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CITRUS LEAFMINER Phyllocnistis citrella Stainton (Lepidoptera, Gracillariidae) (Contacts) ----- CLICK on Photo to enlarge &
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Mature citrus trees can tolerate leaf damage without appreciable harm to the
tree or its fruit. As the leafminer expands its range, local parasitoid
species are likely to keep it under sufficient control in mature
orchards. Therefore, it is best to avoid treating with insecticides
that would disrupt those natural enemies. Young trees in the nursery setting or newly planted trees in orchards
can experience reduced tree growth if the infestation of citrus leafminer is
heavy and prolonged. At the moment, Admire applied through the
irrigation is the best method of suppressing citrus leafminer in young trees
(ca. 4 years old). Various researchers from the University of
California at Riverside, Cal Poly San Luis Obispo, and the California
Department of Food and Agriculture Biological Control Program are studying
the biological and chemical control of this pest. HISTORY
The
small leafmining moth, Phyllocnistis citrella Stainton, family
Gracillariidae (subfamily Phyllocnistinae), or the citrus leafminer (CLM),
was found in late May 1993 in several citrus nurseries in Homestead, Florida,
other parts of Dade County, Broward County, and Colier County. CLM is a new
world, continental United States, and Florida resident. It is potentially a
serious pest of citrus and related Rutaceae, and some related ornamental
plants (Beattie 1989; Clausen 1993; Kalshoven 1981). CLM has previously been
intercepted in the United States in 1914 (ports not noted) on citrus and Atalantia
sp. horticulture stock imports from the Philippines (Sasser 1915). CLM is
considered a potentially serious threat to Florida citrus and native
Rutaceae. It has not previously been reported mining fruit rinds, but several
possible cases have been observed in
Adults of the citrus leafminer are minute moths (4 mm wingspread) with
white and silvery scales on the forewings, with several black and tan
markings, plus a black spot on each wingtip. The hind wings and body are
white, with long fringe scales extending from the hind wing margins. In
resting pose with wings folded, the moth is much smaller in appearance (about
2mm). The head is very smooth-scaled and white and the haustellum has no
basal scales. Citrus leafminer is most easily detected by its meandering
serpentine larval mine, usually on the ventral side of the leaf. Larvae are
minute (to 3 mm), translucent greenish yellow, and located inside the leaf mine.
The pupa characteristically is in a pupal cell at the leaf margin. Adults
generally are too minute to be easily noticed, and are active diurnally and
evenings.
DISTRIBUTION
A
widespread Asian species (Clausen 1931, 1993; CAB 1970), described from
Calcutta, India (Stainton 1856), CLM now is known from East Africa - Sudan to
Yemen (Badway 1967), through southern Asia - Saudi Arabia to India (Fletcher 1920)
and Indonesia (Kalshoven 1981), North to Hong Kong and China, Philippines
(Sasscer 1915), Taiwan (Chiu 1985; Lo and Chiu 1988) and southern Japan
(Clausen 1927). It is also found in New Guinea and nearby Pacific Islands
(CAB 1970), and Australia (Beattie 1989; Hill 1918; Wilson 1991). CLM also
occurs in South Africa and more recently in parts of West Africa (CAB pers.
comm.). The Australian introduction occurred before 1940, and has since 1969
been reported from northern Queensland. For the period from May to November
1993, CLM has spread to all Florida citrus counties south of Tampa and
Orlando, with isolated sites as far north as Alachua and Wakulla Counties.
The potential exists for CLM spreading to Louisiana and Texas. HOST PLANTS
CLM is common on species of citrus and related Rutaceae within its
range (Kalshoven 1981). CLM is most commonly found on leaves of grapefruit (Citrus
X paradisi Macfad.) and pummelo (pomelo) (Citrus maxima (Burm.)
Merr. (Badawy 1967). Recorded Rutaceae include Aegle marmelos (L.)
