The hyperparasitoid Marietta picta mediates the coexistence of primary parasitoids of goji berry psyllid

Abstract

Hyperparasitoids could disrupt the biological control system established by primary parasitoids. In Ningxia, China, accidentally introduced Marietta picta Andre was found since 2016 to hyperparasitize the primary parasitoid Tamarixia lyciumi Yang, a native biocontrol agent against the goji berry psyllid Paratrioza sinica Yang et Li. Self-introduced Psyllaephagus arenarius Trjapitzin is also a primary parasitoid of P. sinica when it was first recorded in 2016 from China. To assess the effect of M. picta on the local biological control system, its type and biological characteristics were studied under laboratory conditions, and the levels of hyperparasitism were estimated from 2015 to 2017 in the field. The laboratory results showed that M. picta was an obligate solitary hyperparasitoid. It preferred to attack the mature larvae of T. lyciumi but was not able to attack P. arenarius . Field surveys suggested that introduction of M. picta reduced the second wave of parasitism by T. lyciumi . Free from the hyperparasitism, the well-timed presence of P. arenarius adequately compensated for this hyperparasitoid-driven loss, significantly decreasing the population of P. sinica . Because of the mediation by M. picta , the newcomer P. arenarius could successfully establish a population and co-exist with T. lyciumi to synergistically suppress the populations of P. sinica.