DOI: 10.5061/dryad.h44j0zpsx
title: Pollen chemical and mechanical defences restrict host-plant use by bees

description: 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 being more tolerant of the pollen defences of their hosts,
 relative to the defences of plant taxa exploited by other species. This
 pattern strongly suggests that bees are adapted to the pollen defences of
 their hosts, and that host-plant use by bees is constrained by their
 ability to tolerate such defences.
description: # 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). * Treatment: whether the larva was a
 control (C) or a treatment (T). * Site: site from which the nest was
 collected. * Bloc: identifier of the artificial nesting structure from
 which the nest was collected. * Nest: identifier of the hole within a
 given artificial nesting structure from which the nest was collected. Only
 one nest was present in each hole. The letter "x" was given to
 nests for which information on their position within the bloc was missing.
 * Cell: identifier of the cell (each containing one egg and a pollen and
 nectar provision) within a given nest. * Date.transferred: date at which
 the provision was manipulated and the egg was put on the manipulated
 provision. This corresponds to the start of larval monitoring. The number
 indicates the day of the month, and the letters correspond to the month in
 roman numerals. * days.to.event: number of days before the larva either
 died or started spinning its cocoon. * status: whether the larvae either
 died (2) or reached the cocoon spinning stage (1). ## Code/Software ###
 osmiini\_survival R code for the analysis of Osmiini survival data. The
 code contains models of the effect of Asteraceae pollen spines and
 *Lupinus* pollen alkaloids on the survival probability of 9 species of
 bees in the Osmiini tribe and their cleptoparasite (sapyga. sp).