Description, Biology, Life Cycle, Damage, Common Names, Images
- J. lybica is a polyphagous species, Vitis vinifera being the preferred summer host plant in southern Portugal as well as in the Mediterranean basin. J. lybica is a thermophilous African species.
- J. lybica females insert the ovipositor in the leaf veins and leaf stalks when laying their eggs. The average number of eggs laid per female is about 50.
- Embryonic development lasts 10 to 15 days.
- The nymph develops in 3 weeks, passing through 5 instars.
Adults abandon the attacked vines until the end of the vegetation period in the autumn. They overwinter on several host plants: alder (Alnus glutinosa), fig, apple, oak (Quercus spp).
- They return to the vines during May of the following year to oviposite and thus initiate the first generation. A total of, mostly overlapping, five generations occurs during the summer months.
- Damage caused by J. lybica can be mistaken for that caused by other factors such as nutritional deficiencies, virus, mite attack, sun scalding, etc. (*) , (*) .
- Most seriously attacked vines are usually the healthier, growing in the southern part of the country ("Alentejo" and "Algarve") where high summer temperatures are common.
- Damage is usually very serious as it affects not only the quality and quantity of grapes but also because the plant reserves for the following season are severely curtailed. Adults and nymphs feed almost continuously, piercing and sucking the cell contents in all leaf veins.
Attacked leaves sooner or later change colour and form. Due to the lack of sap movement their borders dry up giving the leaf a scorched appearence. Curling of the leaves towards the undersides occurs frequently.
- After very severe attacks leaves drop to the ground leaving the grapes exposed to the sun thus causing "scalding" of the berries.
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.