Plant volatiles and oviposition behavior in the selection of barley cultivars by wheat stem sawfly (Hymenoptera: Cephidae)

Authors: ACHHAMI, BUDDHI - MONTANA STATE UNIVERSITY; Reddy, Gadi V.P.; HOFLAND, M.L. - MONTANA STATE UNIVERSITY; SHERMAN, JAMIE - MONTANA STATE UNIVERSITY; PETERSON, ROBERT - MONTANA STATE UNIVERSITY; WEAVER, DAVID - MONTANA STATE UNIVERSITY

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2021
Publication Date: 4/22/2021
Publication URL: https://handle.nal.usda.gov/10113/7478396
Citation: Achhami, B.B., Reddy, G.V., Hofland, M., Sherman, J.D., Peterson, R.K., Weaver, D.K. 2021. Plant volatiles and oviposition behavior in the selection of barley cultivars by wheat stem sawfly (Hymenoptera: Cephidae). Environmental Entomology. 20:1-8. https://doi.org/10.1093/ee/nvab035.
DOI: https://doi.org/10.1093/ee/nvab035

Interpretive Summary: Volatile compounds from barley influenced host selection and oviposition behaviors of wheat stem sawfly. We initiated a study in the greenhouse using two barley cultivars: ‘Craft’ and ‘Hockett.’ ‘Hockett’ has a greater number of wheat stem sawfly eggs per infested stem and is therefore a more susceptible cultivar, whereas ‘Craft’ has both a lower number of eggs and greater larval mortality due to antibiosis and is therefore a more resistant cultivar. Volatile compounds from barley influenced host selection and oviposition behaviors of wheat stem sawfly. The question arises does the ovipositing female of wheat stem sawfly display a similar host selection and oviposition behaviors as is known for wheat cultivars? The results provide evidence to support the attractiveness of (Z)-3-hexenyl acetate and its role to attract ovipositing wheat stem sawfly females to a specific cultivar of barley. Consequently, our study provides a foundation to manipulate cultivar traits that change insect preference that can be exploited for pest management.

Technical Abstract: Wheat stem sawfly, Cephus cinctus Norton, females display complex behaviors for host selection and oviposition. Susceptible hollow stem wheat (Triticum aestivum L.) cultivars release a greater amount of attractive compound, (Z)-3-hexenyl acetate and receive a greater number of eggs compared to resistant solid stem wheat cultivars. However, barley (Hordeum vulgare L.) is becoming a more common host for C. cinctus in Montana. Therefore, one question that arises is how similar are host selection and oviposition behaviors on barley cultivars compared to wheat cultivars? To answer this question, we carried out greenhouse experiments using two barley cultivars: ‘Hockett’ and ‘Craft.’ Between these cultivars at Zadoks scale 34 and 49, we compared host selection decision using a Y-tube olfactometer, compared oviposition behaviors on stems, and counted the number of eggs inside individual stems. In Y-tube bioassays, we found a greater number of C. cinctus females were attracted to the airstream passing over ‘Hockett’ when the choices were the airstreams passing over ‘Craft’ and ‘Hockett.’ Although the frequencies of oviposition behaviors were similar between these cultivars, the number of eggs was greater in ‘Hockett.’ Volatile profiles indicated that the amount of linalool was greater in the airstream from ‘Craft’ than in ‘Hockett’ at Zadoks stage 34 while the amount of (Z)-3-hexenyl acetate, was greater in airstream from ‘Hockett’ at both Zadoks 34 and 49. These results suggest that volatiles of barley plants strongly influenced host selection behavior of ovipositing C. cinctus females, while discriminating behaviors do not differ between cultivars.