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Polyphagous Insect Examples


Polyphagous insect examples

In this post, we will know about polyphagous insect pests and their examples.

What is this?

An insect which is known for attacking on different plant species is a polyphagous insect. It is not a specific pest of any particular crop.

Contents
(1). Role in crop ecosystem
(2). Host plant resistance
(3). Examples of polyphagous insect-pests
(4). Description of some insect-pests
(5). Frequently asked questions

(1). Role in crop ecosystem

Any insect which is specific to a crop is known for damaging that particular crop, for example, rice gandhi bug is specific to paddy plants. But, a polyphagous insect may attack on any important crop. Hence, they are very important in a pest management programme. In the absence of subsidiary hosts, they can feed on main crop.

(2). Host plant resistance

They are not specific to any individual crop, that’s why it become very difficult to develop a resistance by the host plants against a polyphagous insect.

(3). Examples of polyphagous insect pests

  • Locust.
  • Termite.
  • White grub.
  • Bihar hairy caterpillar.
  • Red hairy caterpillar.

Also read: Major insect-pests of rice

(4). Description of some insect-pests

4.1: Locust

Locusts are international pest. It is the type of pest which can cause famine. Thye attack as group, although they don’t fly against the wind.

4.1.1. Host plant: Various.

4.1.2: Identification

Eggs: The colour of the egg is yellow.
Nymph: Green or black.

4.1.3: Life cycle

Egg stage: Egg stage ranges from 20 to 30 days during the summer season, while it ranges from 45 to 102 days during the winter season.
Nymph stage: 7 to 9 months.
Generations: One to two generations in a year.

4.1.4: Control

  • Use 0.1% of neem based insecticide.
  • Make poision bait.
  • You can make fence to check its attack.

Also read: Important objective mcq on insecticides.

4.2: Termite

4.2.1. Host: Various

Termite is a very common insect. It is a devastating pest. Young termites directly damage its host by feeding on root and stem.

4.2.2: Identification

  • It is a soft bodied creature.
  • Egg is light yellow.
  • Nymph is white and yellow.
  • Adult is dusty white.

4.2.3: Life cycle

Egg stage: It lasts from 21 to 90 days.
Nymph stage: It is 6 to 13 months.
Adult stage: It ranges from 1 to 2 months.
Generations: Mostly one generation in a year.

4.2.4: Control

4.2.4.1: Mechanical measures

Irrigation: Do regular irrigation to prevent the attack of termite.
Manure: Don’t use fresh cow dung as manure.
Agricultural residues: Decompose it.
Crop rotation: Grown onion or garlic instead of sugarcane or wheat.

4.2.4.2: Biological control

Make a small packet of asafoetida. Use a cotton cloth for making a small pocket. Keep it at the opening irrigation channel. Asafoetida will dissolve in irrigation water. Hence, it will be applied to all plants by the irrigation water. It will control the attack of termite.

4.2.4.3: Chemical control

Use chlorpyriphos 20 EC to control it

For ground: 12.5 ml of chlorpyriphos.
Other crops: 2.5 ml of chlorpyriphos.

4.3: White grub

4.3.1. Host: Various.

White grub is a polyphagous insect, but sorghum, pearl millet, sugarcane, groundnut, pigeon pea, french bean, chilli, bringal, and okra are the major hosts.

Grub start to damage te plants after the emergence from eggs. Plants start to wilt. Grubs are active from July to October.

4.3.2: Identification

Egg: It is white.
Grub: Whitish brown.
Adult: Brownish and shiny.

4.3.3: Life cycle

Egg stage: Female lays eggs in moist soil. Grubs emerge from eggs after 7 to 13 days.
Grub stage: First grub stage is 2 to 3 weeks. Second grub stage is 4 to 5 weeks, and thrid grub stage is 6 to 8 weeks. The send and thrid grub stages cut the grown roots of the plants.
Worm stage: 7 to 8 days.
Adult stage: 7 to 12 days.
Generations: One generation in a year.

