Harmonia axyridis (Pallas) and Propylea japonica (Thunberg) (both Coleoptera: Coccinellidae) are two common aphidophagous predators that overlap in their natural niche; therefore, interactions between these two predator species could affect their overall prey consumption. The consequences of intraguild interactions on the foraging efficiency of the two coccinellid species were investigated by evaluating the functional responses of single beetles and intra‐ and interspecific combinations to densities of the spirea aphid, Aphis citricola van der Goot (Hemiptera: Aphididae), on apple seedlings, during 2 and 12 h under laboratory conditions. A type II functional response was observed in all the bioassays. Solitary H. axyridis consumed significantly more aphids than single P. japonica in both exposure periods. However, at intermediate prey densities the prey consumption of P. japonica was slightly greater than that of H. axyridis. The 95% confidence intervals of the functional response curves of conspecific and heterospecific pairs overlapped at 2 h. In contrast, conspecific pairs of H. axyridis showed a higher functional response curve at 12 h compared to a combination of H. axyridis and P. japonica. Prey's predation risk reduction was only detected for paired H. axyridis and mixed predators compared to their estimated functional responses at the 2‐h foraging period. By comparing functional responses between intraguild predatory lady beetle combinations, we could further predict the potential ecosystem service provided by these natural enemies.
The trailing suction hopper dredger (TSHD) is a ship that excavates sediments from the sea bottom while sailing. Soil properties have a strong effect on the dredging process. The parameter with the greatest importance is the real-time soil grain diameter d m. This, however, cannot be directly measured by available sensors. In this paper, an alternative method is proposed to solve this problem. A new estimation method is developed on the basis of an existing sedimentation model and measuring system data. The loading process with several grain diameters is simulated to perform a sensitivity analysis of soil type. Simulation results show that the dredging efficiency is strongly affected by fine soil. This soil-related estimation problem is solved with a continuous-discrete feedback particle filter (CD-FPF), which is a recently developed filter for a CD time system. For comparison, a bootstrap particle filter (BPF) is also used to simulate the steplike changes in d m in both the no-overflow and constantvolume loading phases. The results show that the CD-FPF outperforms the BPF in terms of accuracy and applicability. Thus, it is recommended to be applied in the estimator of artificial intelligence (AI) dredging systems.
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