McCann Samantha, Crossland Michael, Greenlees Matthew, Shine Richard
School of Life and Environmental Sciences University of Sydney Sydney NSW Australia.
Department of Biological Sciences Macquarie University Sydney NSW Australia.
Ecol Evol. 2020 Aug 31;10(18):10177-10185. doi: 10.1002/ece3.6678. eCollection 2020 Sep.
Laboratory experiments have shown that the viability of embryos of the invasive cane toad () can be reduced by exposure to chemical cues from older conspecific larvae. These effects (very strong in laboratory trials) may offer an exciting new approach to controlling this problematic invasive species in Australia. However, the degree to which the method works in natural environments has yet to be assessed.Our experiments in the laboratory and in seminatural outdoor waterbodies show that chemical cues from tadpoles do indeed suppress the growth, development, and survival of conspecific larvae that are exposed as embryos and do so in a dose-dependent manner; higher tadpole densities cause greater suppression of embryos.In seminatural outdoor waterbodies, suppressor-exposed tadpoles were less than half as likely to survive to metamorphosis as were controls, and were much smaller when they did so and hence, less likely to survive the metamorph stage. Additionally, female cane toads were less likely to oviposit in a waterbody containing free-ranging (but not cage-enclosed) tadpoles, suggesting that the presence of tadpoles (rather than the chemical cues they produce) may discourage oviposition.Broadly, our results suggest that the suppression effect documented in laboratory studies does indeed occur in the field also, and hence that we may be able to translate that approach to develop new and more effective ways to reduce rates of recruitment of peri-urban populations of cane toads in their invasive range.
实验室实验表明，接触来自同种老年幼虫的化学信号会降低入侵性甘蔗蟾蜍（ ）胚胎的活力。这些影响（在实验室试验中非常显著）可能为控制澳大利亚这种有问题的入侵物种提供一种令人兴奋的新方法。然而，该方法在自然环境中的有效程度还有待评估。我们在实验室和半自然户外水体中进行的实验表明，来自蝌蚪的化学信号确实会抑制作为胚胎暴露的同种幼虫的生长、发育和存活，并且呈剂量依赖性；蝌蚪密度越高，对胚胎的抑制作用越大。在半自然户外水体中，接触抑制信号的蝌蚪存活至变态的可能性不到对照组的一半，而且即便存活下来体型也小得多，因此在变态阶段存活的可能性也较小。此外，雌性甘蔗蟾蜍不太可能在含有自由游动（而非圈养）蝌蚪的水体中产卵，这表明蝌蚪的存在（而非它们产生的化学信号）可能会抑制产卵。总体而言，我们的结果表明，实验室研究中记录的抑制作用在野外也确实会发生，因此我们或许能够将该方法转化为新的、更有效的方式，以降低甘蔗蟾蜍在其入侵范围内城市周边种群的补充率。
