Sexual Behavior of the Desert Locust During Intra- and Inter-Phase Interactions

Mating and reproduction behaviors and strategies are fundamental aspects of an organism’s evolutionary and ecological success. In locusts, intra- as well as inter-phase reproductive interactions among gregarious and solitarious locust populations have a major impact on the locust population dynamics. However, practically all previous work on locust sexual behavior has been limited to the gregarious phase. Here we provide a first detailed description of pre-copulatory behavior of solitarious desert locusts. We compare our findings with those of previous reports of pre-copulatory behavior of gregarious locusts, focusing on the behavioral elements that serve in inter-sex signaling and communication. We also studied inter-phase (mixed pairs) reproductive interactions. Solitarious males were found to invest more in pre-copulatory courtship and signaling compared to their gregarious counterparts; and solitarious females played a more dominant role in the inter-sex communication than gregarious females. The solitarious females were also less likely to demonstrate rejection-related behavioral patterns than gregarious females. As a consequence of the particular characteristic behavior of each phase, the most successful among intra- and inter-phase pairs were gregarious males with solitary females. Least successful were solitary males paired with gregarious females, indicating a strong asymmetry in inter-phase reproductive interactions.