Leaf herbivory by insects during summer reduces overwinter browsing by moose

Abstract

BackgroundDamage to plants by herbivores potentially affects the quality and quantity of the plant tissue available to other herbivore taxa that utilize the same host plants at a later time. This study addresses the indirect effects of insect herbivores on mammalian browsers, a particularly poorly-understood class of interactions. Working in the Alaskan boreal forest, we investigated the indirect effects of insect damage to Salix interior leaves during the growing season on the consumption of browse by moose during winter, and on quantity and quality of browse production.ResultsTreatment with insecticide reduced leaf mining damage by the willow leaf blotch miner, Micrurapteryx salicifoliella, and increased both the biomass and proportion of the total production of woody tissue browsed by moose. Salix interior plants with experimentally-reduced insect damage produced significantly more stem biomass than controls, but did not differ in stem quality as indicated by nitrogen concentration or protein precipitation capacity, an assay of the protein-binding activity of tannins.ConclusionsInsect herbivory on Salix, including the outbreak herbivore M. salicifoliella, affected the feeding behavior of moose. The results demonstrate that even moderate levels of leaf damage by insects can have surprisingly strong impacts on stem production and influence the foraging behavior of distantly related taxa browsing on woody tissue months after leaves have dropped.Electronic supplementary materialThe online version of this article (10.1186/s12898-018-0192-x) contains supplementary material, which is available to authorized users.

Is summer food intake a limiting factor for boreal browsers? Diet, temperature, and reproduction as drivers of consumption in female moose

“…Increasing spring temperatures in particular have a negative effect on moose densities, possibly due to increased stress in late spring prior to the shedding of winter coats [74]. Additionally, warming temperatures are predicted to increase insect herbivory, which could decrease moose browsing in winter [81]. Warmer spring temperatures also promote higher moose tick populations, which increases hair loss, weight loss, anaemia and secondary bacterial infections [82–86].…”