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Order
- THYSANOPTERA
(Greek, thysanos = fringe; pteron = wing)
Common Name: thrips
Distribution: Cosmopolitan
Suborders: Terebrantia, Tubulifera
Description
Thrips feed on the sap of plants. The distinguishing characteristic of
thrips is the possession of two pairs of fringed wings. Compound eyes are
well developed and three simple eyes (ocelli) may be present in winged
forms. The antennae are composed of short straight segments (filiform).
The mandibles and mouthparts are highly modified for rasping and sucking
and as a result the left mandible has become a stylet while the right
mandible has almost disappeared (atrophied). The winged forms are capable
of weak flight, but can cover large distances when assisted by the wind.
Nymph
Females lay eggs directly into plant tissues or crevices in vegetation.
The emerging juveniles resembles the adults but are wingless (nymphs). The
nymphs mature by successive moults but some of these stages may involve
considerable resting when large amounts of internal tissue alteration
takes place. Female thrips are diploid but male thrips (if they are
present) are haploid as they are produced from unfertilised eggs. Some
species of thrips inhabit litter while others manufacture galls in which
they have complete protection while feeding. Females lay their eggs in a
slit in plant tissue. The egg hatches and the developing nymph causes the
plant tissues to swell and form a gall. In the centre of the gall is a
cavity where the nymph continues to feed and develop.
Members
Thrips.
Food
Thrips feed on plant sap obtained by rasping at the vegetation surface and
sucking up the resulting fluid. Litter inhabiting thrips consume fungi.
Importance
Thrips are of immense importance as pests in horticulture. Some crops
subject to thrips damage are onions, tobacco, pears, apples, bananas and
citrus, but there are many more. Numerous flowering plants are also
attacked. When fruit is attacked it is rendered valueless for market due
to the loss of juices from the fruit together with the brownish blotches
produced by the thrips method of feeding. The browning of roses by thrips
infestations is well known to gardeners. |