Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
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Female long-tailed mealybug on the ornamental plant Ruscus (magnification 64x). Photo © Rebeccah Waterworth.
Generic lures to attract several species
Because more than one mealybug species can be present in a vineyard, the research team has investigated the possibility of combining pheromones to make “generic” mealybug lures that would attract all four species simultaneously, so that growers would only have to put out one trap, instead of one trap for each species that might be present.
With some types of insects, for example lepidopteran pests, using mixtures of pheromones would be risky because the pheromones can interfere strongly with each other, resulting in none of the target species being attracted to a lure containing a blend of the pheromones of each species. However, preliminary trials withmixtures of a couple of themealybug pheromones have indicated that there is minimal interference, and the concept of generic mealybug lures for vineyards may be practical.
If there is no interference among any of these pheromones, then it will even be possible to make custom mixtures of the pheromones that contain only two or three pheromones, for vineyards where there are only two or three species present. However, it will also be necessary to check that non-target species of mealybugs, which are not of economic importance, are not crossattracted to the pheromone lures, resulting in false positives.
Commercial development of pheromones
Currently, of these four pheromones, only the vine mealybug pheromone is commercially available, but Millar is working to transfer the manufacturing technology to companies that produce pheromone products.
None of the pheromones are protected by patents, so all are freely available for commercial development. However, companies also need to know that there is a substantial market for these products, so growers should communicate their needs to company representatives to expedite the entry of mealybug pheromone traps into the marketplace.
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Mealybug pheromone characteristics
These pheromones all share a number of desirable characteristics for use in pheromone trapping.
First, they are all very powerful attractants for male mealybugs, so that even small populations can be detected. This can also be a disadvantage because mealybugs have been caught in traps located over onequarter mile from the nearest known infestation.
Second, field trials have shown that the standard rubber septum type pheromone lures remain attractive for at least two months under field conditions, minimizing the number of lure changes required throughout one season.
Third, the lures require only a tiny dose of pheromone (0.025 milligrams or less), which will help to keep lure manufacturing costs down
The fourth characteristic is both an advantage and a disadvantage. That is, the chemical
structure of each pheromone is different, so each pheromone specifically attracts only its own species
The advantage is that if you see mealybug males in a trap baited with the pheromone for species X, you know immediately that these males must be species X, without having to try and identify them.
The disadvantage is that in vineyards with more than one mealybug species, youmight have to put out separate traps for each species.
One further issue is that “grass” mealybugs (Phenococcus sp. and Chorizococcus sp.) have been caught in pheromone traps baited with the vine mealybug pheromone in some North Coast vineyards. It is not yet clear whether they were attracted to the pheromone, or were simply present in such high densities that they were accidentally caught in the traps. This will be resolved soon in further field tests.