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 (rm = 0.1540 d-1), finite rate of increase (λ = 1.1666 d-1) and net reproductive rate (R0 = 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.
Highlights
This study concerns one of the most effective predators of mealybugs in warm regions, namely the recently described Nephus arcuatus Kapur (Coleoptera: Coccinellidae), which is indigenous to warm regions of Southwestern Iran (Löbl & Smetana, 2007)
The average temperatures in this region ranged from 36.7°C in July to 35.6°C in August over the period 2008 to 2012, high densities of N. arcuatus were observed in orchards and on ornamental plants infested with mealybugs
In the study reported here we found that an increase in temperature led to a reduction in the developmental period of pre-adult stages of N. arcuatus
Summary
This study concerns one of the most effective predators of mealybugs in warm regions, namely the recently described Nephus arcuatus Kapur (Coleoptera: Coccinellidae), which is indigenous to warm regions of Southwestern Iran (Löbl & Smetana, 2007). It occurs in Yemen and Saudi Arabia (Ramindo & van Harten, 2000). This small coccinellid has a high searching capacity, especially in warm regions and is an important biological control agent of the spherical mealybug, Nipaecoccus viridis (Newstead) in orchards in Dezful, Southwestern Iran. Mealybugs are controlled by releases of either a single predator (Mani & Thontadarya, 1989; Afifi et al, 2010) or parasitoid (Meyerdirk et al, 1988; Muniappan et al, 2006; Amarasekare et al, 2009), or of both (Kairo et al, 2000; Abd-Rabou, 2008)
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