Search Results (3)

Apolygus lucorum, a phytozoophagous mirid bug, plays an important role in the species interactions within fruit tree and cotton ecosystems. Previous research has mainly focused on the phytophagous damage that it causes to crops, while its role as a predator of arthropods remains poorly understood. In this study, we systematically investigated the functional responses of A. lucorum to three crop pests: eggs of Helicoverpa armigera, nymphs of Aphis gossypii, and nymphs of Bemisia tabaci. The results show that the predatory behavior of A. lucorum towards all three prey species followed a Holling type II functional response model. Predatory performance varied significantly depending on prey species, developmental stage, and sex of the mirid. The theoretical maximum predation rate was highest for A. gossypii (833.33 individuals/day) and lowest for B. tabaci nymphs. Adult mirids and older nymphs (4th instar) exhibited higher predation rates than younger nymphs. Field-collected A. lucorum from Bt cotton fields were analyzed using molecular diagnostics, and the result confirmed natural predation on A. gossypii, which was consistent with observed pest occurrence patterns in the field. Overall, this study clarifies the prey selectivity and stage-dependent predatory strategies of A. lucorum, providing insights into its trophic flexibility as a facultative predator. These findings contribute to a more comprehensive understanding of its ecological role in agricultural ecosystems, but do not support its use as a biological control agent given its predominantly phytophagous nature and documented pest status. Full article

Bradymonabacteria, as the representative of the facultative prey-dependent predators, were re-classified from the preceding Deltaproteobacteria into the phylum Myxococcota and proposed as a novel class named Bradymonadia. However, it was ambiguous whether their predatory pattern and properties were similar to those of the other myxobacterial predators. Therefore, the physiologic features were compared to determine the similarities and differences during the process of group attack and kin discrimination. Comparative genomic analyses were performed to conclude the core genome encoded commonly by bradymonabacteria, Myxococcia, and Polyangia. In conclusion, we proposed that bradymonabacteria have a predation pattern similar to the that of the representative of opportunistic predators like Myxococcus xanthus but with some subtle differences. Their predation was predicted to be initiated by the needle-less T3SS*, and the S-motility mediated by T4P also participated in the process. Meanwhile, their group attacks relied on cell contact and cell destiny. Inter-species (strains) kin discriminations occurred without the existence of T6SS. However, no extracellular lethal substance was detected in the fermentation liquor culture of bradymonabacteria, and the death of prey cells could only be observed when touched by their cells. Moreover, the prey-selective predation was observed when the predator encountered certain prey from Bacillus (G⁺), Algoriphagus (G⁻), and Nocardioides (G⁺). Bradymonabacteria can be regarded as a potential consumer and decomposer, and preying on many sea-dwelling or human pathogenic bacteria allows this group a broad application prospect in marine culture and clinical disease control. Our study will provide more evidence for its exploitations and applications. Full article

Over recent decades, intraguild predation (IGP) has attracted special attention, both from the theoretical and practical standpoints. The present paper addresses the interference competition between two Trichogramma species (egg parasitoids)—on the one hand, the extrinsic interactions (i.e., the indirect competition between female T. achaeae and T. brassicae), and on the other, the intrinsic interactions between the larvae of both species. Furthermore, T. achaeae is a better competitor than T. brassicae due to a dual mechanism—the former acts as a facultative hyperparasitoid of the latter, exclusively considering parasitism relationships as well as presenting predation activity by host feeding, which gives preference to eggs previously parasitized by T. brassicae over non-parasitized eggs. Both mechanisms are dependent on the prey density, which is demonstrated by a change in the functional response (i.e., the relationship between the numbers of prey attacked at different prey densities) of T. achaeae adult female—it changes from type II (i.e., initial phase in which the number of attacked targets increases hyperbolically and then reaches an asymptote, reflecting the handling capacity of the predator), in the absence of competition (an instantaneous search rate of a′ = 9.996 ± 4.973 days⁻¹ and a handling time of T_h = 0.018 ± 0.001 days), to type I (i.e., linear increase in parasitism rate as host densities rise, until reaching a maximum parasitism rate, and an instantaneous search rate of a′ = 0.879 ± 0.072 days⁻¹ and a handling time of T_h ≈ 0) when interference competition is present. These results show that there is a greater mortality potential of this species, T. achaeae, in conditions of competition with other species, T. brassicae in this case. Based on this, their implications in relation to the biological control of pests by parasitoid species are discussed. Full article