Natural selection of
strains resistant
Population density
of pest
I
I
‘13
Era
Pre-agriculture
Agriculture withoh
Agriculture with
Agriculture with
Agriculture in the future11 Use of new Desticides
pesticides
pesticides
pesticides and
three possibilities :resistonce to
pesticides
2) Integrated control
3) Exclusion of pests from enclosed
( - c 2000 BC)
(C 2000 BC- c 1945)
( C 1945-c 1960)
(C 1960- 1
artificial environments
Characteristics. NotLiral complexity
Higher populotion level
Greater fldcruations
Coincidence of
1) Continuation of shortlived ad hoc control
reduced chemical 2) Partial return to, and use of complexity
control and low
3) Increased simplification by total control
because more food ovoiloble
Greater fluctuations
predator and/or
of rhe crop environment
because environment simpler
porosite populations
because environment
simplified further
Quolitative change
in pest species
FIG. 6. Diagram illustrating the historical development of peat control and pest fluctuations.