Cassid (Cassida vittata Vill.)
Identification :
- Cassidia is a beetle belonging to the Chrysomelidae family.
- The adult cassid has a flattened, oval body measuring between 4 and 6 mm in length.
- The elytra are pale green to dark green, with the presence of two longitudinal and parallel bands of shiny metallic green.
- The prodorsum extends over the head and legs.
- The larva is about 6 mm long, green, with 16 pairs of lateral spines and behind two strong pincer-shaped spines.
- This clamp folds down on the back where the droppings accumulate.
Biology :
- Adult cassids overwinter in the soil, under various debris, on other crops such as sugar cane or on weeds.
- In the Gharb region, adults appear on beet plots around the middle of January and begin to puncture the foliage.
- After mating, female cassis lay about ten eggs at a time, grouped together in a viscous mass that sticks to the petiole and / or the underside of the attacked plants.
- After an incubation period of about 10 days (depending on climatic conditions), the larvae hatch and begin to gnaw voraciously, and avidly, the epidermis of the leaves of the sugar beet.
- The larvae, after 4 stages of development, pupate on the leaves to give the first adults.
- The pupal stage takes place after about twenty days and the adults of the 1st generation appear 2 to 3 weeks later.
- Studies in the Gharb region have shown that this pest is only one generation old.
Symptoms :
- Cassidia is a very serious pest of sugar beet, resulting in a reduction in the sugar content of infested plants.
- The larvae erode the underside and then repeatedly pierce the parts between the secondary veins.
- The damage caused by the summer wave of adults is often more evident because of their gathering on plots not harvested before their emigration and the voracity that accompanies pre-diapause (constitution of the reserves necessary for summer rest).
Control :
- According to Moroccan researchers, assuming the outbreaks are the most damaging, a maximum of 3 well-positioned treatments meet the needs of adequate protection.
- According to the same researchers, the most favorable hypothesis is 2 treatments, if however the outbreaks are perceived well enough before they have started to do damage.
- Chemical control using AVAUNT 150EC at a rate of 250 ml / ha.
