Discrimination of the bumblebee species Bombus lucorum, Bombus cryptarum and Bombus magnus by morphological characters and male labial gland secretions (Hymenoptera: Apidae).

Abstract

Spring queens of B. lucorum, B. cryptarum and B. magnus from 2 localities in Brandenburg/Germany and Scotland/United Kingdom respectively were determined by morphological characteristics. The lateral border of the collare at the border of the pronotallobus or at the episternum proved to be an especially useful character. Queens with fresh colour can be determined safely; they are good morphospecies without overlap of characters. Distribution maps (EE) for B. cryptarum and B. magnus from Berlin and Brandenburg are given. From the catch dates available the spring phenology of the queens flight activity is reconstructed. Queens of B. cryptarum emerge early in spring, their activity is 2-3 weeks ahead of B. magnus. Artificial colonies were reared from safely determined spring queens and the cephalic part of the labial glands of males from these colonies was investigated by GC/MS. About 50 compounds were determined, a mixture of straight chain fatty acid derivatives (alcohols, esters and hydrocarbons). By the labial gland secretions three different taxa can be distinguished. The labial gland secretions of males of B. magnus from Scotland and Brandenburg are identical the species recognition signals are stable over extended area. The labial gland secretions of males of B. cryptarum from Brandenburg and of males from artificial colonies reared from safely determined spring queens from Scotland are also identical, B. cryptarum has been identified to be part of the British bumble bee fauna for the first time. The differences of the labial gland secretions used as species recognition signals confirm the morphological findings, B. lucorum, B. cryptarum and B. magnus are good species.