ECOLOGICAL IMPORTANCE OF WEED AND INSECT DIVERSITY IN WHEAT FIELDS UNDER DIFFERENT CHEMICAL INTENSIFICATION

The study was focused to collect, identify and compare the species richness and abundance of weeds and insects with respect to their ecological importance in wheat fields with low (organic) and high (conventional) inputs (LIP and HIP, respectively) in the four major zones of Punjab (Pakistan). The pesticidal effect was significant in all the four wheat crop zones in terms of their floral and faunal diversity. The LIP fields of all these systems except that of CWZ were highly diversified with respect to weeds and insects number and species richness. The weed species ranged from 5-10 in HIP fields while the number ranged from 11-18 in LIP fields. Some of the weeds such as C. iberica and C. didymus seemed to be indicated or of higher nutrient quantities of P or K in the soil. Out of 29 species of insects belonging to reportedly phytophagous families, 14 were reported to be the major (8) and minor (6) pest of wheat crop. The rest 15 species have not yet been reported as the major or minor pests of wheat crop. This meant that at least 15 or more than 50% phytophagous invertebrates are used to feed on weed plants. An aphid, Microsiphum miscanthi infested the pair fields in all zones but surprisingly their number was almost double in HIP fields but predator species were abundant in LIP fields.