January 29, 2018 | Author: Anonymous | Category: Science, Biology, Zoology, Entomology
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PESTS OF CITRUS Dr. Jamba Gyeltshen 7/05/08


Common pests • Chinese Fruit Fly - Bactrocera minax • The trunk borer - Anoplophora sp • Citrus Shield Bug - Rhynchocoris poseidon • Citrus Leaf Miner - Phyllocnistes citrella • Sucking pests - scale insects, aphids, mealy bugs, black flies 2

Chinese Fruitfly • Puparia remain in soil for 5 to 7 months • Adults emerge - late April to late May • Become sexually mature - early June • Lay eggs- mid June to late July


Seasonal phenology of Fruitfly



Management • Fortnightly protein bait spray applications from early May to late July would reduce the fly population markedly and prevent oviposition in developing fruit. • Because the oviposition period is well defined, from mid June to late July, a systemic insecticide cover spray in early July followed up by a second treatment in late July, would provide high mortality of eggs in fruit. • The extended period between fruit fall and pupation, at least 18 days, would provide opportunity for cultural control practices. Collection of fallen fruits only once every ten days would prevent the development of puparia and thus reduce the fly population for the next year.


Citrus Trunk borer


Trunk borer • • • • • • • • •

Eggs laid between June and August Eggs deposited in the bark of trunk and large branches Each female lays 1-5 eggs under the bark Larvae feed between the bark and wood Young trees are ring barked Larvae later tunnel into the wood Sawdust like frass observed Life cycle takes 2 years Larvae pupate in the wood and emerge in April-May


Trunk borer Management • Maintain the basin clean • Regularly inspect the trunks for any wounds or bulging spots • Catch and kill adults whenever spotted • Poke holes with wire to kill the larvae • Plug holes with a cotton soaked in kerosene, diesel or petrol. • Close the hole with a mud paste or cow-dung • Remove and burn affected and unproductive trees 9

Citrus Shield Bug • Lay 12 to 16 eggs on citrus leaves in summer • Nymphs take 4-6 weeks to develop into adult bugs • Young nymphs stay in groups (gregarious) often in neat circles • Fruits drop as a result of their feeding • Fruit drop occur between April to September 10

Citrus Shield Bug • Natural control takes place: egg parasitoids, predator (red tree ant) • Encourage red tree ant • Destruction of the young nymphs physically in the morning


Citrus Leaf miner

Fig. 1. Phyllocnistis citrella Stainton, adult (4 mm wing spread).

Fig. 2. Adult in resting pose (2 mm)


Citrus Leaf miner • Eggs are laid singly on underside of young leaves • Larvae make serpentine mines (tunnels) • Fecal matter is seen as a black trail • Pupation takes place at the edge of the leaf


Citrus Leaf miner • Serious problem in young trees and nurseries • Causes distortion, curling and growth retardation • Severe infestation: spraying a systemic insecticide (Dimethoate)


Citrus Swallowtail


Management • Collection and destruction of larva could be done in nurseries or in small areas with limited infestation. • If its not feasible to handpick and destroy, insecticides may be applied.


Sucking pests • • • • •

Black citrus aphids Scale insects Mealy bugs Psyllids Mites


Scale insects

Glover scale, Lepidoaphis gloveri

Soft brown scale Coccus hesperidum

Florida red scale Chrysomphalus aonidum 18

California red scale


Management •

As far as possible avoid spraying insecticides against aphids, scales, mealybugs and mites. Horticultural oil sprays or Tree spray oils are generally recommended against sucking pests. Trunk banding with nondrying sticky glue in order to deny access of attending ants to small Homoptera. 20

Summary of Citrus IPM •

• • • • • • • • •

Control of trunkborers by hand killing of young borers and plugging holes of older larvae with wads drenched in diesel or kerosene. Hand picking of citrus swallowtail, Papilio larvae in nurseries and young trees Spraying with Actellic or Dimethoate on nurseries infested by the Citrus Leaf Miner Bait spraying with malathion/molasses against fruit flies in April-August Collecting and destruction (burning, drowning, deep burying) of dropped fruits every 10 days interval Male fruit fly trapping with Cu-lure/Methyl eugenol in isolated orchards. Conservation/Enhancement of colonies of Red Tree Ants in the southern orchards against Citrus Shield Bug. Handkilling of congregations of Citrus Shield Bug nymphs on tree trunks. As far as possible avoidance of spraying against whiteflies, blackflies, aphids, scales, mealybugs and mites. Horticultural oil sprays are generally recommended against sucking pests. Trunk banding with non-drying sticky glue in order to deny access of attending ants to small Homoptera.


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