Insects Cause Diseases of Plants

Since plants have life, plants, like other organisms, have to contend with various hostile environments to survive. It can be a disease caused by an attack by a microbe or damage caused by an attack by an insect or a larger animal. But if this is the case – these insects and germs are helping each other to damage the plant, but the damage will be multiplied. That’s why botanists and agronomists are working to reduce plant damage to a great extent, and the importance of plant pathology continues to grow.

E.C. In the words of Stackman,

“Plant pathology is bringing us deep and much-needed. It is playing a leading role in revealing the vast and changing world of micro-organisms and identifying human friends and foes among them. It shows how to fight many harmful micro-organisms and how to put good micro-organisms in our work”.

This interaction between micro-organisms or pathogens and various insects increases both the amount of damage to the plant and the risk of damage. Insects can spread the disease to different micro-organisms in different ways:

1. Insects only cause disease without the help of pathogens,
2. The proliferation of pathogens or micro-organisms,
3. Inoculating pathogens into plants,
4. Infiltration of micro-organisms into plants,
5. Direct attack on plants by pathogens, and
6. Preservation of pathogens.

Insects only cause disease without the help of pathogens

We know that fungi, bacteria, viruses, etc., cause plant diseases. Insects can also cause plant diseases. Although not all insects can cause disease in plants, some of them can spread disease. Some insects have the ability to secrete a chemical called phytotoxin . These can later cause disease in plants. These powerful insects are called toxicogenic insects.

In most cases, hemipteran is toxic to a variety of insectivorous plants. They basically have piercing-sucking typefaces that act as ‘dotpen.’ The proboscis pierces the plant’s body with a needle and sucks the sap of the cell. During sucking, they enter phytotoxic substances into the body of plants. As a result, the normal physiological processes of the plant are disrupted, and the plant or part of the plant dies.

These diseases are called apathogenic or physiological diseases. For example, potato leafhopper ( Impoasca faba ) causes hopper burn-in potato, squash bug ( Anasa tristis ) causes pineapple wilt in gourd crop, pineapple milling ( Pseudococcus brevips ) causes pineapple millibag wilt. Diseases caused by toxicogenic insects are called ‘toxicosis,’ ‘toxemias,’ or ‘phytotoxemias.’ Some venomous insects can only excrete toxins at a certain stage in their life cycle. The active toxic phase of toxicogenic insects is called ‘toxiniferous.’ But the green leafhopper can excrete toxins in both nymphs and adults.

Proliferation of pathogens

Pathogen transfer is the transfer of pathogens from a diseased plant (sensitive host plant) to another plant/place. A pathogen cannot cause disease at all stages of its life cycle. For example, a fungus can cause disease only at the stage of its spore formation, known as the inoculative stage. If that inoculum does not spread widely, disease production will be reduced or not complete. There is no organ in that inoculum by which they can spread. For their proliferation, they rely on certain agents, called disintegrating agents. For example, air, water, insects, humans and other animals. Although air is one of the most important and major means of spreading spores, insects can spread some diseases. For example, sugarcane gummosis (Xanthomonas azonopodis PV. Vascularum ) (a bacterial disease), rice leaf blight by green leafhopper (nephrotoxic viruses ), Cucurbit mosaic diseaseaphids ( Ephesus gossip ).

Inoculating pathogens into plants

Inoculation means transporting the inoculum to a specific part of the plant where infection can occur. Inoculation must occur in a specific part. E.g., powdery mildew. However, insects play an important role in inoculation. For example, the relationship between fruit blossom blight disease and bees. It is a bacterial disease that infects different parts of the flower. During the collection of honey from infected flowers, bees also collect inoculum and then transfer it to other uninfected flowers. Thus, it helps in the spread of Blossom Blight disease.

Another example is seed inoculation. Cotton stigmatomycosis disease and the relationship between the red cotton bugs. It is also known as internal bowl rot. The red cotton bug has spores of this pathogen in the style of the mouth part of the insect. It enters the cotton bowl by insects. Due to the presence of a hard pericarp, the pathogen cannot enter the bowel by itself.

Infiltration of micro-organisms into plants

Ingress is the process by which a pathogen enters a plant (host). Most pathogens fail to enter the plant through the plant’s cuticle, as it consists of their (plant) immune system and the combination of cutin, lignin, cellulose, hemicellulose, waxy substance etc. So pathogens try to enter the host through wounds or other natural open spaces. For example, green leafhoppers and infections by fungi and bacteria. In this case, there is a possibility of bacterial and fungal infections in rice plants with eating places and ovipositional markings. 

Another example is White Grub and Crown Gull. White grab fish are ground-dwelling insects. These cut and eat the roots. When any part of the roots is exposed, they come in contact with the Crown Gull pathogen.

Direct attack of plants by pathogens

Invasion or attack means spreading pathogens in the tissues inside the plant (host). Insects also help in the attack of pathogens in plants in this way. For example, Brinjal Shoot and Fruit Bora insect, and Sooty Mold fungus. Insects make tunnels in the fruit, and fungi enter through the tunnels and decompose in the internal tissues. Another example is the wood-boring beetle and wood-rotting fungus. Two species of wood-boring beetles mainly eat tree peat: Monocamas scuttelatus and Monocamas not alas. The woody part of the tree is attacked by the wood-boring fungus Pyrenophora gigantic through wounds made by beetles, and subsequently, the wood is damaged.

Preservation of pathogens

All living things want to survive, and pathogens are no exception. During adverse weather conditions, such as winter, insects also survive through diaphase and help the germs to survive. Examples include the bacterial wilt of cucumber beetle and cucumber beet, or the relationship between corn flea beetle and bacterial corn wilt . Cucumber beetle is the primary source of secondary bacterial wilt infection of cucumber plants in extreme winter weatherization of pathogens.