The identification of boll weevil, Anthonomus grandis grandis (Coleoptera: Curculionidae), genes involved in pheromone production and pheromone biosynthesis

Authors: Perkin, Lindsey; Perez, Jose; Suh, Charles

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2021
Publication Date: 10/1/2021
Citation: Perkin , L.C., Perez, J.L., Suh, C.P. 2021. The identification of boll weevil, Anthonomus grandis grandis (Coleoptera: Curculionidae), genes involved in pheromone production and pheromone biosynthesis. Insects. 12(10). Article 893. https://doi.org/10.3390/insects12100893.
DOI: https://doi.org/10.3390/insects12100893

Interpretive Summary: Boll weevil eradication programs in the U.S. typically position pheromone traps around cotton fields to detect boll weevils and to indicate the need for insecticide treatments. It is widely recognized that many traps fail to capture weevils during the summer months when plants are actively fruiting, even though respective fields may be heavily infested with boll weevils. Several reasons for these trap detection failures have been proposed, but the most widely accepted reason is that the amount of pheromone produced by weevils in the field simply overwhelms and out-competes the pheromone released from traps. We identified the genes involved in boll weevil pheromone production which may be targeted with modern molecular approaches to eliminate or reduce pheromone production in the boll weevil. Elimination of pheromone-producing weevils in the field would not only improve the detection efficiency of traps, but could also reduce weevil mating success as well as reduce or delay weevil colonization in cotton fields, all of which would reduce the number of subsequent insecticide applications.

Technical Abstract: Eradication programs for the boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), rely almost exclusively on pheromone traps to indicate the need for insecticide applications. However, the effectiveness of traps in detecting weevil populations is reduced during certain times of the year, particularly when cotton is actively fruiting. Consequently, this could result in fields becoming heavily infested with weevils. It is widely speculated that the lack of weevil captures in traps during this period is largely due to the overwhelming amount of pheromone released by weevils in the field, which outcompete the pheromone released from traps. Thus, this work sought to improve the current boll weevil transcriptome so that new control methods that target critical biological processes, such as pheromone production, can be explored. Using the new transcriptome, an RNA-seq experiment revealed 192 differentially expressed genes between pheromone-producing and non-pheromone producing boll weevils. Of those genes, 63 were up-regulated and 129 were down-regulated, and most had gene annotations associated with pheromone production, energy metabolism, or development. This work improves the molecular resources for the boll weevil, advances our understanding of boll weevil pheromone production, and brings us one step closer to developing gene-level control strategies for this cotton pest.