Influence of LED lighting regimes and low nighttime temperatures on aphid predators in controlled-environment strawberry

Abstract: Controlled-environment agriculture (CEA) enables precise regulation of growing
conditions, including temperature and artificial lighting. Previous research has shown that
nighttime temperature declines (ND) and unconventional lighting regimes, such as blue-light
night interruption (BLNI) and continuous low-intensity lighting (CLI), can improve crop yield and quality. However, the effects of these practices on beneficial insects remain poorly
understood. Strawberry production relies heavily on biological control for pest management,
and the success of these programs depends on environmental conditions that support predator performance. Two preliminary screening experiments were conducted to evaluate the effects of LED photoperiod regimes and temperature on Aphidoletes aphidimyza aphid predation and developmental time. In Experiment 1, BLNI was compared with a short day (SD) light regime under reduced night temperature conditions. In Experiment 2, CLI lighting was compared with long day lighting (LD) under both ND and constant temperature conditions. Predation was assessed by daily counts of aphids consumed throughout larval development. Development from egg to adult was also assessed. In both experiments, predation was similar under the light treatments compared. In Experiment 2, predation was significantly greater under constant temperature than under low night temperature conditions. Numerically higher consumption levels were observed in the longer photoperiod experiment (Experiment 1) than in the shorter photoperiod experiment (Experiment 2). In Experiment 1, developmental time was shorter in BLNI compared to SD, mostly due to differences in the pupal stage. No significant differences in developmental time were seen in Experiment 2. Results suggest that nighttime temperature may have a stronger influence on A. aphidimyza performance than subtle differences among similar lighting regimes do. These preliminary findings support the need for subsequent experiments using stronger photoperiod contrasts.