Study of volatile chemical constituents and insect-plant interaction in Piper mollicomum Kunth (Piperaceae) from Tijuca Forest, Rio de Janeiro - RJ, Brazil

Abstract

The aim of this work was to investigate the seasonal variation of essential oils (EOs) from leaves, inflorescences and infrutescences of Piper mollicomum Kunth and to identify which chemical and abiotic factors correlate with the frequency of visitation of their potential pollinators. The EOs were obtained by hydrodistillation in a modified Clevenger apparatus characterized and quantified by Gas Chromatography coupled to Mass Spectrometry (GC-MS) and by GC coupled to Flame Ionization Detector (GC-FID). Observations were made weekly, from October 2019 to February 2020, totaling 112.5 h. The main compounds present in the EOs were identified as 1,8-cineole (16.22 to 36.66%) and linalool (1.59 to 20.05%). Eupatoriochromene showed a distinction between leaves (0.81 to 3.66%) and reproductive parts (16.57 to 64.35%). The weekly observations revealed a high frequency of bee visits, and the results related to Spearman's correlation (potential pollinators versus major constituents) showed a strong positive correlation between constant insect visits and percentage of linalool and E-nerolidol in the inflorescences, in addition to negative correlation with germacrene D. A strong negative correlation was observed between humidity and the frequency of bee visits.