Cultivar Preferences of Ovipositing Wheat Stem Sawflies as Influenced by the Amount of Volatile Attractant

Abstract

The wheat stem sawfly, Cephus cinctus Norton, causes severe losses in wheat grown in the northern Great Plains. Much of the affected area is planted in monoculture with wheat, Triticum aestivum L., grown in large fields alternating yearly between crop and no-till fallow. The crop and fallow fields are adjacent. This cropping landscape creates pronounced edge effects of sawfly infestations and may be amenable to trap cropping using existing agricultural practices. The behavioral preference for two wheat varieties was assessed in the context of developing trap crops for this insect. In field nurseries, stem lodging assessments indicated that the cultivar 'Conan' was infrequently damaged, whereas 'Reeder' was often heavily damaged. In laboratory choice and no-choice tests, 'Reeder' was significantly preferred by ovipositing wheat stem sawfly females. These two cultivars did not differ significantly in height or developmental stage, factors known to impact sawfly preference. Although Conan received fewer eggs than Reeder in no-choice tests, oviposition was further reduced in choice tests, indicating that females clearly preferred Reeder. In field trials where the overall dimensions of the spatial structure in choice tests was varied, females always selected Reeder over Conan in alternating block, row, and interseeded planting scenarios. Reeder releases greater amounts of the attractive compound, (Z)-3-hexenyl acetate than Conan but is similar to Conan for three other known, behaviorally active volatile compounds. The results are discussed in terms of cultivar selection for large scale trap crop experiments for the wheat stem sawfly.

Both Volatiles and Cuticular Plant Compounds Determine Oviposition of the Willow Sawfly Nematus oligospilus on Leaves of Salix spp. (Salicaceae)

“…While β-ocimene dominated the volatile blend (about 62 %) of S. nigra, this compound was present in only 6 % of the S. viminalis blend. By studying behavioral orientation, Weaver et al (2009) suggest that (Z) and (E)-β-ocimene determine the suitability for oviposition of the However, the most abundant compound may not be necessary as an orientation cue: a particular ratio of compounds might be essential as previously mentioned (Bruce et al 2005). Other volatile compounds found in our study have been identified as electroantennogramactive in sawflies.…”

Terpenoid Variations within and among Half-Sibling Avocado Trees, Persea americana Mill. (Lauraceae)

“…Variation in emissions of volatile chemicals among plant genotypes has been primarily demonstrated in cultivated agricultural plants, such as maize [48], cotton [49], wheat [50], and rice [51], and few studies have reported intraspecific variation in chemical emission in natural populations of plants [52]–[54]. Chemical profile comparisons in this study between half-and full-sibling avocado trees are correlated with the genetic differences.…”

Identification of Novel QTL for Sawfly Resistance in Wheat

“…Piesik et al (2008) showed that wheat stems reliably produce several volatile compounds that infl uence attraction of female WSS for oviposition. Reeder and Conan diff er for the production of these compounds (Weaver et al (2009). Markers identifi ed in this study will allow derivation of near-isogenic lines to determine the genetic relationship between volatile production and the newly identifi ed QTL.…”