Which factor is NOT known to induce defoliation in cotton plants?

Defoliation in cotton plants can be influenced by various environmental and biological factors. Among the options presented, beneficial insects do not induce defoliation. In fact, many beneficial insects, such as pollinators and natural pest predators, play a positive role in supporting plant health and overall crop productivity.

Light frost can induce defoliation by causing damage to the leaves and stems of the cotton plant, leading to premature leaf drop. Drought conditions can also result in defoliation as the plant may shed leaves to conserve water and maintain vital physiological processes. Mineral deficiencies, such as lack of essential nutrients like nitrogen, can affect the health of the plant and lead to leaf drop as the cotton plant attempts to manage its nutrient uptake.

On the other hand, beneficial insects contribute to a healthier ecosystem within the cotton field and help in pest management, making them unlikely to cause defoliation. Thus, while other factors listed can indeed induce defoliation, beneficial insects are typically more associated with supporting plant health rather than harming it.