Induced resistance against leafminer eggs by extrusion in young potato plants

Abstract

Egg extrusion patterns were investigated as an inducible defensive mechanism in potato plants against the leafminer Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae). Increased multiplication rates in leaf cells surrounding an egg of L. huidobrensis leads to its exposure through the leaf cuticle, which might increase the risk of mortality. Extrusion rates were evaluated in laboratory tests, in relation to plant and leaf age in Solanum tuberosum L. var. Spunta. Stratified field sampling was also carried out in order to assess leafminer distribution on new and old leaves. Extrusion was higher in young plants, being restricted in older ones to new, still expanding leaves. Plant reaction was independent of egg density. In the field, damage was concentrated in older foliage, in line with the extrusion results. The relevance of egg extrusion for pest management is discussed.

Keywords:

• Liriomyza huidobrensis
• plant defences
• Solanum tuberosum
• damage distribution
• egg mortality

Acknowledgements

We are very grateful to A. Salvo, L. Cagnolo and two anonymous referees for useful comments on the manuscript and to all land owners who gave permission for field sampling. We would also like to thank native speaker Dr Paul Hobson for revision of the manuscript. This study was supported by Secretaría de Ciencia y Técnica – Universidad Nacional de Córdoba. M.V. and G.V. are PhD student and Fellow Researcher, respectively, at Consejo Nacional de Investigaciones Científicas y Técnicas.