were subjected to analysis of variance (ANOVA), which was followed by Fisher’s test at 5% probability level, in the SISVAR software. More than 35,000 fruits were assessed. In addition to variations between experiments, results have evidenced that the rate of brocaded fruits remained high.

Biocontrol of Large Patch Disease in Zoysiagrass (Zoysia japonica) by Bacillus subtilis SA-15: Identification of Active Compounds and Synergism with a Fungicide

Bacillus subtilis SA-15 is a plant growth-promoting bacterium isolated from non-farming soil. We aimed to identify lipopeptides produced by B. subtilis SA-15 and evaluate the control efficacy of B. subtilis SA-15 against large patch disease caused by Rhizoctonia solani AG 2-2 (IV) in zoysiagrass (Zoysia japonica). Bacillus subtilis SA-15 inhibited mycelial growth of R. solani AG 2-2 (IV) in vitro and produced fengycin A and dehydroxyfengycin A, which are antifungal compounds. Fengycin A and deghydroxyfengycin A inhibited R. solani mycelial growth by 30.4 and 63.2%, respectively. We formulated B. subtilis SA-15 into a wettable powder and determined its control efficiency against large patch in a field trial. The control efficacy was 51.2–92.0%. Moreover, when B. subtilis SA-15 powder was applied together with half the regular dose of the fungicide pecycuron, the control efficacy was 88.5–100.0%. These results indicate that B. subtilis SA-15 can be used to control soil-borne diseases, including large patch caused by R. solani, because of lipopeptide production. The use of this bacterium can also reduce the amount of fungicide needed, providing an eco-friendly management option for turfgrass.

Preparation and application of thidiazuron nanoparticles via electrostatic self-assembly as defoliant in cotton

Nanopesticides can offer some benefits including better spreadability, leaf retention, a reduction usage of active ingredients and environmental pollution. Up to now, the green fabrication of nanopesticide is still a challenge work. In this study, the environmentally friendly thidiazuron-loaded nanoparticles (TDZ NPs) were fabricated through the electrostatic self-assembly by using two ionic polysaccharides chitosan and sulfobutylether-β-cyclodextrin (SCD). Firstly, thidiazuron (TDZ) was encapsulated by SCD to form the anionic building block, which can form TDZ NPs with the cationic polysaccharide chitosan through the electrostatic self-assembly. The resulting TDZ NPs were in the average size of 137 ± 28 nm, have low polydispersity index (< 0.1). Meanwhile, the TDZ NPs contain positive charge on the particle surface, which can promote the interaction with the leaf surface to improve the spreadability and retention. Moreover, the TDZ NPs can maintain stable for at least four weeks. In terms of biological testing, the defoliation rate of TDZ NPs reached 65.5 ± 5.3%, while the defoliation rate of thidiazuron wettable powder (TDZ WP) was only 44.9 ± 2.5%. Compared with the TDZ WP treatment, the photosynthesis of the leaf was more severely damaged and the release rate of ethylene was increased more by the TDZ NPs treatment. In addition, the expression of GhACS2, GhACO3 and GhERF113 were all up-regulated. The results indicated that TDZ NPs showed better bioactive effects than TDZ WP. And the TDZ NPs prepared by this method is of great significance in improving the quality of cotton in mechanized production, reducing environmental pollution and reducing labor input.

Molluscicidal effect of immersion with 50% wettable powder of niclosamide ethanolamine salt against Oncomelania hupensis on the soil surface and inside the soil layer in winter

