Grape leafhopper

The grape leafhopper (Erythroneura bigemina) is a destructive pest belonging to the order Hemiptera and the family Cicadellidae. These tiny, sap-sucking insects are widely recognized in viticulture for their ability to significantly weaken vines and reduce the photosynthetic capacity of the foliage through persistent feeding.

The primary host for this species is the grapevine. Both nymphs and adults reside on the underside of leaves, piercing the leaf tissue with their specialized mouthparts to extract vital cell contents. While they primarily target grapevines, their presence can become a major concern in commercial vineyards, leading to reduced yields and inferior grape quality.

The biological cycle consists of egg, nymph, and adult stages. Overwintering occurs in the adult stage within leaf litter, debris, or under the loose bark of the grapevine trunk. As spring temperatures rise, the adults emerge to feed and deposit eggs into the leaf tissues. Multiple generations typically occur during a single growing season, leading to potential population explosions in mid-to-late summer.

Feeding damage is characterized by stippling — small, white or yellowish dots on the leaves where cell contents have been removed. Heavy infestations lead to extensive chlorosis, causing the leaves to dry out, turn brown, and drop prematurely. This premature senescence hinders the vine's ability to accumulate sugars, resulting in lower brix levels and delayed fruit ripening.

Effective control measures include:

• Maintaining orchard sanitation by removing and destroying leaf litter and plant debris in autumn.
• Applying systemic or contact insecticides during the nymphal growth phase to prevent adult emergence.
• Implementing biological control by preserving populations of predatory insects like spiders and parasitic wasps.
• Regular monitoring using sticky traps to determine the necessity of intervention based on population thresholds.