Composition of Strawberry Floral Volatiles and their Effects on Behavior of Strawberry Blossom Weevil, Anthonomus rubi.

The strawberry blossom weevil (SBW), Anthonomus rubi, is a major pest in strawberry fields throughout Europe. Traps baited with aggregation pheromone are used for pest monitoring. However, a more effective lure is needed. For a number of pests, it has been shown that the attractiveness of a pheromone can be enhanced by host plant volatiles. The goal of this study was to explore floral volatile blends of different strawberry species (Fragaria x ananassa and Fragaria vesca) to identify compounds that might be used to improve the attractiveness of existing lures for SBW. Floral emissions of F. x a. varieties Sonata, Beltran, Korona, and of F. vesca, were collected by both solid-phase microextraction (SPME) and dynamic headspace sampling on Tenax. Analysis by gas chromatography/mass spectrometry showed the floral volatiles of F. x ananassa. and F. vesca were dominated by aromatic compounds and terpenoids, with 4-methoxybenzaldehyde (p-anisaldehyde) and α-muurolene the major compounds produced by the two species, respectively. Multi-dimensional scaling analyses separated the blends of the two species and explained differences between F. vesca genotypes and, to some degree, variation between F. x ananassa varieties In two-choice behavioral tests, SBW preferred odors of flowering strawberry plants to those of non-flowering plants, but weevils did not discriminate between odors from F. x ananassa and F. vesca flowering plants. Adding blends of six synthetic flower volatiles to non-flowering plants of both species increased the preference of SBW for these over the plants alone. When added individually to non-flowering plants, none of the components increased the preference of SBW, indicating a synergistic effect. However, SBW responded to 1,4-dimethoxybenzene, a major component of volatiles from F. viridis, previously found to synergize the attractiveness of the SBW aggregation pheromone in field studies.

Long-Term Monitoring for Resistance of Botryotinia fuckeliana to Anilinopyrimidine, Phenylpyrrole, and Hydroxyanilide Fungicides in Switzerland.

In Switzerland, the use of phenylpyrrole, anilinopyrimidine, and hydroxyanilide fungicides for control of Botryotinia fuckeliana, causal agent of gray mold in grapes, has been restricted to one treatment per fungicide class per year as part of an anti-resistance strategy. Resistance development in B. fuckeliana was monitored from 1995 to 2001 for the anilinopyrimidine cyprodinil and the phenylpyrrole fludioxonil and from 1997 to 2001 for the hydroxyanilide fenhexamid in experimental vineyards in Richterswil and Stäfa, Switzerland. In total, over 2,400 field isolates were tested. In 1996, the first case of field resistance to anilinopyrimidines was encountered in Richterswil. Efficacy of the anilinopyrimidine cyprodinil decreased significantly, and 54% of the isolates were resistant to anilinopyrimidines. During 7 years of monitoring, one field isolate was found that showed a slightly decreased sensitivity to the phenylpyrrole fludioxonil. Resistance to the hydroxyanilide fenhexamid was not found in 1997 and 1998. From 1999 to 2001, the level of fenhexamid-resistant isolates increased to 100% in Stäfa. The analysis of monitoring and efficacy data showed that subpopulations of B. fuckeliana resistant to cyprodinil and fenhexamid have increased significantly; however, the efficacy of a mixture of fludioxonil and cyprodinil and of fenhexamid alone was still effective. The objective of this study was to initiate long-term monitoring in order to establish an early resistance-detection system as a tool to assess the effectiveness of the anti-resistance strategy used in Switzerland.