Butterflies and moths are conspicuous flower visitors but their role in plant-pollinator interactions has rarely been quantified, especially in tropical rainforests. Moreover, we have virtually no knowledge of environmental factors affecting the role of lepidopterans in pollination networks. We videorecorded flower-visiting butterflies and hawkmoths on 212 plant species (> 26,000 recorded hrs) along the complete elevational gradient of rainforests on Mount Cameroon in dry and wet seasons. Altogether, we recorded 734 flower visits by 80 butterfly and 27 hawkmoth species, representing only ~ 4% of all flower visits. Although lepidopterans visited flowers of only a third of the plant species, they appeared to be key visitors for several plants. Lepidopterans visited flowers most frequently at mid-elevations and dry season, mirroring their local elevational patterns of diversity. Characteristics of interaction networks showed no apparent elevational or seasonal patterns, probably because of the high specialisation of all networks. Significant non-linear changes of proboscis and forewing lengths were found along elevation. A positive relationship between the lengths of proboscis of hesperiid butterflies and tube of visited flowers was detected. Differences in floral preferences were found between sphingids and butterflies, revealing the importance of nectar production, floral size and shape for sphingids, and floral colour for butterflies. The revealed trait-matching and floral preferences confirmed their potential to drive floral evolution in tropical ecosystems.

The crucial role of microbes in the evolution, development, health, and ecological interactions of multicellular organisms is now widely recognized in the holobiont concept. However, the structure and stability of microbiota are highly dependent on abiotic and biotic factors, especially in the gut, which can be colonized by transient bacteria depending on the host’s diet. We studied these impacts by manipulating the digestive microbiota of the detritivore Armadillidium vulgare and analyzing the consequences on its structure and function. Hosts were exposed to initial starvation and then were fed diets that varied the different components of lignocellulose. A total of 72 digestive microbiota were analyzed according to the type of the diet (standard or enriched in cellulose, lignin, or hemicellulose) and the period following dysbiosis. The results showed that microbiota from the hepatopancreas were very stable and resilient, while the most diverse and labile over time were found in the hindgut. Dysbiosis and selective diets may have affected the host fitness by altering the structure of the microbiota and its predicted functions. Overall, these modifications can therefore have effects not only on the holobiont, but also on the “eco-holobiont” conceptualization of macroorganisms.

1. Butterflies and moths are well-visible flower visitors. Nevertheless, almost no quantification of their role in plant-pollinator interactions exists at a community level, especially from tropical rainforests. Moreover, we have virtually no knowledge on environmental and other factors affecting lepidopteran flower visits. 2. We focused on the role of butterflies and hawkmoths as flower visitors in tropical rainforests of Mount Cameroon, especially on its elevational and seasonal changes. We also analysed their preferences to selected floral traits, with a specific focus on pollination syndromes. 3. We video-recorded flower visitors of 1,115 specimens of 212 plant species (>26,000 recording hrs) along the complete elevational gradient of rainforests in two main seasons, and compared frequencies of flower-visiting lepidopterans to other visitors. We compared characteristics of plant-lepidopteran networks among elevations and seasons, and analysed patterns of selected lepidopteran traits. Finally, we analysed inter-family differences in their floral preferences. 4. Altogether, we recorded 734 flower visits by 80 butterflies and 27 hawkmoth species, representing only ~4% of all 18,439 flower visits. Although lepidopterans visited only a third species, they appeared key visitors of several plants. The most flower visits by lepidopterans were recorded in mid-elevations and dry season, mirroring the general patterns of lepidopteran diversity. The networks showed no apparent elevational or seasonal patterns, probably because of the surprisingly high specialisation of interactions in all networks. Significant non-linear changes of proboscis and forewing lengths were found along elevation, and long-proboscid hesperiid butterflies visited flowers with longer tubes or spurs. Substantial differences in floral preferences were found between sphingids, and papilionid, nymphalid and lycaenid butterflies, revealing importance of nectar production, floral size and shape for sphingids, and floral colour for butterflies. 5. Butterflies and hawkmoths were confirmed as relatively minor visitors of tropical forest flowers, although they seemed crucial for pollination of some plant species. Moreover, the revealed floral preferences and trait-matchings confirmed a potential of some lepidopteran families to drive floral evolution in tropical ecosystems.