Orthogalumna terebrantis Wallwork

Acari: Cryptostigmata: Galumnidae

The adult mites are small, less than 1 mm long. The body outline is obovate or tear drop shaped and strongly convex, with a pair of flap-like lateral projections in the anterior half. The mites can be readily and easily identified by their shiny and dark pitchy brown to black colour and the small, beetle-like body shape and appearance.

         

It is a native of the Americas and was originally described from Uruguay (Wallwork, 1965). It was introduced in India in 1982 and is found in all the places where the water hyacinth weevils (Neochetina spp.) have established.

The mite is an exotic bioagent of water hyacinth. In the laboratory, its life cycle is completed in 25-27 days. Eggs are laid within leaf laminae and feeding by the larval and nymphal stages caused yellow linear mines on the leaves. In the laboratory, the adult longevity was 78.75 days, and each female laid an average of 58.5 eggs. Females prefer young central leaves for oviposition; O. terebrantis was also capable of reproducing parthenogenetically (Ganga Visalakshy & Jayanth, 1991).

The mite has established in all the areas where Neochetina spp. are present. It helps in speeding up the collapse of water hyacinth already infested by Neochetina spp. Its impact is more pronounced in partially shaded areas and under bridges. Production and field release techniques for the mite are similar to those of Neochetina spp.

• Ganga Visalakshy, P. N. G. and Jayanth, K. P. 1991. Studies on the life history and development of Orthogalumna terebrantis Wallwork, an exotic oribatid of Eichhornia crassipes. Entomon, 16(1): 53-57.
• Singh, S.P. 1994a. Technology for production of natural enemies. Technical Bulletin No. 4, Project Directorate of Biological Control, Bangalore, India. 221 p.
• Singh, S.P. 1994b. Fifteen years of AICRP on biological control. Technical Bulletin No. 8, Project Directorate of Biological Control, Bangalore, India. 320 p.
• Wallwork, J.A. 1965. A leaf boring galumnid mite (Acari: Cryptostigmata) from Uruguay. Acarologia, 7: 758-764.