Crop impacts due to Chinese mole shrews
Both plant and animal foods were detected in our study, indicating thatA. squamipes may be an omnivorous generalist. No significant differences were detected in the numbers and alpha diversity of plant food items between the seasons (Figure 1A and 2), indicating that the availability of plant-derived foods were balanced throughout the year. This opportunistic forager supplemented its diet with plant material, especially grains, in time of food shortages during winter when invertebrate preys are scarce (Figure 1 and Table 1). The Chinese mole shrew opts to feed on cultivated crops or stored grains (such as peanuts and rice) more often during autumn and winter because of the lack of more preferred prey, especially in winter (Figure 4B and 6). The reason for the abundance and high FOs of peanuts and rice in the diet may very well be their continued availability during autumn and winter. In southwest China, peanuts and rice are harvested during autumn. They are the staple food grains and stored for usage throughout the year. In addition, balsam pear and lettuce have been detected in the diet, suggesting that the Chinese mole shrew may cause damage to common vegetables in rural communities. Plant materials were also detected in the diet of several shrew species, such as armored shrew (Churchfield et al. 2010), and Southern short-tailed shrew (Sylvester et al. 2012), and Asian musk shrew (Brown et al. 2014). However, very few studies have reported that shrews can cause damage to and contamination in grains. In this study, the proportional increase in crops eaten in autumn and winter suggests that the Chinese mole shrew poses a threat to crop production and grain stores (Figure 4B), especially in rice-based farming systems. As a result, there may be potential negative impacts on agricultural production and people’s health due to consumption and contamination of crops (Oyafuso 2015). Therefore, development of methods to control the shrew populations on farmlands is necessary, and dietary analysis of A. squamipes can contribute to devising suitable poison baits.
Over 100 plant species were identified in stomach content of A. squamipes . Some of these may have been secondarily ingested via consumption of many large earthworms as reported by Churchfield et al. (2010). For A. squamipes , this dietary diversity may be a compensatory strategy to meet its high-energy requirements by exploiting a wider variety of plant food items. However, a previous study also demonstrated that plant material (seeds or foliage) constitutes a smaller proportion of the overall shrew diet (Churchfield et al. 2012) as a result of missing data from highly digested plant foods. Thus, further investigation of shrew diet with higher taxonomic resolution is required to better understand the food composition of the species and determine their actual impact.
In summary, we found that A. squamipes has a diverse diet comprising a range of invertebrates and plant material. The single most important prey item, whether in terms of FOs, dietary composition or volume contribution, was earthworms. We revealed that the diet of this shrew contains a much higher prevalence and diversity of earthworms than previously known. We also found that plant materials (such as rice and peanuts) were consumed more frequently during the harvest season, implying that the Chinese mole shrew is omnivorous and play a pest role, despite being taxonomically classified as an insectivore. Therefore, the Chinese mole shrew is capable of shifting its dietary preferences to adapt to seasonal fluctuations of food resources, particularly during winter when the diversity and abundance of invertebrates are lowest. Characterizing the diet of A. squamipes may have implications for the evaluating crop impacts and control of this shrew species.