Diapause induction and post-diapause development in Sesamia inferens Walker
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
The investigations on diapause induction and post-diapause development in Pink stem borer, Sesamia
inferens Walker larvae were conducted under laboratory conditions at varying temperature and
photoperiodic combinations of 10±1 and 14±1oC (10:14 h LD), 25±1oC (12:12 h LD), 30±1 and 34±1oC
(13:11 h LD). Diapause was observed at temperature and photoperiod combinations of 10±1 and 14±1oC
(10:14 h LD) and no diapause induction was recorded at 25±1oC (12:12 h LD), 30±1 and 34±1oC (13:11 h
LD). The larval period of S. inferens was longer (61.74 and 52.41 days) at 10±1 and 14±1oC. It was
significantly shorter at 25±1oC (30.11 days), 30±1oC (24.87 days) and 34±1oC (23.89 days). The minimum
larval survival (pupation) of 64.01 and 65.45 per cent was recorded at diapausing temperature. It was
significantly more at 25±1oC (86.36 %), 30±1oC (81.32 %) and 34±1oC (71.86%), respectively. Pupal period
was prolonged significantly to 12.64 : 14.12 and 10.52 : 12.04 days in males and females at diapasing
temperatures, respectively. However, it was significantly less in non-diapausing populations exposed at
25±1, 30±1 and 34±1oC (5.85-8.09 days in males and 7.24-10.23 days in females), respectively. Overall, S.
inferens had longer total development period of 81.2 : 82.68 and 69.75 : 71.23 days in males and females
individuals at both diapausing temperatures. At 25±1, 30±1 and 34±1oC, it reduces significantly to 36.5044.04
days in males and 37.89-46.18 days in females individuals. The highest population loss of 62.48 and
60.15 per cent was recorded at 10±1 and 14±1oC (10:14 h LD). Whereas, at 25±1oC (12:12 h L:D), 30±1 and
34±1oC (13:11 h LD) loss of only 6.3, 26.13 and 42.01 per cent was recorded. Morphometric parameters of
diapausing larvae revealed that it completely lacks cuticular pigmentation and had reduction in the body size
(9.98-12.03 mm) and head capsule width (0.62-0.67 mm). The non-diapause larvae had 12.88-26.95 mm
body size and 0.71-1.91 mm head capsule width. The pupal (male: 9.59-10.58 mm length and 1.65-1.92 mm
breadth; female: 11.42-12.52 mm length and 2.36-2.69 mm breadth) and adult sizes (male: 10.10-11.04 mm
length and 2.04-2.48 mm breadth; female: 13-14.41 mm length and 3.25-3.76 mm breadth) of diapause
populations were smaller and adults emerged from these populations were darker in colour than nondiapausing
(male: 11.66-12.57 mm length and 3.23-3.52 mm breadth; female: 14.95-15.55 mm length and
4.42-4.63 mm breadth of adults and for pupa male: 10.86-12.24 mm length and 2.64-3.21 mm breadth and
female: 12.76-14.66 mm length and 3.28-4.02 mm breadth) populations. About 14.6 per cent (10±1oC)
diapausing larvae exhibited additional 2 instars followed by 9.3 per cent of larvae (14±1oC). The diapause in
S. inferens significantly reduces the percentage pupation (64.01-65.45) and weights of pupae (62.98-65.41
mg of male and 128.69-133.7 mg of female), ultimately lowering the weight (34.98-37.83 mg of male and
50.4-52.70 mg of female) and reproductive performance of adults. The results clearly indicate that a
reduction in oviposition period, fecundity and egg viability in a diapausing population of S. inferens
ultimately leads to a reduction in population growth parameters. Larvae of S. inferens undergo for some
biochemical adaptations for its survival during the diapausing conditions. More amount of proteins (27.5659.81
mg/g b.wt.) and glycogen (23.82-30.26 mg/g b.wt.) were estimated at temperature exposure of 2530oC.
Lipids (10.53-12.02 mg/g b.wt.), trehalose (19.95-22.89 mg/g b.wt.) and total soluble sugars (24.9129.76
mg/g b.wt.) were significantly high in diapausing conditions. In present studies, facultative diapause
was observed at 10±1 and 14±1oC alongwith shortday exposure of (10:14 h LD), indicated that population
might be surviving during December-January under North-Indian winter and even the lower surviving
population is sufficient for its carryover.
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Citation
Manmeet Kaur (2021). Diapause induction and post-diapause development in Sesamia inferens Walker (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.