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Keywords:

  • Blennosperma, endangered plant, Frankliniella, herbivore, insect, mitigation, patch isolation, patch size, thrips, translocation, vernal pool

Abstract

As a restoration strategy, translocation of endangered plant populations may be a risky procedure with uncertain outcomes. Often, very little ecological information is known about these populations before, as well as after, translocation. The endangered vernal pool plant, Blennosperma bakeri, is a case in point. As a consequence of vernal pool habitat destruction, many populations of B. bakeri have been transplanted or translocated to various receptor sites. In this study, we examine the incidence of a thrips herbivore, Frankliniella minuta, in natural and translocated populations of B. bakeri in relation to floral patch size and degree of isolation and present implications for B. bakeri restoration and management. At a vernal pool mitigation site in California, U.S.A., thrips were present in both kinds of B. bakeri populations, and the range of thrips densities in both kinds of populations was similar for adults and immatures. Significant negative relationships between patch size, patch isolation, and numbers of flower heads infested with adult or immature thrips were found only among natural patches. Natural patches tended to be smaller in size than translocated patches, but patch isolation distances were similar. Some evidence suggests that B. bakeri is a F. minuta host plant, but the impact of these herbivores on B. bakeri remains unclear. Our findings, although preliminary, suggest that the distribution and abundance of F. minuta varied with floral patchiness, thrips stage, and the natural or translocated status of B. bakeri populations. In addition, our results provide a starting point for understanding the spatial context of plant–herbivore interactions in artificially altered vernal pool landscapes.