New Horizons in Insect Science Towards Sustainable Pest Management

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Molecular Characterization and Management of Shoot and Fruit Borer Conogethes ... 211


0.63 × 0.41 mm in size. After incubation of 6–7
days, the eggs turn dark brown with a dark head
(Bilapate 1978 ; Jarvis 1914 ; Thyagaraj 2003 ).
Then phenology of host plant influences the
size, growth, and development of eggs (Bilapate
1978 ; Jacob 1981 ; Twine 1971 ). There was a sig-
nificant difference in percent egg hatching from
65.0 ± 0.76 to 90.5 ± 1.38 and incubation period
from 4.19 ± 0.80 to 9.35 ± 1.05 days under var-
ied temperature and relative humidity (Thyaga-
raj 2003 ; Wang and Cai 1997 ). Temperature and
relative humidity play an important role in egg
hatching (Rajan 1965 ). The egg characteristics
under various temperature ranges and relative hu-
midity conditions have been extensively studied
in laboratory (Kalshoven 1929 ; Thyagaraj 2003 ).
First instar (neonate) larva bored the pseu-
dostem or capsule. On pseudostem, the larva
bored at the base of leaf axis and entered inside
the cardamom shoot tissue (Jacob 1981 ). The
excreta plugged at the entry hole on the shoot
indicated larval boring (Thyagaraj 2003 ). Larva
fed on the shoot was light greenish, while those
on capsules were dull yellow (Bilapate and Talati
1977 ; Thyagaraj 2003 ). The larva remains inside
the pseudostem till pupation. Therefore, it is dif-
ficult to study the larval instars directly. Dyar’s
law was applied to record the number of larval
instars, and there were five larval instars (Asante
1991 ; Dyar 1890 ; Thyagaraj 2003 ). Observa-
tions revealed that there was no major difference
among the instars except for head and body size.
All larval instars were active and when disturbed,
tried to fall down with a fine silken thread (Bi-
lapate and Talati 1978 ; Kondo and Miyahara
1930 ; Kodoi 1990 ; Thyagaraj 2003 ; Twine 1971 ;
Young and Shaw 1962 ).
The growth and development of different lar-
val instars varied with varying temperature and
relative humidity. Each larval instar lasted for
3–4 days. Sloan ( 1945 ) reported that, larval pe-
riod of C. punctiferalis lasted 3 weeks under nor-
mal conditions and 2–3 weeks in winters. Yang
and Shaw ( 1962 ) studied the peach borer biology
in China and reported 4–5 generations a year, the
larvae overwintering in the flowers, stem, and
fallen leaves. The duration of the larval stage
varied from 20–23 days in August–September at


21–35 °C to 22–26 days in October–January at
14–28 °C and larvae were found in the field until
February, and also the total larval period extend-
ed up to 12–14 days (Bilapate 1977 ; Jacob 1981 ;
Kondo and Miyahara 1930 ; Twine 1971 ; Wang
and Cai 1997 ; Xi et al. 1996 ). The larval period
varied from 12.55 ± 2.00 to 19.59 ± 5.50 days
and the percent survival varied from 49.6 ± 0.18
to 92.8 ± 1.39. 28.0 ± 1.0 °C and 80.0 ± 5.0 % RH
were most favorable for larval development
(Thyagaraj 2003 ).
Pupation of Conogethes took place in co-
coons inside or between the capsules, and the
pupal stage lasted for 7–10 days (Patel and
Gangrade 1971; Bilapate and Talati 1978 ; Gour
and Sriramulu 1992 ).The duration of devel-
opment varied from 27 days at 30 °C to 48–51
days at 20 °C. Pupal period took over 8 weeks
and more in winter on sorghum in Queensland
(Sloan 1945 ).According to Wu ( 1995 ) 86.5 % lar-
vae of C. punctiferalis pupated in leaf axils and
in ears of maize and 13.5 % pupated in stalks.
There is a clear difference in size, shape, and
weight of male and female pupae. Female pupae
were larger (17.81 × 6.29 mm with 0.127 gm in
weight). Male pupa measured 14.30 × 4.26 mm
with 0.108 gm in weight, shorter, slightly nar-
rower, and the genital opening was located in the
posterior region of the ninth abdominal segment
and flanked by a pair of pads. Significant differ-
ence was also noticed between the sexes in terms
of length and diameter (Thyagaraj 2003 ). Pupal
period extended up to 7.90 ± 2.80 mean days in
laboratory. There was no significant difference
in the pupal period under different temperature
regimes (20.0–38.0 ± 1.00 °C (Bilapate and Talati
1977 ; Jacob 1981 ; Mishra and Teotia 1965 ; Wang
and Cai 1997 ). There is a morphological dimor-
phism in the Conogethes pupa that helps in sex
determination.
Development and reproduction of C. punctife-
ralis were investigated at five different tempera-
tures (15, 19, 23, 27, and 31 °C) with chestnut as
food in China. The results showed that tempera-
ture had significant effects on the developmental
duration, survival rate, pupal weight, and repro-
duction. The developmental duration at every
stage reduced with increasing temperatures from
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