Contrasting roles for host plant recognition in Group IX Ips and solitary bees

Many herbivorous insects specialize on plant hosts whose toxins they can tolerate, dispose of or use, but there are other reasons for host association.  Pine bark beetles in the Ips Group IX confusus complex co-occur in the southwestern US, where they attack different pine hosts.  Two species attack different pinyon pine species, but their progeny actually fared better in the third species’ host phloem (ponderosa pine).  However, sexual pheromones of this Ips trio proved to be cross-attractive to females. Furthermore, males did not discriminate among female’s courtship stridulations either (although the sounds are distinctive).  Host association alone ensures proper mate association in sympatry.  Many solitary bees are also oligophagous, in their case for pollen.  Although males of numerous specialist bees use floral hosts to find mates (akin to Ips), floral specialization neither guides correct mate association nor avoids pollen toxins for such oligolectic bees.