Paulo, Daniel F.
Junqueira, Ana C. M.
Arp, Alex P.
Vieira, Andre S.
Skoda, Steven R.
Perez-de-Leon, Adalberto A.
McMillan, William O.
Scott, Maxwell J.
Azeredo-Espin, Ana M. L.
 Smithsonian Trop Res Inst STRI, Microscopy Lab, Tupper Bldg, Panama City 084303092 - Panama
 USDA ARS, Knipling Bushland US Livestock Insects Res Lab, Screwworm Res Site, Pacora - Panama
 USDA ARS, Vet Pest Genom Ctr, Screwworm Res Site, Pacora - Panama
 USDA ARS, San Joaquin Valley Agr Sci Ctr, Parlier, CA 93648 - USA
 Smithsonian Trop Res Inst STRI, Lab Ecol & Evolutionary Genom, Gamboa - Panama
 North Carolina State Univ, Dept Entomol & Plant Pathol, Campus Box 7613, Raleigh, NC 27695 - USA
Total Affiliations: 10
MAY 31 2021.
Web of Science Citations:
The evolution of obligate ectoparasitism in blowflies (Diptera: Calliphoridae) has intrigued scientists for over a century, and surprisingly, the genetics underlying this lifestyle remain largely unknown. Blowflies use odors to locate food and oviposition sites; therefore, olfaction might have played a central role in niche specialization within the group. In insects, the coreceptor Orco is a required partner for all odorant receptors (ORs), a major gene family involved in olfactory-evoked behaviors. Hence, we characterized the Orco gene in the New World screwworm, Cochliomyia hominivorax, a blowfly that is an obligate ectoparasite of warm-blooded animals. In contrast, most of the closely related blowflies are scavengers that lay their eggs on dead animals. We show that the screwworm Orco orthologue (ChomOrco) is highly conserved within Diptera, showing signals of strong purifying selection. Expression of ChomOrco is broadly detectable in chemosensory appendages, and is related to morphological, developmental, and behavioral aspects of the screwworm biology. We used CRISPR/Cas9 to disrupt ChomOrco and evaluate the consequences of losing the OR function on screwworm behavior. In two-choice assays, Orco mutants displayed an impaired response to floral-like and animal host-associated odors, suggesting that OR-mediated olfaction is involved in foraging and host-seeking behaviors in C. hominivorax. These results broaden our understanding of the chemoreception basis of niche occupancy by blowflies. (AU)