Corr. Serr. in India (Fletcher 1920), Atalania sp. in the Philippines
(Sasscer 1915), Murraya paniculata (L.) Jack. in India (Pruthi and
Mani 1945), Poncirus trifoliata (L.) Raf. in India (Clausen 1933), and
various native Rutaceae in Indonesia (Kalshoven 1981). Other reported hosts
include Jasminum sambac (L.) Aiton (Oleaceae) in India (Fletcher
1920), mistletoes on citrus (Loranthus spp., Loranthaceae) in the
Philippines (Reinking and Groff 1921), Pongamia pinnata (Leguminosae)
in India (Margabandhu 1933), and Alseodaphne semecarpifolia Nees
(Lauraceae) in India (Latif and Yunus 1951). Florida records include various Citrus
sp., Kumquat (Fortunella crassifolia Swingle), and calamondin (X
Citrofortunella microcarpa (Bunge) D.O. Winjnands). Several other hosts have been
reported for CLM but larvae do not complete their life cycle on these
incompatible hosts: Murraya koenigii L. Sprengel (Rutaceae) in India
(Fletcher 1920), Jasminum sp. and Jasminum cinnamomum Kobuski
(Oleaceae) in India (Pruthi and Mani 1945), Dalbergia sissoo Roxb. ex
DC (Leguminosae) in India (Latif and Yunus 1951), Salix sp.
(Salicaceae) in India (Pruthi and Mani 1945), and Grewia asiatica L.
(Tiliaceae) in India (Latif and Yunus 1951).
BIOLOGY
The biology of Citrus Leafminer has been reported on by a number of
researchers, including Badawy (1967), Beattie (1989), Clausen (1927, 1931,
1933), Fletcher (1920), Kalshoven (1981), Latif and Yunus (1951). Eggs of CLM
are laid singly on the underside of host leaves. Egg eclosion occurs within
2-10 days, whereupon larvae immediately enter the leaf and begin feeding.
Larvae make serpentine mines on young leaves (sometimes also young shoots),
resulting in leaf curling and serious injury. Leaf mines are usually on the
ventral leaf surface, except in heavy infestations when both leaf surfaces
are used. Usually only one leaf mine is present per leaf, but heavy
infestations can have 2 or 3 mines per leaf; up to 9 mines on large leaves
have been found in Florida. As with similar leafminers, larvae are protected
within the leaf during their feeding cycle. Larvae have 4 instars and
development takes from 5-20 days. Pupation is within the mine in a special
pupal cell at the leaf margin, under a slight curl of the leaf. Pupal
development takes 6-22 days. Adults emerge about dawn and are active in the
morning; other activity is at dusk or night. Females lay eggs evenings and at
night (Badawy 1967; Beattie 1989). CLM may help spread citrus canker (Hill
1918; Ando et al. 1985) because of leaf damage from the mine.
Generations per year appear to be continuous: 6 in southern Japan
(Clausen 1931), 9-13 in north central India (Lal 1950); 10 in southern India
(Pandey and Pandey 1964). Development time totals about 13-52 days (Pandey
and Pandey 1964), depending on weather and temperate conditions. Adults live
for only a few days. Florida generations are produced about every 3 weeks.
Symptoms of infestation include: 1) leaves with serpentine mines,
usually on ventral surfaces; 2) curling of leaves (may harbor mealybugs); 3)
epidermis appearing as a silvery film over leaf mines; 4) pupation chamber
near leaf margin, the edge of which is rolled over, and exposed portion of
chamber with a distinct orange color; and 5) succulent branches of green
shoots may also be attacked (Beattie 1989; Pandey and Pandey 1964).
CONTROL
Local species of parasitoids adapt readily to the mines created by
this insect. Thus, in time the infestations
decline to noneconomic levels unless disturbances such as insecticidal
spraying occur. Parasitoids reported for CLM include
39 species from Southeastern Asia, Japan, and Australia, mostly Chalcidoidea
(Heppner 1993; Kalshoven 1981; Lo and Chiu 1988). A pheromone to attract
males of CLM has been developed in Japan by Ando et al. (1985), called (7Z,
11Z)-7,11-hexadecadienal. Most work has been done using chemical control,
especially in India. Various spray regimes, timing of growth flushes, and
promotion of biological control are recommended in Australia (Beattie 1989).
