Hovering and standing guards: nest defense strategies in a polymorphic stingless bee (Tetragonisca angustula)

Abstract The stingless bee, Tetragonisca angustula, has a sophisticated nest defense strategy carried out by guards that are larger compared to other workers. Guards display two different strategies: flying near the colony entrance (hovering guards) or positioning themselves at the entrance tube (standing guards). To better understand the roles played by each guard behavioral phenotype in nest defense, we investigated whether their behaviors were distinctly displayed when faced with different threats. We used two types of bait (flying and walking) to simulate threats to the colony and compared the behaviors displayed by the guards in relation to the species used as bait and the guard function. We also investigated if the species and the type of bait influenced the number of guards before and after the presentation. We found a significant interaction between the behaviors displayed by the guards and the bait species. Hovering guards were more influenced by flying baits, and standing guards by walking baits. The presence of Lestrimellita limao caused a high proportion of recruitment and aggressive behavioral responses from guards, confirming specialization against this potential enemy. Our results show that the two behavioral phenotypes are capable of recognition and act with complementary behaviors depending on the threat.