Biological parameters of parasitoid Psyllaephagus pistaciae and its host agonescena pistaciae in relation to temperature

Abstract

The biological parameters of the parasitoid, Psyllaephagus pistaciae, and its host, Agonoscena pistaciae were determined under controlled conditions. Both insects developed quickly at temperatures ranging from 27.5 to 35°C and 25 to 32.5 °C for the parasitoid and psyllid, respectively. The parasitoid and its host are well adapted to temperatures ranging from 20 to 35°C, which occur in pistachio growing areas of Iran. The theoretical lower thermal threshold of the parasitoid was found slightly higher than that of its psyllid host, however the differences were less than 1 °C. Both virgin and mated parasitoids started ovipositing soon after emergence on the first day, and the unmated wasps laid only male eggs. The psyllid did not lay eggs on the first day after emergence, however continuous mating opportunity was necessary for oviposition during adult life. The intrinsic rate of increase $(r_m)$ of parasitoid (0.20) was close to that of the female psyllid (0.22) at the same temperature. Temperature influenced the demographic parameters of A. pistaciae. Increasing the temperature from 20 to 30 °C leads to a reduction in the generation time (T), doubling time (DT), and to an increase in rm value. Temperatures above 30°C resulted in a sharp decrease in $r_m$ and $R_m$ values and but increased the generation time and doubling time. The results indicated that the biological parameters of the parasitoid and its host coincide and both species develop and reproduce successfully over a wide range of temperature.