Spatiotemporal variation in the role of floral traits in shaping tropical plant-pollinator interactions.

The pollination syndrome hypothesis predicts that plants pollinated by the same pollinator group bear convergent combinations of specific floral functional traits. Nevertheless, some studies have shown that these combinations predict pollinators with relatively low accuracy. This discrepancy may be caused by changes in the importance of specific floral traits for different pollinator groups and under different environmental conditions. To explore this, we studied pollination systems and floral traits along an elevational gradient on Mount Cameroon during wet and dry seasons. Using Random Forest (Machine Learning) models, allowing the ranking of traits by their relative importance, we demonstrated that some floral traits are more important than others for pollinators. However, the distribution and importance of traits vary under different environmental conditions. Our results imply the need to improve our trait-based understanding of plant-pollinator interactions to better inform the debate surrounding the pollination syndrome hypothesis.

Analysis of Thaumatotibia leucotreta (Lepidoptera: Tortricidae: Olethreutinae) mitochondrial genomes in the context of a recent host range expansion.

BACKGROUND: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick, 1913), is a significant pest of various important economic crops and is a EU quarantine pest. In the last decade the pest has been reported on Rosa spp. In this study we determined whether this shift occurred within specific FCM populations across seven eastern sub-Saharan countries or whether the species opportunistically switches to this novel host as it presents itself. To achieve this, we assessed the genetic diversity of complete mitogenomes of T. leucotreta specimens intercepted at import and analysed potential linkages with the geographical origin and host species. RESULTS: Genomic, geographical and host information were integrated into a T. leucotreta Nextstrain build which contains 95 complete mitogenomes generated from material intercepted at import between January 2013 and December 2018. Samples represented seven sub-Saharan countries and mitogenomic sequences grouped in six main clades. DISCUSSION: If host strains of FCM would exist, specialization from a single haplotype towards the novel host is expected. Instead, we find specimens intercepted on Rosa spp. in all six clades. The absence of linkage between genotype and host suggests opportunistic expansion to the new host plant. This underlines risks of introducing new plant species to an area as the effect of pests already present on the new plant might be unpredictable with current knowledge.

Differences in Nectar Traits between Ornithophilous and Entomophilous Plants on Mount Cameroon.

Despite a growing number of studies, the role of pollinators as a selection agent for nectar traits remains unclear. Moreover, the lack of data from some biogeographic regions prohibits us from determining their general importance and global patterns. We analyzed nectar carbohydrate traits and determined the main pollinators of 66 plant species in the tropical forests of Mount Cameroon (tropical West Africa). The measured nectar traits included total sugar amounts and proportions of sucrose and hexoses (i.e., glucose and fructose). We report the nectar properties for plants visited by five pollinator groups (bees, butterflies, moths, hoverflies, and specialized birds). Our results indicate that, rather than specific evolution in each of the five plant groups, there was a unique nectar-trait evolution in plants pollinated by specialized birds. The ornithophilous plants had a higher proportion of sucrose and produced larger sugar amounts than the plants pollinated by insects. We also demonstrated a significant phylogenetic signal in the nectar properties in some lineages of the studied plants.

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

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.

First records of 31 species of butterflies and moths (Lepidoptera) in Cameroon, with remarks on their elevational ranges.

BACKGROUND: The biodiversity of West and Central Africa is understudied, including butterflies and moths (Lepidoptera). Cameroon, through its position in between few biogeographic regions and diversity of habitats, is an important hotspot of lepidopteran diversity. However, the country also ranks low when it comes to local biodiversity knowledge. During our long-term ecological projects in the Cameroonian part of the Gulf of Guinea Highlands, we collected rich material of butterflies and moths, including a number of interesting faunistic records. NEW INFORMATION: In this study, we report 31 species of butterflies and moths which have not yet been recorded in Cameroon. These species comprised eight new genera records for the country. In many cases, our records represented an important extension of the species' known distribution, including ten species whose distribution ranges extended into the Guinean biogeographic region. We also comment on the species' elevational distribution ranges on Mount Cameroon where most of our records originated. Additionally, we confirm the presence of a butterfly Telchinia encedena, after more than a century since its first and so far its only record in Cameroon.

The role of ultraviolet reflectance and pattern in the pollination system of Hypoxis camerooniana (Hypoxidaceae).

Apart from floral morphology and colours perceived by the human eye, ultraviolet (UV) reflectance acts as an important visual advertisement of numerous flowering plant species for pollinators. However, the effect of UV signalling on attracting pollinators of particular plant species is still insufficiently studied, especially in the Afrotropics. Therefore, we studied the pollination system of Hypoxis camerooniana in montane grasslands of Mount Cameroon, West/Central Africa. We focused mainly on the effects of the flowers' UV reflectance on its visitors. We experimentally removed UV reflection from petals either completely or partially. Thereafter, flower visitors were recorded and pistils were collected post-flowering to quantify germinated pollen tubes per treatments. The most important visitors were bees, followed by flies. Due to their contacts with reproductive organs bees are considered as the primary pollinators. Visitation rates were lower when UV reflectance was completely removed, whereas the decrease of frequency on half-treated flowers did not differ significantly from control treatments. The complete removal of UV also affected bees' landing behaviour, but not that of flies. We showed that the presence of UV reflectance is more important than UV pattern for bees visiting flowers of H. camerooniana. We hypothesize that exploiting all flowers irrespective of their pattern can be more efficient for pollinators in the open grasslands of high altitudes to spot these relatively scarce flowers by their UV reflectance. Furthermore, we highlight the necessity of both experimental and natural controls in similar studies to control for additional effects of the used UV manipulations. Many plants advertise their flowers with UV reflectance visible to their insect visitors. By manipulating the UV reflectance and pattern of Hypoxis camerooniana in the Afromontane grasslands of Mount Cameroon, we have shown how crucial it is for the predominant visitor, bees. Both bees' preferences for flowers and their behaviour during visits are influenced by changes in UV reflectance. However, the presence of some UV signal is more important than the specific pattern. Especially in montane grasslands with higher UV irradiation, the UV floral colours are important for recognition of flowers by potential pollinators.

The use of low cost compact cameras with focus stacking functionality in entomological digitization projects.

Digitization of specimen collections has become a key priority of many natural history museums. The camera systems built for this purpose are expensive, providing a barrier in institutes with limited funding, and therefore hampering progress. An assessment is made on whether a low cost compact camera with image stacking functionality can help expedite the digitization process in large museums or provide smaller institutes and amateur entomologists with the means to digitize their collections. Images of a professional setup were compared with the Olympus Stylus TG-4 Tough, a low-cost compact camera with internal focus stacking functions. Parameters considered include image quality, digitization speed, price, and ease-of-use. The compact camera's image quality, although inferior to the professional setup, is exceptional considering its fourfold lower price point. Producing the image slices in the compact camera is a matter of seconds and when optimal image quality is less of a priority, the internal stacking function omits the need for dedicated stacking software altogether, further decreasing the cost and speeding up the process. In general, it is found that, aware of its limitations, this compact camera is capable of digitizing entomological collections with sufficient quality. As technology advances, more institutes and amateur entomologists will be able to easily and affordably catalogue their specimens.