Population Growth Parameters of Scymnus nubilus Fed Single-Aphid Diets of Aphis fabae or Myzus persicae

Abstract

Life tables are an important tool to forecast the performance of biological control agents used in pest management programs, and they are often assessed in terms of population growth. In the present study, the suitability of the aphids Aphis fabae Scopoli and Myzus persicae (Sulzer) for the ladybird predator Scymnus nubilus Mulsant was assessed for the first time. For this, we evaluated and compared the life history traits of immature individuals and adults of the predator fed single-aphid diets and the consequences of the single-aphid diets for the demographic parameters. Scymnus nubilus that were fed A. fabae were significantly more fecund and presented a shorter immature development time than those fed M. persicae. The predators fed A. fabae had a significantly higher net reproductive rate, an intrinsic and finite rate of increase, while their doubling time was significantly lower than that of those fed M. persicae. The aphid species used in this study are new additions to the essential prey list of the ladybird, with the predator presenting a better biological performance than that found on the previously known essential prey species.