DOI: 10.5061/dryad.37dv8
title: Data from: Differential aphid toxicity to ladybeetles is not a function of host plant or facultative bacterial symbionts

description: Herbivores often defend themselves from predation by transmitting toxic
 plant-produced chemicals to their enemies. Polyphagous herbivores
 sometimes exhibit differential toxicity when found on various host plant
 species, which is generally assumed to reflect variation in plant
 chemistry. Here, however, we provide evidence that host-associated
 herbivore lineages can intrinsically differ in their toxic properties.
 Lineages of Aphis craccivora originating from black locust (Robinia
 pseudoacacia) are unsuitable food for the ladybeetle Harmonia axyridis,
 resulting in death of both larvae and adults, whereas aphid lineages
 originating from alfalfa (Medicago sativa) support larval development and
 adult reproduction. We show that locust-origin aphids remain toxic and
 alfalfa-origin aphids remain non-toxic when reared on any of three legume
 plants (fava, alfalfa or locust). Furthermore, toxicity is not a function
 of the facultative bacterial symbiont Arsenophonus, which is naturally
 present in locust-origin aphid lineages and facilitates aphid use of
 locust. Experimentally cured locust-origin lineages remain toxic, and an
 experimentally transinfected alfalfa-origin lineage remains non-toxic to
 H. axyridis. Instead, Arsenophonus plays an indirect role in the
 distribution of toxic aphid lineages by facilitating aphid use of locust.
 It is the parthenogenetic coinheritance of Arsenophonus and the toxic
 trait that observationally correlates locust-feeding with toxicity in A.
 craccivora, rather than host plant chemistry per se. Our results clearly
 demonstrate that aphid lineages intrinsically vary in their toxic
 properties in a way that neither plant chemistry nor bacterial symbionts
 can explain. A more inclusive paradigm is needed for understanding
 variation in herbivore defence against predators.
description: Aphis craccivora
 suitability for Harmonia axyridisData from experiments
 testing intrinsic suitability of Aphis craccivora to Harmonia axyridis.
 Each experiment is a separate tab (5 tabs total). For all, aphidtrt
 indicates original plant of aphid collection. Current rearing plant
 indicated by tab for each experiment. For larval experiments, each column
 represents developmental status per subsequent day of the experiment (1=
 1st instar, 2= 2nd instar, 3=3rd instar, 4=4th instar, 5=pupa, 6=adult, x
 = dead, a = alive but instar not recorded). Columns all the way to the
 right indicate total survival time (in days), whether the individual was
 censored (alive =1) or not censored (dead =0) at the end of the
 experiment, and if the individual died before the end of the experiment,
 it's instar at death (individuals still alive are indicated with an
 x). For adult experiment, everything the same except columns indicate
 number of eggs per day, with 0 indicating an adult that was alive but
 didn't lay eggs, and x indicating an adult that had died. Total eggs
 in column at the right, plus survival (in days), and whether the beetle
 was alive (censor = 1) or dead (censor = 0) at the end of the experiment.
 For the Arsenophonus experiment, aphids either were infected with
 Arsenophonus (=1), or from colonies that did not have Arsenophonus
 (=0).White_et_al_FE_aphidtoxicity_dataforDryad.xlsx