To evaluate the molluscicidal effect of 50% wettable powder of niclosamide ethanolamine salt (WPNES) against Oncomelania hupensis on the soil surface and inside the soil layer by immersion method in winter. O. hupensis snails were placed on the soil surface and 2, 5 cm and 10 cm under the soil layer outdoors in winter, and then immersed in 50% WPNES at concentrations of 1 mg/L and 2 mg/L for 1, 3 d and 7 d, while dechlorinated water served as controls. Snail mortality was observed following immersion with 50% WPNES on the soil surface and inside the soil layer. Following immersion with 50% WPNES at concentrations of 2 mg/L and 1 mg/L outdoors in winter, the 3-day corrected snail mortality rates were 98.0% and 76.0% on the soil surface, and the 7-day corrected snail mortality rate was both 100.0%. Following immersion with 50% WPNES at concentrations of 2 mg/L and 1 mg/L outdoors in winter, the 7-day corrected snail mortality rates were 95.5% and 85.6% 2 cm below the soil layer, 66.0% and 6.4% 5 cm below the soil layer. However, the 7-day snail mortality rate swere comparable between the 50% WPNES treatment group (at 2 mg/L and 1 mg/L) and controls 10 cm below the soil layer (both P > 0.05). Immersion of 50% WPNES at a concentration of 2 mg/L for 7 days presents a high molluscicidal efficacy against O. hupensis on the soil surface and 5 cm within the soil layers in winter.

Development of novel spray-dried and air-dried formulations of Metarhizium robertsii blastospores and their virulence against Dalbulus maidis.

The present research addressed spray-drying and air-drying techniques applied to Metarhizium robertsii blastospores to develop wettable powder (WP) formulations. We investigated the effect of co-formulants on blastospore viability during drying and assessed the wettability and stability of formulations in water. The effect of oxygen-moisture absorbers was studied on the shelf life of these formulations stored at 26°C and 4°C for up to 90days. Additionally, we determined the virulence of the best spray-dried and air-dried formulations against the corn leafhopper Dalbulus maidis. While sucrose and skim milk played an essential role as osmoprotectants in preserving air-dried blastospores, maltodextrin, skim milk, and bentonite were crucial to attain high cell survival during spray drying. The lowest wettability time was achieved with spray-dried formulations containing less Ca-lignin, while charcoal powder amount was positively associated with formulation stability. The addition of oxygen-moisture absorbers inside sealed packages increased from threefold to fourfold the half-life times of air-dried and spray-dried formulations at both storage temperatures. However, the half-life times of all blastospore-based formulations were shorter than 3months regardless of temperature and packaging system. Spray-dried and air-dried WP formulations were as virulent as fresh blastopores against D. maydis adults sprayed with 5 × 107 blastospores mL-1 that induced 87.8% and 70.6% mortality, respectively. These findings bring innovative advancement for M. robertsii blastospore formulation through spray-drying and underpin the importance of adding protective matrices coupled to oxygen-moisture absorbers to extend cell viability during either cold or non-refrigerated storage. KEY POINTS: • Cost-effective wettable powder formulations of M. robertsii blastospores were developed. • Bioefficacy of formulations against the corn leafhopper was comparable to fresh blastospores. • Cold storage and dual oxygen-moisture absorber are critical for extended shelf life.

Hygienic evaluation of diflubenzuron-based pesticides in various application technologies

Introduction. In connection with the widespread introduction of new preparative forms of pesticides and methods of their introduction into the environment, the urgent task of the modern period is to minimize the risk of exposure to pesticides on the health of workers and the population-the use of diflubenzuron of low and medium toxicity increases. Therefore, a mandatory criterion for assessing risk is registration tests, carried out during several stages - as hazard identification, hazard characterization, exposure assessment, risk characterization. Purpose of work. To assess the regularities of the formation of the risk of diflubenzuron by exposure and by the absorbed dose, depending on the type of preparative form of pesticides with different technologies of their introduction and regulating safe use measures. Materials and methods. The obtained exposure levels of insecticides based on diflubenzuron in the air and on the skin were compared with the hygienic standards calculated and experimentally established as follows: MPC (mg/m3) in the air of the working area and approximate admissible level (AAL) (mg/cm2) of skin contamination. The exposure level risk was determined by the safety level (SL) SLsumm value. The risk of exposure to insecticides based on diflubenzuron for the operator / user / refueller / pilot / signaller based on the absorbed dose, determined by the safety factor - SLp, and the exposure -SBsumm, is considered acceptable when SLsumm and SLp &lt;1. Results. The paper presents the risk analysis results of the impact of diflubenzuron-based insecticides studied in natural conditions using 27 drugs with different preparative forms and methods (technologies) of their introduction into the environment. The risk of exposure to insecticides (SLsumm) for all technologies is acceptable SL. The risk of absorbed dose (SLp) was more significant regardless of the type of formulation. Wettable powder formulations are more unfavourable to use than other formulations. Conclusion. The conditions for the use of preparations based on diflubenzuron in the technologies of ground boom spraying and fan spraying of field and horticultural crops, in the treatment of field and forest crops by the aerial method, in the treatment of field and horticultural crops in private household plots, in the treatment of champignons in protected ground, compliance with regulations and measures safety meet hygienic requirements.

