PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
DIAPAUSE
ARRESTED
DEVELOPMENT
DIAPAUSE IS A STATE OF ARRESTED DEVELOPMENT
It is principally an adaptation, synchronizing the life cycle of the insect
with the seasonal changes in its environment.
Insects may stop developing even though most conditions are favorable.
DIAPAUSE MAY OCCUR IN ANY STAGE OF THE LIFE CYCLE, eg egg,
larva, pupa or adult and is usually constant for a particular species:
European red mite - Egg stage
Oriental fruit moth - Larval stage
Australian plague locust - Egg stage
ENVIRONMENTAL
CONDITIONS
THERE IS A RANGE OF CONDITIONS which insects may need before a
diapause is broken, including:
TEMPERATURE
Winter eggs of the European red mite require 150-200 days at
temperatures of less than l0 o C before hatching occurs in spring, just before
the time of apple bloom, so that there is plenty food for the nymphs.
European red mite
LIGHT
In the oriental fruit moth diapause of the larva is controlled by
temperature and daily exposure to light (photoperiod).
Knowledge of the photoperiodic response, which appears to be rather
general in diapausing insects, has proved useful in rearing insects in the
laboratory and predicting pest outbreaks, etc.
Insects and allied pests - Biology 21