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

6.1. INTRODUCTION
CHAPTER VI
FIELD OBSERVATIONS ON MOTH BEHAVIOUR
This chapter summarizes the field observations made on aggregation,
mating, oviposition, and flight behaviour of the teak defoliator moth. Laboratory
studies made in the past have given information on the oviposition and
reproductive behaviour (Sudheendrakumar, 1994). However, very few studies
have been reported on the behaviour ofmoths under natural conditions.
Sudheendrakumar (1994) reported that under laboratory conditions, moths
emerged from field collected pupae attained sexual maturity within 2 days while
those from pupae reared in the laboratory took 3 days. Mating occurred
predominantly in the second half of the scotophase, between 01.00 to 05.00 h.
Duration of copulation was found to be ranging from 50-220 min. After mating,
egg-laying started within 18-24 hours and continued up to a maximum period of
11 days. The fecundity ranged from 287 to 606. Egg-laying was continuous in
most ofthe (75%) observed moths.
Relatively no information is available on the flight activity of the moth.
However, short-range migration of the moths has been postulated to explain the
observed spatial distribution of outbreaks (Nair and Sudheendrakumar, 1986).
Aggregation of newly emerged moths has also been reported ( Nair, 1988). The
fact that outbreak populations of the insect consist predominantly of a single
instar had suggested that during outbreaks, egg- laying occurs at a site on a single
day. The admixture of two instars was attributed to the difference in the
developmental time between individuals.