Floral Volatiles: A Promising Method to Access the Rare Nocturnal and Crepuscular Bees

Carlos A Martínez-Martínez,Clemens Schlindwein,Cristiane Krug,Emanuella L Franco,Paulo Milet-Pinheiro,Renan O A C Kobal,Sidnei Mateus,Guaraci D Cordeiro,Herbeson O J Martins,Mariana A Stanton,Stefan Dötterl,Isabel Alves-Dos-Santos

doi:10.3389/fevo.2021.676743

Abstract

Crepuscular and/or nocturnal bees fly during the dusk, the dawn or part of the night. Due to their short foraging time and sampling bias toward diurnal bees, nocturnal bees are rarely collected and poorly studied. So far, they have been mostly sampled with light and Malaise traps. However, synthetic chemical compounds resembling floral volatiles were recently found to be a promising alternative to attract these bees. By reviewing available literature and collecting original data, we present information on the attraction and sampling of nocturnal bees with scent-baited traps. Bees were actively captured with entomological nets while approaching to filter papers moistened with distinct chemical compound, or passively caught in bottles with scent baits left during the night. So far, all data available are from the Neotropics. Nocturnal bees belonging to three genera, i.e., Ptiloglossa, Megalopta, and Megommation were attracted to at least ten different synthetic compounds and mixtures thereof, identified from bouquets of flowers with nocturnal anthesis. Aromatic compounds, such as 2-phenyletanol, eugenol and methyl salicylate, and the monoterpenoid eucalyptol were the most successful in attracting nocturnal bees. We highlight the effectiveness of olfactory methods to survey crepuscular and nocturnal bees using chemical compounds typically reported as floral scent constituents, and the possibility to record olfactory preferences of each bee species to specific compounds. We suggest to include this method in apifauna surveys in order to improve our current knowledge on the diversity of nocturnal bees in different ecosystems.

Highlights

The nocturnal and/or crepuscular behavior in bees arose independently in four of the seven bee families: Andrenidae, Apidae, Colletidae, and Halictidae (Wcislo et al, 2004; Warrant, 2007; Danforth et al, 2019)
A systematic review of the literature on nocturnal bees lured with chemical compounds was conducted on Google Scholar, JSTOR, NCBI, Scopus, and Web of science, with the following combinations of keywords: “Compounds” OR “Chemical lures” OR “Floral scent” OR “Floral volatile” OR “Nocturnal bees” OR “Nocturnal and Crepuscular bees” OR “Nocturnal anthesis” OR “Volatile organic compounds.”
The nocturnal bees were mostly sampled with bottles scent traps left during the night

Summary

Introduction

The nocturnal and/or crepuscular behavior in bees arose independently in four of the seven bee families: Andrenidae, Apidae, Colletidae, and Halictidae (Wcislo et al, 2004; Warrant, 2007; Danforth et al, 2019). The main anatomical characteristics that indicate nocturnal and/or crepuscular behavior in these bees are the large size of their ocelli and compound eyes, as well as the high number of ommatidia (Kelber et al, 2006; Warrant et al, 2006; Berry et al, 2011), characteristics that improve visual orientation in low light conditions (Wcislo et al, 2004). During pollination studies at night, nocturnal bees are recorded on flowers (Hopkins et al, 2000; Somanathan and Borges, 2001; Franco and Gimenes, 2011; Krug et al, 2015; Cordeiro et al, 2017; Soares and Morellato, 2018, Cordeiro et al, 2021)

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