tailieunhanh - The Insects - Outline of Entomology 3th Edition - Chapter 12

Chapter 12 INSECT SOCIETIES The study of insect social behaviors is a popular entomological topic and there is a voluminous literature, ranging from the popular to the highly theoretical. The proliferation of some insects, notably the ants and termites, is attributed to the major change from a solitary lifestyle. | TIC12 5 20 04 4 41 PM Page 299 Chapter 12 INSECT SOCIETIES Vespid wasp nest. After Blaney 1976. TIC12 5 20 04 4 41 PM Page 300 300 Insect societies --------------------------------------------------------------------------- The study of insect social behaviors is a popular entomological topic and there is a voluminous literature ranging from the popular to the highly theoretical. The proliferation of some insects notably the ants and termites is attributed to the major change from a solitary lifestyle to a social one. Social insects are ecologically successful and have important effects on human life. Leaf-cutter ants Atta spp. are the major herbivores in the Neotropics and in south-western US deserts harvester ants take as many seeds as do mammals. Ecologically dominant tramp ants can threaten our agriculture outdoor behavior and biodiversity Box . Termites turn over at least as much soil as do earthworms in many tropical regions. The numerical dominance of social insects can be astonishing with a Japanese supercolony of Formica yessensis estimated at 306 million workers and over 1 million queens dispersed over km2 amongst 45 000 interconnected nests. In West African savanna densities of up to 20 million resident ants per hectare have been estimated and single nomadic colonies of driver ants Dorylus sp. may attain 20 million workers. Estimates of the value of honey bees in commercial honey production as well as in pollination of agricultural and horticultural crops run into many billions of dollars per annum in the USA alone. Social insects clearly affect our lives. A broad definition of social behavior could include all insects that interact in any way with other members of their species. However entomologists limit sociality to a more restricted range of co-operative behaviors. Amongst the social insects we can recognize eusocial true social insects which co-operate in reproduction and have division of reproductive effort and subsocial below social .