Prediction of changing predator–prey interactions under warming: A simulation study using two aphid–ladybird systems

Predator–prey interactions are key factors for understanding ecosystem structure and function. Global warming alters the dynamics and stability of predator and prey populations in the long term. Extreme temperatures can also lead to short-term population outbreaks and collapses. Thus, it is necessary to consider time scales when predicting warming effects on predator–prey interactions. Two aphid–ladybird systems, Myzus persicae–Coccinella septempunctata (M-C) and Aphis gossypii–C. septempunctata (A-C), were investigated. Using a temperature-dependent predator–prey model, the short- (SIS, daily interactions) and long-term interaction strength (LIS, interactions after reaching a persistent state) were quantified under different temperatures based on a dynamic index. SIS and LIS increased with temperature, but the patterns and magnitudes of the two systems differed. SIS increased linearly and exponentially in the A-C and M-C system, respectively. However, the SISs in the A-C system were stronger than those in the M-C system under most temperature ranges. LIS increased linearly with temperature in both systems; its values in the M-C system were always larger than those in the A-C system. The abruptly increasing SIS in the M-C system caused population collapse, which was the main reason for the magnitude reversal between the SISs and LISs of the two systems. The A-C system did not collapse, but a decoupled SIS and subsequent aphid outbreak were temporarily observed under extreme temperatures. Understanding how time scales influence interaction strengths may be critical to predicting population stability and fluctuations in ecosystems.