Elevational and seasonal patterns of butterflies and hawkmoths in plant-pollinator networks in tropical rainforests of Mount Cameroon

Jan E J Mertens,Ishmeal N Kobe,Vincent Maicher,Tomasz Pyrcz,Štěpán Janeček,Pavel Potocký,Sylvain Delabye,Szabolcs Sáfián,Lucas Brisson,Yannick Klomberg,Robert Tropek

doi:10.1038/s41598-021-89012-x

Abstract

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.

Highlights

Compared to bees and flies, butterflies and hawkmoths represent minor pollinators in probably all terrestrial ecosystems[3,6]
Based on rich community-wide datasets sampled along the elevational gradient and during the two seasons (Table 1), we set the following aims: (1) To evaluate the role of flower-visiting butterflies and hawkmoths in plant-pollinator networks and understand how elevation and seasonality affect their relative importance in pollination communities
Species richness of all lepidopterans and lycaenids showed a gradual decrease along elevation, whilst sphingids peaked at 350 m a.s.l. (Fig. 1a)

Summary

Introduction

Compared to bees and flies, butterflies and hawkmoths represent minor pollinators in probably all terrestrial ecosystems[3,6] Both groups are often regarded as generalised nectar feeders visiting all available nectar-rich flowers[8,9]. Besides the highly specialised long-proboscid groups such as most sphingids and noctuids, adults of many groups have dysfunctional or even no proboscis[8] Such differences hamper any attempts at quantifying the general pollination role of lepidopterans. Based on rich community-wide datasets sampled along the elevational gradient and during the two seasons (Table 1), we set the following aims: (1) To evaluate the role of flower-visiting butterflies and hawkmoths in plant-pollinator networks and understand how elevation and seasonality affect their relative importance in pollination communities. Based on rich community-wide datasets sampled along the elevational gradient and during the two seasons (Table 1), we set the following aims: (1) To evaluate the role of flower-visiting butterflies and hawkmoths in plant-pollinator networks and understand how elevation and seasonality affect their relative importance in pollination communities. (2) To analyse the elevational and seasonal changes in the structure of the pollination networks, with a specific focus

Methods

Results

Conclusion