Adventures Among Ants - Mark W. Moffett [159]
4. A swarm and column raider like Pheidologeton diversus, P. silenus could also be called a “marauder ant,” but for clarity in this book I restrict this term to diversus. Pheidologeton silenus is in some ways more convergent with army ants: colonies lack stable trails, often abandon half-eaten bonanzas at the end of a raid, and are decisively carnivorous, mostly carving prey into pieces that are then carried by two or three workers. Even with its faster armies, silenus takes less and less diverse food than diversus, with a preference for poky insect larvae. See MW Moffett 1988, Foraging behavior in the Malayan swarm-raiding ant Pheidologeton silenus, Ann. Entomol. Soc. Am. 81: 356–361.
5. MW Moffett 1986, Behavior of the group-predatory ant Proatta butteli, Insectes Soc. 33: 444–457.
6. Other ant species catch prey in a group this way, for example Myrmicaria opaciventris, which has workers that move near their trails in such numbers that they jointly seize prey ten times their length, a tactic similar to that of Proatta, but perhaps with less “sitting” or “waiting”; see A Dejean, B Schatz, M Kenne 1999, How a group foraging myrmicine ant overwhelms large prey items, Sociobiology 34: 407–418. It is unclear in these species whether the ants should be described as foraging as a “group,” in the sense that they may be constrained or guided in some way by their nestmates. That could be the case if workers clump together by actively orienting toward one another or a feature in the environment, as suggested for another species by HC Morais 1994, Coordinated group ambush: A new predatory behavior in Azteca ants, Insectes Soc. 41: 339–342. Alternatively, the ants could ignore each other but, being inactive, end up close enough together to jointly catch prey.
7. A Dejean, C Evraerts 1997, Predatory behavior in the genus Leptogenys: A comparative study, J. Insect Behav. 10: 177–191.
8. The widely spread out searches of the solitary foragers in most large ant colonies tend to result in a steadier intake of food; see D Naug, J Wenzel 2006, Constraints on foraging success due to resource ecology limit colony productivity in social insects, Behav. Ecol. Sociobiol. 60: 62–68.
9. Forget that all the workers in a raid constantly come and go; the effect would be the same if they all stayed within the swarm.
10. Sun Tzu, The Art of War, in Roots of Strategy: The Five Greatest Military Classics of All Time, ed. Thomas Raphael Phillips (Mechanicsburg, Pa.: Stackpole Books, 1985), pp. 21–63.
11. These swarm raiders are essentially all African and American, leaving the marauder ant to occupy the swarm-raider niche in Asia.
12. In a sense, what this means is that not only don’t individuals serve as scouts, but a group of workers can’t jointly serve as a scout for other raids, either. A tactic with some characteristics of mass foraging occurs in species with a trunk trail that rotates gradually at a speed that depends on food availability. See S Goss, J-L Deneubourg 1989, The self-organising clock pattern of Messor pergandei, Insectes Soc. 36: 339–346; and RA Bernstein 1975, Foraging strategies of ants in response to variable food density, Ecology 56: 213–219.
13. See, e.g., H Topoff, J Mirenda, R Droual, S Herrick 1980, Behavioural ecology of mass recruitment in the army ant Neivamyrmex nigrescens, Anim. Behav. 28: 779–789. It could also be that recruitment and exploratory signals are the same, but the pheromone is deposited at a higher concentration and thus is more attractive. Workers in some solitary-foraging species can lay exploratory trails to investigate novel terrain on their own; see, e.g., EO Wilson 1962, Chemical communication among workers of the fire ant Solenopsis saevissim, 1: The organization of mass-foraging, Anim. Behav. 10: 135–147. See also chapter 16.
14. In army ants, the existence of exploratory trails is inferred from the posture of the foragers at the front: each presses her body against the ground in a manner that suggests she is releasing