Ward of pest with vermicompost by mixing worm castings (worm poo) into your topsoil. Vermicompost wards off white flies, aphids, bark beetles, psyllids, spider mites and other pests that feed on plant juices. According to recent studies, applying earthworm castings to the soil around your plants increases the production of a certain enzyme chitinase. The digestive system of earthworms produces an enzyme called chitinase. This enzyme is a degrader of chitin, the substance that comprises the exo-skeletons of most insects. When used properly, worm castings help to repel chewing and sucking insects like aphids, whiteflies, and hard-shelled plant bugs. If a bug feeds on the leaves of a plant which has absorbed the chitinase, its exoskeleton will soon begin to dissolve, and death will come quickly.
According to research conducted by North Carolina State University, the mechanisms behind insect resistance of plants grown in soil amended with vermicompost may provide an ecological friendly means of managing pests in vegetable crops. A 20 percent concentration of vermicompost mixed into the soil will boost the resistance of host plants against caterpillar and aphids.