Conditions for surface cultivation on liquid nutrient media of the producer strain of microbiopreparation M-24 Penicillium sp., the antagonist of the sunflower Phoma rot pathogen

In recent years (2019-2021), research has been carried out at the biomethod laboratory of the V.S. Pustovoit All-Russian Research Institute of Oil Crops on the development of environmentally safe microbiopreparations of a multifunctional type of action with a prolonged shelf life against the pathogen of sunflower Phoma rot caused by the fungus Phoma macdonaldii Boerema, a teleomorph is Plenodomus lindquistii Gruyter, Aveskamp & Verkley. To develop the elements of the technological regulations for the production of a microbiopreparations in the preparative form of a “wettable powder” when growing the producer strain M-24 Penicillium sp. on the liquid nutrient media, there were determined the following optimal conditions for cultivating the strain: temperature is 25 °C, pH is 6; to use starch as a source of carbon nutrition is advisable; the optimal source of nitrogen nutrition is corn extract.

Lethal Effects of Commercial Kaolin Dust and Silica Aerogel Dust With and Without Botanical Compounds on Horn Fly Eggs, Larvae, Pupae, and Adults in the Laboratory.

The horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae), is an important bloodsucking ectoparasite of cattle throughout much of the world. The fly is mostly controlled using conventional synthetic insecticides but as concerns about resistance increase, alternative tactics have come under heightened scrutiny. Four desiccant dust products: Surround WP, a kaolin clay-based wettable powder; CimeXa, comprised of silica aerogel; Drione, silica aerogel + pyrethrins; and EcoVia, silica aerogel + thyme oil, were assessed for their lethal effects against horn fly eggs, larvae, pupae, and adults, under laboratory conditions. Although Surround WP and CimeXa did not prevent egg hatching and (when mixed with manure substrate) pupal development, the two products were associated with moderate reductions of emerged adults, and with complete adult contact mortality within 6 hr and 24 hr, respectively. Drione and EcoVia eliminated egg hatching, pupal development, and adults within 15 min to 1 hr, respectively, whether the flies were exposed to treated filter paper substrate or exposed by immersion in the dusts. Implications for horn fly control and advantages of inert desiccant dust formulations are discussed.

Bio-efficacy of Plants based Formulations for the Management of Cowpea Aphid (Aphis craccivora Koch.)

Background: The cowpea (Vigna unguiculata) is damaged by various insect pests of which cowpea aphid (Aphis craccivora) causes heavy damage to the tender leaves of the plant and reduces its yield. Two plant based formulation (prepared in the Chemistry Laboratory) viz. Polygonum hydropiper floral parts and Tobacco (Nicotiana tabacum) leaf, were used for safe management. Methods: The studies were done during 2019-2020 in BCKV, Kalyani, West Bengal, India for controlling of cowpea aphid by using plant based formulation. For preparing wettable powder formulation from Polygonum hydropiper floral parts and tobacco leaf the different ingredients are required viz. china clay, silica gel, wetting agent, dispersing agent etc. Physico-chemical analysis was done for preparation of accurate Wettable Powder formulation. Result: Cowpea aphid causes damage the tender leaves of the plant. It was revealed that imidacloprid (Confidor 17.8 SL) @ 1.0 ml/3L was found the most effective treatment against aphids giving more than 80% control followed by tobacco leaf (50 WP) @ 8 g/L of water (more than 70% control), fipronil (Regent 5% SC) @ 2.5 ml/L of water and Polygonum floral parts (50 WP) @ 8 g/L of water (more than 65% control both). The quality parameters of WP (50%) formulation was satisfactory as per the FAO specifications in terms of wet sieved test, wettability, foaming and suspensibility performed on the 0-day and also after 15th day at room temperature, at 65°C and at freezing temperature conditions.

