Isolation and extreme sex‐specific expression of cytochrome P450 genes in the bark beetle, Ips paraconfusus, following feeding on the phloem of host ponderosa pine, Pinus ponderosa

Abstract

We have identified cDNAs and characterized the expression of 13 novel cytochrome P450 genes of potential importance in host colonization and reproduction by the California fivespined ips, Ips paraconfusus. Twelve are of the Cyp4 family and one is of the Cyp9 family. Following feeding on host Pinus ponderosa phloem, bark beetle transcript levels of several of the Cyp4 genes increased or decreased in males only or in both sexes. In one instance (IparaCyp4A5) transcript accumulated significantly in females, but declined significantly in males. The Cyp9 gene (Cyp9T1) transcript levels in males were > 85 000 x higher at 8 h and > 25 000 x higher at 24 h after feeding compared with nonfed controls. Transcript levels in females were approximately 150 x higher at 24 h compared with nonfed controls. Cyp4G27 transcript was present constitutively regardless of sex or feeding and served as a better housekeeping gene than beta-actin or 18S rRNA for the real-time TaqMan polymerase chain reaction analysis. The expression patterns of Cyp4AY1, Cyp4BG1, and, especially, Cyp9T1 in males suggest roles for these genes in male-specific aggregation pheromone production. The differential transcript accumulation patterns of these bark beetle P450s provide insight into ecological interactions of I. paraconfusus with its host pines.