Failure of ovarian development in the Douglas-fir bark beetle, Dendroctonus pseudotsugae; an analysis of gut proteases and female-specific proteins

Abstract

The failure of ovarian development in Douglas-fir bark beetles denied of their natural gallery environment and maintained on host bark chips was investigated. Such insects possessed a high activity of proteolytic enzymes in their guts but relatively small amounts of female-specific proteins both in haemolymph and the oocytes. Topical application of farnesyl methyl ether did not increase the activity of gut proteases but resulted in increased amounts of female-specific proteins in haemolymph and ovaries. Thus it appears that the Douglas-fir bark beetles maintained on bark chips do not suffer from an inability to break down the ingested proteins, but synthesize and transfer less than normal amounts of female-specific proteins to the developing oocytes.