Introduction

Vegetable producers around the world heavily rely on the use of chemical pesticides to ensure pest control. Although pesticides do not directly contribute to agricultural yields, there is evidence to suggest that intensive use of pesticides has significantly increased agricultural production (Brethour and Weersink, 2001). However, pesticide use also poses risks to human health and the environment (Travisi et al., 2006). Thus, it is important to examine the trade-offs associated with the costs and benefits of pesticides under different empirical contexts.

Several studies show that there are significant social and environmental costs to pesticide use (Ajayi, 2000; Antle and Pingali, 1994; Antle and Capalbo, 1994, Rola and Pingali, 1993). Some of these studies (Rola and Pingali, 1993; Rahman, 2002) also suggest that indiscriminate pesticide use can lead to larger pest-related yield losses relative to situations where pesticides are not applied. In the absence of pest attacks, pesticide use only results in extra costs and no real benefits. Nevertheless, in the hope of combating the problem of pests, farmers frequently apply high doses and disproportionate combinations of several pesticides, contributing to a pesticide treadmill in certain areas (Shetty, 2003). Farmers in developing countries in particular continue to use pesticides at increasing rates (WRI, 1998).

Pesticides do not enhance productivity directly like other standard factors of production such as land, labour and capital. Rather, they help farmers compete against pests that would otherwise reduce agricultural output.