(d) : The natural method of pest and pathogen control involving use of viruses, bacteria and other insects (which are their natural predators and pests) is called biocontrol or biological control. For example, free living fungus Trichoderma exerts biocontrol over several plant pathogens for the control of plant diseases. Baculoviruses (mostly of genus Nucleo­ polyhedrovirus) are also used as biocontrol agents but they are used for the control of insects and arthropods. Bacillus thuringiensis is a soil bacterium which is used as biopesticide. Glomus species are the most common fungal partners of mycorrhiza residing in the roots of higher plants.