MAJOR INSECT PESTS INITIATING CITRUS DECLINE PROBLEM IN NEPAL.ppt

IT DESCRIIBE ABOUT DIFFERENT INSECT PEST OF CITRUS IN NEPAL.

1. MAJOR INSECT PESTS
INITIATING CITRUS DECLINE
PROBLEM IN NEPAL AND
THEIR MANAGEMENT
Ganapati Pandey
Sr. horticulturist
(Retired)

2. More than fifty-two insect pests
are reported infesting citrus
trees in Nepal. A list of important
citrus insect pests is given in
Table 1 but detail-text only for
the major insect pests
responsible for citrus decline in
Nepal is presented here.

3. Table 1. Important insect pests of citrus in Nepal
Insects Scientific name Order/Family Remarks (vector)
Aphids Toxoptera citricida, Toxoptera aurantiiAphididae/Homoptera Ttristeza virus and
citrus vein enation
Scale insects Quadraspidiotus perncioisus,
Aonidiella aurantii, Aonidiella
orientalis, Lepisdosaphes beckii,
Hemiberlesia rapax, Pulvinaria psidii,
Saissetia coffeae, Coccus hesperidum
Icerya purchasi, Icerya seychellarum
Diaspididae/ Homoptera
Coccidae/ Homoptera
Margarodidae/ Homoptera
Mealy bug Nipaecoccus vastator Pseudococcus
citriculas
Pseudococcidae/
Homoptera
Spiny whiteflyAleurocanthus spiniferus Aleurodidae/ Homoptera
Citrus psylla Diaphorina citri Psyllidae/ Homoptera huangbinglung virus
Spined fruit bugRhynchocoris poseidon Pentatomidae/Heteroptera
Leaf eating
caterpillars
Papilio demoleus, Paraleseda plagiferaPapilionidae/Lepidoptera
Lasiocampidae/Lepidoptera
Leaf miner Phyllocnistis citrella Phyllocnistidae/Lepidoptera
Fruit fly Bactrocera dorsalis, Bactrocera minaxTephrididae/Diptera
Stem and shoot
borers
Agrilus sp., Oberea butangensis Buprestidae/Coleoptera
Cerambycidae/Coleoptera

4. Brown citrus aphid : Toxoptera citricida

5. Brown citrus aphid (winged) : Toxoptera citricida

6. Parasitised brown citrus aphids: Toxoptera citricida

7. Brown aphid colony: Toxoptera citricida

8. Adults and nymphs of California red scale, Aonidiella aurantii

9. Old adults and females of Aonidiella aurantii on citrus fruits

10. San Jose scale, Quadraspidiotus perniciosus: crawlers (yellow) and
adults (scales).

11. Citrus purple scale, Lepisdosaphes beckii, on orange

12. Greedy scale: Hemiberlesia rapax

13. Brown coffee scale: Saissetia coffeae

14. Brown soft scale, Coccus hesperidum, on citrus leaf

15. Cottony cushion scale: Icerya purchasi

16. Eggs and Nymphs of spiny whitefly: Aleurocanthus spiniferus

17. Citrus psylla: Diaphorina citri
Eggs Nymphs

18. Nymphs
Egg
Resting adult
Different stages of citrus psylla, Diaphorina citri

19. Spined fruit bug: Rhynchocoris poseidon
Nymph
Adult

20. Crop damage: Feeding damage on mandarin fruits by spined fruit bug

21. Butterfly Caterpiller
Orange butterfly (citrus dog)

22. Citrus leaf miner, Phyllocnistis citrella
Moth
Symptoms on leaf: serpentine mines with a silvery appearance

23. Oriental fruit fly: Bactrocera dorsalis

24. Chinese citrus fly: Bactrocera minax

25. MAJOR CITRUS INSECT PESTS AND THEIR
MANAGEMENT
Asiatic citrus psyllid, Diaphorins citri Kuwayana
Brown citrus aphid, Toxoptera citricida (Kirkaldy)
California red scale, Aonidiella aurantii (Maskell)
Citrus purple scale, Lepidosaphes beckii (Neumann)
Citrus leaf miner, Phyllocnistis citrella Stainton
Oriental fruit fly, Bactrocera dorsalis (Hendel)
Spined fruit bug, Rhynchocoris poseidon Kirkaldy

