Sexual dimorphism of brown marmorated stink bug

The brown marmorated stink bug is a relatively new member of the Croatian entomofauna, whose biology and ecology are still being researched. The species is known for its polyphagy and is invasive, as evidenced by damage to field, vegetable, and fruit crops around the world. The aim of this study was to determine the sexual dimorphism of Halyomorpha halys based on phenotypic characters on the dorsal and ventral sides of the body. Sixty individuals of each sex were isolated. Each individual was photographed from the dorsal and ventral sides using a digital camera, then the forewing and hindwing pairs were removed, mounted on microscope slides, and photographed. Photographs of the dorsal side of the body were used to measure the values of body length, pronotum width, body surface area, and the surfaces of the forewing and hindwing pairs. Differences on the ventral side of the body were determined by visual inspection. The results of the study showed that males and females differed statistically in all measurements and that the species exhibited female-biased sexual size dimorphism. These traits (larger and more powerful physique and especially wings) make females the more suitable sex for migratory flight and thus responsible for the rapid expansion of the population into new areas. Differences between the sexes have also been noted in coloration on the ventral side of the body. The red pigmentation of the sternum was much more pronounced in males than in females, further confirming the sexual dimorphism of the species in body coloration.