Effect of temperature on population growth and life table parameters of Nephus arcuatus (Coleoptera: Coccinellidae)

Abstract

The development, reproduction and life table parameters of the predator Nephus arcuatus Kapur (Coleoptera: Coccinellidae), the most important predator of the spherical mealybug, Nipaecoccus viridis (Newstead) (Homoptera: Pseudococcidae) were studied at five constant temperatures (15, 20, 25, 30 and 35 ± 1°C, 65 ± 5% RH and a photoperiod of 14L : 10D). The duration of total pre-adult stage was found to decrease with increase in temperature from 60.0 days at 20°C to 15.3 days at 35°C. The oviposition period lasted 58.5, 44.7, 53.2 and 24.5 days at 20, 25, 30 and 35°C, respectively, with females laying an average of 164.8, 415.2, 660.4 and 136.6 eggs, respectively, at these four temperatures. Life table data were analyzed using an age-stage, two-sex life table. The intrinsic rate of increase (r m = 0.1540 d-1), finite rate of increase (λ = 1.1666 d-1) and net reproductive rate (R 0 = 197.9 offspring) were greatest at 30°C. The shortest mean generation time (T = 30.6 days) was recorded at 35°C. These results indicate that N. arcuatus can successfully survive and reproduce at temperatures of around 30°C and has the potential to be an effective biological control agent of N. viridis and other mealybugs in warm regions.

Prey preference and consumption capacity ofNephus arcuatus(Coleoptera: Coccinellidae): the influence of prey stage, prey size and feeding experience

“…Thus, mass rearing of N. arcuatus on either N. viridis or P. citri should not change the prey selection of the predator once released in the field, enabling N. arcuatus to feed successively on different mealybug species without reducing its predation potential. These findings combined with the results of Zarghami et al (2014) showed that N. arcuatus can successfully survive and reproduce in temperatures of around 30°C and indicate that N. arcuatus could make an important contribution to the control of mealybugs in warm regions.…”

“…Kaur and Virk (2012) observed that the adults of C. montrouzieri, the key competitor in controlling mealybugs, consumed 1613.81 first instars and 73.4 adult females of P. solenopsis in their lifetime when held at a temperature of 27°C (longevity of male: 68.30 days; longevity of female: 61.78 days). Mustu and Klincer (2013) reported that the adults of Nephus kreissli Fürsch and Uygun consumed 23.5 eggs of Planococcus ficus Signoret in 24 h. Zarghami et al (2014) reported the longevity of male and female N. arcuatus held at 30°C to be 116.5 days and 86.1 days, respectively. Our experiment was performed in a 24-hour period (less than that of Kaur and Virk (2012)), yet based on the results and the greater longevity of N. arcuatus, this predator could be more efficient in controlling mealybugs.…”

“…The plastic container had a hole (2 cm in diameter) in the middle of the lid, which was covered by a piece of fine net to provide ventilation. Experimental conditions were based on the optimal temperature for N. arcuatus activities and were 30 ± 1°C, 65 ± 5% RH, and a 14 L:10 D photoperiod (Zarghami, Kocheili, Mossadegh, Allahyari, & Rasekh, 2014). …”

“…must be mass-reared and released on a yearly basis to control mealybugs(Mossadegh, Eslami Zadehend, & Esfandiari, 2008). Meanwhile, N. arcuatus is the most abundant predator in orchards from spring to fall and often controls N. viridis in citrus orchards (author's observation) Zarghami et al (2014). studied the effect of temperature on the population growth and life table parameters of N. arcuatus as a predator of N. viridis and noted that N. arcuatus can develop within a wide range of temperatures (20-35°C), with an optimal temperature of 30°C.…”

Functional Responses ofNephus arcuatusKapur (Coleoptera: Coccinellidae), the Most Important Predator of Spherical MealybugNipaecoccus viridis(Newstead)

“…This small coccinellid occurs widely and abundantly in citrus orchards in Dezful, southwestern Iran (personal observation). Recent investigations on the biology and consumption capacity of this predator confirm its potential for the control of N. viridis in the citrus orchards [11,12]. However, more studies are needed to develop this predator within a successful biological management programme.…”