Thermal effects on the biological parameters of the predatory mirid Pilophorus gallicus (Hemiptera: Miridae)

Pilophorus gallicus Remane (Hemiptera: Miridae) is a predatory mirid reported in deciduous trees in the western Mediterranean area. This work aimed to determine the biological and demographic parameters for this species at different temperatures (15, 20, 25 and 30 degrees C). Egg hatching times shortened from 57.8 days at 15 degrees C to 9.2 days at 30 degrees C, and nymphal development times declined from 62.8 days at 15 degrees C to 11.1 days at 30 degrees C. The hatching and nymphal survival rates were low at 15 and 30 degrees C. The lower thermal thresholds for the egg and nymphal development were 12.4 and 12.0 degrees C, respectively. These high thermal thresholds could be a safety mechanism to avoid the emergence of nymphs in the unfavorable winter period. Female weight increased between 15 and 25 degrees C and decreased at 30 degrees C. The fecundity increased from 70.2 eggs per female at 15 degrees C to 212.4 eggs per female at 25 degrees C, and decreased to 88.5 eggs per female at 30 degrees C. Fertility ranged from 9.4% at 15 degrees C to 40.9% at 25 degrees C, being 24.9% at 30 degrees C. The intrinsic rate of natural increase (r(m)) rose from 0.001 to 0.081 between 15 and 25 degrees C and decreased to 0.05 at 30 degrees C. In summary, this species performs poorly at low temperatures and has a relative tolerance of high temperatures (30 degrees C); its performance was best at 25 degrees C. Knowledge of the variation in the biological parameters with temperature may be very useful for the understanding of its ecology and population dynamics.