Mealybugs are scale insect pests belonging to the family Pseudococcidae which tend to live together in clusters in plant parts. They suck sap from plants and excrete the excess sugars as a substance called honeydew, which facilitates the development s sooty mold. They also act as vectors for various plant diseases.
Distribution & Host Range
- Mealybugs attack both indoor and outdoor plants.
- They are found in all parts of the world but mostly occur naturally in warmer regions.
- These insect pests have a wide range of cultivated plants, both broadleaved and grasses. For example. Fruit trees, vegetables, ornamentals, etc.
Identification of Mealybugs
Generally, mealybugs are small, soft-bodied sucking insects with a characteristic cottony appearance. Adult mealybugs are mostly found on leaves, stems and roots in colonies and are covered with whitish masses, which makes them difficult to eradicate.
However, different mealybug species have varied characteristics.
For example;
- Citrus mealybug (Planococcus citri) – anal filaments are less than one-eighth the length of the body. This species produces an egg mass which is irregular and remains under body of female.
- Solanum mealybug (Phenacoccus solani) – body is covered with very short waxy filaments. Long tails and stripes on the body are absent. This species does not produce an egg mass or ovisac.
- Mango Mealybug (Drosicha mangiferae) – females can be identified by their flat shape, covered with white mealy powder.
- Pineapple mealybug (Dysmicoccus brevipes) – this species is associated with roots of host plants. Body color is light pink to grey and has 17 pairs of wax filaments.
Biology
- Mealybugs are sexually dimorphic, females are wingless while males are smaller and have wings.
- This insect pest does not undergo a complete metamorphosis.
- The mature female lays eggs in an egg sac of white wax, usually in clusters on the twigs, branches, or bark of the host plant but sometimes on the plant’s leaves and terminal ends.
- The eggs are small in size varying from 0.3 to 0.4mm in length and their development takes between 3 and 9 days.
- An individual mealybug may takes approximately 30 days to grow through all the nympal stages under normal conditions.
- Mealybugs can withstand cold conditions as eggs and other life stages, both on the host plant and in the soil. In warm climates; the insects stay active and reproduce round the year.
Feeding & Damage
- Mealybugs feed on plant parts through piercing and sucking. Both nymphs and adults suck the sap causing withering and yellowing of leaves while fruits may drop prematurely. Heavy infestation can cause defoliation and even death of the plant.
- Infested growing points become stunted and swollen. Severity of infection depends on the susceptibility of the host species.
- Heavy clustering of mealybugs can be seen under leaf surface giving the appearance of a thick mat with waxy secretion.
- While feeding, they excrete copious amount of honey dew that attracts ants. The honey dew facilitates for the development of black sooty mold on leaf surfaces. This inhibits photosynthesis. Mealybugs also affect the development of flowers and stems especially in succulents with fleshy stems.
- Infested fruits can be entirely covered with the white, waxy coating of the mealybug, and this can cause shriveling of the fruits.
Survival
Mealybugs have the ability to overwinter and can live for relatively long periods without water or food. They can survive cold conditions both on host plants and in soil. Their broad host range gives a survival advantage.
Management
Infestation by these pests can cause up to 100% crop loss if not controlled. Therefore, it is very important to eradicate mealybugs.
There are several ways that can be used to manage and control this pest as follows;
Chemical Control
To effectively control mealybugs, the chosen insecticide should have a systemic characteristic.
The following products are therefore fit for the control of this pest;
- EMERALD 10ml/20l
- LOYALTY 5g/20l
- AMAZING TOP 5g/20l
- LEXUS 8ml/20l
NB: Always mix the insecticide with INTEGRA 3ml/20l.
Integra ensures that the products you spray sticks to the leaves and stem, spreads to all areas of the leave and penetrates to the underside of the leaf.
- To cleanse the sooty mold, spray JAMBO CLEAN 100ml/20l.
Cultural Control
This involves the following;
- Removal of all the infested materials from the field.
- Crop rotation with non-host plants
- Ensuring field sanitation
- Field borders should be free from weeds and debris that may harbor this pest.
