By Lauren Diepenbrock
Lebbeck mealybugs (Nipaecoccus viridis) have quickly made an impact on citrus groves in Central and South Florida since the pest was first found in 2019. While management techniques are still being studied, this article describes actions growers can take to find this pest before it becomes a problem.
Lebbeck mealybugs excrete sugary honeydew, much like many other piercing-sucking pests in citrus. That sugary excretion provides a food substrate for sooty mold to colonize on. Because lebbeck mealybug can develop large populations very quickly, appearance of dense areas of sooty mold should be inspected to determine the source.
LEAF AND BRANCH SYMPTOMS
When lebbeck mealybugs feed, they excrete a toxin that causes leaves to curl, similar to bunchy symptoms caused by unrelated diseases. Similarly, branches will exhibit dieback several inches behind the feeding site. Typically, these symptoms are seen in relation to feeding sites where several mealybugs are clustered together.
Distorted fruit are not always found at sites of infestation. It is believed that most physical damage is done to young, developing fruit rather than mature fruit. Lebbeck mealybug can still establish and feed on fully developed fruit, but the damage does not generally appear to be severe. Most fruit infested at this point should be salvageable for processing, though perhaps not for fresh market harvest.
Fruit drop is an ongoing challenge in Florida citrus, which can be exacerbated by lebbeck mealybug feeding. Because the mealybug tends to feed at the calyx junction, the distortions caused by the feeding of this pest can tease apart the junction over time, causing fruit to drop.
YOUNG TREE DEATH
Heavy infestation can lead to death of young trees. Lebbeck mealybug infestation can be challenging to detect in trees that are protected from Asian citrus psyllids under individual protective covers (IPCs), so scouting IPCs for sooty mold or high-traffic ant trails should be performed regularly. Additionally, IPCs should not be the sole management for young trees; they need insecticide applications for lebbeck mealybug and other pests that could establish in the bags.
Lauren Diepenbrock is an assistant professor at the UF/IFAS Citrus Research and Education Center in Lake Alfred.