**2. Importation of pesticides into West Africa**

As agricultural production system moves more and more from subsistence to market – oriented large scale farming, a concomitant increase in pesticide usage arise (Sosan *et al,*

Is Pesticide Use Sustainable in Lowland Rice Intensification in West Africa? 315

the Senegal River Valley of Senegal, Mauritania, and Mali principally for vegetable production and herbicides/fertilizers for irrigated rice cultivation. Overall, we do not want to experience pest and disease resurgence as a result of high use of chemical pesticides (Figure 2). The only way we can prevent it or reduce the negative effect is to educate irrigated rice farmers on the danger ahead of the indiscriminately use of pesticides. There is high overuse of chemical

Over the decades, chemical pesticide use has posed a threat to subsistence farming in West Africa because of the well known technical drawbacks such as high cost, lack of adequate protection for the user, absence of safety warnings, excessive and wasteful use leading to environmental pollution. A case in point is the Gezira irrigation scheme in Sudan, where continuous use of pesticides against the cotton jassid, *Empoaca lybica* has led to resistance in the whitefly (*Bemisia tabaci*), cotton bollworm (*Helicoverpa armigera*), and aphids (*Aphis gossypii*). This, in turn, has led to even higher rates of pesticide application and the consequent emergence of secondary pest outbreaks due to the selective removal of natural enemies from the crop system. For instance, citrus leafminer (*Liriomyza trifolii*) is native to Asia but has been a minor pest of citrus in Africa until recent years when it is now considered as the major threat to citrus (Abete *et al.,* 2000). The picture was not different in Madagascar where *Spodoptera littoralis* became a serious pest due to over-use of chlorinated hydrocarbons including monophos-DDT against cotton pests. Pesticide overuse to control pests in other crops such as cotton, coffee, cacao, groundnuts has resulted in the development of resistance to dieldrin and DDT by two mosquito species, *Anopheles gambiae*  Giles and *Anopheles rofipes* (Gough) in the West African countries of Ivory Coast, Nigeria,

In South East Asia, Brown Planthopper (BPH), a secondary pest of rice, suddenly became a major pest due to insecticide misuse. Since 2005, outbreaks of rice BPH have occurred in

Non-target organisms are organisms that the pesticides are not intended to kill. Natural enemies include insect predators, insect parasitoids, and insect pathogens. Over 98% of sprayed insecticides reach a destination other than their target species, including non- target species. Successful biological control using five exotic parasitoids against the potato tuber moth, *Phthorimaea operculella*, both native of South America was achieved in Zimbabwe and Zambia. Unfortunately, this system has broken down due to increase in pesticide use by farmers unaware of the value of biological control, and due to the need other pests. Overuse of pesticides in Ghana to control cocoa mirids resulted in the killing of numerous non-target beneficial organisms. As a consequence, the shield bug, *Batl1ycoelia thalassina*  (HerrichSchaeffer), a secondary pest resurged and caused a yield loss of 18% of the cocoa

crop in Ghana's Eastern and Brong-Ahafo Regions (Owusu, 1971, Alfred *et al.,* 2001,).

Chemicals pollute the water body thus making it unsafe for human use e.g. drinking, washing of farm produce, etc. Many of the pesticides used are persistent soil contaminants,

fertilizers and pesticides in cotton compared to rice in West Africa.

**3. Cases of pesticide mis-use** 

Ghana, Mali, Burkina Faso, Togo, and Senegal.

**3.2 Human and animal health hazards** 

East-Asian countries such as Vietnam, China and Japan.

**3.1 Destruction of non-target organisms and natural enemies** 

2008). The climatic conditions of West Africa especially rainfed lowland ecology is conducive for build up of pest populations. Pesticide use in Africa accounts for less than 5% of global pesticide use and per hectare averages are low, estimated at around 1 kg/ha active ingredient applied (compared with 3- 7kg/ha in Latin America and Asia (PAN, 2010). However, low use volumes do not necessarily equate to low risk, particularly as some of the most toxic pesticides continue to be applied in Africa especially in West Africa, often under extremely dangerous conditions (PAN, 2010). Though, there are differences in the rate of agrochemicals application across the agroecological zones, pesticide use was high in dry savannah of West Africa (Ephraim *et al.,* 2010). Pesticide use in Africa accounts for only 2– 4% of the global pesticide market of US\$31 billion (Williamson *et al.,* 2008). Although Africa is currently neither a major consumer nor producer of chemicals in global terms, pesticides use in the African agricultural sector is likely to increase as a result of the growing commercialization as well as the growing focus of development agencies on improving yields of small farmers (Nelson *et al.,* 2006). Most African countries were net importers of pesticides. In Ghana, the number of pesticides dumped by the chemical industries was between 163 to 180 units as at 2002 (Suglo, 2002). In Kabba area of Kogi State, Nigeria, the number of pesticide users increased dramatically from 42% in 1971 to 78% in 1998 (Youm *et al.,* 1990). Importation of agrochemicals into sub-Sahara Africa increased in monetary values from \$16.1 million in 1973 to \$30 million in 1977 (Youm *et al.,* 1990). Most of the pesticides brought into West African countries have been banned. Pesticide that is banned for agricultural purposes in 52 countries due to its hazardous nature is being used in Ghanaian agriculture (Glover *et al.,* 2008). Most farmers in Africa increasingly depend on pesticides alone to control insect pest, and without satisfactory understanding of the associated hazards. Nigeria ranked first among West African countries in terms of quantities of pesticides use (Abete *et al.,* 2000). Thus, Nigeria alone accounted for nearly 93% of UK pesticide exports to West African countries. Pesticides are the main sources of pollution in

Fig. 2. Pesticide application on rice field

the Senegal River Valley of Senegal, Mauritania, and Mali principally for vegetable production and herbicides/fertilizers for irrigated rice cultivation. Overall, we do not want to experience pest and disease resurgence as a result of high use of chemical pesticides (Figure 2). The only way we can prevent it or reduce the negative effect is to educate irrigated rice farmers on the danger ahead of the indiscriminately use of pesticides. There is high overuse of chemical fertilizers and pesticides in cotton compared to rice in West Africa.
