Bacillus thuringinesis has been used as a biological control of pests. The bacteria Bacillus thuringiensis are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees. These bacteria produce a cry protein which when eaten by insects, release toxin in their gut and the larvae gets killed. The  scientists have been able to introduce B. thuringiensis toxin genes into plants with the help of genetic engineering. Such plants are resistant to attack by insect pests. Bt-cotton is one such example which is being cultivated in some states of our country.