Effects of Individual Versus Group Rearing on Life‐History Traits and Demographic Parameters of Scolothrips longicornis (Thysanoptera: Thripidae)

ABSTRACT

Scolothrips longicornis is a specialized predator of the two‐spotted spider mite, Tetranychus urticae , and represents a promising agent for biological control programs. Despite its importance, the effects of group rearing on its life‐history traits and population growth remain poorly understood, although such information is highly relevant for mass‐production systems. In this study, we compared the developmental, reproductive and demographic parameters of S. longicornis reared either individually or in groups of five predator pairs while feeding on T. urticae eggs under controlled conditions (25°C ± 1°C, 60% ± 10% RH, 16:8 L:D). Data were analyzed using the age‐stage, two‐sex life table approach. Predators reared individually exhibited significantly longer developmental and adult longevity, higher fecundity and a greater net reproductive rate ( R ₀) than those reared in groups. In contrast, the intrinsic rate of increase ( r ) and finite rate of increase (λ) did not differ significantly between rearing systems. These results demonstrate that group rearing can substantially influence several key life‐history traits of S. longicornis , likely through intraspecific interactions occurring within the rearing arena. Nevertheless, the similar values of r and λ indicate that overall population growth potential remains comparable under both rearing regimes. The findings provide valuable insights for the development and optimization of mass‐rearing protocols and support the effective use of S. longicornis in biological control programs targeting T. urticae .