(Z)-5-tetradecen-1-ol: A secondary pheromone of the yellowheaded spruce sawfly, and its relationship to (Z)-10-nonadecenal
The yellowheaded spruce sawfly,Pikonema alaskensis (Rohwer), was known to possess a potent secondary pheromone with the polarity of an alcohol, based on earlier studies with Florisil fractions. Purification of the 25% ether-hexane Florisil fraction (polarity as with alcohols) and the hydrolyzed 5% ether-hexane fraction (polarity as with esters) from 50,000 females yielded a total of ca 3μg of an active compound identified as (Z)-5-tetradecen-1-ol (Z5–14∶ OH). When added to 100 ng of (Z)-10-nonadecenal (Z10–19∶Al), which behaves as the primary pheromone in this sawfly, 0.5 ng of syntheticZ5–14∶ OH caused an 8.8-fold increase in the greenhouse bioassay response, compared toZ10–19∶Al alone.E5–14∶ OH caused a 2.8-fold increase. Only the combination ofZ5–14∶ OH andZ10–19∶ Al consistently elicited mating attempts among males. When Hercon® formulations ofZ5–14∶OH andZ10–19∶ Al were used together to bait traps, catches were up to four times higher than for theZ10–19∶ Al alone, but this increase was seen only after emergence and mating activity in the field population were virtually complete. TheZ5–14∶ OH was inactive alone, and at higher levels it depressed trap catches toZ10–19∶ Al. The Hercon formulations ofZ5–14∶ 0H andZ10–19∶Al together were as attractive as virgin females.Z10–19∶Al alone and the (Z,Z)-9,19 hydrocarbon dienes (found in all females and able to oxidize in air to produceZ10–19∶Al) were similar to mated females. ThusZ5–14∶:OH accounted for the difference in attractiveness between virgin and mated females.
Identification of a Female-Specific, Antennally Active Volatile Compound of the Currant Stem Girdler
We identified (Z)-9-octadecen-4-olide as a female-specific, antennally active compound from the currant stem girdler Janus integer Norton. Female specificity was demonstrated by gas chromatographic comparison of liquid chromatography fractions of male and female volatile emissions and whole body extracts. The γ-lactone was identified by coupled gas chromatographic-electroantennographic detection (GC-EAD), coupled gas chromatographic-mass spectrometric (GC-MS) analysis, microchemical reactions, and GC and MS comparison with authentic standards. GC-EAD analysis of female volatile emissions and cuticular extracts showed a single peak of activity on male antennae, which was not present in male-derived materials. Female antennae did not respond to any of the tested materials. The hydrogenation product of the natural EAD-active material was a known saturated γ-lactone. The mass spectrum of the dimethyl disulfide derivative of the natural γ-lactone was consistent with a double bond present in the 9 position. Comparison of the natural γ-lactone and a synthesized racemic mixture of (Z)-9-octadecen-4-olide on a chiral GC column showed the presence of a single enantiomer in the natural material.
Spatial distribution of root lesion nematodes (Pratylenchus spp.) in a long-term no-till cropping system and their relationship with soil and landscape properties
The Cook Agronomy Farm of Washington State University is a long-term precision agriculture study site. Since 2000, the farm has been in various three-year no-till rotations with winter wheat, spring wheat, and various rotation crops such as barley, canola, peas, lentils, and chickpea. The spatial distribution of root lesion nematodes (Pratylenchus spp.) and their relationships with soil and terrain variables were studied by collecting soil samples at 127 and 124 geo-referenced points in two 12-ha fields during the spring of 2010 and 2011, respectively. Pratylenchus spp. were detected in more than 85% of the sampled locations in both fields. Nematode densities spatially mapped using ArcGIS software occurred in an aggregated pattern. Previous rotation crops had no effect on the spatial distribution. Classification and regression tree analysis (CART) using soil and terrain variables, and nematode density, explained 61 and 34% of the variability associated with nematode density in 2010 and 2011, respectively. Soil edaphic factors, such as organic matter, were stronger predictors of nematode populations than rotation effects.