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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #132881
Title: A REINVESTIGATION OF THE ROLE OF SUNFLOWER CHEMICALS IN HOST SELECTION BY FEMALE BANDED SUNFLOWER MOTH, COCHYLIS HOSPES (WALSINGHAM) (LEPIDOPTERA: TORTRICIDAE)

Author
item FOSTER, STEPHEN - NORTH DAKOTA STATE UNIV
item NOLL, M - NORTH DAKOTA STATE UNIV
item GRUGEL, SHARON
item CHARLET, LAURENCE

Submitted to: Journal of Kansas Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2003
Publication Date: 6/25/2003
Citation: FOSTER, S.P., NOLL, M., GRUGEL, S.R., CHARLET, L.D. A REINVESTIGATION OF THE ROLE OF SUNFLOWER CHEMICALS IN HOST SELECTION BY FEMALE BANDED SUNFLOWER MOTH, COCHYLIS HOSPES (WALSINGHAM) (LEPIDOPTERA: TORTRICIDAE). JOURNAL OF KANSAS ENTOMOLOGICAL SOCIETY. 2003. V. 76 (3). P. 387-396.

Interpretive Summary: The banded sunflower moth feeds exclusively on wild and cultivated sunflower and causes economic losses through seed destruction in commercial fields. Chemicals released by the sunflower plant influence the host selection of female moths. Earlier studies reported that pre-bloom sunflower heads were more attractive than post-bloom heads. Experiments were designed to clarify the roles of any stimulatory or possible inhibitory chemicals from sunflower plants, and to identify other possible factors involved in the selection process. Pentane, dichloromethane, and methanol extracts of pre-bloom sunflower heads, as well as pentane extract of sunflower leaves, all elicited egg laying by females. Studies suggested that both volatile and nonvolatile chemicals are involved in host selection. Behavioral observation supported this, with females landing more frequently and staying longer on models treated with extract. Females laid significantly more eggs on isolated bracts from pre-bloom heads than from post-bloom heads. However, dichloromethane extracts of the bracts from the heads of the two growth stages were equally stimulatory to females. Together these results suggest that changes in bract structure over time, may be responsible for the preference of females for pre- over post-bloom heads. These studies provide the basis for future studies aimed at isolating the chemical involved in host selection by female banded sunflower moths.

Technical Abstract: The involvement of host plant chemicals in host selection by female banded sunflower moth, Cochylis hospes, was reinvestigated. Pentane, dichloromethane, and methanol extracts of R3 (pre-bloom) Helianthus annuus (sunflower) heads, as well as pentane extract of sunflower leaves, all elicited oviposition by females. Rotary evaporation of a pentane extract of R3 sunflower heads resulted in decreased, but still significant, activity in the extract, suggesting that both volatile and nonvolatile chemicals are involved in host selection. Behavioral observation supported this, with females landing more frequently and staying longer on models treated with extract. The basis of female preference for pre-bloom sunflower heads was investigated. In contrast to a previous report, sunflower pollen, or its solvent extracts, had little or no effect on the ovipositional response of females on a substrate treated with a stipulatory pentane sunflower head extract. Females laid significantly more eggs on isolated involucral bracts from pre-bloom heads than from post-bloom heads. However, dichloromethane extracts of the bracts from the heads of the two growth stages were equally stimulatory to females when tested in a binary choice test. Together these results suggest that temporal changes in bract morphology, may be responsible for the preference of females for pre- over post-bloom heads. These studies provide the basis for future studies aimed at isolating the chemical involved in host selection by female C. hospes.