Volume 43, Issue 2 p. 154-161
Original Article

Entrapped sand as a plant defence: effects on herbivore performance and preference

ERIC F. LOPRESTI

Corresponding Author

ERIC F. LOPRESTI

Department of Entomology, University of California, Davis, California, U.S.A.

Correspondence: Eric F. LoPresti, Department of Entomology, University of California, 380 Briggs Hall, 1 Shields Avenue, Davis, CA, 95616 U.S.A. E-mail: [email protected]Search for more papers by this author
PATRICK GROF-TISZA

PATRICK GROF-TISZA

Department of Entomology, University of California, Davis, California, U.S.A.

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MORIA ROBINSON

MORIA ROBINSON

Department of Evolution and Ecology, University of California, Davis, California, U.S.A.

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JESSIE GODFREY

JESSIE GODFREY

Department of Plant Sciences, University of California, Davis, California, U.S.A.

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RICHARD KARBAN

RICHARD KARBAN

Department of Entomology, University of California, Davis, California, U.S.A.

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First published: 20 November 2017
Citations: 10
Associate Editor: Takayuki Ohgushi

Abstract

1. Abrasive material in the diet of herbivorous organisms comes from a variety of sources, including crystalline silica or calcium in plant tissues, accidentally ingested soil while digging or grazing, and entrapped substrate on the surfaces of plants. A wide variety of plants entrap substrate, usually with glandular trichomes.

2. A previous study demonstrated that entrapped sand provided resistance to herbivory in the field. In this study, the following questions were addressed: how does entrapped sand on Abronia latifolia (Nyctaginaceae) leaves and stems affect preference and performance of a common herbivore, the large-bodied caterpillar Hyles lineata (Sphingidae); does this effect differ from those experienced by an internally feeding leaf miner?

3. Using a combination of experimental and observational approaches, it was found that sand comprised ∼4–5% of ingested weight during normal feeding of H. lineata caterpillars. This entrapped sand caused extensive wear to their mandibles, they avoided sand-covered plants when given the choice, and the sand negatively impacted performance metrics, including pupal weight, development time, and growth rate. In contrast, a leaf-mining caterpillar did not have a preference for or against feeding on sandy plants.

4. These results are similar to studies on mandibular wear due to grasses, and herbivorous insects that feed on these two plant groups may have similar morphologies. It is hypothesised that increased wear potential may be a convergent solution to abrasive plants in both mammals (hypsodonty) and insects.