SEMINAR IN-CHARGE
Dr. S.K. Shrivastava
Head of the Deptt.
Department of Entomology
PRESENTED BY
R. S. Marabi
Ph.D. (Ag.) Scholar
Roll No.:188
Credit seminar
on
Bemisia tabaci : An obnoxious insect pest
Department of Entomology
College of Agriculture, JNKVV, Jabalpur- 482 004 (M.P.)
Introduction
Whitefliesare Hemipteran insects which belong to family Aleyrodidae.They are small and typically feed on the undersides of plant leaves and suck the cell sap. It was first reported as a pest in 1919 in India (Hussain and Trehan, 1933). Since then, it has been recognized as a pest of crops in tropical and subtropical countries.C.N.: Whitefly S. N.: Bemisia tabaci (Gennadius,1989)
Cont.
To date more than 1200 species of whiteflies have been identified .The genus Bemisia contains 37 species and is thought to have originated from Asia (Mound & Halsey, 1978). B. tabaci have wide host range of 506 species in 74 plant families (Greathead, 1986). It transmit over 200 different plant viruses belonging to the genus Begomovirus.So far about 6 biotypes of B. tabaci have been detected worldwide by molecular methods (Hilje, 2003).Taxonomic position of Bemisia tabaci
Kingdom Animal
Phylum Arthropoda
Class Insecta
Division Pterygota
Sub-division Exopterygota
Order Hemiptera
Sub order-Homoptera
Family Aleyrodidae
Genus Bemisia Species tabaci
Geographical distribution
The B. tabaci is not genetically uniform. Based on mitochondrial DNA markers, the B. tabaci complex (comprising B and non-B type variants) can be placed into five major groups according to their geographical origin:
(1) New World (US, Mexico, Puerto Rico),
(2) Southeast Asia (Thailand, Malaysia),
(3) Mediterranean basin (Southwest Europe, North Africa, Middle East),
(4) Indian subcontinent (India, Pakistan, Nepal),
(5) Equatorial Africa (Cameroon, Mozambique, Uganda, and Zambia) (Frohlich et al.1999).
Species of whiteflies
Behavior & population biology
Dispersal
Whitefly tend to remain in groups until the population becomes dense.
This means infestations stay concentrated in a few places, especially during the earlier stages of the crop.
Later as temperatures rise, they become more active and spread widely over the whole crop.
Adults are the most important dispersal stage.
Distribution
Only the first nymph (crawler) stage of whitefly is capable of movement, and this is limited to short distances, usually on the same leaf on which it hatched.
Adults of greenhouse whitefly only lay eggs on the young leaves at the top of the plant, so as the plant grows, younger nymphs are found on the upper parts of the plant and older ones are found lower down.
In contrast, sweet potato whitefly adults tend to lay eggs over the entire plant, so all life cycle stages can be found on the same leaf.
Morphology and marks of identification
Egg:
Adult females lay their elongated oval eggs on the undersides of the youngest leaves towards the shoot tips with the help of a short stalk.
Females may produce up to 300 eggs in their lifetime.
They are about 0.25 mm long and oval in shape.
For the first couple of days the eggs are transparent to pale cream-yellow, then after a day or two they begin to turn brown-black.
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Egg
Egg
Egg
Crawler (1st nymphal stage):
The egg hatches into the first instar which is mobile and called crawler stage.It is flat, oval, almost transparent and only 0.3 mm long with tiny legs that allow it to move across the leaf surface. It remains at this location until it turns into an adult. A modified alimentary system concentrates sugar in the interior midgut while the excess fluid is passed on to the midgut and excreted outside the body as honeydew.Scale (2nd 4th nymphal stages):
When the crawler moults, it turns into a legless, 0.30.4 mm long, scale-like creature that is fixed to the leaf surface. The body is oval and almost transparent, although some yellow internal organs may be visible.