Optimization of Culture Conditions and Production of Bio-Fungicides from Trichoderma Species under Solid-State Fermentation Using Mathematical Modeling.

Agro-industrial wastes suitable for economical and high mass production of novel Trichoderma species under solid-state fermentation were identified by optimizing the culture conditions using a mathematical model and evaluating the viability of the formulated bio-product. Fourteen inexpensive, locally available, organic substrates and cereals were examined using a one-factor-at-a-time experiment. The fungus colonized nearly all substrates after 21 days of incubation, although the degree of colonization and conidiation varied among the substrates. A mixture of wheat bran and white rice (2:1 w/w) was found to support maximum growth of T. asperellum AU131 (3.2 × 107 spores/g dry substrate) and T. longibrachiatum AU158 (3.5 × 107 spores/g dry substrate). Using a fractional factorial design, the most significant growth factors influencing biomass production were found to be temperature, moisture content, inoculum concentration, and incubation period (p ≤ 0.05). Analysis of variance of a Box–Behnken design showed that the regression model was highly significant (p ≤ 0.05) with F-values of 10.38 (P = 0.0027, T. asperellum AU131) and 12.01 (p < 0.0017, T. longibrachiatum AU158). Under optimal conditions, maximum conidia yield of log10 (8.6) (T. asperellum AU131) and log10(9.18) (T. longibrachiatum) were obtained. For wettable powder Trichoderma species formulations, it was possible to maintain conidial viability at room temperature (25 °C) for eight months at concentrations above 106 CFU/g.

Nematicidal Activity of Grammicin Biosynthesis Pathway Intermediates in Xylaria grammica KCTC 13121BP against Meloidogyne incognita.

Grammicin, a polyketide metabolite produced by the endolichenic fungus Xylaria grammica KCTC 13121BP, shows strong nematicidal activity against Meloidogyne incognita. This study was performed to elucidate the grammicin biosynthesis pathway of X. grammica KCTC 13121BP and to examine the nematicidal activity of the biosynthesis intermediates and derivatives against M. incognita. Two grammicin biosynthesis intermediates were isolated from a T-DNA insertion transformant (strain TR-74) of X. grammica KCTC 13121BP and identified as 2-(hydroxymethyl)cyclohexa-2,5-diene-1,4-dione (compound 1) and 2,5-dihydroxybenzaldehyde (compound 2), which were also reported to be intermediates in the biosynthesis pathway of patulin, an isomer of grammicin. This indicates that the grammicin biosynthesis pathway overlaps almost with that of patulin, except for the last few steps. Among 13 grammicin biosynthesis intermediates and their derivatives (except grammicin), toluquinol caused the highest M. incognita J2 mortality, with an LC50/72 h value of 11.13 µg/mL, which is similar to grammicin with an LC50/72 h value of 15.95 µg/mL. In tomato pot experiments, the wettable powder type formulations (WP) of toluquinol (17.78 µg/mL) and grammicin (17.78 µg/mL) also effectively reduced gall formation on the roots of tomato plants with control values of 72.22% and 77.76%, respectively, which are much higher than abamectin (16.67%), but lower than fosthiazate (100%). The results suggest that toluquinol can be used directly as a biochemical nematicide or as a lead molecule for the development of new synthetic nematicides for the control of root-knot nematode diseases.