Biology, predatory potential and growth parameters of the syrphid fly, Scaeva pyrastri (L.) (Diptera: Syrphidae) feeding on the cabbage aphid, Brevicoryne brassicae (L.)

Abstract Background Scaeva pyrastri (L.) (Diptera: Syrphidae) is a large-size Palaearctic region syrphid fly. The larval stage of S. aphidophagous in nature, while the adults are efficient pollinators various crops. Therefore, this study was carried out to investigate predation efficacy, biology and population growth parameters on cabbage aphid, Brevicoryne brassicae (Hemiptera: Aphididae) as prey using age–stage-specific two-sex fertility table. Results results showed that mean total development duration 8.31 days pre-adult 19.82 ± 0.25 long. In adult stage, longevity female (18.57 0.37 days) longer than male (15.50 0.17 days). pre-ovipositional, ovipositional post-ovipositional periods were 4.25 0.25, 8.50 0.46 3.25 0.31 days, respectively, female’s fecundity 37.75 1.16 eggs per female. table indicated age-specific ( m x ) increased gradually peaking at 27th day pivotal age (2.71 day) decreased thereafter. life expectancy observed 18th (20.25 19th (16.44 flies, respectively. attained maximum reproductive value v xj 25th day, which 26.05 needed produce one individual. had net reproduction rate 15.10 4.19 offspring individual true generation time 28.86 0.28 days. intrinsic increase greater zero (0.093 0.011) finite λ (1.098 0.012), B. suitable for . values related number aphids consumed by larvae were: C o 377.06 26.54 nymphs ω 19.58 0.78. Conclusions considerable predatory potential fitted well biological control aphids, especially brassicae. However field still unknown; thus, will be helpful determining efficacy against