Atta cephalotes

Nomenclature

Species: Atta cephalotes (Linnaeus, 1758)

Usage: valid
Vernacular name: Leaf Cutting Ant

General description

Atta cephalotes is the most widely distributed species of leaf cutting ant. It occurs from southernmost Mexico to Ecuador and Brazil, and from the Lesser Antilles as far north as Barbados (Hölldobler and Wilson 1990). An apparently disjunct population occurs in the Atlantic Coastal Forests of Brazil (Solomon 2007). The species is widely regarded as a significant pest on crops including citrus, coffee, cocoa and ornamentals (Cherrett 1986; Cherrett and Peregrine 1976). The ecological success and ubiquity of A. cephalotes is owed in large part to its broad niche tolerance with respect to both nesting habitats and diet breadth (Solomon 2007). The species has evolved to specialize in forest gaps, and consequently thrives in disturbed habitats such as farms and plantations (Cherrett and Peregrine 1976). Niche modeling suggests that the current range of A. cephalotes is limited by dispersal constraints rather than suitable habitat (Solomon 2007), and could cause significant ecological and agricultural devastation should it become introduced elsewhere (Hölldobler and Wilson 1990; Mikheyev 2008). A pest risk assessment of unprocessed Eucalyptus concluded the introduction of South American Atta species into the United States was a low probability (Kliejunas et al. 2001).

External links

AntWeb | AntWiki | EOL | BOLD

Risk statement

The species is widely regarded as a significant pest on crops including citrus, coffee, cocoa and ornamentals.

Diagnostic description

Antenna 11-segmented. Antennal club indistinct. Antennal insertions at least partly covered by frontal lobes. Antennal scrobe lacking. Antennal scapes not conspicuously short; easily extended beyond eye level. Posterolateral corners of head spinose; lacking pair of small teeth anterior to posterolateral spines. Head smooth and shiny, not covered by hexagonal microsculpture. Head of soldier appearing wooly, covered in abundant long fine overlapping hairs. Mandibles triangular. Waist 2-segmented. Petiole with a distinct and upright node. Postpetiole attached to lower surface of gaster. Dorsum of promesonotum with 2 pairs of spines or teeth. Propodeum armed with spines. First gastral tergite lacking numerous tubercles. Yellow to reddish brown.

Atta cephalotes is highly variable, both among castes of the same colony and across populations. Workers vary enormously in shape, color, sculpture and pubescence (Borgmeier 1959). The species is most readily confused with A. sexdens, but can be distinguished by the wooly hairs on the heads of major workers and the shinier integument caused by the lack of hexagonal microsculpture, and the lack of small teeth or dents on the head anterior to the posterolateral spines. The pronotal spines of A. cephalotes tend to be more curved than those of its congeners, but this is a highly variable character.

The majors of A. cephalotes are also distinguished from its two congeners native to the United States (A. mexicana and A. texana) by the presence of wooly hairs on the cephalic dorsum. The petiolar spiracles are visible from above in the two native species, but cannot be seen from above in A. cephalotes (Borgmeier 1959). Atta cephalotes is distinguished from its close relatives in the genus Acromyrmex by the presence of only three long spines on the mesosomal dorsum, and the absence of tubercles on the mesosomal and gastric dorsum. 

Look alikes

Atta sexdens, Acromyrmex octospinosus

Distribution

From Wetterer (2005):

In tropical Asia and tropical islands of the Indian and Pacific Oceans, A. gracilipes occurs throughout the moist lowlands, but is not commonly found in arid regions and sites above 1200 m elevation. In tropical Africa, it is known only from Dar es Salaam and nearby Zanzibar. In tropical Australia, A. gracilipes has been recorded primarily from moist monsoon rainforests along perennial springs and streams in the northern region and in a few towns on the north and east coasts. In the Neotropics, there are records of A. gracilipes from western Mexico.

In subtropical Asia, A. gracilipes ranges up to 26-27oN in northern India, southern China, and southern islands of Japan. I found only six records from latitudes >27o, two from exterminated urban populations (Auckland, New Zealand; Brisbane, Australia) and three from probably temporary populations (Valparaíso, Chile; Durban, South Africa; Zayul, Tibet). The sixth population, on Amami-Oshima Island, Japan, may or may not be temporary.

Anoplolepis gracilipes is not yet known from many moist lowland tropical areas where it would probably thrive, including west-central Africa and much of the Neotropics. Populations in western Mexico are prevented from expanding eastward by a central mountain range, but may be able to spread south, around the mountains, to the Caribbean, Central America, and South America. Records from arid Baja California, Mexico indicate that A. gracilipes can invade and persist in areas with arid climates, perhaps due to moderating effects of irrigation.

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