Vale Glyn A, Hargrove John W, Lehane Michael J, Solano Philippe, Torr Stephen J
Natural Resources Institute, University of Greenwich, Chatham, United Kingdom; South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa.
South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa.
PLoS Negl Trop Dis. 2015 Mar 24;9(3):e0003615. doi: 10.1371/journal.pntd.0003615. eCollection 2015 Mar.
Tsetse flies occur in much of sub-Saharan Africa where they transmit the trypanosomes that cause the diseases of sleeping sickness in humans and nagana in livestock. One of the most economical and effective methods of tsetse control is the use of insecticide-treated screens, called targets, that simulate hosts. Targets have been ~1 m2, but recently it was shown that those tsetse that occupy riverine situations, and which are the main vectors of sleeping sickness, respond well to targets only ~0.06 m2. The cheapness of these tiny targets suggests the need to reconsider what intensity and duration of target deployments comprise the most cost-effective strategy in various riverine habitats.
METHODOLOGY/PRINCIPAL FINDINGS: A deterministic model, written in Excel spreadsheets and managed by Visual Basic for Applications, simulated the births, deaths and movement of tsetse confined to a strip of riverine vegetation composed of segments of habitat in which the tsetse population was either self-sustaining, or not sustainable unless supplemented by immigrants. Results suggested that in many situations the use of tiny targets at high density for just a few months per year would be the most cost-effective strategy for rapidly reducing tsetse densities by the ~90% expected to have a great impact on the incidence of sleeping sickness. Local elimination of tsetse becomes feasible when targets are deployed in isolated situations, or where the only invasion occurs from populations that are not self-sustaining.
CONCLUSION/SIGNIFICANCE: Seasonal use of tiny targets deserves field trials. The ability to recognise habitat that contains tsetse populations which are not self-sustaining could improve the planning of all methods of tsetse control, against any species, in riverine, savannah or forest situations. Criteria to assist such recognition are suggested.
采采蝇分布于撒哈拉以南非洲的大部分地区，它们传播锥虫，这些锥虫会导致人类患昏睡病以及牲畜患那加那病。采采蝇控制最经济有效的方法之一是使用经杀虫剂处理的模拟宿主的纱窗，即诱捕目标。过去诱捕目标面积约为1平方米，但最近研究表明，那些栖息在河流区域、作为昏睡病主要传播媒介的采采蝇，对面积仅约0.06平方米的诱捕目标反应良好。这些微小诱捕目标成本低廉，这表明有必要重新考虑在各种河流栖息地，何种诱捕目标部署强度和持续时间构成最具成本效益的策略。
方法/主要发现：一个用Excel电子表格编写并由应用程序可视化Basic管理的确定性模型，模拟了局限于一片由不同栖息地片段组成的河流植被带中的采采蝇的出生、死亡和移动情况，在这些栖息地片段中，采采蝇种群要么能够自我维持，要么若无外来迁入则无法维持。结果表明，在许多情况下，每年仅几个月高密度使用微小诱捕目标将是最具成本效益的策略，可迅速将采采蝇密度降低约90%，预计这将对昏睡病发病率产生重大影响。当在孤立区域部署诱捕目标，或仅从无法自我维持的种群发生入侵的地方部署诱捕目标时，采采蝇的局部根除变得可行。
结论/意义：微小诱捕目标的季节性使用值得进行实地试验。识别包含无法自我维持的采采蝇种群的栖息地的能力，可改善在河流、稀树草原或森林环境中针对任何种类采采蝇的所有控制方法的规划。文中提出了有助于此类识别的标准。
