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CLASS: SS 2
TOPIC: PESTS OF CROPS
CONTENT:
- Meaning and Classification of Crop Pests
- Name and Description of Important Insect pest of Crops
SUB TOPIC 1: Meaning and Classification of Crop Pests
A pest can be described as an organism, whether plant or animal, which cause economic damage to crop plant, livestock, man and his possessions. They attack crops on the field as well as in the store. They may harm crops directly or introduce diseases into them.
Examples of pests are insects, rodents, higher parasitic plants etc
CLASSIFICATION OF CROP PESTS
Pests are classified in different ways as follows:
- Insect pests
- Non-insect pests
INSECT PEST: These are the most serious pests of agricultural importance, and the group includes all insects which cause damages to crops and crop products. Examples of insect pests are grass hopper, weevils, beetles, white flies, termites, crickets and locusts. They feed on crops either on the field or in the store.
B.NON-INSECT PESTS: These are organisms other than insects which attack and feed on crops. They cause a lot of damages to crops though they are not as many as insect pests. Examples of non-insect pests include rodents like giant rats, grass cutter, monkeys, nematodes and birds
CLASSIFICATION OF INSECT PESTS BASED ON MOUTH PARTS/MODE OF FEEDING
Insect pests are classified into different groups based on their mouth parts and the mode of feeding. The groups include: (a) Biting and chewing insects (b) Piercing and sucking insects (c) Boring insects
(a) BITING AND CHEWING INSECTS: This group of insects has mouth parts adapted for biting and chewing. They possess strong mandible and maxillae which they use for biting and chewing plant parts. Other parts of their mouth are labium and labrum. They consist of insect larvae or caterpillars as well as adult ones. Examples of insects with biting and chewing mouth parts are grass hoppers, crickets, locusts, mantis, termites, leaf worm, army worms and yam beetles.
(b) PIERCING AND SUCKING INSECTS: These insects have mouth parts that have been modified to pierce the tissues of plants and suck the contents of the part of the plants they attack. They have strong mouth part called proboscis which enables them to pierce through plants and suck liquid materials (sap) from the plant tissues. They weaken and inject poison (toxin) into the plants they attack. Examples of piercing and sucking insects are cotton strainers, capsids, mirids, aphids, mealy bugs, moths, scale insects, white flies and butter flies
(c) BORING INSECTS: The insects in this group have mouth parts that are modified for boring into stems, fruits and seeds. Examples of boring insects include stem borers, maize weevils, rice weevils, bean weevils, palm weevils and rhinoceros beetle of coconut palm
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