There are longer hairs on top of the body. It remains immobile, feeding off sap and moulting between nymphal stages (Reddy & Rao, 1989).Cont
Pupa:
An oval, white case with a fringe of white threads projecting outwards around the body.The fourth nymphal stage starts off flat and oval. At the end of this stage it stops feeding, swells, becomes denser and forms waxy, spiny rods over its bodyAs a result it becomes creamy white in appearance and about 0.7 mm long.Shortly before it emerges parts of the adult, especially its eyes, can be seen through the pupa skin.Cont
Adult:
The males are about 0.9 mm and females are about 1.1 mm long with a pale yellow body which remains covered with pairs of tent like white wings of uniform size. At rest, the wings are held in an inverted V position. Adult emergence usually takes place from their pupal case (pseudo-pupa) in the morning. Compound eyes of the adult are red colour.Adult B. tabaci
Life cycle of B. tabaci
4-7 days
4-7days
2-3 days
2-4days
2-3 days
Inc. Metamorphosis
TLC- 15-18 days
(Temp. 25-32C)
Generation-11-15/year
Pupa
300 eggs
Weather factors
The availability of favourable weather (dry and humid) in recent years has paved the way for build up of whitefly population (Singh et al., 1998).The mild winter conditions in North India during the last two decades are known to trigger further carryover of whitefly.Host plants of B. tabaci
S.No.Host plantsBotanical nameVegetable crops1TomatoLycopersicon esculentum2PotatoSolanum tuberosum3OkraAbelmoschus esculentus4RadishRaphanus sativus5CabbageB. oleracea var. capitata 6BroccoliB. oleracea var. italica 7CauliflowerB. oleracea var. botrytis8EggplantSolanum melongena9LettuceLactuca sativaCont
S.No.Host plantsBotanical nameCucurbits1MelonCucumis melo2WatermelonCitrullus lanatus3CucumberCucumis sativus4AyoteCucurbita moschataOilseed crops1SoybeanGlycine max2SunflowerHelianthus annuus3SesameSesamum indicumPulses1Common beanPhaseolus vulgaris2BlackgramVigna mungo3MungbeanVigna radiataCont
S.No.Host plantsBotanical nameTuber crops 1Sweet potatoIpomoea batatas2CassavaManihot esculentaFruits crops1PapayaCarica papaya2GuavaPsidium guajavaSpices crops1ChilliCapsicum annuum2Hot pepperCapsicum frutescensCont
(Devid, 2003)
S.No.Host plantsBotanical nameFiber crop1CottonGossypium hirsutumOther/forage/weeds 1TobaccoNicotiana tabacum2Alfalfa Medicago sativa3SidaSida rhombifoliaNature of Damage
Whiteflies cause damage to the plant by two ways: Direct feeding: Introducing toxic saliva and decreasing the plants' overall turgor pressure. Both nymph and adult whitefly cause direct damage when they suck plant juices. As a result, infestations of whitefly can give plants a yellow, mottled look, stunting their growth, causing wilting and defoliation and thereby seriously reducing crop yield.Cont
Nymphs of sweet potato whitefly inject enzymes that cause changes in the plants chemistry. The result can be irregular ripening of fruit which remain hard and sour tasting, with retarded internal colour.
SPFMV/SPFMV.htm
2. Indirect damage:
I. Sooty mold growth: encouraged by the honeydew secretion that block photosynthesis.
Leaves and fruits of tomato infected by honeydew of whiteflies
Cont
Cont
II. As a vector of plant viruses:
Transmission of plant viral diseases through adult whiteflies have the potential to cause crop losses indirectly by transmitting plant viruses.
Bean calico mosaic virus Arizona 1998
The ability of whiteflies to carry and spread disease is the widest impact on global food production viz; TYLcV, MYMV etc.
Cont
Cont
Plant
Virus
(Astier et al., 2001)
Plant virus transmitted by insect vectors
55%11%11%9%7%5%2%Plant virus transmitted by Bemisia tabaci
Cont
S.N.Host plantName of diseaseReference8Courgettes (Cucurbita pepo Squash leaf curl virus (SqLCV)Lazarowitz & Lazdins, 19919Beansbean golden mosaic (BGMV) viruses, MYMIVAzam et al.199410Poinsettia (Euphorbia pulcherrima)Euphorbia mosaic virus (EuMV)Martinez, 200011Gerbera (Gerbera sp.)Gerbera mosaic virus (GMV)Visalakshy, 200113OkraBhindi yellow vein mosaic virus (BYVMV)Briddon et al. 200114Lettuces (Lactuca sativa)Lettuce infectious yellows virus(LIYV)Martelli et al. 200216SoybeanSoybean crinkle leaf virus (SCLV) MYMIVBiswas and Varma ,200117CucumbersCucumbervein yellowingvirus(CVYV)Morris, 2006Symptoms of plant virus caused by Bemisia
Cabbage leaf curl virus
Cotton leaf crumple virus
Tomato leaf curl virus
Potato leaf curl virus
www.apsnet.org
Cucumber mosaic virus
galleryhip.com
Bhindi yellow vein mosaic virus
Cassava yellows virus
www.apsnet.org
Pest status & economic importance
Cont.
