Sures within the case of host plants containing deleterious chemical substances (red arrows). Even so, the insects may sequester plant compounds, andor generate defensive chemicals themselves, and they’re able to also combine chemical with non-chemical defensive traits, which are all traits ultimately utilised upon attack by organic enemies (green arrows).Boevet al. BMC Evolutionary Biology 2013, 13:198 http:www.EW-7197 web biomedcentral.com1471-214813Page three ofetc. [4,5,15,28-31]. Even a single compound can be multifunctional [32], and different compounds often act in synergy [33]. Much more frequently, dose-dependent effects of a chemical are ubiquitous, as currently observed about 500 years ago by Paracelsus (e.g., [34-36]). Ultimately, the interspecific activity of allelochemicals have led to a subset of names and definitions based on the beneficialdetrimental action with the compounds for the emitter versus receiver, but again, a given compound can fulfill a number of of such ecological functions [37]. To better realize the evolution of chemical defensive strategies in phytophagous insects, we aimed to reconstruct the phylogeny on the Tenthredinidae sawflies, which constitute the main group of herbivorous Hymenoptera, and which show a large diversity in life histories. Tenthredinids exhibit high intimacy with their host plant given that females lay their eggs into the plant tissue [11]. Their larvae generally live freely on plant leaves and are preyed upon by quite a few vertebrate and invertebrate predators [38]. Two distinct chemical defensive strategies are known amongst tenthredinid larvae. Around the one hand, species within the subfamily Nematinae possess eversible PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21338381 ventral glands, which emit a volatile secretion that may be probably aimed mostly against predatory insects and secondarily towards birds [39]. On the other hand, some tenthredinid species, in particular these belonging towards the blennocampine tribe Phymatocerini, are characterized by being able of `easy bleeding’, which is a phenomenon so far unknown from other insects and which is distinct from reflex bleeding [40]. In species capable of simple bleeding, the larval integument readily disrupts beneath exogenous mechanical pressure at any point with the physique [40-42], plus the oozing hemolymph that contains sequestered plant secondary metabolites [14,43-45] is strongly feeding deterrent to biting predators for instance ants and wasps [40,43,46]. Comparative bioassays and modeling with the integument surface structure indicate that quick bleeders are 
more correctly defended against such invertebrate predators than against birds [41,47]. In addition to ventral glands and quick bleeding, alternative or complementary larval defenses incorporate a created pubescence, an integumental secretion layer [48,49], and an endophytic life style by galling, rolling, mining or boring in diverse plant tissues [50,51]. Furthermore, there’s diversity within the cryptic or aposematic appearance, and degree of gregariousness among tenthredinid larvae [39,52,53]. Such a large and diversified range of defensive devices inside this insect group prompted us to search for evolutionary patterns, by seeking an explanatory framework of ecological aspects that would account for this diversity. As a result, we mapped ecological and defensive traits on phylogenetic trees, and tested correlations among character pairs, using the aim to infer the relative effect of invertebrates versus vertebrates in the evolution of chemically-based defenses.Our basic hypothesis was that if vertebrates could be the mai.