Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
Photo by Naved Sabir, NCIPM
Photo by Naved Sabir, NCIPM
Two-spotted spidermite
Damage Symptoms and webbing of mites in cucumber
Life cycle:
The egg of T. urticae is translucent and pearl-like. It
hatches into a nymph, which in turn develops into a
protonymph, and then a deutonymph. Depending on mite
species, temperature, host plant humidity etc the development
from egg to adult often takes one or two weeks or more. Males
not only develop faster than females, but guard and fight for
deutonymph females. The male who wins, mates with the
female soon after its emergence. Haploid males are produced
from the unfertilized eggs. Fertilized eggs produce diploid
females which survive the winter in diapause.
Spidermites can reproduce throughout the year in the
closed environment of greenhouse. The adults are
typically, pale green orange or yellow in colour, but later
generations are red in colour; the two spotted mite
hatches in 3 days at the temperature of 27 o C , into first
stage larvae having only three pair o
f legs. The larvae feed for few days and molts into
first nymphal stage which has four pair of legs. It then molts into second nymphal stage which
turns into adult. Depending upon the ambient temperature and other biotic and abiotic factors the
life cycle may vary from 6 days to 40 days. Life cycle tends to stop below 10 o C and 40 o C. Life
cycle is faster at higher temperatures and hence in greenhouses under Indian conditions the
multiplication of spidermites is alarmingly rapid. Under favourable conditions the spidermites can
complete 5-6 generations per year.
Temp. o C Duration of spidermite
life cycle
40 o C Development stopped
Spidermite eggs that have not yet hatched are impermeable to most miticides; the same is
true of larvae and nymphs that are moulting. During moulting, spidermites remain immobile
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