Oryzaephilus

Abstract: Aggregation pheromone production by Oryzaephilus surinamensis (L.) and O. mercator (Fauvel) was measured as a function of adult age and population density. Porapak Q-captured volatiles were monitored weekly from mixed-sex adults feeding on rolled oats at two different population densities. Macrolide aggregation pheromones (cucujolides) were produced by males of both species by the end of the first week after eclosion and maximum production rates were still maintained more than 3 mo later. For O. mercator , the previously identified cucujolides were 3( Z ),11( R )-dodecen-11-olide and 3( Z ),6( Z ),11( R )-dodecadien-11-olide, and for O. surinamensis , 3( Z ),6( Z ),11( R )-dodecadien-11-olide, 3( Z ),6( Z )-dodecadienolide, and 5( Z ),8( Z ),13( R )-tetradecadien-13-olide. O. surinamensis less than 1 mo after eclosion showed a two- to threefold increase in cucujolide production compared with adults maintained at a fivefold higher population density. In comparison, cucujolide production by young O. mercator was less sensitive to the presence of conspecifics. At the lower population density, adults of both species more than 1 mo after eclosion produced almost optically pure ( R )-(−)-1-octen-3-01. Laboratory bioassays in a two-choice, pitfall olfactometer indicated that l-octen-3-01 alone serves as an aggregation pheromone, and when added to mixtures of cucujolide pheromones, it extends the attractive range of the cucujolides for both Oryzaephilus species.