A certain species of moth, the corn earworm, attacks maize crops by laying eggs on the silks. The hatching larvae feed on the developing kernels, causing physical damage and promoting harmful mould growth. To minimize this issue, agricultural breeders aim to develop maize plants that have both a very tight husk cover, which physically prevents larval entry, and a high concentration of maysin (a natural compound in silks that stunts larval growth).
Suggest why corn earworm moths are attracted to maize plants.
Breeders cross different varieties of maize to obtain offspring with desired phenotypic characteristics. The features of three maize varieties are shown below:
| Maize variety | Phenotypic characteristic |
|---|---|
| Golden-Yield | tight husk cover |
| Sweet-Ruby | high maysin concentration in silks |
| Silver-King | deep root system |
Describe how breeders could use selective breeding to develop maize plants with both tight husk cover and high maysin concentration in silks.
Describe two differences between selective breeding (artificial selection) and natural selection.
Farmers sometimes spray chemical synthetic pyrethroid insecticides on maize crops to control these pests. Give two ecological or biological disadvantages of using these chemical treatments.
