Mukhopadhyay Amritendu, Quader Suhel
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, Karnataka, India.
Environ Entomol. 2018 Oct 3;47(5):1143-1151. doi: 10.1093/ee/nvy090.
Nectar larcenists extract nectar from flowers without pollinating them. A reasonable expectation is that any form of nectar larceny should have a detrimental effect on the plant's reproductive success. However, studies reveal an entire range of effects, from highly negative to highly positive. This variation in effect may be partly explained by additional, unmeasured, effects of nectar larcenists on plants. In a study system where two ant species Tapinoma melanocephalum (Fabr.) (Hymenoptera: Formicidae) and Trichomyrmex destructor (Jerd.) (Hymenoptera: Formicidae) act as nectar larcenists, we examined the effect of larceny on the female reproductive success of Clerodendrum infortunatum Gaertn. (Lamiales: Lamiaceae) in rain forest fragments of the Western Ghats, India. This was done through a combination of field observations and a series of field experiments looking at the effects of excluding ants from inflorescences. We found that T. destructor reduces fruit set considerably. Rather than this being a consequence of nectar larceny, however, our experiments show that the negative effect arises instead from the herbivorous behavior of the ant. At a population level, both ant species prefer edges over interiors of forest patches, spatially concentrating the interaction zone to forest edges. Simultaneously considering multiple ecological interactions and disentangling their relative contributions might explain the large variation across species in the observed effect of larceny. The overall population effect of nectar larceny and herbivory is likely to depend on the spatial structuring of plants and ants.
盗蜜者从花朵中窃取花蜜而不进行授粉。一个合理的预期是，任何形式的盗蜜行为都应对植物的繁殖成功率产生不利影响。然而，研究揭示了一系列影响，从高度负面到高度正面。这种影响的差异可能部分归因于盗蜜者对植物产生的额外的、未测量的影响。在一个研究系统中，两种蚂蚁，黑头酸臭蚁（膜翅目：蚁科）和破坏毛蚁（膜翅目：蚁科）充当盗蜜者，我们研究了盗蜜行为对印度西高止山脉雨林片段中海州常山（唇形目：唇形科）雌性繁殖成功率的影响。这是通过实地观察和一系列实地实验相结合来完成的，这些实验观察了将蚂蚁排除在花序之外的影响。我们发现破坏毛蚁会显著降低坐果率。然而，我们的实验表明，这种负面影响并非盗蜜行为的结果，而是蚂蚁的食草行为导致的。在种群水平上，这两种蚂蚁都更喜欢森林斑块的边缘而非内部，在空间上将相互作用区域集中在森林边缘。同时考虑多种生态相互作用并理清它们的相对贡献，可能有助于解释在观察到的盗蜜影响中物种间的巨大差异。盗蜜和食草行为对总体种群的影响可能取决于植物和蚂蚁的空间结构。
