Inbreeding and learning affect fitness and colonization of new host plants, a behavioral innovation in the spider mite Tetranychus urticae

Habitat fragmentation increases the isolation of natural populations resulting in reduced genetic variability and increased species extinction risk. Behavioral innovation through learning, i.e., the expression of a new learned behavior in a novel context, can help animals colonize new suitable and increasingly fragmented habitats. It has remained unclear, however, how reduced genetic variability affects learning for colonizing more or less suitable habitats. Here, we show that inbreeding in a subsocial invertebrate, the spider mite Tetranychus urticae, reduces novel host plant colonization and reproductive fitness. When provided with the possibility to learn from previous experience with a host plant species, outbred mites showed aversive learning ability, but inbred mites did not adapt their behavior. We further found a putative general cost of learning in both inbred and outbred mites. Our results reveal that inbreeding affects the learning component of behavioral innovation for host plant colonization.