Ploidy determination in Bombus terrestris males: cost-efficiency comparison among different techniques

Diploid males represent a cost for the viability of populations in haplodiploid species with a single-locus complementary sex determination system. In such social species as bumble bees, their presence affects colony growth and reproduction, therefore, the detection of diploid males is an important aspect to implement conservation actions and for the breeding companies of this important pollinator. In this study, we applied and compared the effectiveness of morphological analyses (sperm count and testis area) with wing morphometrics (traditional and geometric) and genetic techniques (microsatellite analysis) to discriminate between diploid and haploid males originated from laboratory-reared B. terrestris colonies. Among the five techniques, microsatellite analyses and wing geometric morphometrics showed the highest efficiency in ploidy assignment and resulted in the most valuable methods according to a cost-effectiveness analysis.