Guild structure and seasonal distribution of insects associated with Amaranthus Hybridus under diverse cultivation practices in the Central Free State

English: Biodiversity is a non-detachable part of the concept of sustainable agriculture. The reliance on only a few crop species in the agricultural landscape poses special problems and risks due to biotic hazards. To enhance diversity, agriculture must diversify crop production and exploit under-utilized and new crops. Amaranthus hybridus is such a crop and has great potential due to its hardiness and high nutritional value. Acceptable crop yield depends on the influence of insects. Some sort of pest management thus forms an integral part of agriculture. Due to detrimental effects on the environment and the high cost of pesticides, farmers are looking for alternative low cost methods, which will provide a long-term solution for pest problems. Cultivation practices are one such method, which aim to enhance natural enemy performance. This study was conducted near the Tempe airport, 20 km northwest of Bloemfontein (SE 2926Aa) in the Free State. A monoculture trial was run in 1997 and 1998, a mixed crop setup in 1998 and a staggered planting date culture in 1999. Monoculture, the most widely used method of farming in the Free State, reduces a complex natural ecosystem to a single plant species environment, resulting in more visual and chemical stimuli for flying phytophagous species, prompting them to land more readily than in a more diverse plant environment. Thus, large populations of phytophages occur in the mono culture, some of which, due to favourable microelimate could develop to pest status. Mixed cropping is a more diverse plant system, thus presenting a greater diversity of niches and consequently a higher diversity of arboreal phytophages and natural enemies. Adjusting planting and harvesting time, such as staggered planting dates, can be used to escape pest damage and keep it below economic levels. By planting early sure pests population peaks can be avoided. The terrestrial insect community is also of major importance, since many predators are groundliving. Terrestrial insects are influenced by the microelimate and shelter provided by plants and preferred stands in which these factors are at an optimum. In this study it was found that predators are most effective in large, sparse stands. To conserve natural enemies it is important to incorporate permanent habitats like border areas where they can overwinter, build up population numbers and from which they can disperse to newly planted crops. This study promotes conservation biological control, which aims at using and enhancing beneficiais, which are already present, by using different cultivation practices. Farmers often lack the biological and ecological information necessary to develop better pest management. This study was aimed at providing that information to obtain maximum yield in the long term with lower production costs.