The pink mealybug (Maconellicoccus hirsutus) is commonly found in tropical Africa, South East Asia and Northern Australia but in 1994 it was identified for the first time in the Caribbean. Despite its wide distribution it had only achieved pest status in Egypt and India but in September 1995, the Agriculture Ministers of the Caribbean and the Americas passed a resolution declaring it a new pest to the Western Hemisphere. In October 1994 it was positively identified in Grenada and by August 1995 in Trinidad. It was later confirmed in St. Kitts.

By October 1995, the pink mealybug had spread across much of Grenada damaging ornamental, agricultural and horticultural plants as well as plantation and natural forest trees. Infestation in Trinidad was limited to certain areas and the Ministry of Agriculture was confident that it would not reach the serious proportions found in Grenada because of the greater abundance of natural enemies and the management effort. However, it was recognized as a national problem and declared a notifiable pest in Trinidad. Several Caribbean nations ceased all trade of fresh produce from these two countries and the social impact of such action was felt immediately, particularly in Grenada. Given the heavy inter-country trade, the pink mealybug has become a threat to all countries in the region.

The adult females are 1-3 mm in length and oval shaped. Although they are pink, they appear white because they congregate in groups to lay eggs and then cover themselves, and the eggs, in a cottony white waxy or mealy material. It is this that begins to look like snow, gathering on all parts of the plant when infestation becomes serious. The protective wax also prevents many pesticides from being effective.

The females lay 300-500 eggs and have a life cycle of 24-30 days depending on prevailing environmental conditions. The eggs and young nymphs are a pale orange colour, hence the "pink" classification, and can be more clearly seen if the white covering is gently brushed off with the flat of the hand. The young nymphs are difficult to see but are dangerous in as much as they will feed on almost any plant they come into contact with, although there are certain 'preferred' species where they tend to accumulate and develop into adults.

The males are slightly greyer than the females and have wings. In badly infested areas they are easily seen at dawn and dusk as they fly from plant to plant. They are smaller than the egg-filled females. Some reports suggest males are not always needed for fertilization.

The pink mealybug has few natural predators in the Caribbean and the climate, flora and fauna favour its growth and development. It will feed on the soft tissues of most plants, injecting toxic saliva that causes the primary symptoms of curling and pleating leaves. As infestation increases the deformed leaves 'rosette', often throughout the whole plant; and young shoots respond by curling and twisting. The plant's growth becomes stunted and shoot tips develop a bushy appearance. Internodes on the stems shorten. Buds may not flower and stems may twist. Gradually white colonies of females gather to lay their eggs. They favour crevices and are often found tucked away in the curled leaves and buds of deformed flowers.

On certain plants the symptoms of leaf pleating, rosetting, curling and shoot malformation may occur without any obvious signs (white masses) of the pink mealybug: this is often confusing for the lay person so it is important to seek expertise from the Ministries of Agriculture for identification.

The pink mealybug excretes a syrup-like substance, 'honeydew', which in turn encourages the development of black sooty mould. In some plants, such as teak and cocoa, the mould can cause considerable secondary damage by preventing photosynthesis from taking place in the leaves.

Other symptoms of the presence of the pink mealybug include dried edges of the leaves. Ants are also attracted by the honeydew and help protect the mealybug from their natural enemies.

The early symptoms to look out for are:

• Leaves curling, crinkling or twisting
• Leaves bunching and remaining unopened
• Flowers not opening and then shrivelling and dying

Later, when the bug is visible the following signs become more prevalent:

Clusters of small soft-bodied insects in white powdery cotton-like masses

Deformed fruits

Distorted or bushy shoots

Blackened leaves from sooty mould

Leaves drying at the edges

The pink mealybug can be found on the stems, leaves, buds, fruit and roots of a wide range of plants. It favours certain 'preferred' host plants but in their absence will feed on a wide range of crops and ornamentals. It has been positively identified on those plants listed in the following Table.

