More than one
thousand species of arthropod pests and nearly 400 pathogens are known to
attack tea all over the world, though only about 300 species of insects and
mites and 58 pathogenic fungi are recorded from tea in India. Crop loss due to
pest and diseases varies between 15 and 20%. Magnitude of the losses is bound
to be higher today in view of the increased production and productivity besides
the variations in climatic conditions.
Mites: Mites are serious pests of
tea and they damage the green tissues of leaves, thereby reducing the
photosynthetic efficiency resulting in yield reduction. Infestation leads to
discoloration of leaves. Most of the species occupy the under surface of the
leaves but a few prefer the upper surface also.
Pink mite, Acaphylla theae (Eriophyidae: Acarina): Important mite pest of tea in southern India causes considerable
damage. During early stages of attack leaves turn pale and curl upwards while
severe infestation leads to brownish discolouration. Pink mites attack tender
crop shoots where “Assam” hybrids are more susceptible. Eggs are shiny,
globular in shape and lay singly on the under surface of the leaves. Eggs are
hatches in 2-3 days; there are two nymphal stages and they are white in colour.
Population builds up initiates in November/December and attains peak in
February/March and declined during May/June. Life cycle completed in 6-9 days.
Purple mite, Calacarus carinatus (Eriophyidae: Acarina): Damaged leaves characterized by the coppery brown discoloration;
presence of numerous white cast skins of the mites along with the live mites;
purple mites are prevalent on the under surface of mature leaves; adults are
very small, spindle shaped, purple colour; fringed body with five longitudinal
white waxy ridges on dorsal side, young ones moult three times; incubation
period ranges 3-5 days with two nymphal stages while total developmental period
was 6-11 days.
Pale mite, Acaphyllisa parindiae (Eriophyidae: Acarina): Adult mite is pale white and dorso-ventrally
flattened; broadly rounded anterior end and tapering posterior end; seen on the
under surface of the mature foliage; incubation period 2-3 days, nymphal stages
4-6 days; development completed in 6-9 days.
Scarlet mite, Brevipalpus
australis (Tenuipalpidae:
Acarina): Symptoms of attack first appear on either side of the
midrib and gradually spread to the entire leaf; feeding leads to brown
discolouration of leaves and severe infestation leads to defoliation; adult
mite is scarlet red in colour and obovate in shape; reproduction is by
parthenogenesis. Eggs are bright red, elliptical, laid in clusters; incubation
period is 7-10 days; developmental stages include three legged larva,
protonymph and deutonymph and each developmental stage is followed by a
quiescent stage; life cycle completed in 30-36 days.
Yellow mite, Polyphagotarsonemus
latus (Tarsonemidae: Acarina):
observed on young leaves, especially on the top two to three leaves and the
bud. Leaves become rough and brittle and corky lines or patches on the surface.
Females are yellowish and bigger than the males and they carrying the “female
nymphs” on their back. Eggs large, obovate, flattened at the bottom; eggs
hatches after 27-32 hours and life cycle completed in 3-5 days.
Control measures (of above
listed mite species) include monitoring the field population by regular
assessments, regulation of the shade trees as per recommendation and enhancing
the populations of natural enemies (phytoseiid mites, predatory thrips and
cecidomyiids) in tea ecosystem. Application of spore suspension of the
entomopathogen, Paecilomyces jumosotroscus (UPASI strain) Mycomite @ 1.5 kg/ha or
neem formulations 0.03-0.15% Aza @ 1000 ml/ha or 1% @ 200-400 ml/ha or 5% @
100-200 ml/ha or sulphur formulations 80% @ 1000 g/ha or dicofol 18.5 EC @ 1000
ml/ha or ethion 50 EC @ 750 ml/ha are recommended. While using power sprayers
use a spray volume of 300-350 l/ha or 400-450 l/ha with hand operated knapsack
sprayer.
Red spider mite, Oligonychus
coffeae (Tetranychidae:
Acarina): Important mite pest
causes considerable damage during the past few years. Infestation starts along
midrib and veins further spreads to the entire upper surface of leaves. Due to
feeding, the maintenance foliage turns ruddy bronze and infested fields
distinct even from a long distance. Severe infestation leads to defoliation.
