Effect of temperature on development time and life table parameters of Nephus hiekei Fürsch, the important predator of Phenacoccus solenopsis Tinsley

Abstract

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) has become a serious threat to agricultural and ornamental plants in Southwest Iran. Pest-control studies have found Nephus hiekei Fürsch (Coleoptera: Coccinellidae), in large numbers on Phenacoccus solenopsis Tinsley, as a potential predator. However, there has been no investigation on this predator. In this research, the biology and age-stage, two-sex life table parameters of N. hiekei feeding on Ph. solenopsis were investigated at three constant temperatures (27, 32 and 37 ± 1 °C, 65 ± 5% RH and a photoperiod of 16: 8 (L: D) h. The duration of total pre-adult stage was found to decrease raising temperature from 26.98 ± 0.36 days at 27 °C to 14.24 ± 0.27 days at 37 °C. The oviposition period lasted 63.95 ± 3.14, 66.42 ± 3.34 and 25.20 ± 1.59 days at 27, 32, and 37 °C, respectively. Females laid an average of 365.68 ± 22.36, 543.79 ± 27.27 and 106.25 ± 6.38 eggs, at these three temperatures, respectively. The intrinsic rate of increase (rm = 0.1333 ± 0.0050 d–1), finite rate of increase (λ = 1.1423 ± 0.0057 d–1) and net reproductive rate (R0 = 188.89 ± 28.34 offspring) as well as gross reproductive rate (GRR = 308.31 ± 39.54 offspring) were greatest at 32 °C. The shortest mean generation time (T = 26.74 ± 0.65 days) was recorded at 37 °C and the longest at 27 °C (T = 56.48 ± 1.0 days). These results indicate that N. hiekei can successfully survive and reproduce at temperatures of around 32 °C, and has good potential to be an effective biological control agent of Ph. solenopsis.