No abstract

This study highlights the importance of alpha-glucosidase inhibitors as mechanisms for endophyte-mediated resistance to insect pests. One of the major benefits which endophytes confer on plants is providing resistance against insect pests. This built-in defense mechanism of the plant can be used for exploring ecofriendly strategies for pest control. In the present study, 34 endophytic fungi were isolated from Tinospora cordifolia and screened for their ability to produce alpha-glucosidase inhibitors. Maximum inhibitory activity was observed in an isolate from T. cordifolia (TN-9S), identified to be Cladosporium sp. The inhibitor was purified using chromatographic techniques. The insecticidal activity of the purified inhibitor was evaluated against Spodoptera litura. The inhibitor induced a significant mortality in the larvae of S. litura and adversely affected its survival and development. It also inhibited the activity of α-glycosidases in vivo in the gut of the larvae. The purified inhibitor was determined to be a phenolic compound with amine groups, demonstrating a noncompetitive type of inhibition in vitro. The production of the inhibitor was optimized. Response surface methodology (RSM) analysis revealed a significant interaction between dextrose and malt extract, with first-order effect of pH.

Fungal endophytes that live inside plant tissues without causing any apparent symptoms in the host plant are important components of plant micro-ecosystems. Endophytic fungi confer profound impacts on their host plants by enhancing their growth, increasing their fitness, strengthening their tolerances to pests and diseases. Moreover, fungal endophytes symbiotic with host plant produce a plethora of bioactive secondary metabolites that are expressed as defensive weapons to protect the host plant against various abiotic stresses. Currently, main focus in endophytic fungi research is associated with the ability of these microorganisms to produce and accumulate biologically active metabolites as these are potent source of novel natural products useful in agriculture sector.

Urbanization and industrialization resulted in rapid increase in volume of solid waste; its management has become one of the biggest problems today. Solid wastes can be disposed off by methods like land filling, incineration, conversion into biogas, recycling, and composting, but its overproduction has led to inappropriate disposal practices such as their indiscriminate and inappropriately timed application to agricultural fields that ultimately leads to water and soil pollution. However, if handled properly, these organic wastes can be used for vermicomposting; it is an effective recycling technology that improves the quality of the products which is disinfected, detoxified, and highly nutritive. It is a low cost, eco-biotechnological process of waste management in which earthworms are used to cooperate with microorganisms in order to convert biodegradable wastes into organic fertilizer. Earthworms excreta (vermicast) is a nutritive organic fertilizer rich in humus, NPK, micronutrients, beneficial soil microbes; nitrogen-fixing, phosphate solubilizing bacteria, actinomycets, and growth hormones auxins, gibberlins and cytokinins, is a suitable alternative to chemical fertilizers, being an excellent growth promoter and protector for crop plants. Thus, vermiculture not only results in management of soild waste but also produces excellent nutrient enriched vermicompost. Vermicompost is beneficial for sustainable organic agriculture and maintaining balanced ecosystem.

Fungal endosymbionts in plants may influence interactions among plants, herbivores and their parasitoids through the production of secondary metabolites. We used a lepidopteran pest and its generalist parasitoid to test the effect of endophyte-infected plants on a third trophic level. Endophytic fungi, Aspergillus flavus and Aspergillus niger, isolated from Acacia arabica, were used to infect cauliflower plants. We found that the presence of the endophyte in the plants significantly extended the development period of Spodoptera litura (Fab.) larvae. Feeding of the host on endophyte-infected plants further adversely affected the development and performance of its parasitoid, Bracon hebetor (Say). A negative impact was also recorded for longevity and fecundity of endophyte-naive parasitoid females due to the parasitization of host larvae fed on endophyte-infected plants. The presence of endophytes in the diet of the host larvae significantly prolonged the development of the parasitoid. A strong detrimental effect was also recorded for larval survival and emergence of parasitoid adults. The longevity and parasitism rate of female wasps were reduced significantly due to the ingestion of endophyte-infected cauliflower plants by S. litura larvae. Overall, we found that both endophytic fungi had a negative impact on the parasitoid.