Adult female elliptical in shape, bright crimson anteriorly and dark pruplish
brown posteriorlym. Mites spin a web of silken threads on the leaf. Eggs
reddish, spherical, provided with a small filament. Incubation period is 4-6
days, before hatching becomes light orange colour. Developmental stages include
six legged larva, protonymph and deutonymph. Each developmental stage is
followed by a quiescent stage and life cycle completed in 10-14 days.
Control measures of red
spider mites can broadly classified as cultural, biological and chemical
control methods. Cultural control measures include monitoring the population
dynamics by regular field assessment, shade/weed management and removal of
alternate host plants (Bidens, Ageratum, Conyza,Crassocephalum, etc). Biological control measures
include allowing the build up of natural enemies (phytoseiid mites and
coccinellid beetles (lady bird beetles) in tea ecosystem and application of
spore suspension of the entomopathogen, Verticillium
lecanii @ 1.5 kg/ha in the evening
hours when humidity is more. Certain chemicals were recommended for control of
red spider mites which include spray formulations of sulphur 80% @ 1000 g/ha,
lime sulphur @ 1:40. If mite persists spray any one of the acaricides like dicofol
18.5 EC @ 1000 ml/ha, ethion 50 EC @ 750 ml/ha, fenpropathrin 10 E @ 500 ml/ha,
combination of dicofol and ethion 500 ml each and dicofol and quinalphos @ 500
+ 350 ml are effective against the pest. While using power sprayers use a spray
volume of 350-400 l/ha or 450-500 l/ha with hand operated knapsack sprayer.
Care must be taken to thoroughly drench the maintenance foliage and chemicals
should be applied only after plucking.
Tea Thrips, Scirtothrips
bispinosus (Thripidae:
Thysanoptera): Prefers young leaves
and buds; continuous feeding causes lacerations which appear as streaks; leaf
surface becomes uneven and curled; feeding marks on the buds later appear as
two parallel lines; attack more pronounced in the fields recovering from pruning;
leads to inordinate delay in tipping and consequent crop loss; adults
characterised by their brown abdomen, Incubation period is 6-8 days; egg hatch
into larva, two larval instars, creamy white in color, prominent eyes; prepupa
and pupae are found in the leaf litter and soil; adults emerge from the pupae
after 3-5 days; weak fliers, dispersal and migration is helped by wind; build
up starts by Nov/Dec. reaches peak in Feb/March or April/May. Monitoring the
population in the field with yellow sticky traps and maintenance of regular
shade besides the natural enemies like Anthocorids and predatory thrips can
reduce the population. Suggested to apply the spore suspension of the
entomopathogen, Verticillium lecanii @ 1.5 kg/ha in the evening hours when
humidity is more. Certain chemicals were recommended for control of thrips;
quinalphos 25 EC @ 750 ml/ha; dimethoate 20 EC @ 500 ml/ha; endosulfan 35 EC @
1000 ml/ha; quinalphos 25 EC + dichlorvos 76 EC @ 750+250 ml/ha. Spray should
be targeted to the shoots on and below the plucking table, and also the side.
Tea mosquito, Helopeltis
theivora (Miridae: Heteroptera:
Hemiptera): Adults and nymphs
punctures the plant tissues with needle like rostrum and suck the sap from
buds, young leaves and tender stems. Punctures appear as reddish brown spots
and due to intensive feeding, leaves curl up, badly deformed and remain small.
Shoots dry up and crop loss is near total in response to severe incidence.
Adults black in colour, red thorax, black and white abdomen and greenish brown
wings. They were active early mornings and late evenings, more in moist shaded
areas. Five nymphal stages and development completed in 15-17 days. Its
incidence was high during July to December and low between January and June.
Monitoring the infestation level in the
field, black plucking, weed control and removal of stalks containing tea
mosquito eggs are important cultural control methods. Allowing builing up of
egg parasitoid (Erythmelus helopeltidis) in the tea ecosystem is a
recommended biological control measure. Certain molecules, endosulfan 35 EC @
1000 ml/ha, quinalphos 25 EC @ 750 ml/ha, chlorpyrifos 20 EC @ 750 ml/ha,
fenthion 80 EC @ 200 ml/ha, quinalphos 25 EC + dichlorvos 76 EC @ 750 + 250
ml/ha recommended for control of tea mosquito. Spraying is suggested in the
early mornings or evenings when these bugs are active.