26. All stages of Asiatic citrus psyllid: Diaphorina citri
Resting
Adult
Egg
Nymphs

27. ASIATIC CITRUS PSYLLID, DIAPHORINA CITRI
KUWAYAMA
Two different kinds of psyllids
Asiatic citrus psyllid (Diaphorina citri)
Distributed in southern Asia including Nepal
African citrus psyllid (Trioza erytreae)
Concentrated in Africa only
Both kinds are branded vectors of citrus
greening disease.

28. IDENTIFICATION
ADULTS: 3 to 4 mm long; body brown mottled
Insect covered with whitish, waxy secretion
Found resting on the terminal portion of plant,
especially on the lower side of the leaves at an angle of 30°.
NYMPHS: 0.25 mm long in 1st instar,
1.5 to 1.7 mm in last (5th) instar;
color generally yellowish orange;
wing pads massive;
large filaments confined to apical plate of abdomen.
EGGS: Approximately 0.3 mm long,
elongate, almond-shaped, fresh eggs pale
eggs placed anchored on plant tissue
with long axis vertical to surface.

29. LIFE HISTORY
Lays more than 800 eggs within two months of life period.
Eggs are laid on tips of growing shoots on and
between unfurling leaves.
Incubation period of egg in summer ranged
from 4 to 6 days.
5 nymphal instars.
A total period of development ranged from
15 and 47 days in summer and winter respectively.
There occur 9 to 12 generations in a year.
Their population thrives well in localities
situated below 1300 m in altitude.

30. DAMAGE
With-drawal of large quantities of sap from the foliage.
Heavy development of sooty mold on
honeydew-covered leaves.
Transmission of the bacteria (Liberobacter asiaticum)
that cause huangbinglung (greening) disease.
Feeding by psyllids in the diseased plant for a
minimum period of 15 minutes is sufficient to
transmit causal agents (phloem limiting organisms)
of greening disease in the healthy plants.
Pathogens are incubated in the body of
psyllids for 21 days before to become virulence.

31. SYMPTOMS IN A DISEASED PLANT
Stunted growth
Sparsely foliated branches
Un-seasonal bloom
Leaf and fruit drop
Twig dieback
Young chlorotic leaves with green banding
along the major veins
Mature leaves with yellowish-green patches
between veins, and yellow midribs
Small, unevenly colored, hard fruits and poor in juice

32. MANAGEMENT
Develop propagative materials at an altitude
at or above 1300 m
Exercise internal plant quarantine
Uproot and burn wild host plants like
Murraya paniculata (Kamini flower)
Vector control using insecticides.
0.05% dimethoate or 0.02% chlorpyrifos or
imidacloprid or Neem oil
Injection of trees with tetracycline antibiotics
Infected bud-wood could be deactivated by
either hot (moist) air, hot water, or 21 days
in the heat therapy chamber
Use effective biological control agents like
Syrphids, chrysopids and lady beetles,
and parasitoid like Tamarixia radiata are.effective against
them.

33. BROWN CITRUS APHID, TOXOPTERA CITRICIDA (KIRKALDY)

Brown citrus aphid, Toxoptera citricida (Kirkaldy)
is an efficient transmitter of
citrus tristeza closterovirus initiating stem pitting
and citrus vein enation (woody gall) luteovirus. in trees.

34. IDENTIFICATION
Body length about 3.2 mm
Its wingless forms are very shiny black and
nymphs are dark reddish-brown.
LIFE HISTORY
Each female aphid produces parthenogenetically.
Nymphs mature within 6 to 8.
A single aphid could produce a population of
over 4,400 in three weeks in the absence of
natural enemies.

