Attraction modulated by spacing of attractants and anti-attractants in a bark beetle and a moth.

In English Coupled gas chromatographic (GC)–electroantennographic
detection (EAD) analyses of ovipositor
extract of calling Hessian fly, Mayetiola destructor, females
revealed that seven compounds elicited responses from
male antennae. Four of the compounds—(2S)-tridec-2-yl
acetate, (2S,10Z)-10-tridecen-2-yl acetate, (2S,10E)-10-
tridecen-2-yl acetate, and (2S,10E)-10-tridecen-2-ol—were
identified previously in female extracts. Two new EADactive
compounds, (2S,8Z,10E)-8,10-tridecadien-2-yl acetate
and (2S,8E,10E)-8,10-tridecadien-2-yl acetate, were identified
by GC–mass spectroscopy (MS) and the use of synthetic
reference samples. In a Y-tube bioassay, a five-component
blend (1 ng (2S)-tridec-2-yl acetate, 10 ng (2S,10E)-10-
tridecen-2-yl acetate, 1 ng (2S,10E)-10-tridecen-2-ol, 1 ng
(2S,8Z,10E)-8,10-tridecadien-2-yl acetate, and 1 ng
(2S,8E,10E)-8,10-tridecadien-2-yl acetate) was as attractive
to male Hessian flies as a similar amount of female extract
(with respect to the main compound, (2S,10E)-10-tridecen-
2-yl acetate). The five-component blend was more attractive
to male flies than a three-component blend lacking the two
dienes. Furthermore, the five-component blend was more
attractive than a blend with the same compounds but that
contained one tenth the concentration of (2S,8E,10E)-8,
10-tridecadien-2-yl acetate (more accurately mimicking the
ratios found in female extract). This suggests that the ratios
emitted by females might deviate from those in gland
extracts. In a field-trapping experiment, the five-component
blend applied to polyethylene cap dispensers in a 100:10 μg
ratio between the main component and each of the other
blend components attracted a significant number of male
Hessian flies. Also, a small-plot field test demonstrated the
attractiveness of the five-component blend to male Hessian
flies and suggests that this pheromone blend may be useful
for monitoring and predicting Hessian fly outbreaks in
agricultural systems.