Vine Mealybug Monitoring in California Vineyards

Temperatures are heating up, and wine growers should keep an eye out for vine mealybug outbreaks in their vineyards.  Monitoring is a critical aspect for developing and executing an effective integrated pest management program.

     Suterra’s traps and lures can help growers and their Pest Control Advisers (PCAs) detect a VMB problem before their population spirals out of control.

TRAP DEPLOYMENT

    Suterra’s VMB trap is a small paper delta trap (SPD) that has a sticky liner and grid built into its design. You simply need to insert the VMB septa lure (which emits the pheromone that will attract males) and hang the trap in an unobstructed area on the vine at cordon height. 

    Users should hang and maintain VMB pheromone traps from March through late October. To stay on top of any VMB outbreaks, traps should be hung at a density of at least one per 10 to 20 acres and at least 2 per block. Place one trap at the center of the vineyard block and one at the point where machinery typically first enters the vineyard. This is where an infestation is most likely to begin.

    The traps should be checked every one to two weeks for vine mealybug. The trap itself should be replaced as frequently as needed when dust, debris, high insect levels, or other insects make it difficult to see VMB in the traps. The septa lure can be reused when replacing traps, and only needs to be replaced once a month. Unused VMB septa lures should be kept in cold storage.

ASSESSING CROPS

     In addition to setting traps, growers are encouraged to conduct visual inspections of plants for crop damage, females, and crawlers. These surveys are best conducted after each flight or once monthly. Vine mealybugs can be elusive, so you should examine at least 100 plants per block per survey.

    Several signs can indicate vine mealybug presence. Initially, you’ll want to look at the external surface of the plant. Vine mealybugs may leave drops of honeydew (the sticky excrement that they produce from feeding on your plants) creating the appearance of wet trunks. Ants also feed on VMB’s honeydew and protect them from predation, so increased ant presence in your vineyard can be a sign of the pest. Rotting clusters of grapes are also a sign of VMB, but ideally you will be able to detect the insects before fruit development.

    To locate a mealybug infestation, you will have to peel back bark and conduct trunk inspections of your vines. In addition to pheromone trapping, these visual inspections are a reliable way to locate VMB infestations, and well worth the time investment. Vine mealybug females and crawlers look very different from the tiny males you’ll see in your traps. They are a waxy white color, about 2.5 to 3.5mm long at adulthood, and are mostly sedentary. You may see them in large clusters on your plants.

IDENTIFICATION

    Suterra’s pheromone traps will catch adult VMB males, which are much smaller than and look very different from the females. Vine mealybug males are tiny (>0.7mm) and can therefore be difficult to identify, even with magnifying equipment. They have two transparent wings, large eyes, a golden-brown body, and long antennae.

    The University of California suggests using a dissecting microscope to confirm identification, as the insect’s diagnostic features may be difficult to see even with a hand lens. To aid in identification, the University has also released a photo identification guide comparing male VMB to similar insects, which can be accessed here.

NEXT STEPS

    If you find Vine Mealybug in your vineyard, consider implementing control methods. In addition to causing crop damage, VMB can spread vineyard diseases like leafroll viruses that can permanently damage grapevines. 

    Vine mealybugs can be difficult to control with insecticide sprays, so many growers use alternative strategies to protect their vineyards from these pests. Suterra’s VMB mating disruption systems are effective and ecologically friendly methods to prevent future generations of VMB and limit crop damage. The products release the sex pheromone of the female VMB into the air, which inhibits the ability of males to find potential mates, preventing them from reproducing. 

    Mating disruptants are species-specific, so beneficial organisms like pollinators and biological control agents are not affected. Suterra’s VMB mating disruptants are available as hand-applied dispensers and a sprayable formulation, allowing the flexibility to use a mating disruption system that works best for your vineyard. A comparison of the available platforms is available here.

    If you would like to learn more, Suterra conducted a FAQ on vine mealybug with several experts in the field that may answer some questions about the pest. If you have inquiries about VMB monitoring or mating disruption, Suterra is also happy to work with you directly. Contact Suterra for more information.