Diversity of Heteroptera in agroecosystems: role of sustainability and bioindication

Heteroptera represent an important part of the global insect fauna in many crops, more on the basis of their numbers than biomass. From 50 to 100 species have been recorded in the most exhaustive censuses of fruit trees or low growing crops, about half of which an really important. Most Heteroptera are small in size and exhibit all food regimes from strict phytophagy to zoophagy. They are rarely host-specific but often show clear preferences for definite strata. The Miridae are usually the main family in undisturbed fauna of fruit trees and cereals, and are rather diverse in these habitats. Mirinae are particularly numerous and diverse on graminous plants but most species complexes are identical on various low-growing plants. Although maize and sunflowers do not appear to be favoured by Heteroptera, they may became attractive while in bloom. Fruit trees, especially apple, show a rich complex of species in which Deraeocorinae and Orthotylinae are well represented. Miridae are very susceptible to chemical sprays and are more easily eliminated from orchards than Anthocoridae. The influence of the environment on the recolonization of cultivated plots by these families has been shown for fruit toes (apple and pear) and some low growing crops (potatoes). Their sensitivity to ecological factors and to the secondary effects of phytosanitary sprays are features that make Heteroptera, especially Miridae, potentially good indicators of ecological change. (C)1999 Elsevier Science B.V. All rights reserved.