Mealybugs
| English name: | Mealybugs |
| Scientific name: | Two species of mealybugs are identified as pests of Durian: Planococcus lilacinus (Cockerell) and Planococcus minor (Maskell). Also Pseudococcus sp. can be found. |
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Pest group: |
Insects |
| Order: | Homoptera |
| Family: | Pseudococcidae |
Description and life cycle
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Several species of mealybugs are found in Durian. They are usually found between the spines of the durian fruit. Very few mealybugs are found on durian leaves. Female are usually about 3.0 mm long. They have a yellow or pink colored body that is covered with a white dust. Eggs are deposited in egg masses containing 100-200 eggs. One female can lay 600-800 egg. The female will die when it stops laying eggs. The eggs are laid in groups inside a kind of "bag". Eggs hatch in about 6-10 days. The young larva have a light yellow color and are not yet covered in a white dust. They move individually to find a place to feed and shelter. Females molt 3 times and carry no wings. After the 3rd molting they start laying eggs. Males molt 4 times, they are smaller than females and they do have wings. Mealybugs can multiply rapidly and have often 2 or 3 generations per year. They feed on a variety of host plants. During periods of food shortage mealybugs will hide in the soil at the roots of plants (e.g. grasses). Mealybugs produce honeydew, which is a liquid rich in sugar. Ants like to feed on honeydew and some ants will therefore protect the mealybugs by chasing away predators and parasitoids. These ants also carry mealybugs around and thus contribute to their distribution. |
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Plant damage and plant compensation
Mealybugs suck juices from flower branches, young fruits and mature fruits. If many mealybugs feed close together this will cause the fruits to develop slow and they will remain small. On big fruits the damage is not so serious as the fruit meat is not damaged. However, presence of mealybugs on fruits reduces the marketing value because consumers consider it a lower quality.
The honey dew that is released by mealybugs will cover leaves and fruits. Fungi (sooty mold) that develop on this honeydew make it become black in color. On leaves this will reduce photosynthesis, which may be reduce growth of the tree if a lot of sooty mold is present. If sooty molds develop on fruits, this will reduce their economic value.
While mealybugs can be tolerated to some extent on fruits for the local market, they are a major pest of export fruits.
Mealybugs attack a variety of other crops (e.g. soybean).
Natural enemies
Larvae and adults of coccinellids (Lady bird beetles) are predators of many kinds of insects, including mealybugs. Also lacewing larvae are predators that help to control the mealybugs. The adult lacewing often deposit their eggs near colonies of mealybugs. Natural enemies of mealybugs include also a number of parasitoids.
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Management and control practices
Prevention activities
 | Conserve the natural enemies of mealybugs by avoiding the use of pesticides. |
| Don't remove all weeds but leave some pockets to provide shelter for natural enemies. |
| If ants are seen that take care of mealybugs, make barriers to stop the ants moving around. This can be done for example by using non-drying glues or grease as a band around tree trunks or on branches. |
What can be done when Mealybugs are present in the field
| If a few mealybugs are present, cut off the infested plant parts. |
| Mealybugs can be reduced by using water sprays. |
| If attack is more serious, try to use a mixture of water and white oil. |
| Spraying synthetic pesticides to control mealybugs in not recommended. While pesticides containing chlorpyrifos, methidathion or malathion would kill the pests, these chemicals are also very harmful to natural enemies. Their use can cause resurgence of other pests, such as African red mite. |
Points to remember about Mealybugs
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