Climate change creates opportune conditions that favour the spread of pests and diseases outside their known active range. Modelling climate change scenarios is oftentimes useful tool to assess the climate analogues to unveil the potential risk of spreading suitability conditions for pests and diseases and hence allows development of appropriate responses to address the impending challenge. In the current study, we modelled the impact of climate change on the distribution of Varroa destructor, a parasitic mite that attacks all life forms of honey bees and remains a significant threat to their survival and productivity of bee products in Tanzania and elsewhere. The data about the presence of V. destructor were collected in eight regions of Tanzania selected in consideration of several factors including potentials for beekeeping activities, elevation (highlands vs. lowlands) and differences in climatic conditions. A total of 19 bioclimatic datasets covering the entire country were used for developing climate scenarios of mid-century 2055 and late-century 2085 for both rcp4.5 and rcp8.5. We thereafter modelled the current and future risk distribution of V. destructor using MaxEnt. The results indicated a model performance of AUC = 0.85, with mean diurnal range in temperature (Bio2, 43.9%), mean temperature (Bio1, 20.6%) and mean annual rainfall (Bio12, 11.7%) as the important variables. Future risk projections indicated mixed responses of the potential risk of spreads of V. destructor, exhibiting both decrease and increases in the mid-century 2055 and late-century 2085 on different sites. Overall, there is a general decline of highly suitable areas of V. destructor in mid- and late-century across all scenarios (rcp4.5 and rcp8.5). The moderately suitable areas indicated a mixed response in mid-century with decline (under rcp4.5) and increase (under rcp8.5) and consistent increase in late century. The marginally suitable areas show a decline in mid-century and increase in late-century. Our results suggest that the climate change will continue to significantly affect the distribution and risks spread of V. destructor in Tanzania. The suitability range of V. destructor will shift where highly suitable areas will be diminishing to the advantage of the honey bees’ populations, but increase of moderately suitable sites indicates an expansion to new areas. The late century projections show the increased risks due to surge in the moderate and marginal suitability which means expansion in the areas where V. destructor will operate. The current and predicted areas of habitat suitability for V. destructor’s host provides information useful for beekeeping stakeholders in Tanzania to consider the impending risks and allow adequate interventions to address challenges facing honey bees and the beekeeping industry. We recommend further studies on understanding the severity of V. destructor in health and stability of the honey bees in Tanzania. This will provide a better picture on how the country will need to monitor and reduce the risks associated with the increase of V. destructor activities as triggered by climate change. The loss of honey bees’ colonies and its subsequent impact in bees’ products production and pollination effect have both ecological and economic implications that need to have prioritization by the stakeholders in the country to address the challenge of spreading V. destructor.

中文翻译：

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气候模式的变化有可能使坦桑尼亚的非洲蜜蜂遭受Varroa破坏因素的蔓延

气候变化创造了有利条件，有利于有害生物和疾病的传播超出其已知的活动范围。对气候变化情景进行建模通常是评估气候类似物以揭示传播有害生物和疾病适宜性条件的潜在风险的有用工具，因此可以制定适当的应对措施以应对迫在眉睫的挑战。在当前的研究中，我们模拟了气候变化对Varroa破坏物分布的影响，Varroa破坏物是一种寄生螨，它攻击所有生命形式的蜜蜂，并仍然对其在坦桑尼亚和其他地方的蜜蜂产品的生存和生产力构成重大威胁。有关V. destructor的存在的数据是在坦桑尼亚的八个地区收集的，这些地区是根据若干因素（包括养蜂活动的潜力，海拔（高地与低地）和气候条件的差异。总共使用了覆盖整个国家的19个生物气候数据集，用于制定2055年中至2085年中的rcp4.5和rcp8.5的气候情景。此后，我们使用MaxEnt对V. destructor的当前和未来风险分布进行建模。结果表明模型性能为AUC = 0.85，温度的平均日变化范围（Bio2，43.9％），平均温度（Bio1，20.6％）和年平均降雨量（Bio12，11.7％）是重要变量。未来的风险预测表明，对毁灭性弧菌传播的潜在风险的反应不一，在2055年中叶和2085年后叶在不同地点呈现出下降和上升趋势。总体而言，高度合适的V区域总体呈下降趋势。跨世纪所有场景（rcp4.5和rcp8.5）中的析构函数。适度的地区表明本世纪中叶的响应是混合的，其下降（在rcp4.5以下）和上升（在rcp8.5以下）以及在世纪末持续增长。略微合适的地区在本世纪中叶呈下降趋势，在本世纪后期呈上升趋势。我们的结果表明，气候变化将继续极大地影响坦桑尼亚破坏弧菌的分布和风险扩散。V. destructor的适用范围将转移到高度适合的区域将减少的地方，从而有利于蜜蜂种群的增长，但是适度适合的地点的增加表明已扩展到新区域。世纪末的预测表明，由于适度和边际适用性的激增，风险增加了，这意味着将在V. destructor的运作区域扩大。V. destructor宿主的当前和预计栖息地适宜性区域为坦桑尼亚的养蜂业利益相关者提供有用的信息，以考虑即将到来的风险并允许采取适当的干预措施来应对蜜蜂和养蜂业面临的挑战。我们建议进行进一步的研究，以了解坦桑尼亚的蜜蜂健康和稳定性中V. destructor的严重性。这将提供一个更好的画面，说明该国将需要如何监测和减少由气候变化引发的弧菌破坏者活动增加所带来的风险。