Behavioral Asymmetries Affecting Male Mating Success in Tenebrio molitor (Coleoptera: Tenebrionidae), an Important Edible Species.

The yellow mealworm, Tenebrio molitor L., is one of the most significant insect species of economic importance for producing protein-rich food and feed. The larvae are a promising fishmeal substitute for fish feed, and a good alternative source for human nutrition. In this study, the effect of behavioral asymmetries on male mating success of T. molitor was evaluated. Males performing antennal waving (63%) when detecting a female approached the apex of the female abdomen in a comparable manner from both sides (32% from left side vs 31% from right side). Fewer males showed antennal waving and also raised the anterior part of their body (37%) during mate recognition; 14% of them approached on the apex of female abdomen from the left side, and 23% of them approached from the right side of female body. The duration of mate recognition, antennal tapping, rubbing behavior, and the whole mating sequence of males that moved on the apex of the abdomen from the left side of females was significantly lower over that of males approaching from the right side (10.7, 12.6, 16.4, and 126.1 s for left-biased males vs 12.2, 14.8, 18.6, and 139.6 s for right-biased males, respectively). Concerning mounting side, left-biased males showed a shorter duration of rubbing behavior and the whole mating sequence (15.5 and 123.2 s) over right-biased (18.9 and 138.3 s) and backside approaching males (19.4 and 144.1 s). The duration of mate recognition, antennal tapping, and copula was not affected by the presence of a male laterality bias. Overall, this study sheds light on how laterality affects mating traits and the male success of this important edible insect species.