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Species Page

coconut scale

Aspidiotus destructor
This information is part of a full datasheet available in the Crop Protection Compendium (CPC);www.cabi.org/cpc. For information on how to access the CPC, click here.

Distribution

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Host plants / species affected

Main hosts

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Actinidia
Cocos nucifera (coconut)
Elaeis guineensis (African oil palm)
Mangifera indica (mango)
Musa (banana)

List of symptoms / signs

Fruit - discoloration
Fruit - external feeding
Fruit - lesions: black or brown
Leaves - abnormal colours
Leaves - abnormal leaf fall
Leaves - necrotic areas
Stems - external feeding

Symptoms

On leaves, A. destructor causes yellow spots to develop beneath the insects, due to the toxicity of saliva injected in to plant tissues while feeding. Entire leaves may turn yellow to brown and fall, and fruits may be discoloured, stunted or fall prematurely. The bright yellow colour of affected coconut palms is clearly visible from a great distance. The undersurface of the leaves is mainly attacked, but frond stalks, flower clusters and young fruit can also be affected. In extreme cases, the leaves dry out, entire fronds drop off and the crown dies.

Prevention and control

Introduction

A. destructor is highly polyphagous and therefore can easily be re-introduced, even if it is successfully controlled on the primary host crop.

Host-Plant Resistance

Differences in size and mortality rates were observed on different coconut cultivars by Tabibullah and Gabriel (1973).

Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:

Impact

A. destructor is potentially the most destructive pest species on coconut, wherever it occurs in the world (Chua and Wood, 1990); the undersurface of the leaves is mainly attacked, but frond stalks, flower clusters and young fruit can also be affected. In extreme cases, the leaves dry up, entire fronds drop off, the crown dies and the whole crop is lost. Neglected coconut plantations are particularly susceptible to damage by A. destructor. A. destructor is also an important economic pest of mango in Asia, Africa, the Philippines, India and Brazil; and of banana in Asia, the Pacific Islands, West Indies, Africa, Madagascar and South America. It attacks the leaves and fruits of oil palms, reducing the quality of the fruits (Chua and Wood, 1990). The species is also a pest of bananas worldwide (Chua and Wood, 1990). However, natural controls appear to keep A. destructor in check in most regions, and few major outbreaks have been recorded in recent years.

Before the introduction of successful biological control in 1955, copra production in Principe fell from 1400 to 500 tons per year owing to an invasion of A. destructor (Rosen, 1990a). After a heavy attack by A. destructor on coconuts in Côte d'Ivoire, yield was reduced by at least 25% over the next 2-3 years, although some heavily infested trees were able to catch up production in the 2 years after elimination of the infestation (Mariau and Julia, 1977).

A. destructor is a cosmetic pest on a wide range of fruits, causing blemishes and other marks that reduce quality. On mango, A. destructor prefers grafted varieties; its economic impact is caused by feeding on tender shoots in nursery plants and because it adversely affects fruit setting in older plants. On oil palm, A. destructor is found feeding on leaves and fruit. It occasionally causes severe damage to guava in India (Hayes, 1970).

This species is highly polyphagous and therefore can easily be re-introduced, even if it is successfully controlled on the primary host crop.