Bionomics of Codling Moth
Effect of Photoperiod on Codling Moth
The photoperiod has been shown to influence postembryonic growth in a number
of insect species (Beck, 1980). In the codling moth is also seems to have
some influence on development (Russ, 1966). Exposure of eggs and first
larval instar larvae to short photoperiod decreases the reproductive activity
of adults (Deseo, 1973; Deseo and Saringer, 1975). A photoperiod of LD
14.75:9.25 gives the fastest growth of codling moth larvae (Setyobudi,
1989). Russ (1966) noticed that codling moth larvae, after termination
of diapause, developed faster to the pupal stage at longer photoperiods
than in complete darkness. The length of photoperiod has the most dominant
effect on the diapause induction. The critical photoperiod for 50 percent
diapause induction (CPh50) varies from 13.5 hours for a population from
Southern California (Petterson and Hamner, 1968) to 14.6 hours for a population
from Olney, Illinois (Danilevsky, 197) and 15.5 hours for a population
from Glassboro, New Jersey (Headley, 1934). It is observed that codling
moth populations from different geographic locations vary greatly in their
diapause response to day length. The photoperiod reaction harmonized the
time of occurrence of the individual stage of the life cycle with the seasonal
variation of the temperature and the time of fruiting of the apple. Fecundity
is also influenced by day length. It is well known that the egg production
of adults from overwintering larvae is considerably lower than the first
generation (Riedl, 1983). According to Deseo (1973; cited by Riedl, 1983),
females from the late summer generation also have a lower fecundity similar
to the overwintering generation. There is considerable variation in the
photoperiod response of different geographic origin. Populations in the
north respond to a longer critical photoperiod than those in the south
(Riedl and Croft, 1978).
In brief, the prevailing photoperiod in field not only affects diapause
induction and expression, but it also affects the rate of development of
the codling moth. It will be discussed more detail under the diapause response
of codling moth later in this paper.
