Topic: Diagnosis Of Pests On The Basis Of Plant Damage

NAME: Bhumika Kapoor Regd. NO. : J-12-AGRI-457COURSE: RAWE- 423

DIVISION OF ENTOMOLOGY

WHAT IS A PEST ???

• PEST- derived from French word ‘PESTE’ and Latin term ‘PESTIS’ meaning “ PLAGUE OR CONTAGIOUS DISEASES”.

• A Pest is any organism which occurs in large numbers and conflict with man’s welfare, convenience and profit.

• Pests include insects, nematodes, mites, snails, slugs, etc. and vertebrates like rats, birds.

Pests : Based On Level Of Infestation

•Pest epidemic : for eg. BPH in Tanjore.•Endemic pest: for eg. Rice gall midge in Madurai.

Pests : According To EIL, GEP and DB:•Key Pest : For Eg. Cotton Bollworm And Diamond Back Moth•Major Pest: For Eg. Cotton Jassid, Rice Stem Borer•Minor Pest/ Occasional Pest: For Eg. Rice Hispa, Ash Weevils•Sporadic Pest: For Eg. White Grub, Hairy Catterpillar•Potential Pest: For Eg. S. Litura Is Potential Pest Of North India.

A SYSTEMATIC APPROACH TO DIAGNOSING PLANT DAMAGE

The Factors causing plant damage can be grouped into two major categories :

• Living Factors: living organisms such as pathogens (fungi, bacteria, viruses, nematodes) and pests (insects, mites, mollusks, rodents...).• Nonliving Factors: mechanical factors (i.e. breakage, abrasions, etc); physical, environmental factors (extremes of temperature, light, moisture, oxygen, lightning); and, chemical factors (chemical phytotoxicities, nutritional disorders, etc).

Plant Identification And Characteristics. Establish what the “normal” plant would look like at the time of year. Describe the “abnormality”: Symptoms & Signs. Examine The Entire Plant And Its Community. Determine the primary problem and part of the plant where initial damage occurred. Look For Patterns: On more than one plant? On more than one plant species?• Non-uniform damage pattern-(scattered damage on one or only a few plant species) is indicative of living factors (pathogens, insects, etc.).• Uniform damage pattern over a large area (i.e. damage patterns on several plant species) and uniform pattern on the individual plant and plant parts indicates nonliving factors (mechanical, physical, or chemical factors).Delineate Time-development Of Damage Pattern:• Progressive spread of the damage on a plant, onto other plants, or over an area with time indicates damage caused by living organisms.•Damage occurs, does not spread to other plants or parts’’ of the affected plant.’ Clear line of demarcation between damaged and undamaged tissues. These clues indicate nonliving damaging factors.

DEFINE THE PROBLEM ?????

SYMPTOMS AND SIGNS OF INSECTS, MITES AND OTHER INSECTS

The location of the feeding damage on the plant caused by the insect’s feeding, and the type of damage (damage from chewing or from sucking mouth parts) are the most

important clues in determining that the plant damage is insect-caused.

FEEDING HABITSoCHEWING INSECTS eat plant tissue such as leaves, flowers, buds, and twigs.

The damage they cause (leaf notching, leaf mining, leaf skeletonizing, etc.) will help in identifying the pest insect. Chewing insects can be beetle adults or larvae, moth larvae

(caterpillars), and many other groups of insects.

POTATO LEAF BETTLECAULIFLOWER CATERPILLER

oSUCKING INSECTS insert their beak (proboscis) into the tissues of leaves, twigs, branches, flowers, or fruit. Damage caused by these pests is often indicated by discoloration, drooping, wilting, leaf spots (stippling), honeydew, or general lack of vigor in the affected plant. Aphids, scale insects, squash bugs, leafhoppers and plant bugs are examples of piercing-sucking insects.

APHIDS DAMAGE ON MUSTARD LEAF HOPPER DAMAGE ON GRAPES

INJURY BY INTERNAL FEEDERS

Many insects feed within plant tissue during a part or all of their destructive stages.•BORERS: The larvae may bore into the terminal shoots and cause death of the shoots as in the case of the cotton bollworm, Earias spp.

COTTON BOLLWORM SUGARCANE BORER

•WORMS OR WEEVILS : The larvae bore into flower buds and cause shedding. Such larvae are usually called bud worms as in the case of the moringa budworm and jasmine budworm, mango nut weevil, etc.

MANGO NUT WEEVIL RICE WEEVIL

• LEAF MINERS : When the larvae, being very small, live in between the two epidermal layers of the leaves and feed on the food material inside. Some of the common examples are the citrus leaf miner, the cashew and mango leaf miner, and the buprestid leaf miner, etc.

CITRUS LEAF MINER TOMATO LEAF MINER

• GALLS: Mostly some species belonging to the families Cecidomyiidae, Cynipidae, Aphididae, Psyllidae and Aleyrodidae and the order Thysanoptera (thrips) are known to cause plant galls on the different parts of plants.

GALL BY FIG THRIPS BLOSSOM MIDGE ON MANGO

• INJURY BY SUBTERRANEAN INSECTS: Subterranean insects are those insects that attack plants

below the surface of the soil. Many soil insects are host specific and most of them damage the crops in their larval stage as in wireworms, chafers, cutworms, flea beetles, etc., and only a few spend their life-cycle in the soil entirely.

•INJURY TO STORED PRODUCTS: The infestation may continue from the material stored earlier and be carried over to fresh material stored later in a godown or storage house as in the grain weevil, Sitophilus oryzae, which infests single grains and the flour moth, Cadra cautella which webs together the grains with silken threads and feeds on them.

GRAIN WEEVIL INDIAN MEAL MOTH

INJURY BY OTHER METHODS

• Injury By Egg-laying: for eg: grapevine stem girdler• Use Of Plant Parts For Making Nests: for eg: the leaf cutter

bee, Megachile anthracina.• Insects As Disseminators Of Plant Diseases: for eg: aphids,

thrips, etc

WHITEFLY LEAF CUTTER BEESTEM GIRDLER

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