The giant willow aphid (Tuberolachnus salignus) and its effects on the survival and growth of willows.
The giant willow aphid (Tuberolachnus salignus) is an invasive pest that can attain large populations on willows (Salix spp.). This has the potential to have a negative impact on the extensive use of willows for soil conservation, and as a source of pollen and nectar for honey bees in New Zealand. A willow nursery field trial was established to evaluate the aphid populations, and the survival and growth of young plants of several willow species and hybrids, during two growing seasons from planting. The willow species and hybrids varied widely in their susceptibility to the aphid, with large aphid populations and plant mortality in the most susceptible willows, and reductions in plant growth in all but aphid-resistant willows. The effects on the plants were not seen in the first season, but occurred during the second season. The aphid can be expected to have some negative impacts in New Zealand, with reductions in growth of some willows commonly used for soil conservation, and for pollen and nectar for honey bees.