Pollen chemical and mechanical defences restrict host-plant use by bees

Plants produce an array of chemical and mechanical defences that provide protection against many herbivores and pathogens. Putatively defensive compounds and structures can even occur in floral rewards: for example, the pollen of some plant taxa contains toxic compounds or possesses conspicuous spines. Yet little is known about whether pollen defences restrict host-plant use by bees. In other words, do bees, like other insect herbivores, tolerate the defences of their specific host-plants while being harmed by non-host defences? To answer this question, we compared the effects of a chemical defence from Lupinus (Fabaceae) pollen and a putative mechanical defence (pollen spines) from Asteraceae pollen on larval survival of nine bee species in the tribe Osmiini (Megachilidae) varying in their pollen host use. We found that both types of pollen defences reduce larval survival rate in some bee species. These detrimental effects were, however, mediated by host-plant associations, with bees b..., , , # Pollen chemical and mechanical defences restrict host-plant use by bees

Data and code to analyse the survival rate of Osmiini larvae exposed or not to Asteraceae spines or *Lupinus* alkaloids in their pollen and nectar provisions.

## Description of the data and file structure

### Osmiini\_survival\_data

This dataset countains data on the survival of Osmiini larvae exposed or not to Asteraceae spines or *Lupinus* alkaloids in their pollen and nectar provisions.

* Year: year of nest collection (2021 or 2022).
* ID: unique identifier for each larva monitored in a given year.
* Species: species name of the larva monitored.
* Stage: whether the monitored larva was introduced to its provision at the larval or egg stage.
* Diet: pollen-host use type of the larva monitored (generalist, Asteraceae specialist, Fabaceae specialist, or cleptoparasite).
* Experiment: sub-experiment to which the larva was assigned (Asteraceae pollen spines: aster or *Lupinus* alkaloids: lup).
* ...