Lygus bug, Lygus sp. (Miridae: Heteroptera: Hemiptera): Adults and nymphs injure the tender plant parts. Mouth parts are
piercing and sucking type. Feeding punctures appear as reddish brown necrotic
spots. Symptoms of damage are similar to that caused by Helopeltis attack and it can be controlled as detailed for Helopeltis.
Tea aphid, Toxoptera
aurantii (Aphididae: Homoptera:
Hemiptera): Colonies seen on tender shoots of young plants and bushes
recovering from pruning. Adults and immature stages suck the sap from tender
shoots. Due to feeding leaves curl up and stunted shoot growth observed. Attack
on young buds delays the recovery of pruned bushes. Colonies of aphids consist
of dark brown alate and apterous adult females and nymphs. Population is more
from January to April and low during June/July. Monitoring the population in
the field with yellow pan water trap, maintenance of regulated shade and manual
removal of infested shoots reduce the population to an extent. Aphids are
largely regulated by biocontrol agents where larvae of the syrphids and the
coccinellids are major predators followed by three species of aphidiid
parasitoids. If pest persists application of neem formulations 0.03-0.15% Aza @
1000 ml/ha or 1% @ 200-400 ml/ha or 5% @ 100-200 ml/ha or spore suspension of
the entomopathogen, Paecilomyces fumosoroseus @ 1.5 kg/ha in the evening hours when
humidity is more are recommended.
Mealy bug, Nipaecoccus
viridis (Pseudococcidae:
Homoptera: Hemiptera): Feeds on the young
shoots and its severe infestation leads to defoliation. Adult female soft
bodied, oval, flattened, dark brown, 2.5-3.0 mm long, female laid a large
number of eggs, hatches out in 7-10 days with a total developmental period of
15-20 days. Monitoring the field population and manual removal of infested
branches controls Mealy bug population. If pest persists Quinalphos 25 EC @ 500
ml/ha or dimethoate 20 EC @ 500 ml/ha is recommended. Addition of non ionic
wetting agent (5 ml/10 l of water) will be helpful in achieving better control.
Brown bug, Saissetia coffeae
(Coccidae: Homoptera:
Hemiptera): Mature scales are:
hemispherical in shape and deep brown in colour; occurs on leaves and tender
stems; females are sedentary; adult males are winged forms; Eggs are seen under
the scale; crawlers disperse and attach themselves with tender plant parts
after hatching. Brown bugs naturally regulated by the parasitoids, Encyrtus infelix and Coccophagus cowperi and it can be controlled as
recommended for Mealy bug.
Green scale, Coccus viridis (Coccidae: Homoptera: Hemiptera): Observed on tender stems and leaves; females yellowish green in
colour and oval in shape; reproduction by parthenogenesis, female lay 600 eggs;
eggs hatch out immediately after deposition; three nymphal instars lasting 4-6
weeks; adults live for 2-5 months. It can be controlled as recommended for
mealy bug.
Root mealy bug, Dysmicoccus
sp. (Pseudococcidae:
Homoptera: Hemiptera): Attack the roots of
young tea plants in nurseries.
Tea Jassid, Empoasca
flavescens (Cicadellidae:
Homoptera: Hemiptera): Adults and nymphs suck
the sap from tender leaves; leaves curl downwards, gradually turn brown and dry
up; adults are yellowish green and measure 2.5-2.75mm long; eggs inserted
singly into the leaves; incubation period varies from 6-13 days; development
completed in 8-15 days according to the temperature. Plucking removes a large
part of eggs and nymphs and it can be controlled as recommended for mealy bug.
Caterpillars: Large group of insects
injurious to tea; flushworms, leaf rollers and tea tortrix are common
caterpillar pests commonly seen in first year fields recovering from pruning.
Make leaf nests by webbing the leaves, one above the other, feed from inside.
Populations seen in large numbers during August to December.
