Biological control of Fallopia species using the psyllid Aphalara itadori
Aphalara itadori (Hemiptera: Psyllidae) is a classical biological control agent for the invasive knotweed species (Polygonaceae) Fallopia japonica, F. sachalinensis and their hybrid F. × bohemica (all EPPO List of Invasive Alien Plants). Host range and performance testing has shown that A. itadori shows interpopulation variation in its performance on the three hosts. Psyllids collected from Hokkaido show a higher performance on F. sachalinensis (the predominant species in that area), whereas a population from Southern Japan (Kyushu), performs best on F. japonica (the only knotweed species present in that area). A new population of psyllids was collected from Murakami (Central Japan) where F. japonica and F. sachalinensis occur and the region has a similar climate to that of North-Western Europe. The performance of this population of psyllid was assessed on the three aforementioned knotweeds. The results of no-choice experiments indicated that the Murakami population performed best on F. × bohemica (juveniles developed the fastest and the number of emerged adults was twice as high as that recorded on the other two Fallopia hosts). The presence of psyllids from the Murakami population had an overall negative impact on final stem length for all knotweeds, though only R. sachalinensis and R. × bohemica showed a reduced rhizome biomass. Based on these results, psyllids from the population from Murakami is expected to have the largest impact in the field on F. × bohemica and F. sachalinensis.
Sources
Camargo AM, Kurose D, Post MJC, Lommen STE (2022) A new population of the biocontrol agent Aphalara itadori performs best on the hybrid host Reynoutria x bohemica. Biological Control 175, https://doi.org/10.1016/j.biocontrol.2022.105007