35. DAMAGE
T. citricida only feeds on newly developed terminals.
Withdrawal of large quantities of sap from the foliage.
Heavy development of sooty mold on
honeydew-covered leaves.
Transmission of citrus tristeza virus (CTV),
a phloem-limited closterovirus, into plant
causes pinholing or honeycombing on sour
orange; stem pitting on true lime, grapefruit,
pummelo etc.; reduced leaf size and vein
clearing; stuntness in susceptible varieties.
The aphid is capable of spreading the virus
for 24-48 hours without reacquisition.
T. citricida also transmits Citrus vein enation
(woody gall) luteovirus.
Currently, there are an estimated 200 million
citrus trees on sour orange rootstock worldwide
and all are at immediate risk of CTV decline.

36. DETECTION AND INSPECTION
Field infestations of T. citricida can best be detected
by periodic visual inspection of new shoot growth
of citrus. Winged forms can be monitored by yellow traps.

37. MANAGEMENT
Citrus scion varieties tolerant to CTV should be planted. These include
mandarins, pummelos, tangelos and tangor. Only CTV-tolerant or
resistant rootstock should be used.
Use healthy bud-wood and nursery stock that are free of disease.
Trees that decline or become stunted can either be replaced or simply
removed and neighbouring trees allowed filling in.
Encourage natural enemies (predators and parasitoids) against these
aphids.
Spring and autumn should be targeted if chemical control is
attempted. Vector control using insecticides: 0.05% dimethoate or
0.02% chlorpyrifos.
Imidacloprid is also effective against aphids.
Neem seed extract (azadirachtin) had a marked effect on the survival,
longevity and fecundity of T. citricida.
Exercise internal plant quarantine. A strong regulatory component is
necessary, covering both propagation and inoculum control (detection
and removal of wild and possibly urban reservoirs of CTV).
Use effective biological control agents against nymphs and adults of
psyllids like syrphids, chrysopids and lady beetles.

38. CALIFORNIA RED SCALE, AONIDIELLA AURANTII (MASKELL)
IDENTIFICATION
Scale of adult female: Pale yellowish grey or pale
ochraeous scales, 1.6 to 2.2 mm. diameter.
The reddish colour is due to the female beneath the scale.
Scale of male pupa: Oblong structure with dimension
of 0.9-1.3mm in length and 0.6 mm in bredth. Scale is
dull reddish brown but paler towards the margin.

39. LIFE HISTORY
Females are ovo-viviparous.
100 to 150 young ones in her lifetime.
The young ones (crawlers) come out and find suitable
sites to settle on the surface of leaves, twigs and fruits.
They take few hours to settle on.
After being settled females moult twice, one after
15 days of settlement and other on the10th day of first moult.
Males moult four times to become mature and
start fertilizing females. Only males possess wings.

40. DAMAGE
Withdrawal of sap from foliage.
Leaf yellowing and drop.
Dieback of twigs and limbs.
Occasionally death of the tree.
Tree damage is most likely to occur in late summer
and early fall when scale populations are highest and
moisture stress on the tree is greatest.
DETECTION AND INSPECTION
Direct inspections can be made of the leaves,
branches and fruit of plants.
Look for reddish scale insects
Males attracted to white and yellow colors.

41. MANAGEMENT
Burn the dropped infested leaves and fruits.
Prune the infested and dead twigs.
Brushing or high pressure washing of twigs
and trunks is recommended.
Treat plants with insecticides: 0.05% dimethoate
or 0.02% chlorpyrifos.
Use summer oil at 0.25 to 2.0 % concentration.
Lady beetles are efficient scale regulators.

42. CITRUS PURPLE SCALE, LEPIDOSAPHES BECKII (NEUMANN)
IDENTIFICATION
Adult female: Mussel-shaped scales are elongate,
curved, narrow in front and broadened behind.
Purplish brown to pale yellowish brown in colour.
3.0 to 3.5 mm long and 0.9 to 1.2 mm broad.

43. LIFE HISTORY
Reproduction can be either sexual or parthenogenetic.
Mature males are winged insects that search out the
immobile females.
After mating, females lay 40 to 80 eggs under the cover.
L. beckii may over-winter in the egg stage.
After egg hatch, crawlers emerge from under the cover
and settle on branches, twigs, leaves, or fruit and begin
to form their covers.
Two generations occur between May and October and a
third may be partially completed before cold weather
starts.
It prefers thick foliage and infestations are usually
heaviest at the centre of trees and on northern aspects.

