Background
The biological diversity on planet earth is declining day by day, due to different factors such as excessive applications of pesticides. The utilization of chemical pesticides affected environment as well as microorganisms. The awareness among the peoples towards the hazards by the residual toxicity of chemical pesticides should be developed for agro-environmental sustainability.
Main body
Entomopathogenic nematodes (EPNs) are the bacto-helminth parasites which show classical mutualism with the genera Xenorhabdus and Photorhabdus. The nematodes along with its endosymbiotic bacteria have a biocontrol potential which could be used to reduce chemical pesticides. Applications of bioagents have been reported and resulted in considerable reduction in pathogens. Furthermore, these bioagents are biodegradable, eco-friendly and easy to apply for protection of crops against diverse pathogenic organism. The nematode-bacterium complexes are effective against huge range of bacteria, fungi, nematodes and insects that are harmful to the crops. Along with biocontrol potential, the endosymbionts produce diverse secondary metabolic compounds, exoenzymes and toxic compounds that show antibiotic, antimycotic, nematicidal, miticidal and anticancerous properties.
Conclusion
The present review deals with the diversity of endosymbiotic microbes from EPNs and their role in biocontrol for the agro-environmental sustainability.
An experiment was conducted to evaluate the performance of forty-nine chrysanthemum genotypes for desirable horticultural traits at ICAR-Indian Institute of Horticultural Research, Hesaraghatta Lake Post, Bengaluru from 2015-17. Significant variations were observed for various vegetative and flowering traits during both years. The results from the pooled data of two years showed that among the genotypes evaluated, maximum plant height was recorded in Arka Chandrakant (69.59 cm), maximum flower diameter in Arka Ravikiran (9.00 cm) and maximum weight of 100 flowers in Marigold (925.04 g). The genotype Roopanjali produced maximum number of flowers per plant (1199.17). Pusa Anmol recorded the minimum number of days to first flowering (60.48 days) while Roopanjali the longest period to first flowering (201.56 days). The genotypes with superior vegetative and floral traits desirable for the different segments of the floriculture industry like loose flower, cut flower and pot plant trade can be utilized in further improvement of chrysanthemum.
Background
Entomopathogens such as nematodes, bacteria and fungi are well recognized for their biocontrol potential. This study was carried out to examine the insecticidal properties of the Heterorhabditis bacteriophora Poinar, Beauveria bassiana Balsamo-Crivelli, Bacillus thuringiensis Berliner,
individually and in combination against 3rd instar larvae of Spodoptera litura Fabricius (Noctuidae: Lepidoptera) under controlled laboratory and greenhouse conditions at Eternal University, Baru Sahib, Sirmaur, Himachal Pradesh.
Results
The results demonstrated that the combined applications of the tested entomopathogens resulted in 100% insect mortality under the laboratory conditions. Among the individual concentrations, applications of 200 IJs/ml were noticed highly virulent with (98%) mortality, followed by B. thuringiensis (96%) and then by B. bassiana (92%). However, single treatments were also evaluated that further showed a highest mortality in the target pest by H. bacteriophora, followed by B. thuringiensis. Among the combined treatments by H. bacteriophora plus B. thuringiensis (200 IJs + 1 × 1012 CFU/cm2) more effective caused (100%) mortality were noticed in the laboratory and (28%) under the greenhouse conditions than H. bacteriophora plus B. bassiana (200 IJs + 1 × 1010 conidia/cm2) that caused (100%) mortality and (34%) damage under both,
laboratory and greenhouse conditions.
Conclusion
Laboratory bioassay and greenhouse evaluation tests demonstrated that the combined sprayed treatments showed reliable and fast synergism. This study could be recommended to the farmers to control the pest.
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