**3.1 Summary**

In summary, the adverse ecological effects from pesticides occur at all levels of biological organization. The effects can be global or local, temporary or permanent, or short-lived (acute) or long-term (chronic). The most serious effects involve loss in production, changes in growth, development and/or behavior, altered diversity or community structure, changes in system processes (such as nutrient cycling), and losses of valuable species. These ecological losses in turn may be economically or socially important. Hence, ecological effects are of serious concern in regulating pesticides use and a variety of tests have been devised to help evaluate the potential for adverse ecological effects of pesticides. Developing an understanding of how these tests and other information can be used to prevent environmental problems caused by pesticides is the basis for ecological risk assessment research.

#### **3.2 Recommendations**

Pesticides destroy the delicate balance between species that characterize the functioning ecosystem. With pesticides now being found routinely in drinking water, on food and in the

onset of or mitigate existing pest resistance. Tank mixing pesticides is the combination of two or more pesticides with different modes of action in order to improve individual pesticide

In summary, the adverse ecological effects from pesticides occur at all levels of biological organization. The effects can be global or local, temporary or permanent, or short-lived (acute) or long-term (chronic). The most serious effects involve loss in production, changes in growth, development and/or behavior, altered diversity or community structure, changes in system processes (such as nutrient cycling), and losses of valuable species. These ecological losses in turn may be economically or socially important. Hence, ecological effects are of serious concern in regulating pesticides use and a variety of tests have been devised to help evaluate the potential for adverse ecological effects of pesticides. Developing an understanding of how these tests and other information can be used to prevent environmental problems caused by

Pesticides destroy the delicate balance between species that characterize the functioning ecosystem. With pesticides now being found routinely in drinking water, on food and in the

application results and delay the onset of or mitigate existing pest resistance.

Fig. 2.9 Impacts of pesticides on human health

pesticides is the basis for ecological risk assessment research.

**3. Summary and recommendations** 

**3.1 Summary** 

**3.2 Recommendations** 

air, we are all taking part in an experiment in pesticide exposure on a global scale, but without the benefit of an exposed control group for comparison. For that matter we are likely not be able to quantify the exact risk of these exposures. Because we cannot know for certain the consequences of the expanding pesticides use, the rational and most protective course of action is to take a precaution approach phasing out the use of the most dangerous pesticides, reducing our reliance on toxic chemicals for pest control and promoting ecologically based pest management.

The adverse effects of pesticides on humans and wildlife have resulted in research into ways of reducing pesticide use. The most important of these is the concept of integrated pest management (IPM), first introduced in 1959. This combines minimal use of the least harmful pesticides, integrated with biological and cultural methods of minimizing pest losses. It is linked with using pesticides only when threshold levels of pest attacks have been identified. There is also a move toward sustainable agriculture which aims to minimize use of pesticides and fertilizers based on a systems approach.

There has been a growing concern recently on the promotion of organic farming which emphasize on techniques such as crop rotation, green manure, compost and biological methods of pest control to maintain soil productivity. Organic farming strictly excludes the use of manufactured fertilizers, pesticides, plant growth regulators, livestock antibiotics, food additives, and genetically modified organisms. Organic foods resulting from organic farming are deemed free from pesticides and hence providing an alternative source of quality and safe food in the future. By promoting the use of organic foods means will push the farmers to opt for organic farming. Market forces are a powerful incentive to encourage famers to go organic.

Pesticides manufacturers should conduct long-term studies on ecosystem-wide impacts to demonstrate that a pesticide has no adverse effects before allowing it to be registered for use in the environment. The fact that present regulations view a pesticide as innocent until proved guilty is detrimental to the environment health. It is critical to know more about the long-term ecological effects of a pesticide before it is released to the environment. Using a combination of prior gained field experience with the existing pesticides and applying fundamental chemodynamic principles to newly developed compounds, we can now predict with some degree of accuracy the fate of new chemicals before they are even used in the environment.

## **4. References**


**8** 

*Iran* 

**Ecological Impacts of Pesticides in** 

Khalil Talebi1, Vahid Hosseininaveh1 and Mohammad Ghadamyari2 *1Department of Plant Protection, College of Agriculture and Natural Science,* 

Pesticides are essential tools in integrated pest management (IPM) programs which can have the great influence if they are used properly. However, the adverse impacts of these compounds on the environment and ecosystem should not be ignored. The ecological effects of pesticides can be discussed from different points of view. Some of the significant consequences of use of pesticides are side effects of the pesticides on non-target organisms, sub-lethal effects of the pesticides on target and non-target organisms, emergence of resistant populations and pesticide residue and their entry into the trophic network. Side effect of the pesticides is a controversial issue in pesticides applications. They kill natural enemies present in the field and ecosystem and destroy the natural equilibrium between the hosts and their natural enemies. In the absence of natural enemies, pest populations increase rapidly and makes more controlling efforts, usually pesticides, necessary. In spite of pests, pesticide resistance in natural enemies is not common due to lower exposure to pesticides. Sub-lethal deposits of pesticides can change some biological traits of the organisms exposed to low and highly low concentrations of the toxicants. Sublethal impacts of pesticides are mostly ignored in ecological pesticide assessment because most pesticide assessments are performed as individual-level bioassays and population-level of toxicants has not been considered. Insects (pests and natural enemies) exposed to sub-lethal concentrations of pesticides show some changes in their life history's traits. Resistant populations emerge due to the misuse of pesticides. The populations with high ecological potential are gradually selected generation by generation and subsequent populations are remarkably or completely insensitive to pesticides. Resistant populations are usually different from natural population in their fertility life table characteristics. Nowadays, the existence of pesticides residue in agricultural crops and their entrance into the trophic network has endangered human health and environment, and it has also necessitated the correct use of the pesticides. In the current chapter, the most significant

ecological impacts of pesticides in agricultural ecosystems have been discussed.

The concept of Integrated Pest Management (IPM) was initially defined as the combined use of natural enemies and pesticides to manage pests (Stern et a1., 1959). The IPM

**2. Impacts of pesticides on natural enemies** 

**1. Introduction** 

*2Department of Plant Protection, College of Agriculture, University of Guilan,* 

 **Agricultural Ecosystem** 

*University of Tehran,* 

