Boisduval scale (Diaspis boisduvalii) (Hemiptera: Diaspididae) in southern Florida: its herbivory on wild orchids and nativity status discussion

The armored scale insect Diaspis boisduvalii (Signoret) (Hemiptera: Diaspididae) has been observed affecting horticulturally grown and wild plants worldwide including orchids. Gaining an understanding of the diet breadth and infestation level of such herbivores on threatened wild orchid populations can raise awareness of their impacts and better guide conservation management. In 2022, we surveyed orchid-dense regions at the Everglades National Park (ENP), Big Cypress National Preserve (BCNP), and Fakahatchee Strand Preserve State Park (FSPSP) in Florida, USA. All orchid species within the surveyed areas were identified, inspected, and individual plants were given a score of D . boisduvalii relative abundance. Six of the 23 orchid species (Orchidaceae) inspected were infested with the scale. These were Bletia purpurea (Lamarck) A.DC. (17 % of surveyed individuals infested), Cyrtopodium punctatum (L.) Lindley (15.8 %), Dendrophylax lindenii (Lindl.) Benth. ex Rolfe (1.8 %), Encyclia tampensis (Lindley) Small (14 %), Prosthechea boothiana (Lindl.) W.E. Higgins (20 %), and Prosthechea cochleate (L.) W.E. Higgins (0.3 %). All affected species except E . tampensis were of endangered or threatened species status in Florida. Overall, the scale infested a greater percentage of orchids in the ENP than that in BCNP and FSPSP. We speculate that the Boisduval scale is most likely an introduced species, a hypothesis supported by historical specimen records. However, the presence of cryptic species could render these historical data misleading. Native origin and impact of D . boisduvalii on wild populations need further research to understand fully. This is one of very few studies of the ecology of an armored scale insect species in a natural environment.