science

Western flower thrips

Western flower thrips is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Western flower thrips rather than just read about it. In short: The western flower thrips [Frankliniella occidentalis (Pergande)] is an invasive pest insect in agriculture. This species of thrips is native to the Southwestern United States but has spread to other continents, including Europe, Australia (where it was identified in May 1993), and South America via transport of infested plant material.

Key takeaways

Western flower thrips belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Western flower thrips to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Western flower thrips from memory before moving on to harder problems.

Reference excerpt

The western flower thrips [Frankliniella occidentalis (Pergande)] is an invasive pest insect in agriculture. This species of thrips is native to the Southwestern United States but has spread to other continents, including Europe, Australia (where it was identified in May 1993), and South America via transport of infested plant material.

Morphology The adult male is about 1 millimetre (3⁄64 in) long; the female is slightly larger, about 1.4 millimetres (1⁄16 in) in length. Males are rare, and are always pale yellow, while females vary in color, often by season, from red to yellow to dark brown. Each adult is elongated and thin, with two pairs of long wings. The eggs are oval or kidney-shaped, white, and about 0.2 millimetres (1⁄128 in) long. The nymph is yellowish in color with red eyes.

Instars The lifecycle of the western flower thrips varies in length due to temperature, with the adult living from two to five or more weeks, and the nymph stage lasting from five to 20 days. Each female may lay 40 to over 100 eggs in the tissues of the plant, often in the flower, but also in the fruit or foliage. The newly hatched nymph feeds on the plant for two of its instars, then falls off the plant to complete its other two instar stages. Nymphs feed heavily on new fruit just beginning to develop from the flower.

Behavioral Flower-feeding thrips are routinely attracted to bright floral colors, especially white, blue, and yellow, and will land and attempt to feed. Some flower thrips will "bite" humans wearing clothing with such bright colors, though no species feed on blood. Such biting does not result in any known disease transmission, but skin irritation is known to occur.

Reproduction Most western flower thrips are female and reproduce by arrhenotokous parthenogenesis; i.e. females can produce males from unfertilized eggs, but females arise only from fertilized eggs.

Hosts It has been documented to feed on over 500 different species of host plants, including a large number of fruit, vegetable, and ornamental crops including Brassica oleracea (broccoli, 'Marathon'). The insect damages the plant in several ways. The major damage is caused by the adult ovipositing in the plant tissue. The plant is also injured by feeding, which leaves holes and areas of silvery discoloration when the plant reacts to the insect's saliva. Nymphs feed heavily on new fruit just beginning to develop from the flower. The western flower thrips is also the major vector of tomato spotted wilt virus (TSWV), a serious plant disease. It has been shown that acquiring TSWV (which only occurs during the larval stages) causes more feeding in the thrips which results in a longer life span eventually. Western flower thrips are a year-round pest, but are less destructive during wet weather.

Management

Trapping WFTs especially like the color blue, being attracted to blue card material and even more so to blue lights. They are somewhat interested in yellow and barely interested in white. Traps can still function even if surrounded with mesh to exclude beneficials such as hoverflies and bees. Commercial semiochemical pheromone lures are also available which can be used in conjunction with blue sticky traps to maximise sticky trap catches of western flower thrips.

Biological controls Damage can be reduced by growing barriers of nonhost plants around crops and by eliminating reservoir plants, plants to which the thrips are especially attracted, such as jimson weed. The thrips' natural enemies include pirate bugs of genus Orius and Neoseiulus cucumeris, a predatory mite species which is the most commonly used biological control agent against western flower thrips in protected crops including cucumber and strawberry. Other agents show promise as biological pest control, including the entomopathogenic fungi Metarhizium robertsii (syn. M. anisopliae) and Beauveria bassiana, and the mirid Dicyphus hesperus.

Genetics A draft genome assembly is available.

References

External links WFT fact sheet Hawaii fact sheet UC Davis IPM Close up photo Archived 2007-09-03 at the Wayback Machine PaDIL diagnostic photos Archived 2007-09-04 at the Wayback Machine CISR: Center for Invasive Species Research Fact Sheet on Western Flower Thrips

Illustrations

Worked examples

Example 1 — a first encounter with Western flower thrips

Start with the simplest possible case. Write down what Western flower thrips claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Western flower thrips before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Western flower thrips ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Western flower thrips

In research: Western flower thrips appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Western flower thrips in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Western flower thrips is common in secondary-school and first-year university syllabi. It links to neighbouring topics Agricultural pest insects, Fauna of the Southwestern United States, Insect vectors of plant pathogens, so understanding it makes those chapters shorter.
In everyday life: Look for Western flower thrips outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Western flower thrips in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Western flower thrips means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Western flower thrips out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Western flower thrips in simple terms?

Why does Western flower thrips matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Western flower thrips?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Western flower thrips.