CONICET | Buscador de Institutos y Recursos Humanos

Plant domestication has resulted in the modification of specific plant traits to increase yield and quality for human consumption. However, selective breeding has frequently led to a reduction of chemical defenses, usually affecting parameters of herbivores behavior. As a result, domesticated plants are generally more susceptible to damage by herbivore insects compared to their wild relatives. In Argentina, willow plantations (Salix spp) are important in forest production. The willow sawfly, Nematus oligospilus is a specialist pest of Salix species. Recently we showed that previous conspecific herbivory on Salix humboldtiana, a native willow from South America, decreased oviposition preference, larval performance and survival of N. oligospilus. This suggests an induced response of the plant to insect damage that can increase its resistance. Here we compared N.oligospilus behavior in two different willow genotypes: wild willow S. humboldtiana and the high domesticated, frequently cultivated for paper fiber S. babylonica (var. Sacramenta). First we studied oviposition preference of N. oligospilus by offering, in dual choices, the two genotypes either undamaged or after egg laying and larval feeding. We also compared the performance of newborn larvae that initiated their development on both willow species on which they hatched from eggs. Our results showed a marked preference for laying eggs on native S. humboldtiana regardless prior insect damage. When comparing the larval performance on wild and domesticated willows, larval development time was shorter, and larval and pupal weight higher on S. humboldtiana. Our results suggest a higher resistance in domesticated S. babylonica to female oviposition and larval feeding of this specialist insect. This differential behavior may be due to a higher constitutive defense levels or lower nutritional values in domesticated willow compared to the wild genotype.