In the ongoing battle against Leafroll virus, the management of mealy bug populations remains essential due to its “virus vector” status. Ant control, rogueing of Leafroll infected vines, and planting only with certified material are all necessary management practices undertaken by producers to curtail the spread of Leafroll virus. The use of indigenous beneficial insects (as predators or parasites to mealy bugs) has also gained traction, particularly over the last decade. Yet, the spread of Leafroll virus is still a reality. What if the vineyard rows and surrounding surface areas could be managed in a way that incorporates certain indigenous vegetation species that might exert further pressure on mealybug populations by providing habitat for more predators or parasitic species? Researchers in Mexico studied the effect of adjacent lands with remnant vegetation on Vine Mealybug numbers.

Project layout

Eight commercial vineyards were selected from two distinct climatic regions: four blocks from Valle de Guadalupe and four from San Antonio de las Minas. Four blocks were adjacent to areas containing remnant vegetation, while the other four blocks were next to un-vegetated areas. Scouting was employed to determine Vine Mealybug (Planococcus ficus) populations, and sticky traps were utilised to monitor and count Anagyrus (an insect that parasitises the Mealybug). The study was conducted over two seasons.

Results

• A lower incidence of Vine Mealybug infestation was recorded in sites adjacent to areas with remnant vegetation.
• The climate also played a role. A lower incidence of Vine Mealybug was recorded at the cooler San Antonio des las Minas sites, when adjacent to areas with remnant vegetation.
• A positive correlation was detected between basal trunk diameter and Vine Mealy bug incidence.
• No correlation was detected between anagyrus parasite numbers, mealybug incidence, occurrence of remnant vegetation, season, or climate.

Significance of the study

This study only investigates Vine Mealybug infestation and whether adjacent areas containing remnant vegetation can impact said infestation. It does not examine the effects of cover crops or indigenous vegetation when employed in the vineyard as a surface management strategy. One can only speculate that similar positive results may be achievable, providing us with another potential tool to utilise in the management strategy against Vine Mealybug and Leafroll virus. This possibility requires further investigation under South African conditions.

Reference:

Guillermo Castillo, Liliana Castro-López, Rafael Bello-Bedoy. Effects of Remnant Vegetation and Microclimatic Conditions on Grapevine Mealybug Incidence in Northwestern Mexican Vineyards. VITIS: Vol. 64, Art. 02, 7 pp. (2025) | DOI: 10.5073/vitis.2025.64.02.