Mealybugs and scale insects
Mealybugs and scale insects cause considerable damage in a wide variety of crops. These insects are difficult to reach with integrated crop protection products due to their waxy secretion and/or shield. Mealybugs and scale insects belong to the Coccoidea Family. They are closely related to aphids. The female insects do not have wings, which means that can only move around via plant material, clothing and birds. The most common species are citrus mealybug (Planococcus citri), obscure mealybug (Pseudococcus affinis), longtailed mealybug (Pseudococcus longispinus) and the boisduval scale (Diaspis boisduvalii).
Mealybug: Adult females lay between 250 and 750 eggs in a woolly waxy secretion. The crawlers are very active and can therefore travel great distances in the crop. The life cycle is as follows: egg, nymphal stages and adult. The females die after laying their eggs. The males have a different life cycle than the females and are also winged.
Scale insects: Adult females lay between 50 and 500 eggs. They lays these eggs under their shield. This means they are difficult to combat. The life cycle is as follows: egg, nymphal stages and adult. The males have a different life cycle than the females; (egg), nymphal stages, prepupal, pupal and adult.
- Due to the sucking action of these insects, large quantities of sap are withdrawn from the crop. This retards growth.
- Some mealybug species can transmit viruses and bacteria.
- The ornamental value (particularly in ornamental crops) can be reduced.