Host plant resistance

• Host plant resistance is defined as the intentional use of resistant crop cultivars to reduce the negative impacts of pests or diseases on crop production systems (Stout, 2014).

Mechanism of Resistance

a. Non-preference / Antixenosis:

• The adverse effect of plant characters on the behavior of insect for orientation shelter and oviposition is called antixenosis.
• Non-preference is usually due to the presence of chemical substance which deter feeding or ovipositor but it may also be due to the absence of chemical attractants or stimulants compared to susceptible plants.
• A physical or chemical property of a plant can make it so unpalatable that it is largely protected from herbivore attack. This type of resistance is often known as non-preference.
• It may involve the presence of feeding repellents (or the absence of feeding attractants), or it may involve physical traits such as hairs, waxes, or a thick, tough epidermis that do not provide the pest with a desirable feeding substrate.
• Alfalfa, for example, has hairy leaves to deter feeding by the spotted alfalfa aphid.

b. Antibiosis:

• : It is the plant characteristics which adversely affect insect behavior and biological processes (e.g. Survival, development and reproduction).
• Insects, attempt to feed the resistant plants but do not develop properly. Thus, antibiosis is due to the presence of toxic substances (mainly) and lack of essential nutrients.
• Plants produce a wide variety of defensive compounds (allelochemicals) that protect them from herbivores.
• These compounds may reduce growth, inhibit reproduction, alter physiology, delay maturation, or induce various physical or behavioral abnormalities in herbivores.

c. Tolerance:

• It is the inherent ability of plant to withstand and support normally destructive population of insect pest without subsequent loss of yield.
• Tolerance to the brown plant hopper exists in the rice ‘Triveni’ ‘Utri Rajipon’ and several wild rice because of their ‘field resistance’ in tillering vegetative plants.