Host-stage selection and oviposition behaviour of Psyllaephagus pistaciae, parasitoid of the common pistachio psylla Agonoscena pistaciae

Host-stage selection and oviposition behaviour of Psyllaephagus pistaciae Ferrière, a major biocontrol agent of the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer, was investigated in the laboratory. All five psyllid nymphal instars were susceptible to parasitism by P. pistaciae, and were suitable for parasitoid development. In a choice test, however, the parasitoid preferentially attacked fourth instar nymphs. Feeding upon host haemolymph was found a common behaviour by P. pistaciae. All instars of the psyllid were accepted for destructive non-concurrent host feeding resulting in killing about 10% of the hosts. Female wasps allocated a relatively short time for antennal examination of all different psyllid nymphal instars, however, the duration of drilling increased with host instar. Parasitoids’ post-ovipositional behaviour showed that females leave the hosts immediately after oviposition and do not deposited an external marker over the host surface. Both adult body size of male and female progeny and sex ratio of P. pistaciae was unaffected by host instar.