Flushworm, Cydia leucostoma (Tortricidae: Lepidoptera): Larva is brown in colour 1 cm long; enters into the bud by making
a small hole, ties up the margins of growing bud and form a case; feeds on the
upper epidermis of leaves; affected leaves become rough, crinkled and leathery;
adult moth very small, less than 1cm long blackish brown in colour; eggs are
pale yellow and laid singly on the undersurface of mature leaves; incubation
period 4-5 days, five larval instars; larva takes 19-25 days for development
inside the leaf case; pupal period varies from 8-10 days; moths were active
during morning and evening hours; Control measures include manual removal of
infested shoots. Flushworm is naturally regulated by the larval and pupal
parasitoids; if pest persists spray neem formulations 0.03-0.15% Aza @ 1000
ml/ha or 1% @ 200-400 ml/ha or 5% @ 100-200 ml/ha or spray the spore suspension
of the entomopathogen, Paecilomyces fumosoroseus @ 1.5 kg/ha in the evening
hours when humidity is more.
Tea tortrix, Homona
coffearia (Tortricide:
Lepidoptera): Caterpillars make leaf
nests by webbing the leaves, one above the other, using silken threads, and
feed from inside; adult moth is brown coloured, bell shaped; eggs are laid in
masses, incubation period 6-8 days; larvae are greenish in colour and about 2
cm long; larval period last for 20-30 days; pupal period ranges from 9-15 days.
Control measures are same as for flushworm.
Tea leaf roller, Caloptilia
theivora (Gracillariidae:
Lepidoptera): Young caterpillar first
mines into the leaf; older larvae roll the leaves from tip downwards, feed from
inside; normally, young leaves are preferred; adult moth is very small, with
narrow wings; eggs are deposited on the undersurface of leaves; larva hatch out
in 2-3 days; larval period is 14-20 days; pupal duration 7-14 days.
Pyralid leaf webber, Ereboenis
saturata (Pyralidae:
Lepidoptera): Larva feeds on older
leaves from the upper surface; leaving the lower epidermis, the skeleton of
leaves; the caterpillar webbed together the individual leaves by silken thread;
feed gregariously from inside the web.
Looper caterpillar, Buzura
suppressaria (Geometridae:
Lepidoptera): Young caterpillars feed
on young leaves and mature larvae prefer older leaves; they made series of
small holes along and a little away from the margin; in severe cases of attack,
tea bushes completely denuded; female deposits upto 200 eggs in batches on the
tree trunks; incubation period 7-10 days; on emergence, caterpillars suspend by
silken threads and get dispersed by wind; larvae dark brown with pale greenish
white lines on the back and side; on the leaves, they move like leeches; after
4-5 weeks, they pupated in the soil for a period of 3-4 weeks; pupa brownish,
2-2.5 cm long, life cycle completed in 8-10 weeks.
Twig caterpillar: Ectropis
bhurmitra (Geometridae:
Lepidoptera): Young caterpillars feed
on young leaves and mature larvae prefer older leaves; in severe cases of
attack, whole leaves are eaten off, leaving the midrib; adult large pale grey
wings and slender body; eggs are bluish laid in clusters; covered by a mass of
buff coloured hairs; incubation period is 7-10 days; mature larvae are dark
brown 4.5 cm long; while resting the larvae are closely resemble a dry twig;
larval period is completed in 3-4 weeks and pupated in the soil; pupae are
1.5-2 cm long and reddish brown colour; life cycle is completed in about 5
weeks.
Blue striped nettle grub, Latoia
lepida (Limacodidae:
Lepidoptera): Feeds the maintenance
foliage; grubs green in colour with three pale blue longitudinal stripes; full
grown grubs measure 3-4 cm long; eggs are flattened, laid in clusters of 10-30;
single female lays more than 500 eggs and hatch in 6-8 days.
Saddle backed nettle grub, Thosea
cervina (Limacodidae:
Lepidoptera): Larvae feed on the leaf
tissue on the under surface; severe cases of infestation completely strip off
the leaves; adult moth is dark reddish brown; mature larvae are 4 cm long,
greenish colour with three brown markings; central marking is saddle shaped,
other two are look like pear; larvae pupate in the soil; pupae are dark brown,
globular and resemble tea seeds.
Fringed nettle grub, Darna
nararia (Limacodidae:
Lepidoptera): Caterpillars scraping
on the under surface of leaves; during severe outbreak, the leaves are
completely eaten off; pale brown adult moths are active at night; eggs are
oval, flattened, shiny and laid singly on leaves; incubation period is about a
week; larvae are about 1.5 cm and pale green in colour; larvae moult five times
and larval duration is five weeks; pupated in the soil for three weeks.
