Abstract
Most plants are subjected to damage from multiple species of herbivores, and the combined impact on plant growth can be non-additive. Since plant response to herbivores tends to be species specific, and change with repeated damage, the outcome likely depend on the sequence and number of attacks. There is a high likelihood of non-additive effects on plant growth by damage from mammals and insects, as mammalian herbivory can alter insect herbivore damage levels, yet few studies have explored this. We report the growth response of young Scots pine trees to sequential mammal and insect herbivory, varying the sequence and number of damage events, using an ungulate-pine-sawfly system. Combined sawfly and ungulate herbivory had both additive and non-additive effects on pine growth—the growth response depended on the combination of ungulate browsing and sawfly defoliation (significant interaction effect). Repeated sawfly herbivory reduced growth (compared to single defoliation) on un-browsed trees. However, on browsed trees, depending on when sawfly defoliation was combined with browsing, trees exposed to repeated sawfly herbivory had both higher, lower and the same growth as trees exposed to a single defoliation event. We conclude that the sequence of attacks by multiple herbivores determine plant growth response.
Highlights
Most plants are subjected to damage from multiple species of herbivores, and the combined impact on plant growth can be non-additive
Induced responses initiated by one herbivore, can affect how plants respond to subsequent herbivory, with potential consequences for plant growth
Induced plant responses are often specific to the herbivore a ttacker[8,9], which leads to the expectation that the sequence of attack by multiple herbivore species could alter the growth response[9,10]
Summary
Most plants are subjected to damage from multiple species of herbivores, and the combined impact on plant growth can be non-additive. Since plant response to herbivores tends to be species specific, and change with repeated damage, the outcome likely depend on the sequence and number of attacks. Since mammal–insect interactions often are highly a symetrical14, sequential[15] and may induce different types of plant responses the outcome for plant growth is likely to differ from multi-insect attacks. Since mammalian herbivory has been shown to both increase and decrease subsequent insect damage levels[4,6,7], there is a possibility for non-additive effects on plant growth by combined attack by these types of herbivores. Antagonistic effects could be due to priming (defences initiated by the first herbivore, rendering the plant prepared for coming attacks)[16,17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
