Hunting behavior by the sand wasp rubrica nasuta (christ 1791) (hymenoptera sphecidae)

Abstract

Rubrica nasuta (Christ 1791) is a solitary wasp that feeds its larvae progressively with adults of at least eight families of flies: Tabanidae, Stratiomyidae, Asilidae, Bombyliidae, syrphidae, Calliphoridae, Tachinidae, and Muscidae. The wasps showed two tactics of searching for prey: a continuous search for flies sparsely distributed in pathways; a restricted search in more profitable patches. In the former, the wasps were seen alongside dirt-roads and in places with open vegetation, flying about 30 cm above the ground. In the latter, restricted searching was observed wherever large quantities of flies were found, for instance, over ephemeral resources like flowers or feces. Restricting the search to a patch could be more profitable but requires previous information about the distribution of the patches. This information could be gained when the wasps are engaged in continuous searching. The R. nasuta searching flight was performed around obstacles, like twigs and leaves, where potential prey could be perching. Once a prey is detected, the wasp hovered to position itself about 25 cm away from and 10 cm lower than the prey. Afterwards, the wasp flew straight towards the prey. Only one successful attack was observed, in which the wasp could be seen stinging the prey at least twice in its ventral side. Some special observations on predator-prey interactions are also described. Considering the great behavioral differences of R. nasuta’s prey, the use of various searching and attack tactics may strongly affect prey selection. © 2002 by the Society of Vertebrate Paleontology.