‘Bt cotton will boost production in Nigeria’
What is your assessment of cotton production in Nigeria today?There are many factors militating against the prospects of cotton farming in Nigeria, one of which is pest attack. Cotton is a cash crop and commonly known as “white gold.” The cotton plant is one of the most technically demanding of all agricultural crops for an […]
What is your assessment of cotton production in Nigeria today?
There are many factors militating against the prospects of cotton farming in Nigeria, one of which is pest attack. Cotton is a cash crop and commonly known as “white gold.” The cotton plant is one of the most technically demanding of all agricultural crops for an appreciable yield. In Nigeria, cotton farmers are currently growing six improved cotton varieties, out of which three medium staple varieties belong to hirsutum (SAMCOT 8 to 10) and three to barbadense species which are long staple (SAMCOT 11 to 13). SAMCOT-8 was released in 1977; SAMCOT -9, SAMCOT-10 in 1989 and SAMCOT-11 to 13 were released in 2003 as contained in ‘Crop varieties released and registered in Nigeria’ Vol 2, 2009, National Centre for Genetics Resource and Biotechnology, Noor Plantation, Ibadan. However, medium staple varieties are mostly cultivated compared to the long staple which are of long duration and require supplementary irrigation. Besides that, pests are the major threat to both medium and long staple varieties.
What are the major pests threatening the growth of cotton varieties in Nigeria?
The most disturbing pests are sucking pests and bollworms. The sucking pests, aphids, jassids and thrips, attack the tender parts of the plants, suck the plant’s sap, make plants weak and may cause a considerable loss in yield if not controlled in time. The bollworms belonging to insect order Lepidoptera, particularly American bollworm – Helicoveraarmigera, Pink bollworm – Pectinophoragossypiela, Spotted bollworm – EariasVitella, Spiny bollworm – EariasInsulana and Leaf roller – Sylepta, derogate all attack the cotton plants at different stages of the crop. Helicoverpa and Earias start their activities when the crop is very young (about six weeks). Their feeding and breeding activities intensify as the crop enters reproductive phase when plenty of squares and bolls become available. Pectinophera appears around the blooming stage and continues to infest green boll. Leaf roller feeds on cotton leaves.
Can these pests be controlled through the use of pesticides and other agro chemicals commonly used in tackling pests in cotton production?
Here in Nigeria, only chemical control is the widely adopted practice. Farmers have to spray chemicals repeatedly at different growth stages to control these pests. Despite these repeated sprays, bollworms continue to cause yield losses to a considerable extent. Among the factors responsible for unsatisfactory control are the abuse of insecticide, spurious products and faulty applications. Another alternative modern technology to control bollworms is the use of Bt cotton which is not adopted in Nigeria up to now. I can assure you that besides curbing the menace of pests, adoption of Bt cotton will boost cotton production in Nigeria.
What is Bt Cotton?
Bt is a short form of soil bacterium Bacillus Thuringiensis, it produces cry proteins which are toxic to many species of insects. Bt cotton is a transgenic plant incorporated with the Lepidopteran specific Bt gene(s) which control bollworm that belong to the insect order Lepidoptera.
How can bollworms be affected by Bt cotton?
When the Lepidoptera insect order larvae feed on Bt plants they ingest Bt protein along with the plant tissues. If it is a susceptible, the Bt proteins get activated in the alkaline mid gut through proteolysis and the activated molecules bind themselves to specific receptors present on the mid gut membrane. Such a specific interaction between the activated Bt protein and receptor results in rupturing and causing pores in the insect gut membrane. The haemolymph carrying ions and vital nutrients leaks into the digestive track and disrupts the digestive processes. This leads to paralysis of the insect gut as a result the insect stops feeding. These sequences of events may take place within few hours. The affected larvae may die after a day or two, but since it has stopped feeding, any further damage to plants is prevented.
Apart from the bollworms, can Bt cottons resist other pests?
No! As I earlier mentioned, it only controls Lepidoptera insect order bollworms which causes a major yield loss in cotton up to about 60%. Bt cotton does not offer protection against sucking pests (Jassids, Aphids, Thrips), other non Lepidopteran pests, diseases or adverse environmental conditions like drought, cold, salinity etc. Appropriate remedial measures have to be taken against these.
Is there any precautionary measure to be taken while planting Bt cotton?
Planting non-Bt cotton as border rows to Bt cotton is currently recommended as a step towards delaying the development of resistance in bollworms to Bt protein. Such non-Bt crop is called refuge. The refuge crop could be 20% of the Bt cotton area with need based insecticide sprays for bollworms and 5% of the area without any chemical spray.
Our conventional pesticides have adverse effects on animals, humans and the environment. What are the effects of Bt cotton on human health, animals, poultry and the environment?
Unlike in the use of pesticides, the feeding of Bt cotton seed, plant parts and cake has been reported not to have any adverse, allergic or toxic effects on animals and poultry. Bt protein requires certain specific conditions for them to be active against the target insects. These include the concerned Bt has to be ingested by the susceptible larvae as it has no contact effect, the insect’s gut should be alkaline (ph-9.5 and above) and also contain a proteolysis enzyme (Trypsin) for activating the Bt protein and there should be specific receptors in the mid gut for the activated protein to bind and initiate structural and physiological changes leading to larval death.
Bt protein will not be activated in humans and higher mammals as their gut is acidic and does not have the proteolytic enzyme to activate the protoxin and also lack the required receptors for the activated Bt toxins to bind. The cotton in which Bt gene has been inserted does not have cross compatibility with outer genera of the family malvaceae. No adverse effect of Bt cotton on the environment has been reported by any of the countries where it is commercially cultivated. Similarly, Bt breaks readily in the environment; because of this Bt poses no threat to ground water.
In addition to curbing bollworms, what are the benefits of Bt cotton farming?
Bt cotton farming reduces the use of pesticides also resulting in the reduction of the cost of cultivation and hazards associated with its application on humans, animals and environment. Bt technology for control of bollworms is made available in the seed itself. Farmers just sow the Bt cotton seeds as they do with conventional seeds. The resulting plants have the inbuilt ability to produce Bt protein within their parts and defend themselves against bollworms. Thus it provides opportunities to grow cotton in areas of severe bollworm infestation. It allows eco-friendly cultivation of cotton and multiplication of beneficial insects that are parasites and predators of bollworms. Bt cotton improve in yield levels and also improves margin of profit to the farmer.
Which countries have so far adopted the technology of Bt cotton successfully and how can Nigerian farmers access it?
To start with the countries that already adopted Bt cotton, we have USA, Colombia, Mexico, Costa Rica, Argentina, Australia, China, India and here in Africa we have Burkina Faso and South Africa. For Nigeria to access the new Bt cotton technology, the government should hasten the passage of biosafety bill. Confined trials of Bt cotton should be conducted to find out if it is more suitable than the conventional varieties we are currently using before it is released for commercial cultivation. We have many agro-technology providers that can supply Nigeria with the new technology one of which is MosetoDowAgro Sciences USA.