In Florida, chemical control recommendations are still being evaluated, but
biological control and semiochemical trapping may be the most likely methods
to help reduce populations of CLM in the long run. Links to Management of Citrus Leafminer View the Current Distribution of Citrus Leafminer in
California Commercial
Sources of CLM Pheromone Traps and Lures Recognizing Citrus Leafminer on Sticky Cards UC IPM Insecticide Guidelines for Citrus Leafminer How to Collect and Preserve Citrus Leafminer Parasites REFERENCES: [Additional references may be found at: MELVYL
Library ] Ando, T., K.Y Taguchi, M Uchiyama, T Ujiye, and
H. Kuroko, 1985. (7Z-11Z)-7,11-hexadecadienal: sex attractant of the citrus leafminer
moth, Phyllocnistis citrella Stainton (Lepidoptera, Phyllocnistidae).
Agric.Biol. Chem. Tokyo 49:3633-3653. Badawy,
A. 1967. The morphology and biology of Phyllocnistis citrella Strait,
a citrus leaf-miner in the Sudan. Bull. Soc. Ent. Egypte 51:95-103. Beattie, G.A.C. 1989. Citrus Leaf miner. NSW Agric. and Fisheries, Agfact,
H2.AE.4:1-4. Chiu,
S.C. 1985. Biological control of citrus pests in Taiwan. Taiwan Agric. Res.
Inst., Spec. Rep. 19:1-8. Clausen,
C.P. 1927. The citrus insects of Japan. USDA, Washington, D.C. Tech. Bul.
15:1-15. _______.
1931. Two citrus leaf miners of the Far East. USDA, Washington, D.C. Tech.
Bull. 252:1-13. _______.
1933. The citrus insects of tropical Asia. USDA, Washington, D.C. Cir.
266:1-35. Commonwealth
Agriculture Bureaux (CAB), Commonwealth Institute of Entomology. 1970. Phyllocnistis
citrella Stnt. IN: Distribution maps of pests. Ser. A, Map No
274. The Eastern
Press Ltd., London. Fletcher,
T.B. 1920. Life histories of Indian insects. Microlepidoptera. Mem. Dept.
Agric. India 6:1-217, 68 pl. Heppner, J.B. 1993. Citrus Leafminer, Phyllocnistis
citrella, in Florida (Lepidoptera: Gracillariidae: Phyllocnistinae). Trop. Lepid. 4:49-64. Hill,
G.F. 1918. History of citrus canker in the Northern Territory (with notes of
its occurrence elsewhere). N. Terr. Austr. Bull. 18:1-8. Kalshoven, L.G.E. 1981. Pests of crops in Indonesia. Jakarta: Ichtiar
Baru. [reprint]
Margabandhu, V. 1933. Insect pests of oranges in the northern Circars. Madras Agric. J.
21:60-68. Lal, K.B. 1950. Insect-pests of fruit trees grown in the plains> Agric.
Anim. Husb. Uttar Pradesh 1:30-45. Latif,
A., and C.M. Yunus. 1951. Food plants of citrus leaf miner in Punjab. Bull.
Ent. Res. 42:311-316. Lo,
K.C., and S.C. Chiu. 1988. The illustrations of citrus insect pests and their
natural enemies in Taiwan. Taichung: Taiwan Agric. Res. Inst. 75 p. Pandey.
N.D., Y.D. Pandey. 1964. Bionomics of Phyllocnistis citrella Stt. (Lepidoptera:
Gracillariidae). Indian J. Ent. 26:417-423. Pruthi,
H.S., and M.S. Mani. 1945. Our knowledge of the insect and mine pests of the
citrus in India and their control. Imp. Council Agric. Res. Sci. Monog.
16:1-42. Reinking,
O.A., and G.W. Groff. 1921. The kao pan seedless Siamese pummelo and its
culture. Philipp. J. Sci. 19:389-437. Sasscer, E.R. 1915. Important insect pests collected on imported nursery stock
in 1914. J. Econ. Ent. 8:268-270. Stainton,
H.T. 1856. Descriptions of three species of Indian Micro-Lepidoptera. Trans.
Ent. Soc. London (n.s.) 3:301-304. Wilson,
C.G. 1991. Notes on Phyllocnistis citrella Stainton (Lepidoptera:
Phyllocnistidae) attacking four citrus varieties in Darwin. J. Austr. Ent.
Soc. 30:77-78. |
