Thermal requirements and population growth parameters of Coccinula elegantula (Col., Coccinellidae), predator of Agonoscena pistaciae (Hem., Psylloidea) in laboratory condition

The common pistachio psyllid, Agonoscena pistaciae Burckhardt & Lauterer is known as the major pest of the pistachio trees, Pistacia vera in Iran. The coccinellid beetle, Coccinula elegantula(Weise) was reported as a predator for A.pistaciae in pistachio orchards. This study was carried out to determine the thermal constant and lower threshold for the C. elegantula under controlled condition (constant temperature ranged 17.5-35°C, 55±5% r.h. and 16:8 L:D). The mean for each temperature, lower threshold and constant temperature were all calculated from the pooled data of female development time from egg to adult exclusion. The theoretical lower threshold and thermal constant for development estimated. The lower threshold was estimated 11.7 ,14.3 and 14.4 °C for egg ,larva and pupa respectively. The lower threshold for complete development from egg to adult emergence was estimated 14.9 °C. The thermal constant for egg, larva and pupa was estimated 59 ,151.5 and 59.5 degree-days (°D) respectively. The degree-days (°D) required for a generation (egg to adult) was estimated 256.4. In present investigation, life table parameters of C. elegantula was studied in the controlled condition (25±5°C, 55± 5% r.h. and 16:8 L:D) feeding on A. pistaciae using QBASIC program. Based on the results, the intrinsic rate of natural increase (rm) and finite rate of increase was obtained 0.09 and 0.07 (female/female/day). Doubling time and mean generation time were 7.39, 43.9. Net reproductive rate and gross reproductive rates were 54.85, 39.36.