Mealybugs

 ( scale insects )

General

• Stinging-sucking insects belonging to the order Hemiptera and the superfamily Coccoideae.
• Several species parasitize vegetables, especially floury plants belonging to the Pseudococcidae family.
• They lack a horny shield (a kind of shell), and the body is usually covered with a white mealy secretion. They also have lateral waxy filaments clearly visible at the periphery of the body, and a cottony secretion containing the eggs can sometimes be noticed at the end of the abdomen.
• By way of example we will describe the characteristics of the species Pseudococcus viburni (Signoret) (syn.  Pseudococcus affinis  [Maskell]).
• Insects observed in open fields and under shelters.
• Examples of species reported on Solanaceae: Pseudococus spp., Paracoccus marginatus , Phenacoccus gossypii , Orthezia spp.
• Organs attacked : leaves, fruits, stems.
• Symptoms :
  • Plant growth reduced due to the numerous bites and food sucks exerted by the larvae and females of mealybugs present, especially on the stem.
  • Deformation of the leaves which can be more or less curled, blistered, embossed, etc.
    • Presence of honeydew and subsequently Sooty mold covering the surface of the affected aerial organs (figures).
    • Sooty mold, by reducing photosynthesis and respiration, causes yellowing and leaf damage. It also stains the fruits or alters their coloring, making them unmarketable (figure).

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• Signs  : Presence of larvae and adults on the affected organs (figures).
• Possible confusion :

Biology

•  Development cycle : involves
  • Eggs laid inside a white waxy ovisac.
  • After hatching, the first instar larvae disperse on infested plants.
  • After the second larval stage, this insect will form two successive false nymphs in which the males will undergo a metamorphosis.
  • Adults, small winged midges whose life is ephemeral. Females, measuring 4 mm in length, do not undergo metamorphosis and therefore do not change shape. The pinkish color of their body is masked by white mealy wax.
• Dispersion : by plant material, but also by workers during cultivation operations, animals.
• P. viburni tolerates cold fairly well and overwinters as a non-diapausing nymph in the soil. It can be maintained on other alternative hosts, in particular on potato, apple tree, lemon tree, vine.

Protection

• Create a crawl space on the farm if the cochineal populations are important.
• Leach with water and treat the walls of shelters, posts, concrete walkways with an insecticide or a contact acaricide.
• Disinfect the equipment used in the greenhouse (drip system, boxes, etc.).
• Disinfect the reused substrate or soil.
• Produce the seedlings in an nursery insect-proof .
• Check the sanitary quality of the plants before and during their introduction into the crop or shelter.
• Remove and destroy infested plant debris and crop residues.
• Reason for  chemical protection, in particular if you use auxiliaries or biopesticides, especially since most insecticides are not very effective on whiteflies.
• Treat plants before uprooting in the presence of high pest populations.