Field Guide of Discovery-based Exercises for - Aseanipm ...

Section 4 • Integrated Insect and Rodent Pests Management
• Destructive insects. A group of insects that feeds on vegetable crops specifically on roots,
leaves, stems, flowers and/or fruits. The feeding of these insects damages crop, which lowers
yield or quality of produce. Destructive insects are grouped based on the kind of feeding they
inflict on vegetable crops:
5 Sucking insects. These insects are normally represented by plant bugs, which have piercingsucking
mouthparts. As sap feeders, majority of these insects have toxin in their saliva,
which when injected into plant produces curling, necrosis and drying of tissues, resulting
sometimes in death of shoots and branches. Some insects like leafhoppers, aphids, and
thrips transmit virus diseases in cucurbits and solanaceous vegetables.
5 Chewing insects. These are insects whose destructive stages have mandibulate or chewing
mouthparts. They feed mostly on leaves, flowers, and fruits. During severe infestation,
insects may defoliate whole plants. Other damages are folding of leaves, pinholes, and
huge holes and feeding on undersurface of leaves. On flowers and fruits, scraped surface
is a sign of damage done by insects. Some common examples are caterpillars of DBM,
cutworm, leaf-folder, and squash beetle.
5 Borer insects. The immature stages of these insects bore or tunnel on fruit or stem of plant.
In severe infestation, many fruits drop prematurely. Stems heavily affected dry up leading
to death of crop. A few examples are shoot borer, pod borer, melon fruit fly, and fruit worm.
5 Miner insects. Immature stages of insects puncture and mine on leaves down to petiole and
stem. On leaves, damage is characterized by transparent mine extending over surface. Heavily
infested leaves may dry up but remain attached to plant. Seriously, infested plants are stunted
and produce injuries on flowers and fruits. Some examples are sweet pea miner and bean fly.
5 Root feeders. Immature stages and some adults of insects feed on living roots or base of
plants, causing stunted growth or death of plants. Yellowing of leaves or plants in patches
is the first indication of damage by these insects. Some result in complete cutting of aerial
portions from roots. A few examples are crickets, mole cricket, and grubs.
• Beneficial Insects. Refer to insect groups that give benefit to farmers in terms of insect pest
reduction and improvement of yield or quality of product.
5 Biological control agents. This refers to any living organism used in reducing pest
population in vegetable farms. The employment of sound agricultural practices will help
conserve and encourage reproduction of naturally occurring enemies of vegetable pests.
The kind of living organism identified can be one of following:
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