Search Results (5)

The mason bee Osmia excavata Alfken (Hymenoptera: Megachilidae) is an essential pollinator for rosaceous fruit trees in northern China, but its populations are declining because of severe infestations by the mite Chaetodactylus hirashimai Kurosa (Acari: Sarcoptiformes). This mite feeds on pollen within mason bee nest tubes, thereby impairing larval development. However, the effects of different floral resources on the fitness of C. hirashimai remain unclear. Herein, we evaluated the development, survival, and reproduction of C. hirashimai reared on four diets (cherry pollen, cherry bee bread, apple pollen, or apple bee bread), by using an age-stage, two-sex life table. Chaetodactylus hirashimai successfully completed its life cycle on all diets. Cherry pollen supported shorter pre-adult development, longer adult longevity, and higher fecundity than apple pollen. Bee bread diets resulted in significantly lower pre-adult mortality (11.76–14.81%), and higher fecundity (270–278 eggs/female) and net reproductive rate (R₀ = 115–120 offspring/individual), than raw pollen (44.64–44.83% mortality; 117–179 eggs/female; R₀ = 40–50 offspring/individual). No significant differences in the intrinsic rate of increase (r) and finite rate of increase (λ) were observed among diets. Our findings demonstrated that cherry pollen is a highly favorable resource for C. hirashimai, and bee bread further enhances mite population growth. This study highlights the ecological conflict between cherry pollination and mite infestation, and these life-table results can provide preliminary laboratory support for subsequent research on integrated mite control in fruit orchards. Full article

Osmia excavata is an excellent pollinator in nature and plays a vital role in the conservation of agro-ecosystems and food security. Given the important role of the gut bacterial community in host health and regulation of host growth and development, using 16S rRNA gene sequencing data, the present study explored the composition of the gut bacterial community and its diversity at different life stages (eggs, young larvae, old larvae, young pupae, old pupae, and 1-day-old adults in cocoons) of the solitary bee Osmia excavata. The results showed that the core phyla in the gut of O. excavata at different life stages were Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota, and the core genera were Sodalis, Tyzzerella, and Ralstonia. The highest intestinal bacterial diversity was found in the Egg period, and the lowest bacterial alpha diversity was found in the 1-day-old Adult period; the bacterial diversity of O. excavata showed a process of decreasing, as it was growing from the Egg period to the 1-day-old Adult period. Our study found that O. excavata undergoes a significant change in the structure of the gut flora when it grows from the young pupae to old pupae stage, a period of growth that coincides with the process of cocooning and isolation from the external environment after food depletion. This suggests that food and environmental factors are key contributors to the structure of the bacterial community in the gut of solitary bees. Full article

The timing of decocooning and nesting during the flowering period are crucial for the reproduction and pollination activities of Osmia excavata. In order to improve the pollination efficiency of O. excavata, it is crucial to find a way to break the cocoon quickly. Our results showed that the decocooning rates at 6, 12, 24, 36, 48, and 72 h after 30 min of water immersion (WI) were 28.67%, 37.33%, 37.33%, 41.33%, 44.33%, and 53.00%, respectively. The decocooning rate fold of 6 h was 14.33 compared with the control group. Transcriptome sequencing resulted in 273 differentially expressed genes (DEGs) being identified between the WI and control groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that muscle-related functions play important roles in O. excavata decocooning in response to WI. Cluster analysis also showed that DEGs in cardiac muscle contraction and adrenergic signaling in cardiomyocytes were up-regulated in response to WI-promoted decocooning. In conclusion, the rate of decocooning can be improved by WI in a short time. During WI-promoted decocooning, muscle-related pathways play an important role. Therefore, the application of this technology will improve the pollination effect of O. excavata. Full article

Insect-associated microorganisms play important roles in the health and development of insects. This study aimed to investigate the similarities and differences in bacterial community structure and composition between the larval gut of Osmia excavata, nest soil, and brood provision from the nest tube. We sequenced larvae gut and their environments’ microorganisms of O. excavata from four locations based on full-length 16S rRNA gene amplicons. The results showed 156, 280, and 366 bacterial OTUs from gut, brood provision, and nest soil, respectively, and three groups shared 131 bacterial OTUs. In the gut, the top two dominant bacteria were Sodalis praecaptivus (68.99%), Lactobacillus micheneri (17.95%). In the brood provision, the top two dominant bacteria were S. praecaptivus (26.66%), Acinetobacter nectaris (13.05%), and in the nest soil, the two most abundant bacteria were Gaiella occulta (4.33%), Vicinamibacter silvestris (3.88%). There were significant differences in diversity between the brood provision groups and the nest soil groups, respectively. Three of the four locations did not differ for gut microbial diversity. Bacteria similar to other solitary bees also existed in the gut of the larvae. Results indicated when the habitat environments were similar, the bacterial community diversity of the gut of O. excavata was similar, despite significant differences among brood provisions and soils, respectively. Full article

(1) Background: Many insects have evolved different strategies to adapt to subzero temperatures and parasites, but the supercooling response of pollinator populations under the brood parasitism pressure has not been sufficiently investigated. (2) Methods: This study assessed the supercooling traits (supercooling points, fresh weight and fat content) of the solitary bee Osmia excavata Alfken and its brood parasite, Sapyga coma Yasumatsu & Sugihara. We measured 4035 samples (3025 O. excavata and 1010 S. coma, one individual as one sample) and discovered the supercooling traits relations between solitary bee and brood parasite. (3) Results: Significant differences in the supercooling points were found between O. excavata (females: −24.18 (−26.02~−20.07) vs. males: −23.21 (−25.15~−18.65) °C) and S. coma (females: −22.19 (−25.46~−18.38) vs. males: −20.65 (−23.85~−16.15) °C, p < 0.0001) in the same sex, and also between sexes of same species. The two species’ supercooling traits (supercooling points, fresh weight, and fat content) were significantly positively correlated. The supercooling points of the solitary bee varies regularly under brood parasitism pressure. (4) Conclusions: Our study indicates the supercooling traits relationships between a solitary bee and its brood parasite and suggests that the supercooling points of the solitary bee increase under the biological stress of its brood parasite in a certain level. Full article