|Crop Knowledge Master|
Paratrechina vaga (Forel)
Victoria L. Tenbrink, Research Associate
Arnold H. Hara, Entomologist
Beaumont Research Center
Paratrechina spp. nest under rocks, in brush, and in other precarious locations, moving the nests frequently (Holldobler and Wilson 1990). It is an opportunisitic species, thriving in cities, in the country, and in the difficult habitat of beaches (Percault 1987).
The range of P. vaga stretches from Australia, the Philippines, and New Guinea more or less continuously across the Pacific to Juan Fenandez (off the coast of Chile in South America). (Wilson & Taylor 1967). In Hawaii it recorded from the populated Islands except Lanai and Niihau (Hawaiian Terrestrial Arthropod Checklist 1992).
Damage by ants to agricultural commodities is usually indirect. Ants of the genus Paratrechina are of the so-called honey ants, which feed on honeydew (Wheeler 1910). Mealybugs, aphids, soft scales and whiteflies secrete honeydew, which attracts the ants. Ants feed on honeydew, driving away the natural enemies of aphids and scale insects. The pests multiply and inflict damage on the plants. In Hawaii this ant infests commercial tropical flower fields.
Ants are social insects. Immatures are fed and cared for throughout development, which takes place in the shelter of the nest. The caste of an adult is established during development and does not change in adulthood. Juvenile stages are usually only a small proportion of the entire life span; individual workers can live for years (Holldobler & Wilson 1990). Development is temperature dependent, being faster at warmer temperatures. There is an upper limit, however, at which damage occurs in extreme heat (Wheeler 1910).
Eggs are laid a queen in the nest where they are protected by workers. They may be fertilized or unfertilized. Eggs are tiny (0.5 mm), white or yellowish ovals (Wheeler 1910).
Young larvae are soft legless, pale grubs shaped like crook-necked squash (fat and bulbous at the bottom and narrow and curled at the head). Adult ants lick the larvae, and the saliva makes them sticky and easily transported in groups when the colony is disturbed (Wheeler 1910). Most ant species have four larval stages. The larvae are attended by adults, usually of the worker caste (Holldobler & Wilson 1990).
The pupae, as well as larvae, are often mistaken for eggs (Wheeler 1910).
Adult ants are polymorphic, i.e., having different body types. All the individuals of one body type form a social unit called a caste, which is also defined by a role in the community. Queens are usually comparatively large reproductives, laying fertile and unfertile eggs throughout their lives. Males are usually short-lived and function only in reproduction. Workers are females which tend all stages of juvenile ants, construct and maintain nests, and forage for food. Adult workers of P. vaga are wingless, with dark brown thorax and with lighter colored abdomen (Huddleston & Fluker 1968). Adults recently emerged from the pupal stage are paler (Wheeler 1910). Commonly, only individuals of the worker caste are encountered because they are the most numerous and the most likely to be found outside the nest. There is no soldier caste (Huddleston et al. 1968)
The pest status of P. vaga stems from its habit of inhabiting structures and agricultural fields.
Biological control -- Parasites
Many external and internal insect and mite parasites of ants live in ant nests. These usually stunt development in the ant. Some wasps and flies lay eggs in worker ants (Wheeler 1910).
Biological control -- Predators
The major predators of ant species are often other ant species Holldobbler & Wilson 1990). Interspecific competition occurs for ants sharing the same habitat. Birds, reptiles, amphibians, arthropods, and mammals, including humans, consume ants (Wheeler 1910).
Ground treatment with insecticides labeled for ant control can be effective in excluding ants from a field or crop. Baits, which are slow-acting so that the worker brings the poison to the colony and shares it, can eliminate colonies. Not all baits are attractive to all ant species; stale or rancid baits are also not attractive. Finding nests and treating them directly can be effective.
1992. Hawaiian Terrestrial Arthropod Checklist. Gordon M. Nishida,[ Ed.] Bishop Museum: Honolulu, Hawaii. 262 pp.
Holldobler, B. & E. O. Wilson. 1990. The Ants. The Belknap Press of Harvard University Press: Cambridge, Mass. 732 pp.
Huddleston, E. W. & S. S. Fluker. 1968. Distribution of ant species of Hawaii. Proc. Haw. Entomol. Soc. 20: 45-69.
Huddleston E. W., A. A. Laplante, S. S. Fluker. Pictorial key of the ants of Hawaii based on the worker form. Proc. Hawaiian Entomol. Soc. 20: 71-79.
Percault, G. H. 1987. The ants of Tahiti. Bulletin de la Societe Zoologiquede France. 112: 429-445.
Wheeler, W. M. 1910. Ants. Columbia University Press: New York. 663 pp.
Wilson, E. O. and R. W. Taylor. 1967. The ants of Polynesia (Hymenoptera: Formicidae). Pacific Insects Monograph 14. Bernice P. Bishop Museum Entomology Department: Honolulu. 96 pp.