Exploring the biosynthetic origins of terpene pheromones in the Asian lady beetle, Harmonia axyridis

Presenting Author(s)

Zarley Alexander Rebholz

Graduate student (PhD)
Virginia Tech
Blacksburg, Virginia, United States

Co-Author(s)

PO

Paul O'Maillle

SRI International
Menlo Park, California, United States
TU

Todd Ugine (he/him/his)

Department of Entomology, Cornell University, Ithaca, NY, USA
Ithaca, New York, United States
DT

Dorothea Tholl

Virginia Tech
Blacksburg, Virginia, United States

The multicolored Asian lady beetle Harmonia axyridis (Pallas) is a highly invasive, cosmopolitan pest that emits a female-specific terpene aggregation pheromone primarily consisting of (E)-β-caryophyllene, a ubiquitous plant volatile rarely reported in animals. Until recently, insects were thought to lack the ability to synthesize terpenes de novo, instead relying on microbial associations and dietary sequestration to obtain terpene metabolites. Recent research in the Coleoptera and Pentatomids has demonstrated the existence of isoprenyl diphosphate synthase (IDS)-like enzymes with terpene synthase function that have evolved independently of similar enzymes in plants and microbes. To explore the biosynthetic origins of terpene pheromones in H. axyridis, we cloned and expressed IDS-like genes from the beetle and assayed the recombinant proteins for TPS enzyme activity. Two IDS-like enzymes displayed TPS activity in vitro; one of which (HaTPS1) is the first caryophyllene-producing enzyme to be documented in an animal. Both TPS genes showed greater transcript abundance in females, suggesting their involvement in biosynthesis of the female-emitted terpene aggregation pheromone.