White banded nettle grub, Thosea
recta Hampson (Limacodidae:
Lepidoptera): Young larvae scrape off
the under surface of the leaf; mature larvae eat large portions of leaves;
adult moths are grayish brown and measure about 2.5 cm across wings; larvae are
green in colour with a silvery white band on the dorsal side; brown oval cocoons
are seen attached to leaves or twigs.
Large jelly grub, Belippa
lalaena (Limacodidae:
Lepidoptera): Larvae eat off large portions of mature leaves; grubs are pale
bluish, 1.5 cm long, rounded and resemble a bulb of jelly; larval period is
about 2 months; cocoons are whitish, rounded and attached to bushes. Control
measures are identical as suggested for caterpillars.
Large Faggot worm, Eumeta
crameri (Psychidae:
Lepidoptera): Infest the older leaves
and bark; in the pruned fields, damage will be severe; male moths are reddish
brown with wings; male moths are reddish brown with wings; females are devoid
of wings and legs; winged males are mate with grub like females; female lay 500
eggs inside the case; incubation period is 10-15 days; young caterpillars construct
silken bags, covering with bark and dry twigs; larval duration is 9-10 months;
before pupation, the bag is suspended from the bush; larva pupated inside the
closed bag; male moth emerges out but the female remains inside the pupa.
Red slug caterpillar, Eterusia
aedea virescens (Zygaenidae:
Lepidoptera): Prefers mature foliage;
by severe attack, the bush frames become naked; adult moths are brightly
coloured in hues of black and pale yellow; eggs pale white in colour and oval
in shape; incubation period is 10-12 days; caterpillars resemble nettle grubs
and moves like slug; larva is brick red colour with six rows of tubercles on
the body; larva ejects a viscous fluid through these pores as a defensive
mechanism, when disturbed; five larval instars completed in 4-5 weeks;
caterpillar spins a pale yellow colour cocoon for pupation; adult emergence
takes place after 3 weeks.
Lobster caterpillar, Neostauropus
alternus (Notodontidae:
Lepidoptera): Commonly seen in new
clearings and nurseries; completely devour all the leaves from a small plant;
forewings of moths are grayish white with few reddish brown spots; eggs are
whitish, finely sculptured and laid in small clusters; incubation period is
5-10 days; the black caterpillars are grotesquely shaped and resemble dry
leaves; larval period is 3-4 weeks; pupated inside a wooly cocoon; adults
emerge after 10-14 days;
Cut worm, Spodoptera litura (Noctuidae: Lepidoptera): Attack the maintenance foliage; made irregular holes on the tea
leaves by feeding; adults have white hind wings; forewings are grayish brown
marked with silvery lines; eggs laid in clusters, hatched in 3-4 days; larvae
are dull olive green in colour and feed for 3 weeks; pupated in the soil for
one week.
Red borer, Zeuzera coffeae (Cossidae: Lepidoptera): Usually, young stems are bored by the caterpillars; as the larva
grows, the tunnel is also extended; holes are made at intervals to eject the
excreta and wood particles; tunnel may run even up to root; moths have white
wings with many black spots; eggs are laid like beads on a thread; caterpillars
emerge in 10 days; they suspend themselves by silken threads and get dispersed;
larvae bore into young stems; larvae tunnel downwards, devouring the woody
parts, especially the pith; tunnels are extended to thicker branches; mature
larva is about 3.5 cm long and purplish brown or reddish brown in colour;
larval duration is 4-5 months; pupated in a special chamber for a month. The
affected branches may be cut to sound wood. The larvae may be killed in situ by
pouring a strong solution of an insecticide like endosulfan or quinalphos by
using an ink filler and plugging the holes.
Hepialid borer, Sahyadrassus
malabaricus (Hepialidae:
Lepidoptera): Young caterpillars bore
into the stems; excavate long cylindrical tunnels; eating of bark and sapwood
resulted in cankers; top end of the tunnel opens into cankers; feeding takes
place at night; it can move forward and backward with equal ease; attacked
bushes can be easily located by the frassy mat, formed of powdered wood and
silk, hanging near the holes; they have grey forewings with faint mottlings;
male produce sharp, pungent, mustard like smell by the scent glands; eggs are
broadcast by the female in flight; a few succeed in tunneling the tea stems;
caterpillars made very long galleries extend up to roots; mature larva is pale
yellow, pencil thick and 6-10 cm long; Larval duration is 10 months; pupated in
the lower part of the tunnel; pupal period lasts for 3-5 weeks. Control
measures same as for red borer.