The pink mealybug is known to attack over 125 plant species, including weeds. These 'host' plants fall into two main categories: 'preferred' hosts where the nymphs are likely to remain, develop into adults and lay their eggs; 'non-preferred' hosts where nymphs will feed initially but adults will not. Symptoms on non-preferred hosts will therefore not usually develop into the white masses. Some reports indicate the mealybug has been found in the soil.

The pink mealybugs, particularly the nymphs, are easily spread. They can be carried on the wind, by the rain, on birds, ants, clothing, and vehicles. In fact, humans are great friends to the travel hungry mealybugs. Carrying planting material and fresh fruit and vegetables across the country or even from one end of a farm to the other, will spread the mealybug.

Ants, attracted by the honeydew, have been seen carrying mealybugs from plant to plant.

Monitoring the movement of fresh produce, including flowers, between countries is an important first step in controlling any spread within the region. This applies to both the import/export trade and to passenger traffic. One person carrying an infested soursop in their hand luggage on their way home from vacation can be the source of new colonies of the pink mealybug in their own country.

Total eradication of the pink mealybug is unlikely in the near future but scientists are working on the most effective, safe and sustainable means of economic control - 'biological control'. This involves the introduction of natural enemies, including parasitic wasps and predators. The wasps are small and do not harm humans.

One reason for the rapid spread of the bug in Grenada is that within the country's own insect population, there appears to be no indigenous natural enemy.

In Grenada the wasp, Anagyrus kamali, was brought in from China. It lays its eggs inside the mealybug thus preventing it from developing further. It will only attack pink mealybugs and so actively seeks them out and destroys them. The adult wasp also punctures adult mealybugs and feeds on the oozing body fluids. The ladybird, Cryptolaemus montrouzieri, is one of many predators feeding on all stages of development of the pink mealybug. Some of these ladybirds may already be present in Caribbean countries. Other natural enemies may exist but have not yet been identified.

The level of infestation and the approach taken by the local Ministry of Agriculture in its national control programme in the country will determine what action the general public or the farming community should take. However, there are five main steps that can be followed until the Ministry issues its own guidelines.

1. Upon sighting a suspected infested plant, request confirmation from the Ministry of Agriculture. This is important because other pests can cause similar symptoms.

 

2. On confirmation, spray the infested plant, or branch, with a recommended pesticide (ask your local Ministry of Agriculture).

 

3. Alternatively, prune the branch, or cut the plant back to the ground, and burn the cuttings in a contained space.

 

4. If burning is not permitted, for example in the dry season, place the plant material in a plastic bag and seal tightly.

 

5. Notify the authorities and find out where they are permitting burning, or where they are disposing of mealybug infested material.

DO NOT move any plant material with suspected pink mealybugs. Moving infested plants is the fastest way to spread the pest.

DO NOT prune your trees and leave the cuttings lying around. All cuttings must be burnt.

DO NOT shake or scatter the infested material.

DO NOT spray unless you are sure you have the pink mealybug; unnecessary spraying may kill off natural enemies that can keep mealybug populations low.

DO NOT carry fresh fruit or vegetables on journeys between countries with confirmed or suspected outbreaks of the pink mealybug unless it has been certified clean.

This factsheet has been produced for the

Regional Action Programme for

Control of the Pink Mealybug

February 1996

Members of the Regional Action Programme:

Ministries of Agriculture, Grenada, Trinidad and Tobago, St. Lucia, St. Vincent and the Grenadines

Caribbean Agricultural Research and Development Institute (CARDI)

Food and Agriculture Organization (FAO)

University of the West Indies (UWI)

Inter-American Institute for Cooperation in Agriculture (IICA)

CAB International (CABI)

US Department of Agriculture/Animal and Plant Health Information Service (USDA/APHIS)

Factsheet designed and compiled by

Alison Eades, CARDI Communications Unit

Funding provided under the

Tropical Produce Support Project (TROPRO), USAID

For further information contact:

The Ministry of Food Production and Marine Affairs

Or Mealybug Referral Service,

C/O Information Centre, CARDI, UWI Campus,

St. Augustine, Trinidad.

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