Morphology and nesting behavior of Xylocopa rufipes (Hymenoptera: Apidae)
HE Chun-Ling1,*, ZHU Chao-Dong2, WU Yan-Ru2
(1. College of Forestry, Henan University of Science and Technology, Luoyang, Henan 471023, China; 2. Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China)
Abstract 【Aim】 To study the morphology and nesting behavior of Xylocopa rufipes Smith, so as to provide a theoretical basis for the conservation and management of carpenter bees. 【Methods】 A sweep net was used to collect X. rufipes adults. The nesting sites and nest substrates of X. rufipes were observed through visual observation and photographing in different regions, and the morphological indexes and the structure and composition of nests of X. rufipes were measured with vernier caliper. The number of foundresses within nests was determined by counting the number of foundresses contained within destructively sampled nests and by observation of female adults as they entered or exited nest entrances. 【Results】 Male and female adults of X. rufipes exhibited some important differences in body shape. Two spines on the outer apex of the hindtibia of female adults distinguished females of subgenus Bomboixylocopa, to which X. rufipes belongs, from all other Xylocopa species. Under natural conditions, X. rufipes chose nesting sites in wood girder trusses on old houses and temporary wood sheds, or firewood piles. Nesting substrates of X. rufipes were mainly dry woods of spruce, paulownia and cotton wood. Nest structure of X. rufipes was mainly divided into two types, i.e., the branched and unbranched, which were accounting for 73.91% and 26.09%, respectively. The entrance hole of nests penetrates the wood inclined to the grain (acute angle). It was nearly round. There were 1-10 tunnels per nest, with 1-8 cells (3.63±2.08 on average) per branch tunnel. The cell length was 15.37±0.22 mm (10.66-21.98 mm on average), the cell diameter was 12.33±1.08 mm (9.79-14.40 mm on average), and the thickness of cell partition was 5.09±0.13 mm (1.87-8.31 mm on average). Destructively sampled nests contained 0-6 live female adults with a mean of 2.08±1.61 live foundresses per nest (n=13 nests). Based on the observed female adults entering and exiting nests in the field in 2014, 2015, and 2016, the average number of females per nest was 2.48±1.24 (n=23 nests). 【Conclusion】 X. rufipes is socially polymorphic with both solitary and social nests in the same population.