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IntroductionThe Yangtze vole (Microtus fortis) is a small herbivorous rodent that usually causes damage to crops and forests in China. Various measures were used to control their population including chemical rodenticides. However, rodenticides may cause secondary damage to the environment and the ecosystem. Therefore, the development of new rodent sterilants is urgent. Considering that some compounds of paper mulberry leaves have been verified that can inhibit the biosynthesis of sexual hormone, we aimed to explore the antifertility effect of paper mulberry leaves on M. fortis.MethodsIn this study, voles were divided into three groups including a male group, a female group, and a breeding group, and paper mulberry leaves were added into basal fodder of voles maintained in laboratory, of which the proportion of leaf weight was 50%. In each group, voles were fed with mixed fodder as treatment (BP) and voles were fed with basal fodder as contrast (CK).Results and discussionAfter feeding for more than 1 month, the results indicated that paper mulberry leaves attracted voles to feed, but inhibited their growth and reproduction. Since the second week, food intakes of BP have been significantly higher than CK (p< 0.05). However, weights of voles in male and female groups were 72.283 ± 7.394 g and 49.717 ± 2.278 g in the fifth week, and both were significantly reduced compared with their original weight (p< 0.05). Meanwhile, testicular volumes of male voles fed with BP were significantly smaller than CK (former: 318.000 ± 44.654 mm3, latter: 459.339 ± 108.755 mm3); the testosterone level, sperm number, and vitality of BP were obviously weaker than CK. Female uteruses and oophoron of BP grew slower, and the organ coefficients of uterus and oophoron fed BP were both significantly lower than CK (p< 0.05). The first reproduction of BP couple voles spent 45 days, while CK spent only 21 days. These results suggest that paper mulberry leaves could be the potential resource to produce sterilants to control rodent populations by delaying their sexual growth and reproduction. If it was practical, the apparent advantages of paper mulberry are that it is an abundant resource and the inhibitory effect could be effective in both male and female individuals. Our conclusion also supports the transformation of rodent management from lethal management to fertility control, which would be more ecologically friendly to agriculture and the ecosystem.

Late Pleistocene Labrador Sea depositional systems developed in front of ice streams and glacier outlets from the Laurentide Ice Sheet (LIS) are documented by Huntec and 3.5 kHz seismic profiles and piston cores. Due to efficient grinding by the LIS, massive amounts of fine-grained sediments and meltwater in addition to the icebergs linked to the Heinrich events (H events) of the last glaciation were delivered to the neighboring Labrador Sea. The position of the Hudson Strait ice stream during the periodic expansion and contraction on the Labrador margin allowed fine-grained sediments and meltwater direct delivery on the lower shelf and upper slope. These discharges were then transported southward by the Labrador Current and western boundary current. In contrast to the lower shelf and upper slope, sediments delivered on the mid to the lower Labrador Slope were transported by the Northwest Atlantic Mid-Ocean Channel to distal sites. The nepheloid flow layer at or near the sea bottom or at mid-water depths developed from meltwater loaded with an excessive charge of fine-grained sediments. Contrastingly, the non-discriminatory ice rafting process delivered detritus of all sizes, but its total contribution to the sediment column was only minor, notwithstanding its paleoclimatic significance during H events. Heinrich H1, H2, and H4 layers were identified by their characteristic nepheloid flow layer deposits, that is, alternating coarse silt and clay-sized laminae with thin ice-rafted debris interspersed by coarse- to fine-grained dropstone. Furthermore, the progressive thinning and eventual disappearance of the fine-laminae (i.e., coarse and fine silt/clay) in H layers at the distal sites suggest the exhaustion and raining out of fines due to long-distance transport. However, the H3 layer was identified by a combination of nepheloid flow layer deposits (upper slope) and finely laminated mud turbidites (lower slope and deep basin) at proximal sites. In the lower Labrador Slope and Basin, the H3 stratigraphic equivalent layer was identified by exorbitantly thick finely laminated carbonate-rich mud turbidites. The divergent sedimentation style (i.e., reflected by the sediment facies) and the thickness of the H3 layer compared to other H events suggest that the Hudson Strait ice stream position was different from other H events. Therefore, our data imply that the divergence in the H3 layer between the eastern and western North Atlantic might lie with the position of the Hudson Strait ice stream on the Labrador continental margin.