Phenacoccus sisymbriifolium Granara de Willink

According to the FDACS-DPI database and ScaleNet (García et al., 2016), there are about 34 genera and 90 species of mealybugs in Florida. More than one third of them occur on roots and are easily overlooked during inspection. Phenacoccus sisymbriifolium Granara de Willink is one of the overlooked root mealybugs in Florida. In general, root mealybugs feed on plant roots by sucking sap from the tissues. In small numbers, they have no obvious effects on plant health. However, the ability for mealybugs to multiply at an exponentially fast rate means they can rapidly transform from a mild problem to a heavy infestation. If the infestation gets too large, the plants are likely to die (Hodgson 2018).

The first sample of P. sisymbriifolium recognized in Florida was collected by Nora Marquez (FDACS-DPI) on January 8, 2019 from Lake County on Bidens alba (L.) DC. (Asteraceae) (FDACS-DPI sample number E2019-0093). Follow up samples were submitted to support the identification on March 12, 2019 by Nora Marquez from the same location (E2019-1068 and E2019-1069). It was identified as a new U.S. continental record and further confirmed by Gregory A. Evans (USDA/APHIS/PPQ) and Scott Schneider (USDA/ARS/SEL). There were several new Florida host and county records subsequently collected by Nora Marquez: E2019- 1744 and E2019-1747 on April 5, 2019 from Sumter County on B. alba and Ambrosia artemisiifolia L. (Asteraceae); E2019-2068 on April 17, 2019 from Lake County on Gamochaeta antillana (Urb.) Anderb. (Asteraceae); E2019-2370 on April 30, 2019 from B. alba from Hernando County; E2019-2374 on May 1, 2019 from Orange County on Ambrosia artemisiifolia L. (Asteraceae). The most recent county record (E2019-3077) was collected by Lily Deeter (FDACS-DPI) on May 9, 2019 from St. Johns County on Gnaphalium sp. (Asteraceae). In addition, Nora Marquez submitted 29 additional samples containing P. sisymbriifolium in the succeeding two months. The roots in most samples were heavily infested. These data indicate P. sisymbriifolium is common and possibly widespread in peninsular Florida. There is no information about the pest status of this species in the literature. However, P. sisymbriifolium was first reported from Solanum sisymbriifolium Lam. a member of plant family Solanaceae (Granara de Willink and Szumik, 2007), which includes commercial vegetable and ornamental plants such as tomato, potato, eggplant and petunia. Therefore, P. sisymbriifolium has the potential of becoming a pest in Florida. However, all the records from Florida were reported from the Asteraceae.