Modeling interactions and dynamics of Aphidius matricariae and Praon volucre (Hymenoptera: Braconidae) on two major aphid species in a greenhouse

Interspecific interactions between parasitoid wasps affect the selection of effective biological control agents. In this study, we investigated the effects of extrinsic interspecific interactions between Aphidius matricariae Halifay and Praon volucre (Haliday) (Hymenoptera: Braconidae) on the population sizes of each parasitoid on Myzus persicae (Sulzer) on sweet pepper and Aphis gossypii Glover on cucumber, at 25 ± 2 °C, 60 ± 5% RH and a 14:10 h L:D photoperiod. The population dynamics of these parasitoids were also analyzed numerically using the Lotka–Volterra competition model. Interspecific interaction between the two parasitoids had reduced the population size of each parasitoid on both host aphids. The effect of this interspecific interaction b was more pronounced for P. volucre. Without interspecific interactions, the mean population size of P. volucre varied from 85.2 ± 10.70 to 107.1 ± 12.40 numbers on M. persicae and from 187.8 ± 18.4 to 249.8 ± 24.7 numbers on A. gossypii. Under conditions of coexistence with A. matricariae, however, the abundance of P. volucre significantly decreased to 8.92 ± 2.65–17 ± 5.16 numbers on M. persicae and 53.6 ± 19–65.3 ± 25.2 numbers on A. gossypii. Phase diagrams and time trajectories showed that coexistence of these two parasitoids on M. persicae and A. gossypii lasted for just a short period after which the inferior parasitoid population, P. volucre, declined to zero.