Shot hole borer, Euwallacea
fornicatus (Scolytidae:
Coleoptera): Female beetles
construct galleries in stems; leads to branch breakage and consequent crop
loss; grubs and adults feed on the fungus, Fusarium
bugnicourtii growing in the
galleries; female beetle are black, 2-2.5 mm long with strongly sclerotised
body; eggs are laid singly inside the gallery, three larval instars; female
lays upto 45 eggs, male female ratio 1:8; population reaches high levels during
April, May, July, October and December; all life stages are seen throughout the
year;
SHB is managed in an integrated way with
the following control measures: Cultural control (medium type of pruning in SHB
infested fields, post prune spraying with any one of the recommended
insecticides, application of N and K2O at 1:2 in the pruned year, assessment of
SHB infestation level at the end of second year or beginning of third year
using the standard sampling method), biological control methods (mid-cycle
control measures in the third and fourth years if the average percentage of
infestation in the new wood is at or above 15%, two rounds of entomopathogen
spray (B. bassiana WP) during May
end, July and October) and chemical control (two rounds of recommended
insecticide spraying during April and December.
White grub: Holotrichia sp. (Melolonthidae: Coleoptera): Larvae eat away the roots of young plants; at times they gnaw the
bark of stems near the ground causing a ring barking effect; adults are
brownish in colour; eggs are deposited in the soil; incubation period 12-18
days; larval period is 8- 10 months; pupal period lasts for 3 months. Pre
heating of nursery soil and check the organic manure/compost thoroughly for
eggs or grubs or pupae before their application. Addition of systemic granular
insecticides in the nursery soil; soil application of endosulfan 35 EC at the
concentration of 1: 500 (20 ml of the chemical in 10 l of water); soil around
each bush may be treated with 1 litre of the spray fluid; application may
preferably be carried out with a soil injector or soil around the plant
loosened and the diluted chemical has to be applied; use knapsack sprayer after
removing the nozzle; application has to be repeated after one month.
Leaf eating beetles, Mimela
xanthorrhina (Scarabaeidae:
Coleoptera): Beetles prefer mature foliage; adult beetles are metallic green in
colour. Application of endosulfan 35 EC @ 1000 ml/ha or quinalphos 25 EC 750
ml/ha recommended for its control.
Leaf eating weevil, Myllocerus
sp. (Curculionidae:
Coleoptera): Application of
endosulfan or quinalphos will be effective.
Grasshoppers & crickets
Grasshoppers: Orthacris
incongruens and Orthacris robusta
(Pyrgomorphidae: Orthoptera): Migrate to tea only when their natural weed hosts are eliminated
and feed on mature tea leaves.
Cricket, Brachytrupes
portentosus: Destructive pest in tea
nurseries. Application of endosulfan or quinalphos will be effective.
Termites, Odontotermes
spp. (Isoptera): Considered only as secondary pests and these are scavengers of
dead and moribund wood.
Termites: Microcerotermes
sp. (Isoptera): Damage tea bushes in north-east India while Glyptotermes dilatatus, Neotermes greeni and Postelectrotermes
militaris attack tea in Sri Lanka.
Tea leaf miner, Tropicomyia
theae (Agromyzidae: Diptera): Leaf mining fly inserts the eggs into the leaves; emerging larvae
make meandering tunnels on the leaves; l arvae are cylindrical, tapering
anteriorly and truncated posteriorly; pupate inside the tunnel at the leaf
margin; developmental period is a month.
Sewing blight: Orasema
sp. (Eucharitidae: Hymenoptera): Wasp lays eggs on tea
leaves; oviposition marks appear as a line of punctures; there is no serious
threat.
Root knot nematode, Meloidogyne
javanica (Heteroderidae: Tylenchida): Causes severe galling of roots of mature tea bushes; leaves become
smaller in size, yellowish in appearance, growth is retarded; eggs and larvae
are relatively large and the stylets are unusually long in larvae and females.
Application of carbofuran 3 G @ 25 g/bush immediately after pruning and repeat
the application after 3 months. Application of neem cake @ 2 kg/bush is also
suggested.