Cabbage Integrated Pest Management : An Ecological Guide.

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Major Cabbage Insect Pests5.10 Whitefly – Bemisia tabaciBemisia tabaci is a very common species of whitefly. However, there are several other species, forexample Aleurodicus dispersus (spiraling whitefly), and Trialeurodes vaporariorum (common whitefly).Other English names: tobacco whitefly, cotton whitefly or sweet potato whitefly.White fly currently is known to attack over 500 species of plants representing 74 plant families. Theyhave been a particular problem on members of the squash family (squash, melons, cucumbers, pumpkins),tomato family (tomato, eggplant, potato), cotton family (cotton, okra, hibiscus), bean family (beans,soybean, peanuts), and many ornamental plants.In Cebu, in the Philippines, serious damage on cabbages by the whitefly Bemisia tabaci occurred duringthe dry season. Injudicious use of pesticides and favorable temperature led to whitefly outbreak in thearea (Ref. FAO-ICP progress report April 1996 – Feb 1999).Description and life cycleThe adult whitefly is very small: about 1 mm long, silvery-white in color and with wings of a waxy texture.It is found often on the underside of the foliage where it sucks the plant sap.When a plant containing whiteflies is shaken, a cloud of tiny flies flutter out but rapidly resettle. The adulthas 4 wings and is covered with a white, waxy bloom. Adults can fly for only short distances but may bedispersed over large areas by wind. Females usually lay their first eggs on the lower surface of the leaf onwhich they emerged, but soon move upwards to young leaves. The female may lay 100 or more eggs.The egg is pear-shaped and about 0.2 mm long. It stands upright on the leaf. The eggs are anchored bya stalk which penetrates the leaf through a small hole made by the female. Water can pass from the leafinto the egg, and during dry periods when there are high numbers of eggs, the plant may become waterstressed.Eggs are white when first laid but later turn brown. Early in the season, eggs are laid singly butlater they are laid in groups. They hatch in about 7 days.When the nymphs hatch they only move a very short distance before settling down again and starting tofeed. Once a feeding site is selected the nymphs do not move. All the nymphal instars are greenishwhite,oval and scale-like. The last instar (the so-called “pupa”) is about 0.7 mm long and the red eyes of1. Egg (actual size about 0.24 mm long)2. & 3. Top and side view of 1 st stage nymph4. 4 th stage nymph (actual size about 0.75 mm long)adult whitefly(from Kerruishet al. 1994)103 Cabbage Ecological Guide - 2000
Major Cabbage Insect Peststhe adult can be seen through its transparent back. The total nymphal period lasts 2 - 4 weeks dependingon temperature. Nymphs complete 3 moults before pupation.Eggs and early instar nymphs are found on the young leaves and larger nymphs are usually morenumerous on older leaves.Attacks are common during the dry season. Whiteflies disappear rapidly with the onset of rain.Plant damage and plant compensationDirect crop damage occurs when whiteflies suck juices from the plant. With high populations plants maywilt, turn yellow and die.Colony of white flies on underside of leaf (from Stoll ‘87)Whiteflies also excrete honeydew, a sweet sticky fluid which may cover the leaves completely. On thishoneydew, mould fungi grow and the leaves may turn black in color. This reduces the capability of theleaves to produce energy from (sun)light (photosynthesis) and may lower harvest quality.In some hosts, damage can result from whitefly feeding toxins that cause plant disorders such as silverleaf of squash and irregular ripening of tomato. Plant viruses also can be transmitted by whiteflies, but forcabbage this is not a serious problem.Natural enemiesWhiteflies are controlled by predatory insects such as green lacewing or coccinellid larvae (lady beetles);by parasitic wasps such as Encarsia or Eretmocerus species; and fungal diseases such as Beauveria,Paecilomyces or Verticillium species.There may be many more natural enemies of whitefly in your area!Natural enemies of whitefly, to name but a few….Studies carried out between 1985 and 1987 in Andhra Pradesh, India, on cotton showed theoccurrence of nymphal parasitism of whitefly due to the aphelinids Eretmocerus serius, Eretmocerussp. and an unidentified aphelinid. Populations of predators included the coccinellids Brumoidessuturalis, Verania vincta, Menochilus sexmaculatus, Chrysoperla carnea, and the phytoseiidAmblyseius sp. Fungal pathogens found included Aspergillus sp., Paecilomyces sp. and Fusariumsp. (Natarajan, 1990)Cabbage Ecological Guide - 2000104
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Why this guide?About this guideThis
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Introduction1.4 Cabbage: a bit of h
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Cabbage Crop DevelopmentPresently t
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Cabbage Crop Development2.2 Suscept
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Major Agronomic Practices3MAJOR AGR
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Major Agronomic Practices3.2.3 Seed
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Major Agronomic PracticesUse protec
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Major Agronomic Practices3.4.2 Soil
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Major Agronomic Practicesthan 7, th
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Major Agronomic Practices3.4.7 Soil
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Major Agronomic PracticesSome of th
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Major Agronomic PracticeslllCreates
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Major Agronomic PracticesWhen a com
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Major Agronomic PracticesIn additio
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Major Agronomic PracticesSome farme
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Major Agronomic PracticesEffects of
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Major Agronomic PracticesAn example
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Major Agronomic Practicesseed beds,
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Major Agronomic Practicesthis layer
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Major Agronomic PracticesPotting se
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Major Agronomic PracticesTransplant
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Major Agronomic Practices3.9 Water
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Major Agronomic PracticesHowever, w
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Major Agronomic PracticesSome examp
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Ecology of Insect Pests and Natural
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Page 75 and 76: Major Cabbage Insect Pests5MAJOR CA
Page 78 and 79: Major Cabbage Insect PestsDiadegma
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Page 98 and 99: Major Cabbage Insect PestsThe adult
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Page 138 and 139: Disease Ecology7.1 Plant diseases a
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Page 142 and 143: Disease EcologyThe disease triangle
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Page 150 and 151: Disease EcologyTrichoderma species
Page 152 and 153: Major Diseases of Cabbage8MAJORDISE
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Major Diseases of CabbageRole of en
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Major Diseases of CabbageOnce there
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Major Diseases of Cabbage· Practic
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Major Diseases of Cabbage¤Points t
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Major Diseases of Cabbagespores wit
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Major Diseases of Cabbage¤Points t
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Major Diseases of Cabbagebut does n
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Major Diseases of Cabbage8.7 Downy
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Major Diseases of Cabbage8.8 Black
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Major Diseases of CabbageNitrogen (
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Weed Management9WEEDMANAGEMENTSUMMA
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Weed ManagementBroadleaf weeds or g
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Weed Managementcompost or it may be
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Weed Management· Check details of
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Weed ManagementTherefore, to date,
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Rodent ManagementRats are a common
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Rodent Management10.4 Rat managemen
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Rodent Management10.4.4 Biological
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Key to Some Common Cabbage Insect P
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Literature and Internet Reference L
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PESTS & DISEASES COMMON TO CABBAGEP
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Plate 3Fig. 13 : Advanced symptoms
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deficiency symptoms ---------------
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chemical --------------------------
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