44. DAMAGE
Yellowish halos develop on leaves
Feeding sites remain green in young fruit.
Defoliation and twig dieback in limited patches on the
lower north side of trees.
Purple scale is an occasional pest in areas where the
climate is mild and humid. It attacks all parts of the tree.
It is noted that young orange trees are not attacked by L. beckii.
DETECTION AND INSPECTION
Scales may be present on bark, stems, leaves and fruit
of infested plants, especially in shaded parts of the canopy.

45. MANAGEMENT
Spread of infected material can be reduced by
pruning and allowing adequate spacing between
plants throughout cultivation.
Mechanical control can be achieved by scraping and
scrubbing to remove scales.
Burn the dropped infested leaves and fruits.
Prune the infested and dead twigs.
Brushing or high pressure washing of twigs
and trunks is recommended.
Treat plants with insecticides: 0.05% dimethoate
or 0.02% chlorpyrifos.
Treatment should be begun as soon as scales are
detected, even in small numbers.
Use summer oil at 0.25 to 2.0 % concentration.
Lady beetles are also efficient scale regulators.
Purple scales are most likely to build up on dusty trees,
such as those next to dirt roads.

46. CITRUS LEAF MINER, PHYLLOCNISTIS CITRELLA STAINTON
IDENTIFICATION
Silvery white moth (about 2 mm long) possesses long
hair-fringed wings, which measure 4 to 5 mm in expansion.
There are brown stripes and a prominent black spot
near apical margin.
Full grown apodous cylindrical larvae are dull
greenish yellow in colour that remain inside the
characteristic snake-like 'mines'

47. LIFE HISTORY
Females lay up to 76 eggs on the underside of leaves.
Eggs are laid singly attached to leaves and twigs.
Incubation of eggs ranges from 2 to 10 days
Larval during is completed in 5 to 10 days.
Larvae feeding leave a silvery snake-like mine lined
with a trail of excreta.
Pupate in a secure pupation chamber.
Pupal period of 5 to 25 days.
Takes about two weeks from egg to moth.
Moths emerge at dawn and are active in the morning.
Moths fly at night and are rarely seen.
Overwintering takes place in the larval or pupal stage.

48. DETECTION AND INSPECTION
Look on underside of young leaves of citrus
for evidence of a serpentine mine with a silvery appearance.
DAMAGE
Retarded growth of young trees.
Dropping of infested leaves.
Distorted leaves
Attacks are most severe in late summer and
early autumn, peaking in March and April.

49. MANAGEMENT
Prune growth flushes
Mechanical control of mining larvae.
Fertilize in late winter to promote strong spring growth
Do not over-water in autumn
Do not fertilize during summer
Use summer oil at 0.25 to 2.0 % concentration
Treat plants with insecticides: 0.05% dimethoate
or 0.02% chlorpyrifos
A single application of imidacloprid resulted in the
control of P. citrella for >100 days.
Planting goat weed, Ageratum conyzoides, as ground
cover under citrus plant.

50. ORIENTAL FRUIT FLY, BACTROCERA DORSALIS (HENDEL)
INTRODUCTION
Oriental fruit fly, B. dorsalis, is reported economically
impairing the citrus crops in the eastern middle mountains.
About 60 to 70 percent citrus fruit dropping occurred in
an infested fruit orchard in Dingla, Khotang district.

51. IDENTIFICATION
ADULT: It is a kind of dipterous fly
Yellow markings on the dark-brown thorax.
Light brown abdomen with a black T-shaped mark.
Transparent wings with narrow yellowish-brown
band along edge.
5 to 7 mm in wingspan and 6 to 8 mm body length.
LARVA: It is a maggot form larva.
White or yellowish body.
Body tapering towards head.
10 mm long.
Puparium is barrel-shaped.
White to yellow-brown in colour.
Usually about 60-80% length of larva.

