Timmermann Ute, Becker Norbert
KABS e.V., Georg-Peter-Suess-Str. 3, 67346 Speyer, Germany.
Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
Bull Entomol Res. 2017 Dec;107(6):705-714. doi: 10.1017/S0007485317000141. Epub 2017 Feb 16.
Since 1980, mosquito breeding habitats in the Upper Rhine Valley were routinely treated with Bacillus thuringiensis var. israelensis (Bti). Bti is considered to significantly reduce the number of mosquitoes, and - especially when used in higher dosages - to be toxic to other Nematocera species, e.g. Chironomidae, which could be food sources for aerial feeding predators. To investigate direct and indirect effects of routine Bti treatment on food sources for aerial feeding predators, the availability of flying insects in treated and untreated areas was compared. A car trap was used for insect collection, which allowed their exact spatiotemporal assignment. The statistical analysis revealed that insect taxa abundance was influenced differently by the factors season, temperature and time of day. Nematocera (Diptera) were the most frequently collected insects in all areas. Chironomidae were the predominant aquatic Nematocera. The comparison of treated and untreated sites did not show significant differences that would indicate any direct or indirect effect of routine Bti treatment on the availability of flying insects. Additional to food availability, food selection must be considered when investigating food resources for aerial feeding predators. In this study, food selection of Delichon urbicum (House Martin) as an example was investigated with the help of neck ring samples. The preferred prey of the investigated D. urbicum colony consisted of diurnal insects with terrestrial larvae (Aphidina, Brachycera, Coleoptera). Chironomidae were consumed, but not preferred.
自1980年以来，莱茵河上游流域的蚊虫滋生栖息地一直定期使用以色列亚种苏云金芽孢杆菌（Bti）进行处理。Bti被认为能显著减少蚊子数量，而且——尤其是在高剂量使用时——对其他长角亚目物种有毒，例如摇蚊科，而摇蚊科可能是空中捕食者的食物来源。为了研究常规Bti处理对空中捕食者食物来源的直接和间接影响，比较了处理区域和未处理区域飞行昆虫的可获得性。使用了一个车载诱捕器来收集昆虫，这使得能够准确确定它们的时空分布。统计分析表明，昆虫类群的丰度受季节、温度和一天中的时间等因素的影响各不相同。长角亚目（双翅目）是所有区域中最常收集到的昆虫。摇蚊科是主要的水生长角亚目昆虫。处理区域和未处理区域的比较没有显示出显著差异，这表明常规Bti处理对飞行昆虫的可获得性没有任何直接或间接影响。在研究空中捕食者的食物资源时，除了食物可获得性之外，还必须考虑食物选择。在本研究中，以家燕为例，借助颈环样本对其食物选择进行了调查。所调查的家燕群体的首选猎物包括具有陆生幼虫的日间昆虫（蚜亚目、短角亚目、鞘翅目）。摇蚊科昆虫被食用，但不是首选。
