**5. Conclusion**

The need to increase rice yields for present and future generation requires that solutions to these pest problems are found that are both sustainable and adoptable in the socio-economic environment of farming communities. Why are there abundant and diverse natural enemies in West Africa rice ecosystems? The answer is simple – low use of pesticides in rice fields. The high cost of pesticides means that few farmers have access to them at present. AfricaRice has demonstrated that managing, rather than destroying, a "friendly weed" (*Paspalum scrobiculatum*) at the edge of rice fields (good sources of parasitoids - *Platygaster diplosisae* & *Aprostocetus procerae* close to the rice crop) offers African farmers free, nonchemical control of the continent's worst rice insect pest - African rice gall midge (Nwilene *et al.,* 2008b). It is significant to note that the natural enemy populations of rice pests are high and the species diverse in West African rice ecosystems. This is evident in the high levels of parasitism of the AfRGM. This may be the reason why West Africa has not suffered the insect resurgent crisis, that occur in Asian rice ecosystems, where the natural enemies of the brown planthopper, *Nilaparvata lugens* (Stål) are being killed through the misuse and inefficient application of insecticides. This provides evidence that pesticide use is less in West African rice ecosystems and that the natural enemies are being conserved. All future IPM strategies development should be designed to preserve, and possibly enhance, the existing and abundant natural enemy populations in West African rice ecosystems. Whereas the challenge in Asia is to stop farmers from overuse of pesticides, in West Africa, it is to prevent future overuse of pesticides. IPM is the only preventive approach and the way out for pest management in lowland rice ecology. In the long-term, everyone benefits from a healthier environment. This generation must rise up to the task of saving the global environment from pollution by discouraging production and importation of synthetic pesticides into West Africa. Smallholder farmers who use pesticides are often unaware of the adverse effect of pesticide applications. In implementing integrated pest management options, existing farmers' knowledge should be carefully analyzed, refined and integrated into the basket of options for them to choose from. There is a need to revisit a number of national policies related to food production and protection, in order to encourage partnership and participation in the identification, analysis, advocacy, and follow-up of plant protection issues as well as public awareness of the effect of pesticides on food and the environment.

#### **6. References**


conclusively that by adopting IPM practices farmers are able to increase the production of rice by 9 - 21%, increase revenue by 14% to 35% while at the same time significantly

The need to increase rice yields for present and future generation requires that solutions to these pest problems are found that are both sustainable and adoptable in the socio-economic environment of farming communities. Why are there abundant and diverse natural enemies in West Africa rice ecosystems? The answer is simple – low use of pesticides in rice fields. The high cost of pesticides means that few farmers have access to them at present. AfricaRice has demonstrated that managing, rather than destroying, a "friendly weed" (*Paspalum scrobiculatum*) at the edge of rice fields (good sources of parasitoids - *Platygaster diplosisae* & *Aprostocetus procerae* close to the rice crop) offers African farmers free, nonchemical control of the continent's worst rice insect pest - African rice gall midge (Nwilene *et al.,* 2008b). It is significant to note that the natural enemy populations of rice pests are high and the species diverse in West African rice ecosystems. This is evident in the high levels of parasitism of the AfRGM. This may be the reason why West Africa has not suffered the insect resurgent crisis, that occur in Asian rice ecosystems, where the natural enemies of the brown planthopper, *Nilaparvata lugens* (Stål) are being killed through the misuse and inefficient application of insecticides. This provides evidence that pesticide use is less in West African rice ecosystems and that the natural enemies are being conserved. All future IPM strategies development should be designed to preserve, and possibly enhance, the existing and abundant natural enemy populations in West African rice ecosystems. Whereas the challenge in Asia is to stop farmers from overuse of pesticides, in West Africa, it is to prevent future overuse of pesticides. IPM is the only preventive approach and the way out for pest management in lowland rice ecology. In the long-term, everyone benefits from a healthier environment. This generation must rise up to the task of saving the global environment from pollution by discouraging production and importation of synthetic pesticides into West Africa. Smallholder farmers who use pesticides are often unaware of the adverse effect of pesticide applications. In implementing integrated pest management options, existing farmers' knowledge should be carefully analyzed, refined and integrated into the basket of options for them to choose from. There is a need to revisit a number of national policies related to food production and protection, in order to encourage partnership and participation in the identification, analysis, advocacy, and follow-up of plant protection issues as well as public awareness of the effect of pesticides on food and the

Abete, T., A. V. Huis and J. K. Ampofo. 2000. Pest management strategies in traditional agriculture: An African perspective. Annual Review of Entomology 45: 631-659. Alfred G., J.V.Suglo, M. Braun. 2001. An Economic and Institutional Analysis of Current

Practice and Factors Influencing Pesticide Use. Pesticide Policy Project Publication

reducing pesticide use by up to 100% (Nacro, 2000; Youdeowei, 2001 and 2004).

**5. Conclusion** 

environment.

**6. References** 

Series No. 10. pp 1-127.


**18** 

**Transgenic Pesticidal Crops and the** 

**Environment: The Case of Bt Maize** 

Dennis Ndolo Obonyo1 and John B. Ochanda Ogola2 *1International Centre for Genetic Engineering and Biotechnology,* 

Stem borers are the most destructive field insect pests of maize (see Plate 1) in sub-Saharan Africa (SSA) (Insect Resistant Maize for Africa [IRMA], 2001; Songa et al., 2001). Important stem borer species include *Busseola fusca* Fuller (Lepidoptera: Noctuidae)*, Chilo partellus*  Swinhoe (Lepidoptera: Crambidae) and *Sesamia calamistis* Hampson (Lepidoptera:

Stem borer control approaches that have been used (with varied degrees of success) fall into four broad categories: chemical (application of insecticides); cultural (use of a range of farm practices to delay or reduce insect attack); biological (use of natural enemies of stem borers); and host plant resistance (the plant offers its own resistance to insects). The use of Bt maize (genetically modified maize expressing a δ-endotoxin from *Bacillus thuringiensis* and therefore having an in-built ability to produce pesticidal toxins) has been found to be effective in the management of stem borers in other parts of the world (Sharma & Rodomiro, 2000). However, this strategy has not been widely employed in Africa despite recent efforts to develop Bt maize suitable for different agro-ecological zones in the region (Muhammad & Underwood, 2004). Also, there is still significant debate regarding the possible risks posed by this technology (Obonyo et al., 2010). Fears

**1. Introduction** 

Noctuidae) (Overholt et al., 1994).

Plate 1. *Sesamia calamistis* larvae feeding on a maize leaf

**and Natural Enemies** 

*2University of Venda,* 

*South Africa* 