Cont.
Percentage of plant virus transmitted B. tabaci
(David, 2003)
Mechanism of plant virus transmission by Insect vectors
Cont
View of adult B. tabaci
Fig.: Showing the digestive system in a nongravid individual and the location of one primary salivary gland in the prothorax. Note: In gravid females the midgut was sometimes found in the thorax pressed against the primary salivary glands. AM- Ascending midgut; CA-Caeca; CC- Connecting chamber; CIB-Cibarium; DM-Descending midgut; EE- External esophagus; FC-Filter chamber; HG- Hindgut; PSG- Primary salivary gland; PSGD-Primary salivary gland duct; RS-Rectal sac; SEG- Subesophageal ganglion; TAGM-Thoracic abdominal ganglionic mass.
Typical feeding mechanism of sucking pests
Model of the ingestion-salivation mechanism of noncirculative, nonpersistent transmission.
Plasmalemma
Stylet
Cell wall
Stylet sheath
Virus
Ingestion from protoplast
Salivation into protoplast
Virus is ingested into the food canal (right), along with the cytoplasm. Virus adheres to the epicuticular lining of the food canal and the common duct at the very distal tip of the stylet, which is shared with the salivary canal. When the aphid first probes a cell after acquiring virus (left), saliva is injected into the cell. The watery salivary secretions will release virus from the cuticle lining the common duct, but virus farther inside the food canal would not be released by this mechanism.
Begomovirus s genomic organization
Mechanism of plant virus transmission
Bowdoin, 2013
Mechanism of feeding
Fig.: Showing the digestive system in a nongravid individual psg-primary salivary gland; e-esophagus; fc-filter chamber; mg-mid gut and hg-hind gut
Tomato yellow leaf curl virus
Management strategies of B. tabaci
Pyramid of IPM Tactics
Insecticides
Predators, parasites, microbials
Monitoring, Traps, barriers etc.
Field sanitation, plant variety, crop rotations etc.
Host plant resistance
*
Cultural Control
Clean cultivation:
Destruction of off-season host plants of whitefly.The removal of weed flora in/around the fields during the crop season e.g. Lantana sp., Solanum sp., Euphorbia sp., Datura sp. and Hibiscus sp. etc.Barrier /Mulching:
Mulching with yellow polythene sheets delayed of tomato leaf curl virus (Cohen and Madjar, 1978).Intercropping :
Cucumber planting in alternate rows 30 days before tomato, delay infection of TLCV (Al-Musa, 1982)
Mechanical control
ag.arizona.edu
Installation of yellow sticky traps in field
Monitoring of B. tabaci
Yellow sticky trap
Regular monitoring of B.tabaci apopulation should be done from the early stage of the crop. Yellow sticky traps can be use monitoring the pest population.Fig.A) An adult big-eyed bug, Geocoris punctipes, B) Green lacewing larva, Chrysoperla sp., C) Pirate bug, Orius insidiosus feeding on preying on whitefly nymphs (http://en.wikipedia.org/wiki/Whitefly)
Biological control
Cont
www.planetnatural.com
Botanical insecticides
Botanicals DosageRemarksReferenceNeemguard0.03%Moderate controlPuri et al. 1998; Dhawan, 1998, 1999, Mann et al. 2001NSKE5%--do--Neem oil 5%Rakshak Gold 1%0.5 lit./haEconeem 1%0.5 lit./haNimbecidine 0.003%5.0 Lit./haVery effectiveAchook 0.15%3.0 Lit./haVery effectiveChemical control
InsecticideDosageRemarksReferencesSeed treatmentImidacloprid 17.8 SL3.5 g/kg seedEffective only where WF is serious as early season pestRao et al. 1990; Jayswal and Sundaramurthy, 1992; Puri et al. 1998; Dhawan, 2000, Butter and Dhawan, 2001Thiomethoxam 70WS4.2 g/kg seed--do--Foliar sprayImidacloprid 17.8 SL0.5 ml/lit.Effective but Comparatively very costlyThiomethoxam 25 WG1000g/haEffectiveTrizophos 40EC600ml/haVery effective Ethion 50EC1000ml/haResistance crop varieties against B.tabaci
Biophysical bases of resistance against B. tabaci
Cont.
