Predation on velvet ants (Hymenoptera : Mutillidae) by Texas hornedlizards (Phrynosoma cornutum)

摘要

Most velvet ants are brightly colored and conspicuous. These wasps possess numerous defensive adaptations, including a well-developed sting in the females (Evans and Eberhard, 1970; Schmidt and Blum, 1977). Certain species of velvet ants exhibit aposematic coloration, mimicry, or are cryptically colored, but these implied functions have not been tested (Cockerell, 1895). In an earlier study of predation on velvet ants, Manley (1984) suggested that insectivorous lizards such as Sceloperus roadster Hallowell and Dipsosaurus dorsalis (Baird and Girard) may prey on terrestrially active velvet ants. Because Texas horned lizards, Phyrnosoma cornutum, typically feed on ants of the genus Pogonomyrmex, and because Dasymutilla dilucida is one of several velvet ant species that are ant mimics, we endeavored to see if adult Texas horned lizards would feed on these and other velvet ants. It should be duly noted that these were only preliminary observations, and that they were not replicated experiments. Studies were conducted at the Southwestern Research Station near Portal, Arizona. Both lizards and velvet ants were collected locally. At 1500 h on 18 July 1992, two horned lizards were fed Pogonomyrmex to induce feeding; large numbers of ants were introduced into an outdoor enclosure (Sherbrooke, 1995). Female velvet ants of 4 species were then dropped simultaneously into the enclosure with horned lizards and ants. Two specimens of each species were used. Velvet ants used were the bright orange Dasymutilla chiron (Mickel, 1928), the dark and rather plain-looking D. diludda (Mickel, 1928), the scarlet D. foxi (Cockerell and Casad, 1894), and the white colored and hirsute D. gloriosa (Cockerell, 1895). Both D. chiron and D. foxi apparently possess aposematic or warning coloration, D. gloriosa possesses cryptic coloration (resembling fruits of the creosotebush, Larrea), and D. dilucida is an ant mimic.