Toxicity of isolated phenolic compounds from Acorus calamus L. to control Spodoptera litura (Lepidoptera: Noctuidae) under laboratory conditions

Background Spodoptera litura (Lepidoptera: Noctuidae), the tobacco cutworm, is an prominent agricultural pest. To reduce the use of chemical pesticides that cause health problems and that leave residue in the environment, some botanical pesticides have been developed. Our research aimed to evaluate the insecticidal efficacy of Acorus calamus L. extract for the control of S. litura under laboratory conditions. Results After 24 h of topical application, the A. calamus methanolic crude extract showed toxicity against secondary instar S. litura larvae (LD50 ~ 7.438 µg/larva). Chrysin (5,7-dihydroxy flavone), one of the isolated phenolic compounds, showed optimal control efficiency (LD50 ~ 2.752 µg/larva) and showed a reduction in carboxylesterase activities, which have detoxification reduction roles in larvae. Conclusion Chrysin in the crude extract of A. calamus may be an active compound to control this pest, and it may be applied as an alternative to minimize the usage of chemical insecticides. Graphical Abstract

Soil supplementation with Si, B and Zn and their synergetic effects in reducing severity of wheat blast (Magnaporthe oryzae Triticum)

Wheat blast (Magnaporthe oryzae Triticum) in Bangladesh and South America is recognized as one major limiting factor of wheat production. Its control using chemical pesticides raises concerns about food safety and pesticide resistance, which have dictated the need for alternative blast management approach, nutrient supplementation could be an ecofriendly alternative. Experiments were carried out under confined net house condition for two consecutive cropping seasons. Single doses of the nutrients (Si, B and Zn) were incorporated during soil preparation. Plants of the wheat blast susceptible variety BARI Gom-26 were inoculated with spores (1 x 107 spores ml-1) of Magnaporthe oryzae Triticum at blast vulnerable pre-heading stage of 52 days age. Typical wheat blast symptoms of spike bleaching from top to downward appeared on sight 14 days after inoculation i.e., 66 days age of the crop. Incidence and severity of blast bleaching of spike were scored for four times starting from 68 days age @ three day’s interval. None of the nutrients could stop the incidence of blast on wheat; however, some nutrients reduced the blast incidence significantly. Solo application of Si, B and Zn or combination of two caused significant reduction of spike bleaching. With the mixed application of Si, B and Zn, > 47% reduction of wheat blast severity was obtained. The results revealed that the soil application of silicon, zinc and boron had a synergistic effect on the intensity of blast disease of wheat. Int. J. Agril. Res. Innov. Tech. 11(2): 76-84, Dec 2021

Nanomaterials and nanotechnology for the delivery of agrochemicals: strategies towards sustainable agriculture

Nanomaterials (NMs) have received considerable attention in the field of agrochemicals due to their special properties, such as small particle size, surface structure, solubility and chemical composition. The application of NMs and nanotechnology in agrochemicals dramatically overcomes the defects of conventional agrochemicals, including low bioavailability, easy photolysis, and organic solvent pollution, etc. In this review, we describe advances in the application of NMs in chemical pesticides and fertilizers, which are the two earliest and most researched areas of NMs in agrochemicals. Besides, this article concerns with the new applications of NMs in other agrochemicals, such as bio-pesticides, nucleic acid pesticides, plant growth regulators (PGRs), and pheromone. We also discuss challenges and the industrialization trend of NMs in the field of agrochemicals. Constructing nano-agrochemical delivery system via NMs and nanotechnology facilitates the improvement of the stability and dispersion of active ingredients, promotes the precise delivery of agrochemicals, reduces residual pollution and decreases labor cost in different application scenarios, which is potential to maintain the sustainability of agricultural systems and improve food security by increasing the efficacy of agricultural inputs. Graphical Abstract

Adoption of Chemical Pesticides Under Commercial Vegetable Cultivation inSri Ganganagar District of Rajasthan

The study was conducted in Sri Ganganagar district of Rajasthan to assess the extent of use of chemical pesticides under commercial vegetable cultivation. The primary data were collected from 100 farm households across 18 villages from 2016 to 2019. Chemical insecticides were used by all farmers whereas biopesticides and botanical pesticides were used by <5% for insect pest control in vegetables. The average number of chemical pesticide sprays in a crop cycle was 14, 15, 15 and 13 in cauliflower, cabbage, tomato and pea crops respectively. Average quantity of chemical pesticides used was 4.23, 3.87, 5.16 and 3.47 kg active ingredient per hectare in cauliflower, cabbage, tomato and pea crops respectively. The study highlights the overuse and misuse of chemical pesticides in vegetable crops where the economic part is edible unlike cotton where the economic part is nonedible.The direct negative impact of chemical pesticides on health of farm workers is estimated in the paper.

RELATIVE TOXICITY OF SOME CHEMICAL PESTICIDES AGAINST JUTE HAIRY CATERPILLAR (SPILOSOMA OBLIQUA W.) IN TOSSA JUTE (CORCHORUS OLITORIUS L.)

