Mealybug

Mealybug is a pest, which can have a considerable negative economic impact on a wide range of crops and ornamentals. The most important species occurring in citrus are Citrus mealybug (Planococcus citri), Oleander mealybug (Paracoccus burnerae) and Long-tailed mealybug (Pseudococus longispinus) while the most important species occurring on grapevines is the Vine mealybug (Planococcus ficus).

Life Cycle

  • In summer, the full life cycle takes between 30 to 45 days to complete and is temperature dependent.
  • Females can lay up to 550 eggs during their lifetime. These eggs hatch within 6 to 10 days releasing active, mobile crawlers.
  • After the crawler period females experience 2 further stages before adulthood is reached.
  • The males, which have wings and can fly, hatch and are present when females are ready for impregnation.
  • The lifespan of adult males is about 3 to 5 days.

Economic Damage

  • A high population of mealybug can lead to: fruit drop, fruit deformation (‘high shoulders’) and development of discoloured welts on the rind of the fruit.
  • Mealybug secrete copious quantities of honeydew which is a substrate for the fungus, sooty mould. Sooty mould is black in colour and may stain the fruit decreasing packout %’s as well as causing a delay in fruit colour development. Photosynthetic potential, especially of young trees, may be negatively affected if sooty mould infection is severe.
  • Mealybug is a phytosanitary pest in some export markets (USA, Japan) and if found on fruit destined for these markets can result in rejection of the consignment and could place these important markets at risk for the future.

 

Seasonal History

Mealybug over-winter in the soil on roots or on the plant. They hide in crevices on the bark, under loose bark and other protected areas such as curled leaves. Populations begin to increase from September, peak in late December early January, and begin to decline towards the end of March/ April, depending on temperature and parasitism. Due to mealybug’s waxy covering and habit of feeding in sheltered areas, they are difficult to control with pesticides, especially late in the season.