Explanation

The ladybird and dragonflies are useful to get rid of aphids and mosquitoes, respectively. (i) A bacteria species namely Bacillus thuringiensis (Bt) is known to kill a wide range of insects such as butterfly, caterpillars, ant etc., some strains of Bt can kill animal and plant parasitic nematodes, protozoans and even cockroaches (ii) Trichoderma is a free-living saprophytic fungi that most commonly lives on dead organic matter in the soil and rhizophere (iii) The fungus is being developed as an effective biocontrol agent of several plant pathogens (iv) Rhizobium is a symbiotic bacterium that lives in the root nodules of legumes and fixes atmospheric nitrogen into organic compounds