Antimicrobial Traits of Beauveria bassiana Against Rhizoctonia solani, the Causal Agent of Sheath Blight of Rice Under Field Conditions.

Beauveria bassiana, an entomopathogenic fungus, has recently drawn attention worldwide not only as a potential biocontrol agent against insect pests but also for its other beneficial roles as plant disease antagonist, endophyte, plant growth promoter, and beneficial rhizosphere colonizer. In the present study, 53 native isolates of B. bassiana were screened for antifungal ability against Rhizoctonia solani, the causal agent of sheath blight of rice. Also, the mechanisms underlying such interaction and the responsible antimicrobial traits involved were studied. Following this, potential B. bassiana isolates were assayed against the reduction of sheath blight of rice under field conditions. The results showed that B. bassiana exhibited antagonistic behavior against R. solani with a percent mycelial inhibition recorded maximum of up to 71.15%. Mechanisms behind antagonism were the production of cell-wall-degrading enzymes, mycoparasitism, and the release of secondary metabolites. The study also deciphered several antimicrobial traits and the presence of virulent genes in B. bassiana as a determinant of potential plant disease antagonists. Under field conditions, combined application of the B. bassiana microbial consortium as a seed treatment, seedling root dip, and foliar sprays showed reduced sheath blight disease incidence and severity up to 69.26 and 60.50%, respectively, along with enhanced plant-growth-promoting attributes. This is one of the few studies investigating the antagonistic abilities of the entomopathogenic fungus B. bassiana against phytopathogen R. solani and the underlying mechanisms involved.

Molecular interaction between plants and Trichoderma species against soil-borne plant pathogens.

Trichoderma spp. (Hypocreales) are used worldwide as a lucrative biocontrol agent. The interactions of Trichoderma spp. with host plants and pathogens at a molecular level are important in understanding the various mechanisms adopted by the fungus to attain a close relationship with their plant host through superior antifungal/antimicrobial activity. When working in synchrony, mycoparasitism, antibiosis, competition, and the induction of a systemic acquired resistance (SAR)-like response are considered key factors in deciding the biocontrol potential of Trichoderma. Sucrose-rich root exudates of the host plant attract Trichoderma. The soluble secretome of Trichoderma plays a significant role in attachment to and penetration and colonization of plant roots, as well as modulating the mycoparasitic and antibiosis activity of Trichoderma. This review aims to gather information on how Trichoderma interacts with host plants and its role as a biocontrol agent of soil-borne phytopathogens, and to give a comprehensive account of the diverse molecular aspects of this interaction.

Biology, Predatory Potential, Life Table, and Field Evaluation of Propylea dissecta (Coleoptera: Coccinellidae), Against Lipaphis erysimi (Hemiptera: Aphididae) on Broccoli.

Propylea dissecta (Mulsant) (Coleoptera: Coccinellidae) is one of the most promising ladybird beetle against many sucking pests. Predation rates, developmental biology, life table, and field assessment of this ladybird were examined against mustard aphid, Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae), on broccoli. Data on the life history were collected at 23 ± 1°C and 70 ± 1% RH and were evaluated using the two-sex, age-stage life table. Results showed that the two-sex, age-stage life table-based net reproductive rate (R0) was 11.264 ± 6.197 offspring. The adult females lived longer (33.8 ± 2.356 d) than the adult males (32.2 ± 0.841 d). The fourth instar consumed most of L. erysimi (113.97 ± 5.76) compared to the other larval stages of the predator. Male (1,821) and female (2,673) consumed more aphids than larvae. The net consumption rate was 741.78 ± 89.91 aphids. Other aphidophagous predators such as Coccinella septempunctata L., Micraspis discolor (F.), Coccinella transversalis (F.), and syrphid (Diptera: Syrphidae) were also noted in broccoli. Our research showed that inoculative release of 150 or 200 adults per 1,000 m2 for two times on broccoli achieved a significant decrease in aphids L. erysimi and Brevicoryne brassicae L. (Hemiptera: Aphididae) (>95%). The release rate of 150 adults per 1,000 m2 for two times may, therefore, be recommended to manage the aphid population on broccoli.