Resistance of Benghal Dayflower (Commelina benghalensis) Seeds to Harsh Environments and the Implications for Dispersal by Mourning Doves (Zenaida macroura) in Georgia, U.S.A.

Authors: GODDARD, R - VALDOSTA STATE UNIV; Webster, Theodore; CARTER, R - VALDOSTA STATE UNIV; GREY, T - UNIV OF GA

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2009
Publication Date: 11/1/2009
Citation: Goddard, R.H., Webster, T.M., Carter, R., Grey, T.L. 2009. Resistance of Benghal Dayflower (Commelina benghalensis) Seeds to Harsh Environments and the Implications for Dispersal by Mourning Doves (Zenaida macroura) in Georgia, U.S.A.. Weed Science. 57:603-612.

Interpretive Summary: Benghal dayflower (aka tropical spiderwort) is an exotic invasive weed in North America. This species is tolerant of glyphosate (e.g. Roundup) and has become one of the more troublesome weeds of agronomic crops in the Southeast Coastal Plain. Benghal dayflower is also on the Federal Noxious Weed List, which regulates the movement of this species as a contaminant of commercial products across state borders. Wildlife has been implicated as one means of spreading Benghal dayflower from farm to farm. The contents of both the crop and gizzard of mourning doves harvested in the autumn months were investigated to determine if mourning doves fed on Benghal dayflower and whether seeds can survive conditions in the bird gut. Research indicated that mourning doves fed selectively on Benghal dayflower with some harvested birds containing hundreds of Benghal dayflower seeds and capsules. Further, some seeds recovered remained highly viable. Seeds extracted from dove crops had 92% germination, while seeds extracted from dove gizzards had 45% germination. Benghal dayflower seeds have a structurally reinforced seed coat that probably aids in survival of mechanical damage through bird intestinal tracts. Benghal dayflower seeds exposed to acid for 2 h had high viability. When evaluating mechanisms for the eradication of Benghal dayflower from agricultural crops, consideration needs to be given to the large number of mourning doves and other bird species that visit cropland and potentially aid in its dispersal.

Technical Abstract: The potential dispersal of Benghal dayflower seeds by mourning doves was studied in southern Georgia, U.S.A. The gut contents (both crop and gizzard) of mourning doves harvested in the autumn months were investigated to determine if mourning doves fed on Benghal dayflower and whether seeds can survive conditions in the bird gut. Research indicated that mourning doves fed selectively on Benghal dayflower with some harvested birds containing hundreds of Benghal dayflower seeds and capsules in their guts. Further, some seeds recovered remained highly viable. Germination rates in seeds taken from bird crops were similar to controls over the first 4 weeks of germination and enhanced over control treatments during the latter 16 weeks of a 20-week germination study. Ultimately, seeds extracted from dove crops had 92% germination as compared to 80% for control seeds. Seeds extracted from dove gizzards had 45% germination, about half that of controls. Benghal dayflower seeds have a structurally reinforced seed coat that probably aids in survival of mechanical damage through bird intestinal tracts. Benghal dayflower seeds exposed to 1.0 M HCl treatment for 2 h had little loss in viability, successfully germinating after such treatment. When evaluating mechanisms for the eradication of Benghal dayflower from agricultural crops, consideration needs to be given to the large number of mourning doves and other bird species that visit cropland and potentially aid in its dispersal.