Plant Disease Vectors: Plant Disease Vectors are living or non-living micro-organism. They are known for their ability to transmit  various diseases across the plant communities.

Insect-pests and plant diseases are major factors of economical loss in agriculture and horticulture. Plant diseases are caused by harmful microorganisms such as virus and bacteria. Insects are known to cause significant economical loss in two ways. Directly, they damage crops by direct feeding. On other side they act as vector of different disease causing agents e.g., virus, bacteria, fungus etc. They do so in following ways:

• Feeding on plants.
• Contact with plants.

‘All those insects which acquire pathogens by feeding or contact with plants are known as vectors of plant diseases’.

A vector is specific to a  plant or plant species. So, the proper knowledge about different vectors is very important for the effective management and control of different plant diseases.

INDEX

S. No.	Heading
1 (A)	List of Important Insect and Mite Vectors of Plant Viruses
2 (B)	List of Important Vectors of Plant Bacteria
3 (C)	List of Important Vectors of Plant Fungus
4 (D)	List of Important Insect Vectors of Phytoplasma

(A). List of Important Insect and Mite Vectors of Plant Viruses

S. No.	Insect	Virus	Host
1.	Acyrthosiphon pisum	Pea mosaic, Onion yellow dwarf	Pea, Onion, Soybean
2.	Aphis craccivora	Alfalfa mosaic	Alfalfa
3.	Aphis gossypii	Sugarcane mosaic	Sugarcane
4.	Aphis rumicis	Bean common mosaic	Beans and pea
5.	Aphis fabae	Dahlia mosaic	Dahlia
6.	Bemisia tabaci	YVM, Papaya leaf curl	Okra, Papaya
7.	Frankliniella schultzei	Tomato spotted wilt	Tomato
8.	Macrosiphum euphorbiae	Potato virus Y	Potato, Tobacco, Tomato
9.	Myzus persicae	Cauliflower mosaic	Cauliflower, Cabbage
10.	Nephotettix nigropictus	Tungro	Rice
11.	Nilaparvata lugens	Grassy stunt	Rice
12.	Aceria tulipae (mite)	Wheat streak mosaic	Wheat, Oat
13.	Abacartus hystrix (mite)	Agropyron mosaic	Wheat
14.	Pentalonia nigronervosa	Banana Bunchy Top	Banana

Source Reference: Gillot (2005)

(B). List of Important Vectors of Plant Bacteria

S. No.	Insect	Disease	Host
1.	Chaetocnema pulicaria	Bacterial wilt	Maize
2.	Diabrotica duodecimpunctata	Cucurbit wilt	Cucumbr
3.	Diaphornia citri	Citrus canker	Citrus
4.	Hylemya cilicrura	Potato blackleg	Potato
5.	Bees, wasps, flies	Fire blight	Apple, pear

Source Reference: Gillot (2005)

(C). List of Important Vectors of Plant Fungus

S.No.	Vector	Disease	Host
1.	Melanoplus differentialis	Cotton wilt	Cotton
2.	Scolytus multistriatus	Dutch elm	Elm
3.	Flies, beetles, aphids	Ergot of cereals	Cereals
4.	Several spp. of insects	Eargot of bajra	Bajra

Source Reference: Gillot (2005)

(D). List of Important Insect Vectors of Phytoplasma

S. No.	Vector	Mycoplasma	Host
1.	Aphrodes albifrons	Clover phyllody	Most clovers
2.	Cestius phycitis	Brinjal little leaf	Brinjal
3.	Graminella nigrifrons	Corn stunt	Maize
4.	Orosius albicinctus	Sesame phyllody	Sesame
5.	Gyponana hasta	Aster yellows	Aster
6.	Recilia dorsalis	Yellow dwarf	Rice

Source Reference: Gillot (2005)

Frequently Asked Questions

Question 01. Which group of insects are known to transmit pathogen among plant communities?

Answer: Insects having piercing and sucking mouth parts, biting and chewing mouth parts are associated with disease transmission.

Question 02. Insects from which order are responsible for more disease transmission?

Answer: It is Hemiptera. Aphids, leaf hoppers, white flies and mealy bugs etc. from Hemiptera are known to transmit 90% of plant diseases.

Question 03. Which insect is known for transmitting more diseases?

Answer: Aphid followed by leafhoppers.

Question 04. What are the types of viruses carried by vectors?

Answer: The types of viruses carried by vectors are as follows:

1. Persistent viruses.
2. Semi-persistent viruses.
3. Non-persistent viruses.

In case of persistent viruses, the insect has to feed on source for a longer period. Non-persistent viruses transmit diseases by feeding on disease source. Generally, leaf hoppers are known as the vector of semi-persistent viruses.

Question 05. How virus-vector relationship is seen?

Answer: The relationship between vector and virus is very specific.

Question 06. What is the mechanism of transmission of phytoplasma?

Answer: Phytoplasma are phloem-limited. Hence, only phloem feeding insects can potentially transmit pathogen.

Question 07. What are the mechanism of transmission of bacteria?

Answer: Insects make wound on plant surface from where bacteria can enter.

Question 08: What are the methods of plant vectors and disease management?

Answer: Follow these measures-

1. Use healthy and disease free seeds.
2. Cultural practice such as inter cropping soybean with okra to reduce the incidence of YVM.
3. Use resistant varieties.
4. Use biopesticides. Example- Use of Paecilomyces farinosus against White flt.
5. Chemical control of vector insects.

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REFERENCES

1. Photo: TNAU
2. Table Data: Gilliot 2005.

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