Blend chemistry and field attraction of commercial sex pheromone lures to grape berry moth (Lepidoptera: Tortricidae), and a nontarget tortricid in vineyards

Regional Variation in Captures of Male Paralobesia viteana (Lepidoptera: Tortricidae) in Monitoring Traps in Michigan Is Not Due to Geographical Variation in Male Response to Pheromone

Paralobesia viteana (Clemens), grape berry moth, is a major pest of grapes in Eastern North America. There is substantial regional variation in the response of male P. viteana to sex pheromone-baited monitoring traps in Michigan vineyards. Males are readily captured in traps in the southwest region, whereas in the northwest very few males are captured, despite larval infestation in grapes in both regions. Y-tube olfactometers and field experiments determined the response of male moths from northern and southern populations to the pheromone blend used in monitoring lures and to females from both regions. In Y-tube choice tests, males responded similarly to the standard pheromone blend, and males did not preferentially choose females from either region. In field trials, traps baited with unmated females were deployed to test the preference of resident males for females from the two regions and for standard pheromone lures. In southwest Michigan vineyards, significantly more males were caught in traps with a 1.0-µg standard pheromone lure than in traps with captive females collected from vineyards in both regions or in traps with a blank lure control. A similar pattern of male captures among lure treatments was observed in northwest vineyards, although many fewer males were trapped and differences among treatments were not significant. We conclude that the observed regional differences in male response to pheromone traps are not caused by variation in pheromone-mediated behavioral responses, suggesting that other biotic and/or abiotic differences determine the regional variation in captures of this species.

Use of Mixture Designs to Investigate Contribution of Minor Sex Pheromone Components to Trap Catch of the Carpenterworm Moth, Chilecomadia valdiviana

Field experiments were carried out to study responses of male moths of the carpenterworm, Chilecomadia valdiviana (Lepidoptera: Cossidae), a pest of tree and fruit crops in Chile, to five compounds previously identified from the pheromone glands of females. Previously, attraction of males to the major component, (7Z,10Z)-7,10-hexadecadienal, was clearly demonstrated while the role of the minor components was uncertain due to the use of an experimental design that left large portions of the design space unexplored. We used mixture designs to study the potential contributions to trap catch of the four minor pheromone components produced by C. valdiviana. After systematically exploring the design space described by the five pheromone components, we concluded that the major pheromone component alone is responsible for attraction of male moths in this species. The need for appropriate experimental designs to address the problem of assessing responses to mixtures of semiochemicals in chemical ecology is described. We present an analysis of mixture designs and response surface modeling and an explanation of why this approach is superior to commonly used, but statistically inappropriate, designs.