ISOLATION OF AND FIELD RESPONSE TO SEMIOCHEMICALS OFTHREE SPECIES OF PITYOPHTHORUS EICHHOFF (COLEOPTERA: SCOLYTIDAE) IN CENTRALCOASTAL CALIFORNIA.

P.L. Dallara¹, S.J. Seybold², W. Francke³and D.L. Wood^1
1Dept. of ESPM, Division of Insect Biology, 201 WellmanHall, University of California, Berkeley, 94720.
²Dept. of Biochemistry/330, University of Nevada, Reno,Nevada 89557-0014.
³Institüt für Organische Chemie, UniversitätHamburg, D-2000 Hamburg, Germany.

Analyses of Porapak-Q volatiles from Pityophthorus spp. fed onPinus radiata D. Don demonstrated that 2-(1-hydroxy-1-methylethyl)-5-methyltetrahydrofuran(trans-pityol) was produced by male P. carmeli Swaine, femaleP. nitidulus (Mannerheim), and female P. setosus Blackman,and (5S,7S)-(-)-7-methyl-1,6-dioxaspiro[4.5]decane (MDOS) was producedby male P. carmeli and male P. nitidulus. Only the (2R,5S)-(+)stereoisomer of trans-pityol was produced by P. setosus.In field bioassays, P. setosus was trapped at (+)-trans-pityol,while P. carmeli and P. setosus were trapped at a combinationof MDOS and (+)-trans-pityol. These treatments selectively attractedmale P. setosus and female P. carmeli. MDOS alone did notattract Pityophthorus spp., but significantly reduced the responseof P. setosus to (+)-trans-pityol. P. nitidulus respondedto combined MDOS/(+)-trans-pityol in one experiment. Lasconotuspertenius Casey and Ips mexicanus (Hopkins) were attracted toMDOS and combined MDOS/(+)-trans-pityol. No attractive or inhibitoryeffects were observed for any taxon in field bioassays of (2S,5R)-(-)-trans-pityol.It is hypothesised that (+)-trans-pityol is an aggregation pheromonecomponent for P. setosus and P. carmeli. MDOS may functionas a pheromone component for P. carmeli, an antiattractant usedby P. carmeli to decrease competition by P. setosus, anda L. pertenius kairomone. These compounds may be of value in studyingrelationships among twig insects and tree pathogens.