CropResponseReferencePoinsettia Non grandular leavesResistanceBilderbac and Mattson, 1977TomatoGlandular leavesResistanceKishna, 1984SoybeanGlabrous leaves and hairsResistanceMcAuslane, 1996CabbageNon waxy leavesResistanceThompson, 1963
Biochemical bases of resistance against B. tabaci
Insecticide resistance management
The indiscriminate and non judicious use of insecticides particularly synthetic pyrethroids like cypermethrin, fenvalerate, deltamethrin and alpha-cypermethrin induces the resurgence of whitefly population due to increased fecundity and growth rate (Anonymous. 1989)The excessive use of insecticides like Acephate in late season also flares up the whitefly population beyond manageable limits (Dhawan et al. 2000).Cont
IRM strategies
Classical findings against plant viruses
Cotton:
Cotton crop damage caused by CLCuV which is transmitted by whitefly.
Table: Economic threshold levels for cotton whitefly in India:
Threshold levelAreaReference20 nymphs/leafPunjabButter and Kular, 19866-8 adults/leafPunjabSukhija et al., 1986Appearance of honeydew symptoms on 50 % plantsPunjabDhawan, 199910 adults/leafAndhra PradeshReddy and Krishnamurthy, 19898-10 adults/leafTamil NaduSundaramurthy, 1992Activity of whitefly in cotton zones in India
Northern Zone
Activity Period
May to November
Max. Activity Period
Sept. to Oct.
Central Zone
Activity Period
January to November
Max. Activity Period
Sept. to Dec.
Southern Zone
Activity Period
February to September
Max. Activity Period
Sept. to Jan.
(Dhawan et al., 2007)
Fig. Distribution of whitefly stages on canopy leaves
Canopy leaves
(Dhawan et al., 2007)
Population
Classical findings .
Soybean:
Yellow mosaic virus:
Causal organism- Mungbean Yellow Mosaic Virus (MYMV)
Alternative hosts: Vigna radiata, Alternanthera sessilis, Sida rhombifolia
Symptoms:
Disease first appears on young leaves with mottling of the leaves with an intense contrast between the yellow and the green areas.Yellow area are either scattered or produced in indefinite bands along the major veins. Rusty necrotic spots appears in the yellow area as the leaves mature.Under severe condition plants produces shriveled and lightweight seeds or sometimes fail to form flowers and pods.Symptoms of virus transmission
Infected with Yellow vein mosaic virus
Management strategies of B.tabaci
MechanicalpracticesResistance /Tolerance var.Seed TreatmentSpray of InsecticidesDestruction of weed hostsJS 97-52, JS 93-05, JS 95-60Thiamethoxam (70 WS) 3.0g/kg seedMetasystox 25 EC 1.0 ml OR Imidacloprid 0.5 ml/liter water ORThiamethoxam (25WG) 100 g/ ha after 35 days of sowing.Removal of infected plants and burn them.References
Dhawan A.K. (1999). Major insect pests of cotton and their integrated management. In: R.K. Updadhyay, G.K. Mukerji and R.L. Rajak (eds). IPM System in Agriculture Vol.6-cash Crops. Aditya Books Pvt. Ltd., New Delhi, pp.165-255.
Greathead,A. H. (1986). Host plants. In Bemisia tabaci-A literature Survey. M. J. W. Cock (Ed.), CAB International Institute of Biological Control, Silwood Park, Ascot, Berks.,UK, pp. 17 - 25.
Husain M.A., and Trehan K. N. (1993). Observations on the life-history, bionomics and control of white-fly of cotton (Bemisia gossypiperda M.& L.). Indian Journal of Agricultural Science 3: 701 - 753.
Natarajan K. (1990). Natural enemies of Bemisia tabaci Gennadius and effect of insecticides on their activity. J. Biol. Cont. 4(2):86-88.
Rao N.V. Reddy A.S. and Reddy P.S. (1990). Relative efficiency of some new insecticides to cotton whitefly, Bemisia tabaci Genn. Indian J.Pl. Prot. 18(1):53-58.
References
Dhawan A.K. (1999). Major insect pests of cotton and their integrated management. In: R.K. Updadhyay, G.K. Mukerji and R.L. Rajak (eds). IPM System in Agriculture Vol.6-cash Crops. Aditya Books Pvt. Ltd., New Delhi, pp.165-255.
Greathead,A. H. (1986). Host plants. In Bemisia tabaci-A literature Survey. M. J. W. Cock (Ed.), CAB International Institute of Biological Control, Silwood Park, Ascot, Berks.,UK, pp. 17 25..
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