H. M. Kulman

Ethyl (Z)-9-hexadecenoate a sex pheromone ofSyndipnus rubiginosus, a sawfly parasitoid.

A female-produced sex pheromone ofSyndipnus rubiginosus Walley (Hymenoptera: Ichneumonidae), a parasitoid of the yellowheaded spruce sawfly,Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae), was isolated and identified from hexane extracts of 250 virgin females. Column chromatography (Florisil), gas chromatography, mass spectrometry, high performance liquid chromatography, and ozonolysis indicated the structure was ethyl (Z)-9-hexadecenoate. The optimum male response is at 300–1000 ng (3–10FE). No cross-attraction betweenS. rubiginosus and the sympatric sawfly parasitoidS. gaspesianus (Provancher) could be demonstrated.

Hydrocarbon components of the yellowheaded spruce sawfly sex pheromone : A series of (Z, Z)-9, 19 dienes.

The primary sex pheromone of the yellowheaded spruce sawfly,Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae), was found to include a series of straight-chain hydrocarbon dienes, all with the double bonds in the 9 and 19 positions and all with the (Z, Z) configuration. The major components, of 29, 31, 33, 35, and 37 carbon atoms, were synthesized. In the field and the greenhouse, the synthetic dienes were far above control levels in activity but, at least during the first hours of bioassay, were somewhat less active than the female-derived materials on a weight basis. In the field, a mixture of all five synthetic dienes, in the proportions found in the females, was more attractive than any single one, on a mole basis. In addition, (Z, Z)-9,19 dienes of 28, 30, 32, 34, 36, 38, and 39 carbons have been detected in females in minor amounts. The first five were bioassayed, and each was found to be similar in activity to the 35-carbon component when compared on a weight basis. The synthetic dienes, while active by themselves, were strongly synergized by two, more polar, Florisil fractions derived from females. Experimental design considerations are discussed.

Differences in foliage quality of young jack pine (Pinus banksiana Lamb.) on burned and clearcut sites: effects on jack pine budworm (Choristoneura pinus pinus Freeman)

SummarySuitability of young jack pine as a host for jack pine budworm was examined on similarly-aged trees growing on two areas previously burned in wildfires and on two previously clearcut areas in northwest Wisconsin. Nitrogen, monoterpenes, and moisture levels of foliage, and xylem water potential were measured and related to larval survival and pupal weight of caged jack pine budworm larvae. Nitrogen, monoterpenes, needle weight, and needle moisture were higher in trees growing on clearcut sites than on burned area trees. Surival of budworms to early and late instar, pupation, and adult eclosion was greater for larvae caged on clearcut-area trees than on burned-area trees. Female pupal weight differed between older (ca 10 years old) and younger (ca 8 years old) trees, but not between clearcut and burned areas. Mean female pupal weight was greatest on lownitrogen trees, where larval survival was lowest. Foliar nitrogen was consistently included as a significant predictor in budworm survival regressions. Regressions indicated larval survival and pupal weight may be associated with different tree- and foliage-related traits. Results suggest long-lasting effects of previous forest disturbance may subsequently affect herbivorous insects such as jack pine budworm.

EVIDENCE FOR A MULTICOMPONENT SEX PHEROMONE IN THE YELLOWHEADED SPRUCE SAWFLY

The existence of a female-produced sex pheromone in the yellowheaded spruce sawfly,Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae) was demonstrated by field and greenhouse bioassays. Virgin females, their empty cocoons (with which they were confined during handling procedures), and the hexane extract of these cocoons were attractive in the field. The only Florisil fraction of this extract consistently attractive by itself was that eluted with hexane, but three, more polar fractions (eluted with 5%, 25%, and 50% ether in hexane) each synergized the hexane fraction, increasing bioassay responses 10–30 times. Fractions derived directly from virgin females yielded comparable results. The greenhouse data corroborated the field data, except that the 5% ether-hexane fraction, while very synergistic in the field, was consistently inactive in the greenhouse.