Studies on the biology and population dynamics of rice leaffolder, cnaphalocrocis medinalis guenee
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Date
2007
Authors
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Publisher
CCSHAU
Abstract
Population dynamics and biology of rice leaffolder were carried
out in the field, laboratory and screen-house at CCS Haryana
Agricultural University, rice research station, Kaul (Kaithal) during
Kharif 2006. The population of rice leaffolder fluctuated in different
periods during the season The maximum number of eggs, larvae and
pupae were observed during the 35th week ( i.e 4th week of August),
36th week ( i.e 1st week September) and 37th week ( i.e 2nd week of
September),respectively. Indicating that maximum population predominated
in September-October. Larval and pupal parasitism was
good during the season while egg parasitism was almost nil. Apanteles
sp. and Cotesia sp. were observed the dominating larval parasitoid.
While Brachymeria sp. and Xanthopimpla flavolineata were dominating
pupal parasitoids. A spider Lycosa sp. was observed to predate upon
larvae and pupae of leaf folder. Total eggs with rainfall and parasitoids
shows negative correlation. When total larval population correlated
with biotic and abiotic factors it shows positive correlation with
maximum temperature and sunshine hours while negative correlation
with other factors. Pupal population exhibits positive correlation with
maximum temperature, sunshine hours and predators only. The eggs
were laid singly or in clusters of two to four maximum (48.20%) on
lower surface of leaf followed by upper surface (32.95%). The
Incubation period was 5.32 ±o.02 days and hatchability ranging from
55.31-77.73 per cent. Full grown larvae measured 15.59 ± 0.24 mm in
length and 1.22 ± 0.22 mm in breadth with 1.11 ± 0.03 mm length and
1.22 ± 0.24 mm breadth in head capsule. Female pupae were longer in
length than male pupae. The leaffolder completed its post-embryonic
development in 30.34 ± 0.48 days (males) 31.16 ± 0.51 days(females)
and passed through five instars with 56.66 ± 1.70 per cent (larval
survival), 51.32 ± 0.80 (per cent pupation) and 89.60 ± 1.29 per cent
(moth emergence). The mean larval and pupal period (male and female)
was 22.10 ± 0.39 and 6.86 ± 0.06, 7.64 ± 0.09 days, respectively. Preoviposition,
oviposition and post-oviposition period were 1.7 ± 0.05, 4.5
± 0.03 and 2.4 ± .03 days, respectively. The average longevity of male
and female was 3.4 ± 0.06 and 8.7 ± .05 days, respectively. The average
fecundity was 100.6 ± 8.6 egg/female with 70.74 ± 2.7 per cent
hatching. Sex ratio showed pre pondrance of male (1:0.91).The adult
male was short lived 3.4±0.06 days as compared to female 8.7±0.05
days. The rice leaffolder passed through three generation during kharif
season.
Description
Keywords
Population dynamics, Biology, Rice leaffolder, Parasitoid, Biotic, Abiotic factors