Reverse chemical ecology approach for sustainable palm tree protection against invasive palm weevils

Abstract

The reverse chemical ecology approach facilitates sustainable plant protection by identifying odorant receptors (ORs) tuned to odorants, especially the volatile molecules emitted from host plants that insects use for detection. A few studies have explored such an approach to develop sustainable pest management programs, especially in host-specialized insect species. We revealed the molecular mechanism of host plant detection of a destructive, invasive insect pest of palm trees (Arecaceae), the Asian palm weevil (Rhynchophorus ferrugineus), by deorphanizing an OR (RferOR2) tuned to several palm-emitted odors. We found that RferOR2 responded explicitly to several ecologically relevant palm-emitted odors and significantly to palm esters when transgenically expressed in Drosophila olfactory neurons. We mapped RferOR2 expression in the R. ferrugineus genome and found that odor specificity is likely to develop equally in both sexes. We inferred that the semiochemicals that attract palm weevils to a palm tree might aid in weevil control efforts by improving attraction, enticing many palm weevils to the traps. We demonstrate that including synthetic palm volatiles in pheromone-based mass trapping has a synergistic effect on pheromones, resulting in significantly increased weevil catches. We proved that insect OR deorphanization could aid in the identification of novel behaviorally active volatiles for inclusion in pest management. These results suggest that targeting RferOR2 may help design receptor antagonists that can interfere with weevil host-searching behavior in sustainable pest management applications.

Red palm weevil olfactory proteins annotated from the rostrum provide insights into the essential role in chemosensation and chemoreception

“…However, RferSOR10 and 18 shares 24.06% and 31.54% protein identity with RferOR1. RferSOR12 was identical to RferOR41, an R. ferrugineus OR tuned to non-host plant volatile and antagonist, a-pinene (Ji et al, 2021) was located in the same clade of RferOR2, an R. ferrugineus OR tuned to palm-derived volatiles (Antony et al, 2023). Interestingly, RferSOR13 appeared near ItypOR46 and 49, reported as PRs in clade 7 (Andersson et al, 2013;Yuvaraj et al, 2021).…”

“…Similarly, we mapped another functionally characterized R. ferrugineus OR, RferOR41 (identical to RferSOR12), tuned to non-host plant volatile, apinene (Ji et al, 2021) and found a cluster in the scaffold 66403 (GenBank: JAACXV010014584.1). It is worth mentioning that the most recently reported R. ferrugineus OR (RferOR2) that is tuned to natural palm-emitted odors (Antony et al, 2023) was reported to be an antennae-specific found that comes under this clade (Figure 6). Interestingly, RferSOR13 appeared located near ItypOR46 and 49 (subfamily 7), reported as receptors for enantiomers of pheromones ipsenol (2-methyl-6-methylen-7-octen-4-ol) and ipsdienol (2methyl-6-methylen2,7-octadien-4-ol) (Yuvaraj et al, 2021).…”

Eurasian spruce bark beetle detects lanierone using a highly expressed specialist odorant receptor, present in several functional sensillum types

“…To date, many ORs have been functionally characterized primarily from Lepidoptera and Diptera [4][5][6][7][8][9], whereas only a few have been characterized from the large and diverse order Coleoptera (beetles). To the best of our knowledge, slightly more than 20 beetle ORs have been functionally characterized to date, which restricts our understanding of the functional evolution of the OR family in beetles [10][11][12][13][14][15][16][17][18][19][20]. The majority of the characterized ORs belong to species in the Curculionidae family (Hylobius abietis L., Rhynchophorus ferrugineus Olivier, Lissorhoptrus oryzophilus Kuschel, Ips typographus L., and Dendroctonus ponderosae Hopkins), which includes the bark beetles and other true weevils, several of which are important pests of trees and other plants [10-13, 15, 19, 20].…”

Eurasian spruce bark beetle detects anti-attractant lanierone using a highly expressed specialist odorant receptor, present in several functional sensillum types

“…To date, many ORs have been functionally characterized primarily from Lepidoptera and Diptera (e.g., [4][5][6][7][8][9], whereas only a few have been characterized from the large and diverse order Coleoptera (beetles). To the best of our knowledge, slightly more than 20 beetle ORs have been functionally characterized to date, which restricts our understanding of the functional evolution of the OR family in beetles (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The majority of the characterized ORs belong to species in the Curculionidae family, which includes the bark beetles and other true weevils, several of which are important pests of trees and other plants.…”