Agrochemicals are widely used in many parts of the world posing direct and indirect threats to organisms. Xenobiotic-related disease susceptibility is a common phenomenon and a proposed cause of amphibian declines and malformations. For example, parasitic infections combined with pesticides generally pose greater risk to both tadpoles and adult frogs than either factor alone. Here, we report on experimental effects of lone and combined exposures to cercariae of the digenetic trematode Acanthostomum burminis and ecologically relevant concentrations of (0.5 ppm) four pesticides (insecticides: chlorpyrifos, dimethoate; herbicides: glyphosate, propanil) on the tadpoles and metamorphs of the Asian common toad, Duttaphrynus melanostictus. All 48 cercaraie successfully penetrated each host suggesting that the pesticides had no short-term detrimental effect on cercarial penetration abilities. When the two treatments were provided separately, both cercariae and pesticides significantly decreased the survival of tadpoles and metamorphs and induced developmental malformations, such as scoliosis, kyphosis, and skin ulcers. Exposure to cercariae and the two insecticides additively reduced host survival. In contrast, mortality associated with the combination of cercariae and herbicides was less than additive. The effect of cercariae on malformation incidence depended on the pesticide treatment; dimethoate, glyphosate, and propanil reduced the number of cercarial-induced malformations relative to both the control and chlorpyrifos treatments. These results show that ecologically relevant concentrations of the tested agrochemicals had minimal effects on trematode infections, in contrast to others studies which showed that these same treatments increased the adverse effects of these infections on tadpoles and metamorphs of the Asian common toad. These findings reinforce the importance of elucidating the complex interactions among xenobiotics and pathogens on sentinel organisms that may be indicators of risk to other biota.

中文翻译：

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农用化学品对亚洲普通蟾蜍十二指肠（Duttaphrynus melanostictus）黄精虫（Acanthostomum burminis）感染疾病严重程度的影响

农用化学品在世界许多地方被广泛使用，对生物构成直接和间接的威胁。与异物有关的疾病易感性是一种普遍现象，也是两栖动物数量下降和畸形的原因。例如，与单独的任何因素相比，寄生虫感染与农药的结合通常对t和成年青蛙造成更大的风险。在这里，我们报告了独生和联合暴露于双生的拟南芥Acanthostomum burminis尾和生态相关浓度的（0.5 ppm）四种农药（杀虫剂：毒死rif，乐果；除草剂：草甘膦，丙胺）对of和meta的变质的实验影响亚洲常见的蟾蜍，Duttaphrynus melanostictus。所有48种cercaraie均能成功渗透到每个宿主中，这表明该农药对cercarial渗透能力没有短期有害影响。当两种疗法分开提供时，尾c和农药都大大降低了and和变态的存活率，并诱发了发育畸形，例如脊柱侧凸，驼背和皮肤溃疡。暴露于尾c和两种杀虫剂会进一步降低宿主的存活率。相反，与尾c和除草剂组合相关的死亡率低于加性病。尾c对畸形发生率的影响取决于农药的处理方法。相对于对照和毒死rif治疗，乐果，草甘膦和丙烷减少了由小脑诱发的畸形的数量。这些结果表明，与生态相关的受试农药对气管吸虫的影响微乎其微，而其他研究表明，相同的处理方法会增加这些感染对ad和亚洲蟾蜍变质的不利影响。这些发现加强了阐明异生物和病原体在前哨生物上的复杂相互作用的重要性，这可能是其他生物群面临风险的指标。