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bioRxiv · 10.1101/2020.06.29.178319

Chemical convergence in a guild of facultative myrmecophilous caterpillars and host plants

Dias Lima, L.·Trigo, J.·Kaminski, L. A.
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Abstract

O_LIAnts exert a strong selective pressure on herbivorous insects, although some caterpillars can live in symbiosis with them using chemical defensive strategies. C_LIO_LIWe investigated the adaptive resemblance of cuticular hydrocarbons (CHCs) in multitrophic systems involving a guild of facultative myrmecophilous caterpillar species (Lepidoptera: Lycaenidae), tending ants (Hymenoptera: Formicidae) and host plants from three families. We hypothesized that the CHCs of the caterpillars would resemble those of their host plants (chemical camouflage). C_LIO_LIWe analyzed CHCs using gas chromatography/mass spectrometry. Morisitas similarity index (SI) was used to compare CHC profiles of caterpillar species with different types of ant associations (commensal or mutualistic), ants and host plants. C_LIO_LIWe found strong convergence between caterpillars CHCs and plants, especially for commensal species that do not provide secretion rewards for ants. Moreover, we found unexpected chemical convergence among mutualistic caterpillar species that offer nectar reward secretions to ants. C_LIO_LIThese results show that the studied caterpillars acquire CHCs through their diet and that they vary according to host plant species and type of ant association (commensalism or mutualism). This chemical camouflage of myrmecophilous caterpillars may have arisen as a defensive strategy allowing coexistence with ants on plants, whereas chemical conspicuousness may have evolved in the context of honest signaling between true mutualistic partners. C_LIO_LIWe suggest the existence of both Mullerian and Batesian chemical mimicry rings among myrmecophilous caterpillar species. Cuticular chemical mixtures can play a key adaptive role in decreasing ant attacks and increasing caterpillar survival in multimodal systems. C_LI Graphical abstractO_LIChemical camouflage can be a defensive strategy of myrmecophilous caterpillars against ants. C_LIO_LI Chemical conspicuousness is proposed as a new strategy mediated by cuticular hydrocarbons in myrmecophilous caterpillars. C_LIO_LIChemical mimicry rings can occur between myrmecophilous caterpillars and especially between mutualistic species that produce nectar rewards for ants. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/178319v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@dd7e3corg.highwire.dtl.DTLVardef@18ab669org.highwire.dtl.DTLVardef@1cdae71org.highwire.dtl.DTLVardef@7783cb_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Dias Lima, L., Trigo, J., Kaminski, L. A.. 2020-06-30. Chemical convergence in a guild of facultative myrmecophilous caterpillars and host plants. https://doi.org/10.1101/2020.06.29.178319

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