Citrus Mealybug in rare fruit
David Astridge, Harry Fay and Rod Elder, Department of Primary Industries and Fisheries.
Citrus mealybug
(Planococcus citri) on a twig
Description
Adult
Adult female citrus mealy bugs are white, about 3 mm long, and covered by a white mealy wax. There are 18 pairs of short waxy filaments around the margin of the body. These are shorter at the head end, and lengthen progressively towards the rear end. The last pair are one quarter the length of the body. They have yellow body fluid observable if the insect is crushed.
The males are short-lived insects. They are similar to the males of armoured scales, with one pair of fragile wings and non-functional mouth parts. They have two long filaments at the rear end.
Immature stages
The pale yellow eggs are laid in an elongated, loose, cottony egg sac extending beneath and behind the female. About 300-600 eggs are laid over 1-2 weeks. There are three moults for females, and four for males. The immature stages are similar in appearance to the adult female.
Life history
The eggs hatch in about a week. The complete lifecycle takes about 6 weeks during the warmer summer months. In Queensland there are at least 6 generations per year, 4-5 in New South Wales and 3-4 in Victoria and South Australia.
Distribution
Citrus mealybug occurs throughout Australia but is much more common in coastal districts and in the areas north of Sydney in the eastern states.
Host range
Casimiroa, citrus, cocoa, durian, mabolo, rambutan, rollinia, soursop and many ornamentals
Management
Importance
Major and frequent pest
Damage
This insect causes damage to casimiroa, cocoa, durian, mabolo, rambutan, rollinia, soursop. Mealybug crawlers settle under the fruit calyx in early November. Later they move to depressions on the surface of the fruit or settle between adjoining fruit. Heavy sooty mould results, causing end rot and fruit drop.
Action level
Monitor at fortnightly intervals from mid-November to near harvest. Sample 5 fruit per tree on each of 20 randomly selected trees per 1 to 5 ha block. Apply spray if 25 or more fruit are infested with 1 or more mealybugs, and if less than 10 fruit have 1 or more Leptomastix dactylopii (main parasitoid) and/or Cryptolaemus montrouzieri (main predator) present.
Control methods
Biological
The most important predator is the mealybug ladybird Cryptolaemus montrouzieri. The larvae are white and mealy with long waxy appendages and grow to 10 mm. The adults have black wing covers and other parts are reddish-brown. The ladybirds are about 4 mm long. Both adults and larvae feed on the mealybug and, once established, the predator is able to control heavy infestations in 2 to 3 months. It is, however, sometimes slow in locating an infestation. Lacewing larvae Oligochrysa lutea also help to control the pest. Parasitism by the introduced parasitic wasp, Leptomastix dactylopii is very effective. This parasitoid should be liberated at 5 to 10 000 per ha, once during October to January and is especially recommended for rollinia, soursop and casimiroa. Heavy ant infestations seriously affect natural enemies and should be controlled by a residual spray to the base of the tree. Serious infestations are often the result of suppression of natural enemies by insecticides. The ladybeetles and wasps can be obtained from 'Bugs for Bugs' at Mundubbera Queensland, phone (07) 41654663.
Chemical
Spray tree
Spray soil around the base of the tree for ants.
Recommended chemicals
Dimethoate is approved for durian, mangosteen and rambutan.Chlorpyrifos is an approved treatment for ants on longan, lychee and pitaya.
Note: This information was correct at the time of publication. However, it is the user's responsibility to ensure that registered agricultural chemicals are used in accordance with legal requirements. (See Further information). Always read the label.
Further information
- For further information on the production of minor tropical fruit contact the DPI&F Business Information Centre on 132523 (local call) 8am to 6pm Monday to Friday or visit DPI&F Information Centres in Mareeba, South Johnstone, Applethorpe, Gatton, Maroochy or Redlands.
- Growers interested in the production of minor tropical fruits can join their local branch of the Rare Fruits Council and subscribe to their newsletter. Contact the Rare Fruits Council at PO Box 1375 Aitkenvale 4814
- The DPI&F library provides a personalised information search service that may be useful for producers seeking information on minor and exotic crops. Contact DPI&F InfoSearch on 07 3239 6989.
- Visit the DPI&F website on www.dpi.qld.gov.au for other DPI&F notes on rare fruits.
- Infopest CD-ROM contains current national information on registered agricultural chemicals and is available from Infopest, DPI&F, GPO Box 46, Brisbane Qld 4001 or by email from infopest@dpi.qld.gov.au
- Smith, D. and Papacek, D.F. 1985, Integrated pest management in Queensland
citrus, Queensland Agricultural Journal 111, 249-259.
Broadley, R.H., Smith, D., Owen-Turner, J.C., Chapman, J.C., Banks, A.G. and Mayers, P. 1987, Protect your citrus, Queensland Department Primary Industries, Information Series QI87012. - Smith, D., Papacek, D.F. and Murray, D.A.H. 1989, The use of Leptomastix dactylopii Howard (Hymenoptera:Encyrtidae) to control Planococcus citri (Risso) (Hemiptera: Pseudococcidae) in Queensland citrus orchards, Queensland Journal of Agricultural and Animal Sciences 45(2), 157-164.
- Smith, D. 1990, Integrated pest management in Queensland citrus, Australian Citrus News 66(12), 6-12.
- Smith, D. Beattie GAC & Broadley, R. (eds.) (1997) 'Citrus pests and their natural enemies'. Queensland Department of Primary Industries, Brisbane.
- Swaine, G., Ironside, D.A. and Corcoran, R.J. 1991, Insect pests of fruit and vegetables, 2nd Edition, Queensland Department Primary Industries, Information Series QI91018.
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.
Last updated 10 November 2005
