Criteria for Selection of Bio-agent or Qualities of Good Bio-agent for Weed Control
1) Host Specificity:
a) The bio-agent recommended for weed control should be host specific i.e. the bio-agent must feed or kill only the host plant (Weed).
b) It should not harm or feed the crops and other useful (economical) plants. Starvation test is conducted for this purpose before using the bio-agent for weed control.
2) Bio-agent Hardiness:
a) The bio-agent should be hardy and must adopt or withstand the new environment in which it is to be used.
b) It should be free from its natural enemies like predators and parasites.
c) It should be capable of surviving in a situation of food shortage for longer period.
3) Feeding Habit:
a) It must be able to kill the host or at least prevent seed production or reproduction of host plant.
b) The bio-agent should be capable of seeking the host.
c) It should be a heavy feeder and consume or cause the death of large population of host rapidly.
4) Base of Multiplication:
The bio-agent should have high rate and ease of natural reproduction to control the host plant in short time. If the natural rate of reproduction is less than more times required for control of host.
Some outstanding examples of successful biological control of weeds.