Advertisements
Advertisements
प्रश्न
Organic farmers prefer biological control of diseases and pests to the use of chemicals for the same purpose. Justify.
Advertisements
उत्तर
Biocontrol means using biological methods to manage plant diseases and pests. Pathogens, pests, and weeds are the main threats to agriculture. Traditionally, they are controlled with insecticides and pesticides, but these chemicals are highly toxic and harmful to humans and animals, and they pollute the environment. Therefore, modern agriculture increasingly relies on biological methods to manage them. Different microbes are used as biocides to control microbial pathogens (such as viruses, mycoplasma, bacteria, and fungi), insect pests, nematodes, and weeds.
Examples of biocontrol agents include:
- Bacteria: Bacillus thuringiensis
- Fungi: Trichoderma
- Insects: Ladybird beetles and dragonflies
APPEARS IN
संबंधित प्रश्न
Find out what the various components of the medium used for propagation of an explant in vitro are?
Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because ______.
In the following questions/statements has four suggested answers. Rewrite the correct answer
Bt cotton is resistant to:
(A) Insects
(B) Herbicides
(C) Salt
(D) Drought
What are biofertilizers? Describe their role in agriculture. Why are they preferred to chemical fertilizers?
Answer the following question.
How is a continuous culture system maintained in bioreactors and why?
The trigger for activation of toxin of bacillus thuringlensis is ______.
Silencing of a gene could be achieved through the use of ______.
Bt cotton is resistant to pest, such as lepidopteron, dipterans and coleopterans. Is Bt cotton also resistant to other pests as well?
You have identified a useful gene in bacteria. Make a flow chart of the steps that you would follow to transfer this gene to a plant.
Insects in the Lepidopteran group lay eggs on maize crops. The larvae on hatching feed on maize leaf and tender cob. In order to arrest the spread of three such Lepidopteran pests, Bt maize crops were introduced in an experimental field.
A study was carried out to see which of the three species of lepidopteran pests was most susceptible to Bt genes and its product.
The lepidopteran pests were allowed to feed on the same Bt-maize crops grown on 5 fields (A-E).
The graph below shows the leaf area damaged by these three pests after feeding on maize leaves for five days.
Key for lepidopteran insect pest species
 |
Species I |
 |
Species II |
 |
Species III |
Insect gut pH was recorded as 10, 8 and 6 respectively for Species I, II and III respectively.
(a) Evaluate the efficacy of the Bt crop on the feeding habits of the three species of stem borer and suggest which species is least susceptible to Bt toxin.
(b) Which species is most susceptible to Bt-maize, and explain why?
(c) Using the given information, suggest why a similar effect was not seen in the three insect species.
