Spatial dynamics of teak defoliator (Hyblaea puera Cramer) - Cochin ...

(b) Spatial pattern
by the initial populations which indicate that there is a
break in the sequence ofoutbreaks.
i. All the infestations occurred in discrete patches in spite of
the existence ofcontiguous infestable plantations.
ii. Not all plantations were equally infested. While some
plantations remained uninfested, some were infested up to
five times during the year.
iii. Sites with high frequency of outbreaks were clustered
together indicating that outbreak incidence is not a random
phenomenon.
This study suggests that controlling the initial populations of the
insect so as to prevent population build up leading to large scale outbreaks is a
valid proposition, since it has shown that the initial populations could
theoretically cause nearly 70% of the outbreaks that occur during the year.
This can be confirmed by controlling the initial populations and then
monitoring the entire plantations. The origin of initial populations during the
year, those during the final phase of outbreaks and a single outbreak in
between is still uncertain. Two possible explanations are (a) aggregation of
stray moths from the same locality, and (b) long-range immigration of moths.
Monitoring of defoliator outbreaks in wider geographic regions can give
indication whether long-range movement of moths causes the presently
unexplained outbreaks.
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