The Size But not the Symmetry of the Wings of Eulaema nigrita Lepeletier (Apidae: Euglossini) is Affected by Human-Disturbed Landscapes in the Brazilian Cerrado Savanna

Abstract

Among other human-related activities, habitat loss and fragmentation are currently ranked as the most important environmental features affecting the persistence of animal and plant populations in landscapes, as well as the maintenance of ecological processes and services. Since these processes are also capable of affecting the ontogenetic development of species inhabiting those landscapes, here we measured the wing veins of male Eulaema nigrita Lepeletier (Apidae: Euglossini) bees in order to evaluate whether the bees sampled in agriculture (AG) areas suffer higher fluctuating asymmetry (FA) than those sampled in Cerrado (CE) areas in the Brazilian state of Goiás. We believe that individuals sampled in CE areas would be less asymmetric than those sampled in AG areas, given a potential higher exposure of these specimens to environmental stresses (mostly pesticides). However, we did not observe a significant trend in the FA measures we obtained, although three wing measures were bigger for bees from CE areas. The lack of significant effects of FA may be related to inherent bionomic features of E. nigrita. For instance, given their high individual dispersal abilities, the individuals we analyzed may have developed in different areas than those where they were sampled. Their generalist feeding behavior may also have given them a higher resistance to environmental perturbations, buffering the normal development of immatures even in areas with local high environmental stress. Nonetheless, higher death rates of individuals from anthropic areas may also have killed the developing immatures of E. nigrita before they reached adulthood consequently equalizing our sampled estimates.

Forewing structure of the solitary bee Osmia bicornis developing on heavy metal pollution gradient

“…These results are in agreement with other studies, showing that both the damselfly Argia tinctipennis (Pinto et al 2012 ) and the Neotropical orchid bee Eulaema nigrita L. (Pinto et al 2015 ) caught in degraded or agriculturally intensively managed habitats remained unaffected by environmental stress, although their wing sizes were smaller due to these stressors. In our study, the bees were developing directly under pollution stress, while in Pinto’s study ( 2015 ) the test bees were caught in the degraded environment, but there was no information about where they actually developed. Orchid bees can cover large distances and adult individuals present in a certain area can originate and develop in other, distant areas (Pokorny et al 2015 ).…”

Urbanisation and wing asymmetry in the western honey bee (Apis mellifera, Linnaeus 1758) at multiple scales

“…A Bonferroni adjusted alpha of 0.0013 was used to account for multiple comparisons. If the left right differences in these either centroid size or Procrustes coordinates 1 through 38 deviated significantly from zero, we concluded directional asymmetry was present in wing size and shape, respectively ( Pinto et al, 2015 ).…”

“…Indeed, red mason bees ( Osmia bicornis , Linnaeus 1758, Hymenoptera, Megachilidae) collected along a zinc, cadmium, and lead contamination gradient in Poland show no difference in wing size or shape asymmetry ( Szentgyörgyi et al, 2017 ). Similarly, euglossine bees ( Eulaema nigrita, Lepoletier 1841, Hymenoptera, Apidae) collected from agricultural landscapes where pesticide use is prevalent did not record higher fluctuating asymmetry than individuals collected from a tropical savannah ( Pinto et al, 2015 ). In carabid beetles, individuals display a species dependent effect of urbanization on elytra size asymmetry with ubiquitous species like Nebria brevicollis (Fabricuis, 1792, Coleoptera, Carabidae), and Leistus rufomarginatus (Duftschmid, 1812, Coleoptera, Carabidae) exhibiting no effect, yet other species including Platynus obscurus (Herbst, 1784, Coleoptera, Carabidae) and Leistus ferrugineus (Linnaeus 1758, Coleoptera, Carabidae) showing increased asymmetry with decreasing distance towards the city centre ( Weller & Ganzhorn, 2004 ).…”

Stressful conditions reveal decrease in size, modification of shape but relatively stable asymmetry in bumblebee wings

“…This type of asymmetry has been thought to be adaptive and genetically determined 16 but see 15 . Besides asymmetry, shift in overall wing shape, size and increase in trait variances have been reported under stressful conditions and have then been proposed as stress indicators 17 – 19 , although they have been very poorly investigated.…”