52. LIFE HISTORY
Oviposition started one week after female emergence and
eggs were laid in batches of 30 to 50 eggs in each batch.
As much as 244 eggs per female observed.
Incubation period varied from 20 to 62 hours.
Average larval period observed 17.1  6.9 days.
Average larval mortality observed 47.6  4.0 percent.
Pupation occurred in soil and lasted an average of
7.0  0.8 days.
Generally adult flies emerged in the morning period of day.
At 30 0C, females and males observed remained active for
an average period of 65  12.5 and 50.0  7 days
respectively.
An average life cycle of fly observed 22.5  0.7 days
(range: 8 to 28 days).
Known hosts number about 140 species.

53. DETECTION AND INSPECTION
Fruits (locally grown or samples of fruit imports) should
be inspected for puncture marks and any associated
necrosis.
Suspect fruits should be cut open and checked for
larvae.
DAMAGE
Impair fruit content.
Immature fruit dropping.

54. MANAGEMENT
Instal simple physical barrier.
Regular collection of dropped infested citrus fruits and feed them to
domestic animals.
Frequently ploughing of soil under the canopy of tree.
Regular collection and destruction of fruit flies trapped in methyl
eugenol trap installed with a minimum density of one trap per
hectare.
Neem seed kernel extract can deter oviposition.
Treatment of soil under the canopy of a tree with 0.025%
chlorpyrifos (Trade names: Durmet, Dursban, Classic,
Tarkash or others).
Applying poison bait prepared of protein hydrolysate and malathion
(at 10:1 ratio) and trace of water for paste preparation.
Spray 0.025% chlorpyrifos @ 20 to 60 ml per tree as spot sprays to
the inside, northeast quadrant of the tree every 10 to 15 days.
Cover insecticide spray of Malathion 50EC @ 1 ml in one liter of
water in a week prior to flowering and subsequent applications a
week after fruit setting and a month prior to harvesting fruits.

55. SPINED FRUIT BUG, RHYNCHOCORIS POSEIDON KIRKALDY
INTRODUCTION
The spined fruit bug, Rhynchocoris poseidon, is a
particular bug found in the citrus orchards in the
middle mountains (Bandipur, Tanahun district,
Pokhara, Kaski district, Madhuban, Sindhuli district
and many other localities) of Nepal. Thin skin oranges
are suffered very much of fruit dropping due to this bug.

56. IDENTIFICATION
Green adults are about 22 mm in body length.
The proximal large portion of each forewing
is made of hard substance and the distal smoky
small portion is membranous.
Hind wings are membranous.
First segment of thorax laterally bears one spine in
each side.
Large scutellum covering most part of forewings
is prominently seen when the bug is viewed from above.
Laterally segmental small projections are
seen on the abdomen.

57. DAMAGE SYMPTOMS
Discolouration or deformation of immature fruits.
Fruits with black dots surrounded by chlorotic field.
Premature fruit drop.
Secondary fungal and bacterial infections in fruits.
Fruit drop due to incidence of bugs ranged from
92-100% depending upon their population.

58. LIFE HISTORY
Over-wintering adults resume activity during April.
Females commence laying eggs 14 numbers at a time
on the dorsal surface of leaves from July to
September. Eggs are laid in two to three batches.
Eggs incubate for a period of 4to 7 days.
A nymph bug takes 22 to 31 days to become an adult.
Life span of a bug is more than 50 days.
Both adults and nymphs feed on immature fruits.
Nymphs are gregarious in nature.

59. MANAGEMENT
Clean cultivation.
Collection and destruction of eggs on leaves.
Sweep net collection and destruction of adults.
Collection and destruction of gregariously
feeding nymphs on immature fruits.
Spraying insecticides: 0.05% endosulphan or
0.05% fenitrothion or 0.03% chlropyrifos
Spraying demoulting hormone: Buprofezin
(applaud) used @ 1 g/litre of water.
Biological control of eggs by means of Trissolcus
latisulcus, Anastatus sp. and Ooencyrtus utitheisae.