One of the major difficulties in the biological control of insect pests is that:

The predator develops a preference to other diets and may itself become a pest
They do not always survive when transferred to a new environment
The method is less effective as compared to the use of insecticides
The practical difficulty in introducing the predator to specific area
The predator develops a preference to other diets and may itself become a pest  

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The light of cities is reduced in comparison to villages due to the presence of:
A. SO2 and SO3
B. SO2 and oxides of nitrogen
C. Hydrocarbons and N2O
D. Suspended particulate matter
Eroded soils are:
A. Rich in plant nutrients
B. Unaltered in plant nutrients
C. Devoid of plant nutrients
D. All of these
When one population is harmed and the other remains unaffected the relationship is called:
A. Amensalism
B. Predation
C. Protoco-operation
D. Parasitism
Measurement involve in forest mensuration:
A. The determination of the dimension, form, volume, age and increments of logs, single trees, stands or whole (B.C.F.T.)
B. It is art of taking measurements for compiling data. In forestry this art is applied / used for measuring the forest produce e.g. Timber, firewood, st
C. Both (a) & (b)
D. None of these
The Tharparkar Desert is situated in:
A. Tharparkar
B. Sanghar
C. Mirpur Khas
D. All of the above
The zone of atmosphere that lies near the ground is:
A. Troposphere
B. Stratosphere
C. Homosphere
D. Heterosphere
Plants growing on burnt soil are called:
A. Heliophilous
B. Hydrophilous
C. Pyrophilous
D. Pyriform

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