Pesticides have been a major contributor to the growth of agricultural productivity and food supply. Pesticides were a key factor in significant agricultural productivity growth during the last century and continue to be a critical factor in reducing crop damage. Fifteen insecticides were investigated to select their effective and economic doses against Hairy caterpillar in a Tossa Jute variety during April-October’ 2020 at the Department of Entomology, Manikganj and Narayanganj, Bangladesh Jute Research Institute (BJRI), Bangladesh following Randomized Completely Block Design with three replications. All new insecticides with a standard were found effective for controlling jute hairy caterpillar giving 95.38, 94.55, 95.19, 92.85, 93.59, 94.22, 93.49, 93.62, 89.84, 95.72, 93.56, 93.38, 94.42, 95.39, 91.34 and 95.41 % at Manikganj; 95.78, 93.32, 93.97, 93.18, 92.09, 92.49, 93.74, 92.93, 92.29, 93.69, 93.95, 93.17, 95.31, 94.99, 92.11 and 94.53 % reduction of infestation at Narayanganj at 5th day after spray over control plot respectively. In Manikganj, the highest fibre yield (3.66 t/ha) was found in the plot treated with Rock 20 EC and the lowest (2.96t/ha) was found in Reset 20WDG treated plot. In case of Narayanganj, the highest fibre yield (3.85 t/ha) was found in the plot treated with Proxy 20 EC and the lowest (2.79t/ha) was found in Daman treated plot. These insecticides can be recommended for the farmer’s use to control jute hairy caterpillar.

ANTIFUNGAL ACTIVITY OF CHITOSAN AGAINST Rhizopus stolonifer

These days instead of chemical pesticides, various natural alternatives have been used for the management of post-harvest diseases. This research was carried out to evaluate the antifungal potential of different chitosan concentrations viz., 5, 10, and 15 mg/µl against Rhizopus stolonifer by the agar dilution and well diffusion methods. The evaluation was carried out after seven days of incubation by measuring the inhibition of R. stolonifer mycelial growth. Results of the study revealed that the chitosan had a significant inhibitory effect on mycelial growth and maximum mycelial growth inhibition was reported at the 10 and 15 mg/µl concentrations and these two treatments are not significantly different. Based on these results, the best concentration (15 mg/µl) was further evaluated by the well diffusion technique. The average inhibition zones formed by the higher concentration was 25mm. Results of the study suggested that chitosan can be used for the management of post-harvesting diseases of tomatoes.

Study of Trichoderma Spp. Application on the Incidence of Moler Disease and Shallot's Growth and Yield

Fusarium wilt disease/moler is a concern in onion cultivation. Many farmers apply chemical pesticides such as azoxystrobin and difenoconazole to control the diseases. Both of these chemical pesticides are currently exhibiting a decline in effectiveness, prompting farmers to increase the dosage and frequency of application. Recommendations for biological control, including Trichoderma spp.. This study aimed to determine the influence of application time of of Trichoderma spp. in various media types on the incidence of moler disease and shallot growth and yield. This study was conducted in Tabalong district, South Kalimantan, from February to June 2019 using a completely randomized design (CRD) factorial comprising two nested designs. The first factor was the type of media in which Trichoderma spp.. was applied, namely solid and liquid. The second factor was the application time of Trichoderma spp.. Level 1 was the application of Fusarium sp. seven days before planting and Trichoderma spp.. seven days after planting. Level 2 included the application of Trichoderma spp.. seven days before planting and Fusarium sp. simultaneously during planting. Level 3 involved the administration of Trichoderma spp.. concurrently with planting and Fusarium sp. seven days later. This investigation used one positive control (without treatment) and one negative control (shallots inoculated with Fusarium). Each experimental unit was consisted of ten plants and replicated three times. The parameters observed were the incubation period of Fusarium sp., disease incidence, number of leaves, plant height, number of cloves, and average clove weight. The study found that the application time of Trichoderma on various types of media affected the incidence of Fusarium disease, the number of leaves, and the number of shallot cloves.When compared to liquid media, the application of solid media resulted in a reduced incidence of Fusarium disease and a greater frequency of flares. The application time on solid media gave a low response to moles. As for liquid media, the lowest incidence of moler disease occurred at the seven days before planting.

Potential of Asparagopsis armata as a Biopesticide for Weed Control under an Invasive Seaweed Circular-Economy Framework

Marine macroalgae have been increasingly targeted as a source of bioactive compounds to be used in several areas, such as biopesticides. When harvesting invasive species, such as Asparagopsis armata, for this purpose, there is a two-folded opportunity: acquiring these biomolecules from a low-cost resource and controlling its spreading and impacts. The secondary metabolites in this seaweed’s exudate have been shown to significantly impact the physiology of species in the ecosystems where it invades, indicating a possible biocidal potential. Considering this in the present work, an A. armata exudate cocktail was applied in the model weed Thellungiella halophila to evaluate its physiological impact and mode of action, addressing its potential use as a natural biocide. A. armata greatly affected the test plants’ physiology, namely, their photochemical energy transduction pathway (impairing light-harvesting and chemical energy production throughout the chloroplast electron transport chain), carotenoid metabolism and oxidative stress. These mechanisms of action are similar to the ones triggered when using the common chemical pesticides, highlighting the potential of the A. armata exudate cocktail as an eco-friendly biopesticide.

Organic Control Strategies for Use in IPM of Invertebrate Pests in Apple and Pear Orchards

Growers of organic tree fruit face challenges in controlling some pests more easily suppressed by broad-spectrum insecticides in conventionally managed orchards. In recent decades, there has been a move towards organically growing varieties normally reliant on synthetic chemical pesticides (e.g., Gala), often to meet retailer/consumer demands. This inevitably makes crop protection in organic orchards more challenging, as modern varieties can be less tolerant to pests. In addition, there have been substantial reductions in plant protection product (PPP) approvals, resulting in fewer chemical options available for integrated pest management (IPM)-maintained orchards. Conversely, the organic management of fruit tree pests involves many practices that could be successfully implemented in conventionally grown crops, but which are currently not. These practices could also be more widely used in IPM-maintained orchards, alleviating the reliance on broad-spectrum PPP. In this review, we evaluate organic practices, with a focus on those that could be incorporated into conventional apple and pear production. The topics cover cultural control, biological control, physical and pest modifications. While the pests discussed mainly affect European species, many of the methods could be used to target other global pests for more environmentally sustainable practices.