Oviposition cues in Nematus oligospilus, a specialist willow sawfly

BRACCINI CELINA; VEGA ANDREA SUSANA; FERNANDEZ PATRICIA CARINA

Congreso; Plant interactions with other organisms: molecules, ecology and evolution. 32nd New Phytologist Symposium.; 2013

The willow sawfly Nematus oligospilus represents a serious pest of Salix spp. due to severe defoliation caused by larval feeding. Like many phytophagous insects, females start attacking a plant by laying eggs on it. The aim of this study is to determine oviposition cues that guide females to their host plants. Specifically, we evaluated oviposition behavior of N. oligospilus and discussed the presence of leaf traits that possibly affect oviposition. Dual choice and no-choice bioassays were performed to study host selection according to leaf side of different willow genotypes. Leaf micromorphology was described through microscopic techniques. Epicuticular waxes were extracted by leaf side and analyzed by means of GC-FID. Results show that N. oligospilus clearly prefers to lay eggs on S. nigra regardless of leaf side. S. viminalis is strongly avoided by females, specially the abaxial leaf surface. Micromorphology analysis of leaves revealed differences in anatomical structure and toughness. Chromatograms suggest differences in the chemical composition of epicuticular waxes not only between genotypes but also between leaf sides of the same genotype. Although preliminary, these results suggest that the strong repellence observed in the abaxial surface of S. viminalis might be due to the presence of an oviposition inhibitory trait that requires further investigation.