February 26, 2007	Monday	Safar 8, 1428

IN broad spectrum wildlife, including birds, animals, insects and soil micro organisms, plays a significant role in maintaining better health condition of crops due to its role as agro environment-friendly agent. It plays a perfectly safe role and incurs no cost unlike fertilisers which is used for better yield which also eradicates harmful insects.

This scenario is best observed in organic farming that increase species richness 30 per cent higher than the conventional farming systems. As a matter of fact, birds, insects and plants usually show an increased species richness in this sort of farming system. Therefore, the uses of organic agriculture methods are more environmentally sound than the intensive application of inorganic nutrients. This ensures increase in biota that ultimately benefits crops as a means of natural biological agents.

But due to altered agricultural landscape and practices, the need to rely on the natural biological control agents is least resorted to. Habitat loss and degradation like loss of complex landscape structures in different ecotones between farmland and other ecosystems as well as the increased use of agrochemical have been linked to the reduction in species richness in agricultural landscapes.

High tropic level taxa such as many bird species could be considered to be those affected by habitat changes at several scales because they often rely on different habitats for nesting and foraging which make them potentially useful as biological indicators. Intensification of agricultural practices has affected different bird species, predator insects and pollinators. Several studies have revealed that birds can be abundantly found on organic farms rather than on conventional farms that uses induced fertility inputs due to application of pesticides and fertilisers.

Birds and insect species found in agricultural landscape feed on weeds that grow in crops which may affect agricultural production,; these biological entities consume the bulk of the pest or harmful insects which is only possible in the organic agriculture. However, in conventional methods of farming, use of herbicides decrease weed abundance that subsequently register deleterious effects on insects and birds that depend on these plant species.

In natural cycle of prey and predation, if some insects are threatening as pest on crops, there are some that are also acting as predators on them to check their population growth. Invertebrates (insects, spiders, worms, etc.,) play an important role in the breakdown of detritus and the recycling of nutrients in the natural environment. They also form the base of the food chain and are eaten by many species. But the use of herbicides and pesticides not only do away with the pest but the useful predator species are also decreased that feed on those harmful insects.

Agricultural landscapes serve as habitat for many of the wildlife species and richness of these species is affected by areas like cropped and non-cropped, wetlands, ponds and pastures etcetera. Proper management and consideration of these areas would ensure promising preservation, restoration and beneficiary wildlife species for a better crop production, as each of these areas is associated with its own site and area specific organisms and species. The maximum role of wildlife as biological control agents is affected by the crop culture, mosaic area and the landscape heterogeneity, which accordingly affect the diversity of predatory insects, butterflies and associated birds.

It has been observed by many a farmer that in the fields mice are eradicated through the use of pesticides, but this practice would also harm the non-harmful insects that feed on harmful insects instead. This practice has one dire consequence of eliminating bird’s species like kites, hawks and crows that feed on them and control pest growth in a natural way without any side affects on the agricultural ecosystem. Within the agriculture and ecosystem food chains, there are also many birds that have established a heavily herbivorous diet. This ecosystem is greatly at stake when intensive pesticides and fertilisers are resorted to use with some dire implications for the biological diversity in the agriculture system.

Its generally accepted notion that when herbicides are not used there would be more weeds but there would also be increased density of predatory insects like beetles and spiders where the non-predatory insects and pest are least common in the organic agriculture. This enhances diversity of soil organisms like earthworms and other associated soil fauna in agriculture.

Moreover, partridges like grey partridge, black partridge, and quails besides sparrows and other birds like starlings etc. are very beneficiary to the crop yield by consuming the bulk of the harmful insects in a natural way. Partridges mostly eat seeds, leaves and insects. They eat seeds from a wide variety of plants, including many grasses and weeds, also waste grain from crops such as wheat, oats, corn, sunflower. Seeds constitute most of diet in fall and winter while in spring they eat more green leaves in spring and insects in summer. Young chicks eat mostly insects. They prefer farmlands as suitable habitat.

Moreover, insects like ladybugs, wasps and flies are found to eat on many larvae and aphids that otherwise affect the crop yield. But due to use of fertilisers and shrinkage of farmland ecosystem these insects and birds appear to be greatly affected and leaving the farmlands to the mercy of the extensive use of fertilisers and herbicides.

It is interesting to point out the cost-benefit ratio of bio-control programmes and the fertilisers application. The current annual worldwide expenditure for fertiliser nitrogen exceeds $20 billion. Biological control proves to be very successful economically, and even when the method has been less successful, it still produces a benefit-to-cost ratio of 11:1.

One study has estimated that a successful bio-control programme returns $62 in benefits for each $1.9 invested in developing and implementing the programme, i.e., a 32:1 benefit-to-cost ratio. The same study had shown that an average chemical pesticide programme only returned profits in the ratio of 13:1. Currently about $1.7 billion are spent annually in Europe on agri-environment schemes. According to a study in the Europe the external costs of agriculture were estimated at about $235 per hectare of grassland and arable, with external benefits equivalent to $22 to $65 per hectare.

In recent years, as the world's population continues to grow and agricultural production must meet the rising demand for food, agricultural expansion into forests and marginal lands, combined with over grassing and urban and industrial growth, has substantially reduced levels of biological diversity over significant areas.

A rapidly growing global human population and changing consumption patterns have stimulated the evolution of agriculture from traditional to modern, intensive systems. Nearly one-third of the world's land area is used for food production, making agriculture the largest single cause of habitat conversion on a global basis.

Nowadays due to technological development beneficial insects that are predator in nature are reared and sold in the developed countries for more output that are of more interest to biologists, agriculture, and environmental sciences. They significantly improve crop and garden yields.

Now around the world diverse of agro-environment schemes are being implemented in an attempt to reverse the decline of farmland birds and their food groups, that is, invertebrate to create foraging, breeding or over wintering habitats because the availability of food determine the birds and insects population and breeding success in an agricultural landscape at a large scale, which in turn determine the crop health, crop yield, financial return and output for the farmers through agro-environment-friendly wildlife.