Nanosilica supplementation in tomato increases oviposition on stems and caterpillar mortality in the tomato pinworm

Silicon-induced responses play a key role in plant defense against herbivory, though the underlying mechanisms remain underexplored. In this study, we examined how mesoporous silica nanoparticles (MSNs) affect tomato (<i>Solanum lycopersicum</i>) defense against an invasive and highly destructive lepidopteran herbivore, the tomato pinworm (TPW), <i>Phthorimaea absoluta</i>. In tomato plants supplemented with MSN, prior exposure to TPW oviposition shifted subsequent egg-laying from a preference for leaves to an even distribution between stems and leaves. This shift was not observed in nonsilicon-supplemented plants. Prolonged oviposition triggered pigmentation in the basal cells of type I glandular trichomes on the stems of silicon-supplemented plants. Chemical analysis by coupled gas chromatography-mass spectrometry revealed that the pigmented trichome was rich in soluble sugars (sucrose and l-arabinose) and waxes, dominated by the saturated hydrocarbon tetracosane. Bioassays with the crude extract of the pigmented trichome and a three-component sugar-wax blend replicated the oviposition and caterpillar response observed with the pigmented trichome, while individual components produced variable effects. While l-arabinose alone replicated the oviposition effects of the three-component sugar-wax blend, sucrose increased oviposition and caterpillar feeding and survival, while l-arabinose and tetracosane caused the highest caterpillar mortality. Additionally, these treatments altered caterpillar gut microbiota composition and influenced frass volatiles, which attracted the TPW natural enemies, <i>Nesidiocoris tenuis</i> (predator) and <i>Neochrysocharis formosa</i> (parasitoid). Our findings suggest that silicon supplementation increases tomato defense against TPW through oviposition-induced responses, which promotes recruitment of natural enemies.