4.3.4: Control

4.3.4.1: Agronomical and mechanical measures

  • Plough the field during the morning time so birds can feed on it.
  • Prune the unwanted branches and twigs during May.
  • Use 3 to 4 light traps during the monsoon season.
  • Use these traps during the early monsoon.
  • You can use pheromones traps after monsoon to control the male population.

4.3.4.2: Biological control

Egg parasitoid: Rhabditis nematode.
Beauveria brongniartii: Mix 1 kg of B. brongniartii and 1 kg of metarhizium anisopliae with 50 kg of well rotten cow dung. Use it be before sowing.

4.3.4.3: Chemical control

Seed treatment: Use 15 ml of chlorpyriphos 20 EC for one kg of seed.
Phorate: Apply 25 kg of phorate 10G for one ha. of land.

4.4: Bihar hairy caterpillar

4.4.1 Host: Various.

The caterpillars cut and chew leaves. It starts to damage the crop from the beginning of monsoon. Attack is severe in low rain area. The pest heavily damages groundnut, sesame, sarso, and some vegetables.

4.4.2: Identification

Caterpillar: These are brown caterpillars with hairs.
Cocoon: Dark brown.
Adult: Colour of the adult is yellow having black spots on it.

4.4.3: Life cycle

Egg stage: 4 to 6 generations in a year.
Cocoon stage: 8 to 15 days.
Adult stage: 6 to 12 days.
Generations: Five to six generations in a year.

4.4.4: Control

4.4.4.1: Agronomical and mechanical measures

  1. Use 8 to 10 pheromone traps to monitor and control the pest.
  2. Destroy the pest.

4.4.4.2: Biological control

Use Trichograma spp.
You can apply N.P.V. against the first and second stage of caterpillar.
We can also use Bt formulations.

4.4.4.3: Chemical control

Use 2 l of chlorpyriphos for one ha. of field.

4.5: Red hairy caterpillar

4.5.1: Host: Various.

The caterpillars cut and chew leaves. It starts to damage the crop from the beginning of monsoon. Red hair caterpillar prefers low rainfall situations and light soil. This is one of the major pest in North India.

4.5.2: Identification

Eggs: First it is light yellow, then brown and finally turns black.
Caterpillar: It is red with white and yellow hairs.
Cocoon: First is yellow, then turns brown.
Adult: The colour of the adult is red and white with black spots on it.

4.5.3: Life cycle

Egg stage: 3 to 4 days.
Cocoon stage: 15 to 20 days.
Adult stage: 3 to 5 days.
Total generations: 3 to 4.
Generations: One generation in a year.

4.5.4: Control

4.5.4.1: Agronomical and mechanical measures

Use at least 10 pheromone traps to monitor and control the pest.
Destroy the pest.

4.5.4.2: Biological control

Use Trichograma spp.
You can apply N.P.V. against the first and second stage of caterpillar.
We can also use Bt formulations.

4.5.4.3: Chemical control

Apply 20 to 25 kg of  malathion for one ha. of field.

(5). Frequently asked questions

Question 01. Which is a non polyphagous insect?

Answer:

  • Gundhi bug.
  • Rice hispa.

(6). MCQ on polyphagous insect-pests

Also read: Entomology multiple choice questions and answers

Question 01. Which is not a polyphagous insect-pests?

(a). Rice hispa.
(b). Sugarcane top borer.
(c). Hadda beetal of brinjal.
(d). None of the above.

Answer: None of the above.

Question 02. Which is a national importance pest?

(a). Locust.
(b). Red hairy caterpillar.
(c). White grub.
(d). Bihar hairy caterpillar.

Answer: White grub.

Question 03. What is the control measure of white grub?

(a). Summer ploughing.
(b). Irrigation.
(c). Spray of neem insecticides.
(d). All of the above.

Answer: Summer ploughing.

Key words: Locust, termite, white grub, Bihar hairy caterpillar, red hairy caterpillar, pests of field crops.

Key phrases: Examples of polyphagous insects.

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