Boisduval scale (Diaspis boisduvalii) in southern Florida: its herbivory on wild orchids and nativity status discussion (Hong et al.)
Description
The armored scale insect, Diaspis boisduvalii (Signoret) (Hemiptera: Diaspididae), has been observed to affect both horticulturally grown and wild plants worldwide, including orchids. Understanding such herbivores' diet breadth and infestation levels in threatened wild orchid populations can raise awareness of their impacts and better guide conservation management. In 2022, we surveyed orchid-dense regions in Everglades National Park (ENP), Big Cypress National Preserve (BCNP), and Fakahatchee Strand State Preserve (FSSP). All orchid species within the surveyed areas were identified and inspected, and each plant was given a score for the relative abundance of D. boisduvalii. Results indicated that six of the 23 orchid species inspected were infested with the scale. These species are 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 cochleata (L.) W. E. Higgins (0.3%). All affected species, except E. tampensis, are listed as endangered or threatened in Florida. Overall, the scale infested a more significant percentage of orchids in ENP compared to BCNP and FSSP. We speculate that the Boisduval scale is likely an introduced species, a hypothesis supported by historical specimen records. However, the presence of cryptic species could render these historical data misleading. The nativity status and impact of D. boisduvalii on wild populations need further research. This is one of the few studies on the ecology of armored scale insect species in a natural environment.